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2957 lines
98 KiB
C++
2957 lines
98 KiB
C++
// Monocypher version 4.0.2
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//
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// This file is dual-licensed. Choose whichever licence you want from
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// the two licences listed below.
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//
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// The first licence is a regular 2-clause BSD licence. The second licence
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// is the CC-0 from Creative Commons. It is intended to release Monocypher
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// to the public domain. The BSD licence serves as a fallback option.
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//
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// SPDX-License-Identifier: BSD-2-Clause OR CC0-1.0
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//
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// ------------------------------------------------------------------------
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//
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// Copyright (c) 2017-2020, Loup Vaillant
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// All rights reserved.
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//
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// 1. Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the
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// distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// ------------------------------------------------------------------------
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//
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// Written in 2017-2020 by Loup Vaillant
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//
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// To the extent possible under law, the author(s) have dedicated all copyright
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// and related neighboring rights to this software to the public domain
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// worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication along
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// with this software. If not, see
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// <https://creativecommons.org/publicdomain/zero/1.0/>
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#include "monocypher.h"
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#ifdef MONOCYPHER_CPP_NAMESPACE
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namespace MONOCYPHER_CPP_NAMESPACE {
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#endif
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/////////////////
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/// Utilities ///
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/////////////////
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#define FOR_T(type, i, start, end) for (type i = (start); i < (end); i++)
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#define FOR(i, start, end) FOR_T(size_t, i, start, end)
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#define COPY(dst, src, size) FOR(_i_, 0, size) (dst)[_i_] = (src)[_i_]
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#define ZERO(buf, size) FOR(_i_, 0, size) (buf)[_i_] = 0
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#define WIPE_CTX(ctx) crypto_wipe(ctx , sizeof(*(ctx)))
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#define WIPE_BUFFER(buffer) crypto_wipe(buffer, sizeof(buffer))
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#define MC_MIN(a, b) ((a) <= (b) ? (a) : (b))
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#define MC_MAX(a, b) ((a) >= (b) ? (a) : (b))
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typedef int8_t i8;
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typedef uint8_t u8;
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typedef int16_t i16;
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typedef uint32_t u32;
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typedef int32_t i32;
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typedef int64_t i64;
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typedef uint64_t u64;
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static const u8 zero[128] = {0};
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// returns the smallest positive integer y such that
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// (x + y) % pow_2 == 0
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// Basically, y is the "gap" missing to align x.
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// Only works when pow_2 is a power of 2.
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// Note: we use ~x+1 instead of -x to avoid compiler warnings
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static size_t gap(size_t x, size_t pow_2)
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{
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return (~x + 1) & (pow_2 - 1);
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}
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static u32 load24_le(const u8 s[3])
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{
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return
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((u32)s[0] << 0) |
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((u32)s[1] << 8) |
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((u32)s[2] << 16);
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}
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static u32 load32_le(const u8 s[4])
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{
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return
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((u32)s[0] << 0) |
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((u32)s[1] << 8) |
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((u32)s[2] << 16) |
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((u32)s[3] << 24);
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}
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static u64 load64_le(const u8 s[8])
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{
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return load32_le(s) | ((u64)load32_le(s+4) << 32);
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}
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static void store32_le(u8 out[4], u32 in)
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{
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out[0] = in & 0xff;
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out[1] = (in >> 8) & 0xff;
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out[2] = (in >> 16) & 0xff;
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out[3] = (in >> 24) & 0xff;
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}
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static void store64_le(u8 out[8], u64 in)
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{
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store32_le(out , (u32)in );
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store32_le(out + 4, in >> 32);
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}
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static void load32_le_buf (u32 *dst, const u8 *src, size_t size) {
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FOR(i, 0, size) { dst[i] = load32_le(src + i*4); }
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}
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static void load64_le_buf (u64 *dst, const u8 *src, size_t size) {
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FOR(i, 0, size) { dst[i] = load64_le(src + i*8); }
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}
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static void store32_le_buf(u8 *dst, const u32 *src, size_t size) {
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FOR(i, 0, size) { store32_le(dst + i*4, src[i]); }
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}
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static void store64_le_buf(u8 *dst, const u64 *src, size_t size) {
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FOR(i, 0, size) { store64_le(dst + i*8, src[i]); }
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}
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static u64 rotr64(u64 x, u64 n) { return (x >> n) ^ (x << (64 - n)); }
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static u32 rotl32(u32 x, u32 n) { return (x << n) ^ (x >> (32 - n)); }
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static int neq0(u64 diff)
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{
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// constant time comparison to zero
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// return diff != 0 ? -1 : 0
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u64 half = (diff >> 32) | ((u32)diff);
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return (1 & ((half - 1) >> 32)) - 1;
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}
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static u64 x16(const u8 a[16], const u8 b[16])
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{
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return (load64_le(a + 0) ^ load64_le(b + 0))
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| (load64_le(a + 8) ^ load64_le(b + 8));
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}
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static u64 x32(const u8 a[32],const u8 b[32]){return x16(a,b)| x16(a+16, b+16);}
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static u64 x64(const u8 a[64],const u8 b[64]){return x32(a,b)| x32(a+32, b+32);}
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int crypto_verify16(const u8 a[16], const u8 b[16]){ return neq0(x16(a, b)); }
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int crypto_verify32(const u8 a[32], const u8 b[32]){ return neq0(x32(a, b)); }
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int crypto_verify64(const u8 a[64], const u8 b[64]){ return neq0(x64(a, b)); }
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void crypto_wipe(void *secret, size_t size)
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{
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volatile u8 *v_secret = (u8*)secret;
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ZERO(v_secret, size);
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}
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/////////////////
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/// Chacha 20 ///
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/////////////////
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#define QUARTERROUND(a, b, c, d) \
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a += b; d = rotl32(d ^ a, 16); \
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c += d; b = rotl32(b ^ c, 12); \
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a += b; d = rotl32(d ^ a, 8); \
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c += d; b = rotl32(b ^ c, 7)
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static void chacha20_rounds(u32 out[16], const u32 in[16])
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{
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// The temporary variables make Chacha20 10% faster.
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u32 t0 = in[ 0]; u32 t1 = in[ 1]; u32 t2 = in[ 2]; u32 t3 = in[ 3];
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u32 t4 = in[ 4]; u32 t5 = in[ 5]; u32 t6 = in[ 6]; u32 t7 = in[ 7];
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u32 t8 = in[ 8]; u32 t9 = in[ 9]; u32 t10 = in[10]; u32 t11 = in[11];
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u32 t12 = in[12]; u32 t13 = in[13]; u32 t14 = in[14]; u32 t15 = in[15];
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FOR (i, 0, 10) { // 20 rounds, 2 rounds per loop.
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QUARTERROUND(t0, t4, t8 , t12); // column 0
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QUARTERROUND(t1, t5, t9 , t13); // column 1
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QUARTERROUND(t2, t6, t10, t14); // column 2
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QUARTERROUND(t3, t7, t11, t15); // column 3
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QUARTERROUND(t0, t5, t10, t15); // diagonal 0
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QUARTERROUND(t1, t6, t11, t12); // diagonal 1
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QUARTERROUND(t2, t7, t8 , t13); // diagonal 2
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QUARTERROUND(t3, t4, t9 , t14); // diagonal 3
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}
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out[ 0] = t0; out[ 1] = t1; out[ 2] = t2; out[ 3] = t3;
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out[ 4] = t4; out[ 5] = t5; out[ 6] = t6; out[ 7] = t7;
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out[ 8] = t8; out[ 9] = t9; out[10] = t10; out[11] = t11;
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out[12] = t12; out[13] = t13; out[14] = t14; out[15] = t15;
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}
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static const u8 *chacha20_constant = (const u8*)"expand 32-byte k"; // 16 bytes
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void crypto_chacha20_h(u8 out[32], const u8 key[32], const u8 in [16])
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{
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u32 block[16];
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load32_le_buf(block , chacha20_constant, 4);
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load32_le_buf(block + 4, key , 8);
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load32_le_buf(block + 12, in , 4);
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chacha20_rounds(block, block);
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// prevent reversal of the rounds by revealing only half of the buffer.
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store32_le_buf(out , block , 4); // constant
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store32_le_buf(out+16, block+12, 4); // counter and nonce
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WIPE_BUFFER(block);
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}
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u64 crypto_chacha20_djb(u8 *cipher_text, const u8 *plain_text,
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size_t text_size, const u8 key[32], const u8 nonce[8],
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u64 ctr)
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{
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u32 input[16];
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load32_le_buf(input , chacha20_constant, 4);
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load32_le_buf(input + 4, key , 8);
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load32_le_buf(input + 14, nonce , 2);
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input[12] = (u32) ctr;
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input[13] = (u32)(ctr >> 32);
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// Whole blocks
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u32 pool[16];
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size_t nb_blocks = text_size >> 6;
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FOR (i, 0, nb_blocks) {
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chacha20_rounds(pool, input);
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if (plain_text != 0) {
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FOR (j, 0, 16) {
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u32 p = pool[j] + input[j];
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store32_le(cipher_text, p ^ load32_le(plain_text));
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cipher_text += 4;
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plain_text += 4;
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}
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} else {
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FOR (j, 0, 16) {
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u32 p = pool[j] + input[j];
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store32_le(cipher_text, p);
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cipher_text += 4;
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}
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}
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input[12]++;
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if (input[12] == 0) {
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input[13]++;
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}
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}
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text_size &= 63;
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// Last (incomplete) block
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if (text_size > 0) {
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if (plain_text == 0) {
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plain_text = zero;
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}
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chacha20_rounds(pool, input);
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u8 tmp[64];
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FOR (i, 0, 16) {
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store32_le(tmp + i*4, pool[i] + input[i]);
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}
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FOR (i, 0, text_size) {
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cipher_text[i] = tmp[i] ^ plain_text[i];
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}
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WIPE_BUFFER(tmp);
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}
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ctr = input[12] + ((u64)input[13] << 32) + (text_size > 0);
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WIPE_BUFFER(pool);
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WIPE_BUFFER(input);
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return ctr;
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}
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u32 crypto_chacha20_ietf(u8 *cipher_text, const u8 *plain_text,
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size_t text_size,
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const u8 key[32], const u8 nonce[12], u32 ctr)
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{
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u64 big_ctr = ctr + ((u64)load32_le(nonce) << 32);
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return (u32)crypto_chacha20_djb(cipher_text, plain_text, text_size,
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key, nonce + 4, big_ctr);
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}
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u64 crypto_chacha20_x(u8 *cipher_text, const u8 *plain_text,
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size_t text_size,
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const u8 key[32], const u8 nonce[24], u64 ctr)
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{
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u8 sub_key[32];
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crypto_chacha20_h(sub_key, key, nonce);
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ctr = crypto_chacha20_djb(cipher_text, plain_text, text_size,
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sub_key, nonce + 16, ctr);
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WIPE_BUFFER(sub_key);
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return ctr;
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}
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/////////////////
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/// Poly 1305 ///
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/////////////////
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// h = (h + c) * r
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// preconditions:
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// ctx->h <= 4_ffffffff_ffffffff_ffffffff_ffffffff
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// ctx->r <= 0ffffffc_0ffffffc_0ffffffc_0fffffff
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// end <= 1
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// Postcondition:
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// ctx->h <= 4_ffffffff_ffffffff_ffffffff_ffffffff
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static void poly_blocks(crypto_poly1305_ctx *ctx, const u8 *in,
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size_t nb_blocks, unsigned end)
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{
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// Local all the things!
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const u32 r0 = ctx->r[0];
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const u32 r1 = ctx->r[1];
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const u32 r2 = ctx->r[2];
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const u32 r3 = ctx->r[3];
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const u32 rr0 = (r0 >> 2) * 5; // lose 2 bits...
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const u32 rr1 = (r1 >> 2) + r1; // rr1 == (r1 >> 2) * 5
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const u32 rr2 = (r2 >> 2) + r2; // rr1 == (r2 >> 2) * 5
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const u32 rr3 = (r3 >> 2) + r3; // rr1 == (r3 >> 2) * 5
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const u32 rr4 = r0 & 3; // ...recover 2 bits
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u32 h0 = ctx->h[0];
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u32 h1 = ctx->h[1];
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u32 h2 = ctx->h[2];
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u32 h3 = ctx->h[3];
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u32 h4 = ctx->h[4];
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FOR (i, 0, nb_blocks) {
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// h + c, without carry propagation
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const u64 s0 = (u64)h0 + load32_le(in); in += 4;
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const u64 s1 = (u64)h1 + load32_le(in); in += 4;
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const u64 s2 = (u64)h2 + load32_le(in); in += 4;
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const u64 s3 = (u64)h3 + load32_le(in); in += 4;
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const u32 s4 = h4 + end;
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// (h + c) * r, without carry propagation
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const u64 x0 = s0*r0+ s1*rr3+ s2*rr2+ s3*rr1+ s4*rr0;
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const u64 x1 = s0*r1+ s1*r0 + s2*rr3+ s3*rr2+ s4*rr1;
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const u64 x2 = s0*r2+ s1*r1 + s2*r0 + s3*rr3+ s4*rr2;
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const u64 x3 = s0*r3+ s1*r2 + s2*r1 + s3*r0 + s4*rr3;
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const u32 x4 = s4*rr4;
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// partial reduction modulo 2^130 - 5
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const u32 u5 = x4 + (x3 >> 32); // u5 <= 7ffffff5
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const u64 u0 = (u5 >> 2) * 5 + (x0 & 0xffffffff);
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const u64 u1 = (u0 >> 32) + (x1 & 0xffffffff) + (x0 >> 32);
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const u64 u2 = (u1 >> 32) + (x2 & 0xffffffff) + (x1 >> 32);
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const u64 u3 = (u2 >> 32) + (x3 & 0xffffffff) + (x2 >> 32);
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const u32 u4 = (u3 >> 32) + (u5 & 3); // u4 <= 4
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// Update the hash
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h0 = u0 & 0xffffffff;
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h1 = u1 & 0xffffffff;
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h2 = u2 & 0xffffffff;
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h3 = u3 & 0xffffffff;
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h4 = u4;
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}
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ctx->h[0] = h0;
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ctx->h[1] = h1;
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ctx->h[2] = h2;
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ctx->h[3] = h3;
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ctx->h[4] = h4;
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}
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void crypto_poly1305_init(crypto_poly1305_ctx *ctx, const u8 key[32])
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{
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ZERO(ctx->h, 5); // Initial hash is zero
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ctx->c_idx = 0;
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// load r and pad (r has some of its bits cleared)
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load32_le_buf(ctx->r , key , 4);
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load32_le_buf(ctx->pad, key+16, 4);
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FOR (i, 0, 1) { ctx->r[i] &= 0x0fffffff; }
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FOR (i, 1, 4) { ctx->r[i] &= 0x0ffffffc; }
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}
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void crypto_poly1305_update(crypto_poly1305_ctx *ctx,
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const u8 *message, size_t message_size)
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{
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// Avoid undefined NULL pointer increments with empty messages
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if (message_size == 0) {
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return;
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}
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// Align ourselves with block boundaries
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size_t aligned = MC_MIN(gap(ctx->c_idx, 16), message_size);
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FOR (i, 0, aligned) {
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ctx->c[ctx->c_idx] = *message;
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ctx->c_idx++;
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message++;
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message_size--;
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}
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// If block is complete, process it
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if (ctx->c_idx == 16) {
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poly_blocks(ctx, ctx->c, 1, 1);
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ctx->c_idx = 0;
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}
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// Process the message block by block
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size_t nb_blocks = message_size >> 4;
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poly_blocks(ctx, message, nb_blocks, 1);
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message += nb_blocks << 4;
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message_size &= 15;
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// remaining bytes (we never complete a block here)
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FOR (i, 0, message_size) {
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ctx->c[ctx->c_idx] = message[i];
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ctx->c_idx++;
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}
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}
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void crypto_poly1305_final(crypto_poly1305_ctx *ctx, u8 mac[16])
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{
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// Process the last block (if any)
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// We move the final 1 according to remaining input length
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// (this will add less than 2^130 to the last input block)
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if (ctx->c_idx != 0) {
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ZERO(ctx->c + ctx->c_idx, 16 - ctx->c_idx);
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ctx->c[ctx->c_idx] = 1;
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poly_blocks(ctx, ctx->c, 1, 0);
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}
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// check if we should subtract 2^130-5 by performing the
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// corresponding carry propagation.
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u64 c = 5;
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FOR (i, 0, 4) {
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c += ctx->h[i];
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c >>= 32;
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}
|
|
c += ctx->h[4];
|
|
c = (c >> 2) * 5; // shift the carry back to the beginning
|
|
// c now indicates how many times we should subtract 2^130-5 (0 or 1)
|
|
FOR (i, 0, 4) {
|
|
c += (u64)ctx->h[i] + ctx->pad[i];
|
|
store32_le(mac + i*4, (u32)c);
|
|
c = c >> 32;
|
|
}
|
|
WIPE_CTX(ctx);
|
|
}
|
|
|
|
void crypto_poly1305(u8 mac[16], const u8 *message,
|
|
size_t message_size, const u8 key[32])
|
|
{
|
|
crypto_poly1305_ctx ctx;
|
|
crypto_poly1305_init (&ctx, key);
|
|
crypto_poly1305_update(&ctx, message, message_size);
|
|
crypto_poly1305_final (&ctx, mac);
|
|
}
|
|
|
|
////////////////
|
|
/// BLAKE2 b ///
|
|
////////////////
|
|
static const u64 iv[8] = {
|
|
0x6a09e667f3bcc908, 0xbb67ae8584caa73b,
|
|
0x3c6ef372fe94f82b, 0xa54ff53a5f1d36f1,
|
|
0x510e527fade682d1, 0x9b05688c2b3e6c1f,
|
|
0x1f83d9abfb41bd6b, 0x5be0cd19137e2179,
|
|
};
|
|
|
|
static void blake2b_compress(crypto_blake2b_ctx *ctx, int is_last_block)
|
|
{
|
|
static const u8 sigma[12][16] = {
|
|
{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
|
|
{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
|
|
{ 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
|
|
{ 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
|
|
{ 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
|
|
{ 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
|
|
{ 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
|
|
{ 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
|
|
{ 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
|
|
{ 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 },
|
|
{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
|
|
{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
|
|
};
|
|
|
|
// increment input offset
|
|
u64 *x = ctx->input_offset;
|
|
size_t y = ctx->input_idx;
|
|
x[0] += y;
|
|
if (x[0] < y) {
|
|
x[1]++;
|
|
}
|
|
|
|
// init work vector
|
|
u64 v0 = ctx->hash[0]; u64 v8 = iv[0];
|
|
u64 v1 = ctx->hash[1]; u64 v9 = iv[1];
|
|
u64 v2 = ctx->hash[2]; u64 v10 = iv[2];
|
|
u64 v3 = ctx->hash[3]; u64 v11 = iv[3];
|
|
u64 v4 = ctx->hash[4]; u64 v12 = iv[4] ^ ctx->input_offset[0];
|
|
u64 v5 = ctx->hash[5]; u64 v13 = iv[5] ^ ctx->input_offset[1];
|
|
u64 v6 = ctx->hash[6]; u64 v14 = iv[6] ^ (u64)~(is_last_block - 1);
|
|
u64 v7 = ctx->hash[7]; u64 v15 = iv[7];
|
|
|
|
// mangle work vector
|
|
u64 *input = ctx->input;
|
|
#define BLAKE2_G(a, b, c, d, x, y) \
|
|
a += b + x; d = rotr64(d ^ a, 32); \
|
|
c += d; b = rotr64(b ^ c, 24); \
|
|
a += b + y; d = rotr64(d ^ a, 16); \
|
|
c += d; b = rotr64(b ^ c, 63)
|
|
#define BLAKE2_ROUND(i) \
|
|
BLAKE2_G(v0, v4, v8 , v12, input[sigma[i][ 0]], input[sigma[i][ 1]]); \
|
|
BLAKE2_G(v1, v5, v9 , v13, input[sigma[i][ 2]], input[sigma[i][ 3]]); \
|
|
BLAKE2_G(v2, v6, v10, v14, input[sigma[i][ 4]], input[sigma[i][ 5]]); \
|
|
BLAKE2_G(v3, v7, v11, v15, input[sigma[i][ 6]], input[sigma[i][ 7]]); \
|
|
BLAKE2_G(v0, v5, v10, v15, input[sigma[i][ 8]], input[sigma[i][ 9]]); \
|
|
BLAKE2_G(v1, v6, v11, v12, input[sigma[i][10]], input[sigma[i][11]]); \
|
|
BLAKE2_G(v2, v7, v8 , v13, input[sigma[i][12]], input[sigma[i][13]]); \
|
|
BLAKE2_G(v3, v4, v9 , v14, input[sigma[i][14]], input[sigma[i][15]])
|
|
|
|
#ifdef BLAKE2_NO_UNROLLING
|
|
FOR (i, 0, 12) {
|
|
BLAKE2_ROUND(i);
|
|
}
|
|
#else
|
|
BLAKE2_ROUND(0); BLAKE2_ROUND(1); BLAKE2_ROUND(2); BLAKE2_ROUND(3);
|
|
BLAKE2_ROUND(4); BLAKE2_ROUND(5); BLAKE2_ROUND(6); BLAKE2_ROUND(7);
|
|
BLAKE2_ROUND(8); BLAKE2_ROUND(9); BLAKE2_ROUND(10); BLAKE2_ROUND(11);
|
|
#endif
|
|
|
|
// update hash
|
|
ctx->hash[0] ^= v0 ^ v8; ctx->hash[1] ^= v1 ^ v9;
|
|
ctx->hash[2] ^= v2 ^ v10; ctx->hash[3] ^= v3 ^ v11;
|
|
ctx->hash[4] ^= v4 ^ v12; ctx->hash[5] ^= v5 ^ v13;
|
|
ctx->hash[6] ^= v6 ^ v14; ctx->hash[7] ^= v7 ^ v15;
|
|
}
|
|
|
|
void crypto_blake2b_keyed_init(crypto_blake2b_ctx *ctx, size_t hash_size,
|
|
const u8 *key, size_t key_size)
|
|
{
|
|
// initial hash
|
|
COPY(ctx->hash, iv, 8);
|
|
ctx->hash[0] ^= 0x01010000 ^ (key_size << 8) ^ hash_size;
|
|
|
|
ctx->input_offset[0] = 0; // beginning of the input, no offset
|
|
ctx->input_offset[1] = 0; // beginning of the input, no offset
|
|
ctx->hash_size = hash_size;
|
|
ctx->input_idx = 0;
|
|
ZERO(ctx->input, 16);
|
|
|
|
// if there is a key, the first block is that key (padded with zeroes)
|
|
if (key_size > 0) {
|
|
u8 key_block[128] = {0};
|
|
COPY(key_block, key, key_size);
|
|
// same as calling crypto_blake2b_update(ctx, key_block , 128)
|
|
load64_le_buf(ctx->input, key_block, 16);
|
|
ctx->input_idx = 128;
|
|
}
|
|
}
|
|
|
|
void crypto_blake2b_init(crypto_blake2b_ctx *ctx, size_t hash_size)
|
|
{
|
|
crypto_blake2b_keyed_init(ctx, hash_size, 0, 0);
|
|
}
|
|
|
|
void crypto_blake2b_update(crypto_blake2b_ctx *ctx,
|
|
const u8 *message, size_t message_size)
|
|
{
|
|
// Avoid undefined NULL pointer increments with empty messages
|
|
if (message_size == 0) {
|
|
return;
|
|
}
|
|
|
|
// Align with word boundaries
|
|
if ((ctx->input_idx & 7) != 0) {
|
|
size_t nb_bytes = MC_MIN(gap(ctx->input_idx, 8), message_size);
|
|
size_t word = ctx->input_idx >> 3;
|
|
size_t byte = ctx->input_idx & 7;
|
|
FOR (i, 0, nb_bytes) {
|
|
ctx->input[word] |= (u64)message[i] << ((byte + i) << 3);
|
|
}
|
|
ctx->input_idx += nb_bytes;
|
|
message += nb_bytes;
|
|
message_size -= nb_bytes;
|
|
}
|
|
|
|
// Align with block boundaries (faster than byte by byte)
|
|
if ((ctx->input_idx & 127) != 0) {
|
|
size_t nb_words = MC_MIN(gap(ctx->input_idx, 128), message_size) >> 3;
|
|
load64_le_buf(ctx->input + (ctx->input_idx >> 3), message, nb_words);
|
|
ctx->input_idx += nb_words << 3;
|
|
message += nb_words << 3;
|
|
message_size -= nb_words << 3;
|
|
}
|
|
|
|
// Process block by block
|
|
size_t nb_blocks = message_size >> 7;
|
|
FOR (i, 0, nb_blocks) {
|
|
if (ctx->input_idx == 128) {
|
|
blake2b_compress(ctx, 0);
|
|
}
|
|
load64_le_buf(ctx->input, message, 16);
|
|
message += 128;
|
|
ctx->input_idx = 128;
|
|
}
|
|
message_size &= 127;
|
|
|
|
if (message_size != 0) {
|
|
// Compress block & flush input buffer as needed
|
|
if (ctx->input_idx == 128) {
|
|
blake2b_compress(ctx, 0);
|
|
ctx->input_idx = 0;
|
|
}
|
|
if (ctx->input_idx == 0) {
|
|
ZERO(ctx->input, 16);
|
|
}
|
|
// Fill remaining words (faster than byte by byte)
|
|
size_t nb_words = message_size >> 3;
|
|
load64_le_buf(ctx->input, message, nb_words);
|
|
ctx->input_idx += nb_words << 3;
|
|
message += nb_words << 3;
|
|
message_size -= nb_words << 3;
|
|
|
|
// Fill remaining bytes
|
|
FOR (i, 0, message_size) {
|
|
size_t word = ctx->input_idx >> 3;
|
|
size_t byte = ctx->input_idx & 7;
|
|
ctx->input[word] |= (u64)message[i] << (byte << 3);
|
|
ctx->input_idx++;
|
|
}
|
|
}
|
|
}
|
|
|
|
void crypto_blake2b_final(crypto_blake2b_ctx *ctx, u8 *hash)
|
|
{
|
|
blake2b_compress(ctx, 1); // compress the last block
|
|
size_t hash_size = MC_MIN(ctx->hash_size, 64);
|
|
size_t nb_words = hash_size >> 3;
|
|
store64_le_buf(hash, ctx->hash, nb_words);
|
|
FOR (i, nb_words << 3, hash_size) {
|
|
hash[i] = (ctx->hash[i >> 3] >> (8 * (i & 7))) & 0xff;
|
|
}
|
|
WIPE_CTX(ctx);
|
|
}
|
|
|
|
void crypto_blake2b_keyed(u8 *hash, size_t hash_size,
|
|
const u8 *key, size_t key_size,
|
|
const u8 *message, size_t message_size)
|
|
{
|
|
crypto_blake2b_ctx ctx;
|
|
crypto_blake2b_keyed_init(&ctx, hash_size, key, key_size);
|
|
crypto_blake2b_update (&ctx, message, message_size);
|
|
crypto_blake2b_final (&ctx, hash);
|
|
}
|
|
|
|
void crypto_blake2b(u8 *hash, size_t hash_size, const u8 *msg, size_t msg_size)
|
|
{
|
|
crypto_blake2b_keyed(hash, hash_size, 0, 0, msg, msg_size);
|
|
}
|
|
|
|
//////////////
|
|
/// Argon2 ///
|
|
//////////////
|
|
// references to R, Z, Q etc. come from the spec
|
|
|
|
// Argon2 operates on 1024 byte blocks.
|
|
typedef struct { u64 a[128]; } blk;
|
|
|
|
// updates a BLAKE2 hash with a 32 bit word, little endian.
|
|
static void blake_update_32(crypto_blake2b_ctx *ctx, u32 input)
|
|
{
|
|
u8 buf[4];
|
|
store32_le(buf, input);
|
|
crypto_blake2b_update(ctx, buf, 4);
|
|
WIPE_BUFFER(buf);
|
|
}
|
|
|
|
static void blake_update_32_buf(crypto_blake2b_ctx *ctx,
|
|
const u8 *buf, u32 size)
|
|
{
|
|
blake_update_32(ctx, size);
|
|
crypto_blake2b_update(ctx, buf, size);
|
|
}
|
|
|
|
|
|
static void copy_block(blk *o,const blk*in){FOR(i, 0, 128) o->a[i] = in->a[i];}
|
|
static void xor_block(blk *o,const blk*in){FOR(i, 0, 128) o->a[i] ^= in->a[i];}
|
|
|
|
// Hash with a virtually unlimited digest size.
|
|
// Doesn't extract more entropy than the base hash function.
|
|
// Mainly used for filling a whole kilobyte block with pseudo-random bytes.
|
|
// (One could use a stream cipher with a seed hash as the key, but
|
|
// this would introduce another dependency —and point of failure.)
|
|
static void extended_hash(u8 *digest, u32 digest_size,
|
|
const u8 *input , u32 input_size)
|
|
{
|
|
crypto_blake2b_ctx ctx;
|
|
crypto_blake2b_init (&ctx, MC_MIN(digest_size, 64));
|
|
blake_update_32 (&ctx, digest_size);
|
|
crypto_blake2b_update(&ctx, input, input_size);
|
|
crypto_blake2b_final (&ctx, digest);
|
|
|
|
if (digest_size > 64) {
|
|
// the conversion to u64 avoids integer overflow on
|
|
// ludicrously big hash sizes.
|
|
u32 r = (u32)(((u64)digest_size + 31) >> 5) - 2;
|
|
u32 i = 1;
|
|
u32 in = 0;
|
|
u32 out = 32;
|
|
while (i < r) {
|
|
// Input and output overlap. This is intentional
|
|
crypto_blake2b(digest + out, 64, digest + in, 64);
|
|
i += 1;
|
|
in += 32;
|
|
out += 32;
|
|
}
|
|
crypto_blake2b(digest + out, digest_size - (32 * r), digest + in , 64);
|
|
}
|
|
}
|
|
|
|
#define LSB(x) ((u64)(u32)x)
|
|
#define G(a, b, c, d) \
|
|
a += b + ((LSB(a) * LSB(b)) << 1); d ^= a; d = rotr64(d, 32); \
|
|
c += d + ((LSB(c) * LSB(d)) << 1); b ^= c; b = rotr64(b, 24); \
|
|
a += b + ((LSB(a) * LSB(b)) << 1); d ^= a; d = rotr64(d, 16); \
|
|
c += d + ((LSB(c) * LSB(d)) << 1); b ^= c; b = rotr64(b, 63)
|
|
#define ROUND(v0, v1, v2, v3, v4, v5, v6, v7, \
|
|
v8, v9, v10, v11, v12, v13, v14, v15) \
|
|
G(v0, v4, v8, v12); G(v1, v5, v9, v13); \
|
|
G(v2, v6, v10, v14); G(v3, v7, v11, v15); \
|
|
G(v0, v5, v10, v15); G(v1, v6, v11, v12); \
|
|
G(v2, v7, v8, v13); G(v3, v4, v9, v14)
|
|
|
|
// Core of the compression function G. Computes Z from R in place.
|
|
static void g_rounds(blk *b)
|
|
{
|
|
// column rounds (work_block = Q)
|
|
for (int i = 0; i < 128; i += 16) {
|
|
ROUND(b->a[i ], b->a[i+ 1], b->a[i+ 2], b->a[i+ 3],
|
|
b->a[i+ 4], b->a[i+ 5], b->a[i+ 6], b->a[i+ 7],
|
|
b->a[i+ 8], b->a[i+ 9], b->a[i+10], b->a[i+11],
|
|
b->a[i+12], b->a[i+13], b->a[i+14], b->a[i+15]);
|
|
}
|
|
// row rounds (b = Z)
|
|
for (int i = 0; i < 16; i += 2) {
|
|
ROUND(b->a[i ], b->a[i+ 1], b->a[i+ 16], b->a[i+ 17],
|
|
b->a[i+32], b->a[i+33], b->a[i+ 48], b->a[i+ 49],
|
|
b->a[i+64], b->a[i+65], b->a[i+ 80], b->a[i+ 81],
|
|
b->a[i+96], b->a[i+97], b->a[i+112], b->a[i+113]);
|
|
}
|
|
}
|
|
|
|
const crypto_argon2_extras crypto_argon2_no_extras = { 0, 0, 0, 0 };
|
|
|
|
void crypto_argon2(u8 *hash, u32 hash_size, void *work_area,
|
|
crypto_argon2_config config,
|
|
crypto_argon2_inputs inputs,
|
|
crypto_argon2_extras extras)
|
|
{
|
|
const u32 segment_size = config.nb_blocks / config.nb_lanes / 4;
|
|
const u32 lane_size = segment_size * 4;
|
|
const u32 nb_blocks = lane_size * config.nb_lanes; // rounding down
|
|
|
|
// work area seen as blocks (must be suitably aligned)
|
|
blk *blocks = (blk*)work_area;
|
|
{
|
|
u8 initial_hash[72]; // 64 bytes plus 2 words for future hashes
|
|
crypto_blake2b_ctx ctx;
|
|
crypto_blake2b_init (&ctx, 64);
|
|
blake_update_32 (&ctx, config.nb_lanes ); // p: number of "threads"
|
|
blake_update_32 (&ctx, hash_size);
|
|
blake_update_32 (&ctx, config.nb_blocks);
|
|
blake_update_32 (&ctx, config.nb_passes);
|
|
blake_update_32 (&ctx, 0x13); // v: version number
|
|
blake_update_32 (&ctx, config.algorithm); // y: Argon2i, Argon2d...
|
|
blake_update_32_buf (&ctx, inputs.pass, inputs.pass_size);
|
|
blake_update_32_buf (&ctx, inputs.salt, inputs.salt_size);
|
|
blake_update_32_buf (&ctx, extras.key, extras.key_size);
|
|
blake_update_32_buf (&ctx, extras.ad, extras.ad_size);
|
|
crypto_blake2b_final(&ctx, initial_hash); // fill 64 first bytes only
|
|
|
|
// fill first 2 blocks of each lane
|
|
u8 hash_area[1024];
|
|
FOR_T(u32, l, 0, config.nb_lanes) {
|
|
FOR_T(u32, i, 0, 2) {
|
|
store32_le(initial_hash + 64, i); // first additional word
|
|
store32_le(initial_hash + 68, l); // second additional word
|
|
extended_hash(hash_area, 1024, initial_hash, 72);
|
|
load64_le_buf(blocks[l * lane_size + i].a, hash_area, 128);
|
|
}
|
|
}
|
|
|
|
WIPE_BUFFER(initial_hash);
|
|
WIPE_BUFFER(hash_area);
|
|
}
|
|
|
|
// Argon2i and Argon2id start with constant time indexing
|
|
int constant_time = config.algorithm != CRYPTO_ARGON2_D;
|
|
|
|
// Fill (and re-fill) the rest of the blocks
|
|
//
|
|
// Note: even though each segment within the same slice can be
|
|
// computed in parallel, (one thread per lane), we are computing
|
|
// them sequentially, because Monocypher doesn't support threads.
|
|
//
|
|
// Yet optimal performance (and therefore security) requires one
|
|
// thread per lane. The only reason Monocypher supports multiple
|
|
// lanes is compatibility.
|
|
blk tmp;
|
|
FOR_T(u32, pass, 0, config.nb_passes) {
|
|
FOR_T(u32, slice, 0, 4) {
|
|
// On the first slice of the first pass,
|
|
// blocks 0 and 1 are already filled, hence pass_offset.
|
|
u32 pass_offset = pass == 0 && slice == 0 ? 2 : 0;
|
|
u32 slice_offset = slice * segment_size;
|
|
|
|
// Argon2id switches back to non-constant time indexing
|
|
// after the first two slices of the first pass
|
|
if (slice == 2 && config.algorithm == CRYPTO_ARGON2_ID) {
|
|
constant_time = 0;
|
|
}
|
|
|
|
// Each iteration of the following loop may be performed in
|
|
// a separate thread. All segments must be fully completed
|
|
// before we start filling the next slice.
|
|
FOR_T(u32, segment, 0, config.nb_lanes) {
|
|
blk index_block;
|
|
u32 index_ctr = 1;
|
|
FOR_T (u32, block, pass_offset, segment_size) {
|
|
// Current and previous blocks
|
|
u32 lane_offset = segment * lane_size;
|
|
blk *segment_start = blocks + lane_offset + slice_offset;
|
|
blk *current = segment_start + block;
|
|
blk *previous =
|
|
block == 0 && slice_offset == 0
|
|
? segment_start + lane_size - 1
|
|
: segment_start + block - 1;
|
|
|
|
u64 index_seed;
|
|
if (constant_time) {
|
|
if (block == pass_offset || (block % 128) == 0) {
|
|
// Fill or refresh deterministic indices block
|
|
|
|
// seed the beginning of the block...
|
|
ZERO(index_block.a, 128);
|
|
index_block.a[0] = pass;
|
|
index_block.a[1] = segment;
|
|
index_block.a[2] = slice;
|
|
index_block.a[3] = nb_blocks;
|
|
index_block.a[4] = config.nb_passes;
|
|
index_block.a[5] = config.algorithm;
|
|
index_block.a[6] = index_ctr;
|
|
index_ctr++;
|
|
|
|
// ... then shuffle it
|
|
copy_block(&tmp, &index_block);
|
|
g_rounds (&index_block);
|
|
xor_block (&index_block, &tmp);
|
|
copy_block(&tmp, &index_block);
|
|
g_rounds (&index_block);
|
|
xor_block (&index_block, &tmp);
|
|
}
|
|
index_seed = index_block.a[block % 128];
|
|
} else {
|
|
index_seed = previous->a[0];
|
|
}
|
|
|
|
// Establish the reference set. *Approximately* comprises:
|
|
// - The last 3 slices (if they exist yet)
|
|
// - The already constructed blocks in the current segment
|
|
u32 next_slice = ((slice + 1) % 4) * segment_size;
|
|
u32 window_start = pass == 0 ? 0 : next_slice;
|
|
u32 nb_segments = pass == 0 ? slice : 3;
|
|
u64 lane =
|
|
pass == 0 && slice == 0
|
|
? segment
|
|
: (index_seed >> 32) % config.nb_lanes;
|
|
u32 window_size =
|
|
nb_segments * segment_size +
|
|
(lane == segment ? block-1 :
|
|
block == 0 ? (u32)-1 : 0);
|
|
|
|
// Find reference block
|
|
u64 j1 = index_seed & 0xffffffff; // block selector
|
|
u64 x = (j1 * j1) >> 32;
|
|
u64 y = (window_size * x) >> 32;
|
|
u64 z = (window_size - 1) - y;
|
|
u64 ref = (window_start + z) % lane_size;
|
|
u32 index = lane * lane_size + (u32)ref;
|
|
blk *reference = blocks + index;
|
|
|
|
// Shuffle the previous & reference block
|
|
// into the current block
|
|
copy_block(&tmp, previous);
|
|
xor_block (&tmp, reference);
|
|
if (pass == 0) { copy_block(current, &tmp); }
|
|
else { xor_block (current, &tmp); }
|
|
g_rounds (&tmp);
|
|
xor_block (current, &tmp);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Wipe temporary block
|
|
volatile u64* p = tmp.a;
|
|
ZERO(p, 128);
|
|
|
|
// XOR last blocks of each lane
|
|
blk *last_block = blocks + lane_size - 1;
|
|
FOR_T (u32, lane, 1, config.nb_lanes) {
|
|
blk *next_block = last_block + lane_size;
|
|
xor_block(next_block, last_block);
|
|
last_block = next_block;
|
|
}
|
|
|
|
// Serialize last block
|
|
u8 final_block[1024];
|
|
store64_le_buf(final_block, last_block->a, 128);
|
|
|
|
// Wipe work area
|
|
p = (u64*)work_area;
|
|
ZERO(p, 128 * nb_blocks);
|
|
|
|
// Hash the very last block with H' into the output hash
|
|
extended_hash(hash, hash_size, final_block, 1024);
|
|
WIPE_BUFFER(final_block);
|
|
}
|
|
|
|
////////////////////////////////////
|
|
/// Arithmetic modulo 2^255 - 19 ///
|
|
////////////////////////////////////
|
|
// Originally taken from SUPERCOP's ref10 implementation.
|
|
// A bit bigger than TweetNaCl, over 4 times faster.
|
|
|
|
// field element
|
|
typedef i32 fe[10];
|
|
|
|
// field constants
|
|
//
|
|
// fe_one : 1
|
|
// sqrtm1 : sqrt(-1)
|
|
// d : -121665 / 121666
|
|
// D2 : 2 * -121665 / 121666
|
|
// lop_x, lop_y: low order point in Edwards coordinates
|
|
// ufactor : -sqrt(-1) * 2
|
|
// A2 : 486662^2 (A squared)
|
|
static const fe fe_one = {1};
|
|
static const fe sqrtm1 = {
|
|
-32595792, -7943725, 9377950, 3500415, 12389472,
|
|
-272473, -25146209, -2005654, 326686, 11406482,
|
|
};
|
|
static const fe d = {
|
|
-10913610, 13857413, -15372611, 6949391, 114729,
|
|
-8787816, -6275908, -3247719, -18696448, -12055116,
|
|
};
|
|
static const fe D2 = {
|
|
-21827239, -5839606, -30745221, 13898782, 229458,
|
|
15978800, -12551817, -6495438, 29715968, 9444199,
|
|
};
|
|
static const fe lop_x = {
|
|
21352778, 5345713, 4660180, -8347857, 24143090,
|
|
14568123, 30185756, -12247770, -33528939, 8345319,
|
|
};
|
|
static const fe lop_y = {
|
|
-6952922, -1265500, 6862341, -7057498, -4037696,
|
|
-5447722, 31680899, -15325402, -19365852, 1569102,
|
|
};
|
|
static const fe ufactor = {
|
|
-1917299, 15887451, -18755900, -7000830, -24778944,
|
|
544946, -16816446, 4011309, -653372, 10741468,
|
|
};
|
|
static const fe A2 = {
|
|
12721188, 3529, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
};
|
|
|
|
static void fe_0(fe h) { ZERO(h , 10); }
|
|
static void fe_1(fe h) { h[0] = 1; ZERO(h+1, 9); }
|
|
|
|
static void fe_copy(fe h,const fe f ){FOR(i,0,10) h[i] = f[i]; }
|
|
static void fe_neg (fe h,const fe f ){FOR(i,0,10) h[i] = -f[i]; }
|
|
static void fe_add (fe h,const fe f,const fe g){FOR(i,0,10) h[i] = f[i] + g[i];}
|
|
static void fe_sub (fe h,const fe f,const fe g){FOR(i,0,10) h[i] = f[i] - g[i];}
|
|
|
|
static void fe_cswap(fe f, fe g, int b)
|
|
{
|
|
i32 mask = -b; // -1 = 0xffffffff
|
|
FOR (i, 0, 10) {
|
|
i32 x = (f[i] ^ g[i]) & mask;
|
|
f[i] = f[i] ^ x;
|
|
g[i] = g[i] ^ x;
|
|
}
|
|
}
|
|
|
|
static void fe_ccopy(fe f, const fe g, int b)
|
|
{
|
|
i32 mask = -b; // -1 = 0xffffffff
|
|
FOR (i, 0, 10) {
|
|
i32 x = (f[i] ^ g[i]) & mask;
|
|
f[i] = f[i] ^ x;
|
|
}
|
|
}
|
|
|
|
|
|
// Signed carry propagation
|
|
// ------------------------
|
|
//
|
|
// Let t be a number. It can be uniquely decomposed thus:
|
|
//
|
|
// t = h*2^26 + l
|
|
// such that -2^25 <= l < 2^25
|
|
//
|
|
// Let c = (t + 2^25) / 2^26 (rounded down)
|
|
// c = (h*2^26 + l + 2^25) / 2^26 (rounded down)
|
|
// c = h + (l + 2^25) / 2^26 (rounded down)
|
|
// c = h (exactly)
|
|
// Because 0 <= l + 2^25 < 2^26
|
|
//
|
|
// Let u = t - c*2^26
|
|
// u = h*2^26 + l - h*2^26
|
|
// u = l
|
|
// Therefore, -2^25 <= u < 2^25
|
|
//
|
|
// Additionally, if |t| < x, then |h| < x/2^26 (rounded down)
|
|
//
|
|
// Notations:
|
|
// - In C, 1<<25 means 2^25.
|
|
// - In C, x>>25 means floor(x / (2^25)).
|
|
// - All of the above applies with 25 & 24 as well as 26 & 25.
|
|
//
|
|
//
|
|
// Note on negative right shifts
|
|
// -----------------------------
|
|
//
|
|
// In C, x >> n, where x is a negative integer, is implementation
|
|
// defined. In practice, all platforms do arithmetic shift, which is
|
|
// equivalent to division by 2^26, rounded down. Some compilers, like
|
|
// GCC, even guarantee it.
|
|
//
|
|
// If we ever stumble upon a platform that does not propagate the sign
|
|
// bit (we won't), visible failures will show at the slightest test, and
|
|
// the signed shifts can be replaced by the following:
|
|
//
|
|
// typedef struct { i64 x:39; } s25;
|
|
// typedef struct { i64 x:38; } s26;
|
|
// i64 shift25(i64 x) { s25 s; s.x = ((u64)x)>>25; return s.x; }
|
|
// i64 shift26(i64 x) { s26 s; s.x = ((u64)x)>>26; return s.x; }
|
|
//
|
|
// Current compilers cannot optimise this, causing a 30% drop in
|
|
// performance. Fairly expensive for something that never happens.
|
|
//
|
|
//
|
|
// Precondition
|
|
// ------------
|
|
//
|
|
// |t0| < 2^63
|
|
// |t1|..|t9| < 2^62
|
|
//
|
|
// Algorithm
|
|
// ---------
|
|
// c = t0 + 2^25 / 2^26 -- |c| <= 2^36
|
|
// t0 -= c * 2^26 -- |t0| <= 2^25
|
|
// t1 += c -- |t1| <= 2^63
|
|
//
|
|
// c = t4 + 2^25 / 2^26 -- |c| <= 2^36
|
|
// t4 -= c * 2^26 -- |t4| <= 2^25
|
|
// t5 += c -- |t5| <= 2^63
|
|
//
|
|
// c = t1 + 2^24 / 2^25 -- |c| <= 2^38
|
|
// t1 -= c * 2^25 -- |t1| <= 2^24
|
|
// t2 += c -- |t2| <= 2^63
|
|
//
|
|
// c = t5 + 2^24 / 2^25 -- |c| <= 2^38
|
|
// t5 -= c * 2^25 -- |t5| <= 2^24
|
|
// t6 += c -- |t6| <= 2^63
|
|
//
|
|
// c = t2 + 2^25 / 2^26 -- |c| <= 2^37
|
|
// t2 -= c * 2^26 -- |t2| <= 2^25 < 1.1 * 2^25 (final t2)
|
|
// t3 += c -- |t3| <= 2^63
|
|
//
|
|
// c = t6 + 2^25 / 2^26 -- |c| <= 2^37
|
|
// t6 -= c * 2^26 -- |t6| <= 2^25 < 1.1 * 2^25 (final t6)
|
|
// t7 += c -- |t7| <= 2^63
|
|
//
|
|
// c = t3 + 2^24 / 2^25 -- |c| <= 2^38
|
|
// t3 -= c * 2^25 -- |t3| <= 2^24 < 1.1 * 2^24 (final t3)
|
|
// t4 += c -- |t4| <= 2^25 + 2^38 < 2^39
|
|
//
|
|
// c = t7 + 2^24 / 2^25 -- |c| <= 2^38
|
|
// t7 -= c * 2^25 -- |t7| <= 2^24 < 1.1 * 2^24 (final t7)
|
|
// t8 += c -- |t8| <= 2^63
|
|
//
|
|
// c = t4 + 2^25 / 2^26 -- |c| <= 2^13
|
|
// t4 -= c * 2^26 -- |t4| <= 2^25 < 1.1 * 2^25 (final t4)
|
|
// t5 += c -- |t5| <= 2^24 + 2^13 < 1.1 * 2^24 (final t5)
|
|
//
|
|
// c = t8 + 2^25 / 2^26 -- |c| <= 2^37
|
|
// t8 -= c * 2^26 -- |t8| <= 2^25 < 1.1 * 2^25 (final t8)
|
|
// t9 += c -- |t9| <= 2^63
|
|
//
|
|
// c = t9 + 2^24 / 2^25 -- |c| <= 2^38
|
|
// t9 -= c * 2^25 -- |t9| <= 2^24 < 1.1 * 2^24 (final t9)
|
|
// t0 += c * 19 -- |t0| <= 2^25 + 2^38*19 < 2^44
|
|
//
|
|
// c = t0 + 2^25 / 2^26 -- |c| <= 2^18
|
|
// t0 -= c * 2^26 -- |t0| <= 2^25 < 1.1 * 2^25 (final t0)
|
|
// t1 += c -- |t1| <= 2^24 + 2^18 < 1.1 * 2^24 (final t1)
|
|
//
|
|
// Postcondition
|
|
// -------------
|
|
// |t0|, |t2|, |t4|, |t6|, |t8| < 1.1 * 2^25
|
|
// |t1|, |t3|, |t5|, |t7|, |t9| < 1.1 * 2^24
|
|
#define FE_CARRY \
|
|
i64 c; \
|
|
c = (t0 + ((i64)1<<25)) >> 26; t0 -= c * ((i64)1 << 26); t1 += c; \
|
|
c = (t4 + ((i64)1<<25)) >> 26; t4 -= c * ((i64)1 << 26); t5 += c; \
|
|
c = (t1 + ((i64)1<<24)) >> 25; t1 -= c * ((i64)1 << 25); t2 += c; \
|
|
c = (t5 + ((i64)1<<24)) >> 25; t5 -= c * ((i64)1 << 25); t6 += c; \
|
|
c = (t2 + ((i64)1<<25)) >> 26; t2 -= c * ((i64)1 << 26); t3 += c; \
|
|
c = (t6 + ((i64)1<<25)) >> 26; t6 -= c * ((i64)1 << 26); t7 += c; \
|
|
c = (t3 + ((i64)1<<24)) >> 25; t3 -= c * ((i64)1 << 25); t4 += c; \
|
|
c = (t7 + ((i64)1<<24)) >> 25; t7 -= c * ((i64)1 << 25); t8 += c; \
|
|
c = (t4 + ((i64)1<<25)) >> 26; t4 -= c * ((i64)1 << 26); t5 += c; \
|
|
c = (t8 + ((i64)1<<25)) >> 26; t8 -= c * ((i64)1 << 26); t9 += c; \
|
|
c = (t9 + ((i64)1<<24)) >> 25; t9 -= c * ((i64)1 << 25); t0 += c * 19; \
|
|
c = (t0 + ((i64)1<<25)) >> 26; t0 -= c * ((i64)1 << 26); t1 += c; \
|
|
h[0]=(i32)t0; h[1]=(i32)t1; h[2]=(i32)t2; h[3]=(i32)t3; h[4]=(i32)t4; \
|
|
h[5]=(i32)t5; h[6]=(i32)t6; h[7]=(i32)t7; h[8]=(i32)t8; h[9]=(i32)t9
|
|
|
|
// Decodes a field element from a byte buffer.
|
|
// mask specifies how many bits we ignore.
|
|
// Traditionally we ignore 1. It's useful for EdDSA,
|
|
// which uses that bit to denote the sign of x.
|
|
// Elligator however uses positive representatives,
|
|
// which means ignoring 2 bits instead.
|
|
static void fe_frombytes_mask(fe h, const u8 s[32], unsigned nb_mask)
|
|
{
|
|
u32 mask = 0xffffff >> nb_mask;
|
|
i64 t0 = load32_le(s); // t0 < 2^32
|
|
i64 t1 = load24_le(s + 4) << 6; // t1 < 2^30
|
|
i64 t2 = load24_le(s + 7) << 5; // t2 < 2^29
|
|
i64 t3 = load24_le(s + 10) << 3; // t3 < 2^27
|
|
i64 t4 = load24_le(s + 13) << 2; // t4 < 2^26
|
|
i64 t5 = load32_le(s + 16); // t5 < 2^32
|
|
i64 t6 = load24_le(s + 20) << 7; // t6 < 2^31
|
|
i64 t7 = load24_le(s + 23) << 5; // t7 < 2^29
|
|
i64 t8 = load24_le(s + 26) << 4; // t8 < 2^28
|
|
i64 t9 = (load24_le(s + 29) & mask) << 2; // t9 < 2^25
|
|
FE_CARRY; // Carry precondition OK
|
|
}
|
|
|
|
static void fe_frombytes(fe h, const u8 s[32])
|
|
{
|
|
fe_frombytes_mask(h, s, 1);
|
|
}
|
|
|
|
|
|
// Precondition
|
|
// |h[0]|, |h[2]|, |h[4]|, |h[6]|, |h[8]| < 1.1 * 2^25
|
|
// |h[1]|, |h[3]|, |h[5]|, |h[7]|, |h[9]| < 1.1 * 2^24
|
|
//
|
|
// Therefore, |h| < 2^255-19
|
|
// There are two possibilities:
|
|
//
|
|
// - If h is positive, all we need to do is reduce its individual
|
|
// limbs down to their tight positive range.
|
|
// - If h is negative, we also need to add 2^255-19 to it.
|
|
// Or just remove 19 and chop off any excess bit.
|
|
static void fe_tobytes(u8 s[32], const fe h)
|
|
{
|
|
i32 t[10];
|
|
COPY(t, h, 10);
|
|
i32 q = (19 * t[9] + (((i32) 1) << 24)) >> 25;
|
|
// |t9| < 1.1 * 2^24
|
|
// -1.1 * 2^24 < t9 < 1.1 * 2^24
|
|
// -21 * 2^24 < 19 * t9 < 21 * 2^24
|
|
// -2^29 < 19 * t9 + 2^24 < 2^29
|
|
// -2^29 / 2^25 < (19 * t9 + 2^24) / 2^25 < 2^29 / 2^25
|
|
// -16 < (19 * t9 + 2^24) / 2^25 < 16
|
|
FOR (i, 0, 5) {
|
|
q += t[2*i ]; q >>= 26; // q = 0 or -1
|
|
q += t[2*i+1]; q >>= 25; // q = 0 or -1
|
|
}
|
|
// q = 0 iff h >= 0
|
|
// q = -1 iff h < 0
|
|
// Adding q * 19 to h reduces h to its proper range.
|
|
q *= 19; // Shift carry back to the beginning
|
|
FOR (i, 0, 5) {
|
|
t[i*2 ] += q; q = t[i*2 ] >> 26; t[i*2 ] -= q * ((i32)1 << 26);
|
|
t[i*2+1] += q; q = t[i*2+1] >> 25; t[i*2+1] -= q * ((i32)1 << 25);
|
|
}
|
|
// h is now fully reduced, and q represents the excess bit.
|
|
|
|
store32_le(s + 0, ((u32)t[0] >> 0) | ((u32)t[1] << 26));
|
|
store32_le(s + 4, ((u32)t[1] >> 6) | ((u32)t[2] << 19));
|
|
store32_le(s + 8, ((u32)t[2] >> 13) | ((u32)t[3] << 13));
|
|
store32_le(s + 12, ((u32)t[3] >> 19) | ((u32)t[4] << 6));
|
|
store32_le(s + 16, ((u32)t[5] >> 0) | ((u32)t[6] << 25));
|
|
store32_le(s + 20, ((u32)t[6] >> 7) | ((u32)t[7] << 19));
|
|
store32_le(s + 24, ((u32)t[7] >> 13) | ((u32)t[8] << 12));
|
|
store32_le(s + 28, ((u32)t[8] >> 20) | ((u32)t[9] << 6));
|
|
|
|
WIPE_BUFFER(t);
|
|
}
|
|
|
|
// Precondition
|
|
// -------------
|
|
// |f0|, |f2|, |f4|, |f6|, |f8| < 1.65 * 2^26
|
|
// |f1|, |f3|, |f5|, |f7|, |f9| < 1.65 * 2^25
|
|
//
|
|
// |g0|, |g2|, |g4|, |g6|, |g8| < 1.65 * 2^26
|
|
// |g1|, |g3|, |g5|, |g7|, |g9| < 1.65 * 2^25
|
|
static void fe_mul_small(fe h, const fe f, i32 g)
|
|
{
|
|
i64 t0 = f[0] * (i64) g; i64 t1 = f[1] * (i64) g;
|
|
i64 t2 = f[2] * (i64) g; i64 t3 = f[3] * (i64) g;
|
|
i64 t4 = f[4] * (i64) g; i64 t5 = f[5] * (i64) g;
|
|
i64 t6 = f[6] * (i64) g; i64 t7 = f[7] * (i64) g;
|
|
i64 t8 = f[8] * (i64) g; i64 t9 = f[9] * (i64) g;
|
|
// |t0|, |t2|, |t4|, |t6|, |t8| < 1.65 * 2^26 * 2^31 < 2^58
|
|
// |t1|, |t3|, |t5|, |t7|, |t9| < 1.65 * 2^25 * 2^31 < 2^57
|
|
|
|
FE_CARRY; // Carry precondition OK
|
|
}
|
|
|
|
// Precondition
|
|
// -------------
|
|
// |f0|, |f2|, |f4|, |f6|, |f8| < 1.65 * 2^26
|
|
// |f1|, |f3|, |f5|, |f7|, |f9| < 1.65 * 2^25
|
|
//
|
|
// |g0|, |g2|, |g4|, |g6|, |g8| < 1.65 * 2^26
|
|
// |g1|, |g3|, |g5|, |g7|, |g9| < 1.65 * 2^25
|
|
static void fe_mul(fe h, const fe f, const fe g)
|
|
{
|
|
// Everything is unrolled and put in temporary variables.
|
|
// We could roll the loop, but that would make curve25519 twice as slow.
|
|
i32 f0 = f[0]; i32 f1 = f[1]; i32 f2 = f[2]; i32 f3 = f[3]; i32 f4 = f[4];
|
|
i32 f5 = f[5]; i32 f6 = f[6]; i32 f7 = f[7]; i32 f8 = f[8]; i32 f9 = f[9];
|
|
i32 g0 = g[0]; i32 g1 = g[1]; i32 g2 = g[2]; i32 g3 = g[3]; i32 g4 = g[4];
|
|
i32 g5 = g[5]; i32 g6 = g[6]; i32 g7 = g[7]; i32 g8 = g[8]; i32 g9 = g[9];
|
|
i32 F1 = f1*2; i32 F3 = f3*2; i32 F5 = f5*2; i32 F7 = f7*2; i32 F9 = f9*2;
|
|
i32 G1 = g1*19; i32 G2 = g2*19; i32 G3 = g3*19;
|
|
i32 G4 = g4*19; i32 G5 = g5*19; i32 G6 = g6*19;
|
|
i32 G7 = g7*19; i32 G8 = g8*19; i32 G9 = g9*19;
|
|
// |F1|, |F3|, |F5|, |F7|, |F9| < 1.65 * 2^26
|
|
// |G0|, |G2|, |G4|, |G6|, |G8| < 2^31
|
|
// |G1|, |G3|, |G5|, |G7|, |G9| < 2^30
|
|
|
|
i64 t0 = f0*(i64)g0 + F1*(i64)G9 + f2*(i64)G8 + F3*(i64)G7 + f4*(i64)G6
|
|
+ F5*(i64)G5 + f6*(i64)G4 + F7*(i64)G3 + f8*(i64)G2 + F9*(i64)G1;
|
|
i64 t1 = f0*(i64)g1 + f1*(i64)g0 + f2*(i64)G9 + f3*(i64)G8 + f4*(i64)G7
|
|
+ f5*(i64)G6 + f6*(i64)G5 + f7*(i64)G4 + f8*(i64)G3 + f9*(i64)G2;
|
|
i64 t2 = f0*(i64)g2 + F1*(i64)g1 + f2*(i64)g0 + F3*(i64)G9 + f4*(i64)G8
|
|
+ F5*(i64)G7 + f6*(i64)G6 + F7*(i64)G5 + f8*(i64)G4 + F9*(i64)G3;
|
|
i64 t3 = f0*(i64)g3 + f1*(i64)g2 + f2*(i64)g1 + f3*(i64)g0 + f4*(i64)G9
|
|
+ f5*(i64)G8 + f6*(i64)G7 + f7*(i64)G6 + f8*(i64)G5 + f9*(i64)G4;
|
|
i64 t4 = f0*(i64)g4 + F1*(i64)g3 + f2*(i64)g2 + F3*(i64)g1 + f4*(i64)g0
|
|
+ F5*(i64)G9 + f6*(i64)G8 + F7*(i64)G7 + f8*(i64)G6 + F9*(i64)G5;
|
|
i64 t5 = f0*(i64)g5 + f1*(i64)g4 + f2*(i64)g3 + f3*(i64)g2 + f4*(i64)g1
|
|
+ f5*(i64)g0 + f6*(i64)G9 + f7*(i64)G8 + f8*(i64)G7 + f9*(i64)G6;
|
|
i64 t6 = f0*(i64)g6 + F1*(i64)g5 + f2*(i64)g4 + F3*(i64)g3 + f4*(i64)g2
|
|
+ F5*(i64)g1 + f6*(i64)g0 + F7*(i64)G9 + f8*(i64)G8 + F9*(i64)G7;
|
|
i64 t7 = f0*(i64)g7 + f1*(i64)g6 + f2*(i64)g5 + f3*(i64)g4 + f4*(i64)g3
|
|
+ f5*(i64)g2 + f6*(i64)g1 + f7*(i64)g0 + f8*(i64)G9 + f9*(i64)G8;
|
|
i64 t8 = f0*(i64)g8 + F1*(i64)g7 + f2*(i64)g6 + F3*(i64)g5 + f4*(i64)g4
|
|
+ F5*(i64)g3 + f6*(i64)g2 + F7*(i64)g1 + f8*(i64)g0 + F9*(i64)G9;
|
|
i64 t9 = f0*(i64)g9 + f1*(i64)g8 + f2*(i64)g7 + f3*(i64)g6 + f4*(i64)g5
|
|
+ f5*(i64)g4 + f6*(i64)g3 + f7*(i64)g2 + f8*(i64)g1 + f9*(i64)g0;
|
|
// t0 < 0.67 * 2^61
|
|
// t1 < 0.41 * 2^61
|
|
// t2 < 0.52 * 2^61
|
|
// t3 < 0.32 * 2^61
|
|
// t4 < 0.38 * 2^61
|
|
// t5 < 0.22 * 2^61
|
|
// t6 < 0.23 * 2^61
|
|
// t7 < 0.13 * 2^61
|
|
// t8 < 0.09 * 2^61
|
|
// t9 < 0.03 * 2^61
|
|
|
|
FE_CARRY; // Everything below 2^62, Carry precondition OK
|
|
}
|
|
|
|
// Precondition
|
|
// -------------
|
|
// |f0|, |f2|, |f4|, |f6|, |f8| < 1.65 * 2^26
|
|
// |f1|, |f3|, |f5|, |f7|, |f9| < 1.65 * 2^25
|
|
//
|
|
// Note: we could use fe_mul() for this, but this is significantly faster
|
|
static void fe_sq(fe h, const fe f)
|
|
{
|
|
i32 f0 = f[0]; i32 f1 = f[1]; i32 f2 = f[2]; i32 f3 = f[3]; i32 f4 = f[4];
|
|
i32 f5 = f[5]; i32 f6 = f[6]; i32 f7 = f[7]; i32 f8 = f[8]; i32 f9 = f[9];
|
|
i32 f0_2 = f0*2; i32 f1_2 = f1*2; i32 f2_2 = f2*2; i32 f3_2 = f3*2;
|
|
i32 f4_2 = f4*2; i32 f5_2 = f5*2; i32 f6_2 = f6*2; i32 f7_2 = f7*2;
|
|
i32 f5_38 = f5*38; i32 f6_19 = f6*19; i32 f7_38 = f7*38;
|
|
i32 f8_19 = f8*19; i32 f9_38 = f9*38;
|
|
// |f0_2| , |f2_2| , |f4_2| , |f6_2| , |f8_2| < 1.65 * 2^27
|
|
// |f1_2| , |f3_2| , |f5_2| , |f7_2| , |f9_2| < 1.65 * 2^26
|
|
// |f5_38|, |f6_19|, |f7_38|, |f8_19|, |f9_38| < 2^31
|
|
|
|
i64 t0 = f0 *(i64)f0 + f1_2*(i64)f9_38 + f2_2*(i64)f8_19
|
|
+ f3_2*(i64)f7_38 + f4_2*(i64)f6_19 + f5 *(i64)f5_38;
|
|
i64 t1 = f0_2*(i64)f1 + f2 *(i64)f9_38 + f3_2*(i64)f8_19
|
|
+ f4 *(i64)f7_38 + f5_2*(i64)f6_19;
|
|
i64 t2 = f0_2*(i64)f2 + f1_2*(i64)f1 + f3_2*(i64)f9_38
|
|
+ f4_2*(i64)f8_19 + f5_2*(i64)f7_38 + f6 *(i64)f6_19;
|
|
i64 t3 = f0_2*(i64)f3 + f1_2*(i64)f2 + f4 *(i64)f9_38
|
|
+ f5_2*(i64)f8_19 + f6 *(i64)f7_38;
|
|
i64 t4 = f0_2*(i64)f4 + f1_2*(i64)f3_2 + f2 *(i64)f2
|
|
+ f5_2*(i64)f9_38 + f6_2*(i64)f8_19 + f7 *(i64)f7_38;
|
|
i64 t5 = f0_2*(i64)f5 + f1_2*(i64)f4 + f2_2*(i64)f3
|
|
+ f6 *(i64)f9_38 + f7_2*(i64)f8_19;
|
|
i64 t6 = f0_2*(i64)f6 + f1_2*(i64)f5_2 + f2_2*(i64)f4
|
|
+ f3_2*(i64)f3 + f7_2*(i64)f9_38 + f8 *(i64)f8_19;
|
|
i64 t7 = f0_2*(i64)f7 + f1_2*(i64)f6 + f2_2*(i64)f5
|
|
+ f3_2*(i64)f4 + f8 *(i64)f9_38;
|
|
i64 t8 = f0_2*(i64)f8 + f1_2*(i64)f7_2 + f2_2*(i64)f6
|
|
+ f3_2*(i64)f5_2 + f4 *(i64)f4 + f9 *(i64)f9_38;
|
|
i64 t9 = f0_2*(i64)f9 + f1_2*(i64)f8 + f2_2*(i64)f7
|
|
+ f3_2*(i64)f6 + f4 *(i64)f5_2;
|
|
// t0 < 0.67 * 2^61
|
|
// t1 < 0.41 * 2^61
|
|
// t2 < 0.52 * 2^61
|
|
// t3 < 0.32 * 2^61
|
|
// t4 < 0.38 * 2^61
|
|
// t5 < 0.22 * 2^61
|
|
// t6 < 0.23 * 2^61
|
|
// t7 < 0.13 * 2^61
|
|
// t8 < 0.09 * 2^61
|
|
// t9 < 0.03 * 2^61
|
|
|
|
FE_CARRY;
|
|
}
|
|
|
|
// Parity check. Returns 0 if even, 1 if odd
|
|
static int fe_isodd(const fe f)
|
|
{
|
|
u8 s[32];
|
|
fe_tobytes(s, f);
|
|
u8 isodd = s[0] & 1;
|
|
WIPE_BUFFER(s);
|
|
return isodd;
|
|
}
|
|
|
|
// Returns 1 if equal, 0 if not equal
|
|
static int fe_isequal(const fe f, const fe g)
|
|
{
|
|
u8 fs[32];
|
|
u8 gs[32];
|
|
fe_tobytes(fs, f);
|
|
fe_tobytes(gs, g);
|
|
int isdifferent = crypto_verify32(fs, gs);
|
|
WIPE_BUFFER(fs);
|
|
WIPE_BUFFER(gs);
|
|
return 1 + isdifferent;
|
|
}
|
|
|
|
// Inverse square root.
|
|
// Returns true if x is a square, false otherwise.
|
|
// After the call:
|
|
// isr = sqrt(1/x) if x is a non-zero square.
|
|
// isr = sqrt(sqrt(-1)/x) if x is not a square.
|
|
// isr = 0 if x is zero.
|
|
// We do not guarantee the sign of the square root.
|
|
//
|
|
// Notes:
|
|
// Let quartic = x^((p-1)/4)
|
|
//
|
|
// x^((p-1)/2) = chi(x)
|
|
// quartic^2 = chi(x)
|
|
// quartic = sqrt(chi(x))
|
|
// quartic = 1 or -1 or sqrt(-1) or -sqrt(-1)
|
|
//
|
|
// Note that x is a square if quartic is 1 or -1
|
|
// There are 4 cases to consider:
|
|
//
|
|
// if quartic = 1 (x is a square)
|
|
// then x^((p-1)/4) = 1
|
|
// x^((p-5)/4) * x = 1
|
|
// x^((p-5)/4) = 1/x
|
|
// x^((p-5)/8) = sqrt(1/x) or -sqrt(1/x)
|
|
//
|
|
// if quartic = -1 (x is a square)
|
|
// then x^((p-1)/4) = -1
|
|
// x^((p-5)/4) * x = -1
|
|
// x^((p-5)/4) = -1/x
|
|
// x^((p-5)/8) = sqrt(-1) / sqrt(x)
|
|
// x^((p-5)/8) * sqrt(-1) = sqrt(-1)^2 / sqrt(x)
|
|
// x^((p-5)/8) * sqrt(-1) = -1/sqrt(x)
|
|
// x^((p-5)/8) * sqrt(-1) = -sqrt(1/x) or sqrt(1/x)
|
|
//
|
|
// if quartic = sqrt(-1) (x is not a square)
|
|
// then x^((p-1)/4) = sqrt(-1)
|
|
// x^((p-5)/4) * x = sqrt(-1)
|
|
// x^((p-5)/4) = sqrt(-1)/x
|
|
// x^((p-5)/8) = sqrt(sqrt(-1)/x) or -sqrt(sqrt(-1)/x)
|
|
//
|
|
// Note that the product of two non-squares is always a square:
|
|
// For any non-squares a and b, chi(a) = -1 and chi(b) = -1.
|
|
// Since chi(x) = x^((p-1)/2), chi(a)*chi(b) = chi(a*b) = 1.
|
|
// Therefore a*b is a square.
|
|
//
|
|
// Since sqrt(-1) and x are both non-squares, their product is a
|
|
// square, and we can compute their square root.
|
|
//
|
|
// if quartic = -sqrt(-1) (x is not a square)
|
|
// then x^((p-1)/4) = -sqrt(-1)
|
|
// x^((p-5)/4) * x = -sqrt(-1)
|
|
// x^((p-5)/4) = -sqrt(-1)/x
|
|
// x^((p-5)/8) = sqrt(-sqrt(-1)/x)
|
|
// x^((p-5)/8) = sqrt( sqrt(-1)/x) * sqrt(-1)
|
|
// x^((p-5)/8) * sqrt(-1) = sqrt( sqrt(-1)/x) * sqrt(-1)^2
|
|
// x^((p-5)/8) * sqrt(-1) = sqrt( sqrt(-1)/x) * -1
|
|
// x^((p-5)/8) * sqrt(-1) = -sqrt(sqrt(-1)/x) or sqrt(sqrt(-1)/x)
|
|
static int invsqrt(fe isr, const fe x)
|
|
{
|
|
fe t0, t1, t2;
|
|
|
|
// t0 = x^((p-5)/8)
|
|
// Can be achieved with a simple double & add ladder,
|
|
// but it would be slower.
|
|
fe_sq(t0, x);
|
|
fe_sq(t1,t0); fe_sq(t1, t1); fe_mul(t1, x, t1);
|
|
fe_mul(t0, t0, t1);
|
|
fe_sq(t0, t0); fe_mul(t0, t1, t0);
|
|
fe_sq(t1, t0); FOR (i, 1, 5) { fe_sq(t1, t1); } fe_mul(t0, t1, t0);
|
|
fe_sq(t1, t0); FOR (i, 1, 10) { fe_sq(t1, t1); } fe_mul(t1, t1, t0);
|
|
fe_sq(t2, t1); FOR (i, 1, 20) { fe_sq(t2, t2); } fe_mul(t1, t2, t1);
|
|
fe_sq(t1, t1); FOR (i, 1, 10) { fe_sq(t1, t1); } fe_mul(t0, t1, t0);
|
|
fe_sq(t1, t0); FOR (i, 1, 50) { fe_sq(t1, t1); } fe_mul(t1, t1, t0);
|
|
fe_sq(t2, t1); FOR (i, 1, 100) { fe_sq(t2, t2); } fe_mul(t1, t2, t1);
|
|
fe_sq(t1, t1); FOR (i, 1, 50) { fe_sq(t1, t1); } fe_mul(t0, t1, t0);
|
|
fe_sq(t0, t0); FOR (i, 1, 2) { fe_sq(t0, t0); } fe_mul(t0, t0, x);
|
|
|
|
// quartic = x^((p-1)/4)
|
|
i32 *quartic = t1;
|
|
fe_sq (quartic, t0);
|
|
fe_mul(quartic, quartic, x);
|
|
|
|
i32 *check = t2;
|
|
fe_0 (check); int z0 = fe_isequal(x , check);
|
|
fe_1 (check); int p1 = fe_isequal(quartic, check);
|
|
fe_neg(check, check ); int m1 = fe_isequal(quartic, check);
|
|
fe_neg(check, sqrtm1); int ms = fe_isequal(quartic, check);
|
|
|
|
// if quartic == -1 or sqrt(-1)
|
|
// then isr = x^((p-1)/4) * sqrt(-1)
|
|
// else isr = x^((p-1)/4)
|
|
fe_mul(isr, t0, sqrtm1);
|
|
fe_ccopy(isr, t0, 1 - (m1 | ms));
|
|
|
|
WIPE_BUFFER(t0);
|
|
WIPE_BUFFER(t1);
|
|
WIPE_BUFFER(t2);
|
|
return p1 | m1 | z0;
|
|
}
|
|
|
|
// Inverse in terms of inverse square root.
|
|
// Requires two additional squarings to get rid of the sign.
|
|
//
|
|
// 1/x = x * (+invsqrt(x^2))^2
|
|
// = x * (-invsqrt(x^2))^2
|
|
//
|
|
// A fully optimised exponentiation by p-1 would save 6 field
|
|
// multiplications, but it would require more code.
|
|
static void fe_invert(fe out, const fe x)
|
|
{
|
|
fe tmp;
|
|
fe_sq(tmp, x);
|
|
invsqrt(tmp, tmp);
|
|
fe_sq(tmp, tmp);
|
|
fe_mul(out, tmp, x);
|
|
WIPE_BUFFER(tmp);
|
|
}
|
|
|
|
// trim a scalar for scalar multiplication
|
|
void crypto_eddsa_trim_scalar(u8 out[32], const u8 in[32])
|
|
{
|
|
COPY(out, in, 32);
|
|
out[ 0] &= 248;
|
|
out[31] &= 127;
|
|
out[31] |= 64;
|
|
}
|
|
|
|
// get bit from scalar at position i
|
|
static int scalar_bit(const u8 s[32], int i)
|
|
{
|
|
if (i < 0) { return 0; } // handle -1 for sliding windows
|
|
return (s[i>>3] >> (i&7)) & 1;
|
|
}
|
|
|
|
///////////////
|
|
/// X-25519 /// Taken from SUPERCOP's ref10 implementation.
|
|
///////////////
|
|
static void scalarmult(u8 q[32], const u8 scalar[32], const u8 p[32],
|
|
int nb_bits)
|
|
{
|
|
// computes the scalar product
|
|
fe x1;
|
|
fe_frombytes(x1, p);
|
|
|
|
// computes the actual scalar product (the result is in x2 and z2)
|
|
fe x2, z2, x3, z3, t0, t1;
|
|
// Montgomery ladder
|
|
// In projective coordinates, to avoid divisions: x = X / Z
|
|
// We don't care about the y coordinate, it's only 1 bit of information
|
|
fe_1(x2); fe_0(z2); // "zero" point
|
|
fe_copy(x3, x1); fe_1(z3); // "one" point
|
|
int swap = 0;
|
|
for (int pos = nb_bits-1; pos >= 0; --pos) {
|
|
// constant time conditional swap before ladder step
|
|
int b = scalar_bit(scalar, pos);
|
|
swap ^= b; // xor trick avoids swapping at the end of the loop
|
|
fe_cswap(x2, x3, swap);
|
|
fe_cswap(z2, z3, swap);
|
|
swap = b; // anticipates one last swap after the loop
|
|
|
|
// Montgomery ladder step: replaces (P2, P3) by (P2*2, P2+P3)
|
|
// with differential addition
|
|
fe_sub(t0, x3, z3);
|
|
fe_sub(t1, x2, z2);
|
|
fe_add(x2, x2, z2);
|
|
fe_add(z2, x3, z3);
|
|
fe_mul(z3, t0, x2);
|
|
fe_mul(z2, z2, t1);
|
|
fe_sq (t0, t1 );
|
|
fe_sq (t1, x2 );
|
|
fe_add(x3, z3, z2);
|
|
fe_sub(z2, z3, z2);
|
|
fe_mul(x2, t1, t0);
|
|
fe_sub(t1, t1, t0);
|
|
fe_sq (z2, z2 );
|
|
fe_mul_small(z3, t1, 121666);
|
|
fe_sq (x3, x3 );
|
|
fe_add(t0, t0, z3);
|
|
fe_mul(z3, x1, z2);
|
|
fe_mul(z2, t1, t0);
|
|
}
|
|
// last swap is necessary to compensate for the xor trick
|
|
// Note: after this swap, P3 == P2 + P1.
|
|
fe_cswap(x2, x3, swap);
|
|
fe_cswap(z2, z3, swap);
|
|
|
|
// normalises the coordinates: x == X / Z
|
|
fe_invert(z2, z2);
|
|
fe_mul(x2, x2, z2);
|
|
fe_tobytes(q, x2);
|
|
|
|
WIPE_BUFFER(x1);
|
|
WIPE_BUFFER(x2); WIPE_BUFFER(z2); WIPE_BUFFER(t0);
|
|
WIPE_BUFFER(x3); WIPE_BUFFER(z3); WIPE_BUFFER(t1);
|
|
}
|
|
|
|
void crypto_x25519(u8 raw_shared_secret[32],
|
|
const u8 your_secret_key [32],
|
|
const u8 their_public_key [32])
|
|
{
|
|
// restrict the possible scalar values
|
|
u8 e[32];
|
|
crypto_eddsa_trim_scalar(e, your_secret_key);
|
|
scalarmult(raw_shared_secret, e, their_public_key, 255);
|
|
WIPE_BUFFER(e);
|
|
}
|
|
|
|
void crypto_x25519_public_key(u8 public_key[32],
|
|
const u8 secret_key[32])
|
|
{
|
|
static const u8 base_point[32] = {9};
|
|
crypto_x25519(public_key, secret_key, base_point);
|
|
}
|
|
|
|
///////////////////////////
|
|
/// Arithmetic modulo L ///
|
|
///////////////////////////
|
|
static const u32 L[8] = {
|
|
0x5cf5d3ed, 0x5812631a, 0xa2f79cd6, 0x14def9de,
|
|
0x00000000, 0x00000000, 0x00000000, 0x10000000,
|
|
};
|
|
|
|
// p = a*b + p
|
|
static void multiply(u32 p[16], const u32 a[8], const u32 b[8])
|
|
{
|
|
FOR (i, 0, 8) {
|
|
u64 carry = 0;
|
|
FOR (j, 0, 8) {
|
|
carry += p[i+j] + (u64)a[i] * b[j];
|
|
p[i+j] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
p[i+8] = (u32)carry;
|
|
}
|
|
}
|
|
|
|
static int is_above_l(const u32 x[8])
|
|
{
|
|
// We work with L directly, in a 2's complement encoding
|
|
// (-L == ~L + 1)
|
|
u64 carry = 1;
|
|
FOR (i, 0, 8) {
|
|
carry += (u64)x[i] + (~L[i] & 0xffffffff);
|
|
carry >>= 32;
|
|
}
|
|
return (int)carry; // carry is either 0 or 1
|
|
}
|
|
|
|
// Final reduction modulo L, by conditionally removing L.
|
|
// if x < l , then r = x
|
|
// if l <= x 2*l, then r = x-l
|
|
// otherwise the result will be wrong
|
|
static void remove_l(u32 r[8], const u32 x[8])
|
|
{
|
|
u64 carry = (u64)is_above_l(x);
|
|
u32 mask = ~(u32)carry + 1; // carry == 0 or 1
|
|
FOR (i, 0, 8) {
|
|
carry += (u64)x[i] + (~L[i] & mask);
|
|
r[i] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
}
|
|
|
|
// Full reduction modulo L (Barrett reduction)
|
|
static void mod_l(u8 reduced[32], const u32 x[16])
|
|
{
|
|
static const u32 r[9] = {
|
|
0x0a2c131b,0xed9ce5a3,0x086329a7,0x2106215d,
|
|
0xffffffeb,0xffffffff,0xffffffff,0xffffffff,0xf,
|
|
};
|
|
// xr = x * r
|
|
u32 xr[25] = {0};
|
|
FOR (i, 0, 9) {
|
|
u64 carry = 0;
|
|
FOR (j, 0, 16) {
|
|
carry += xr[i+j] + (u64)r[i] * x[j];
|
|
xr[i+j] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
xr[i+16] = (u32)carry;
|
|
}
|
|
// xr = floor(xr / 2^512) * L
|
|
// Since the result is guaranteed to be below 2*L,
|
|
// it is enough to only compute the first 256 bits.
|
|
// The division is performed by saying xr[i+16]. (16 * 32 = 512)
|
|
ZERO(xr, 8);
|
|
FOR (i, 0, 8) {
|
|
u64 carry = 0;
|
|
FOR (j, 0, 8-i) {
|
|
carry += xr[i+j] + (u64)xr[i+16] * L[j];
|
|
xr[i+j] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
}
|
|
// xr = x - xr
|
|
u64 carry = 1;
|
|
FOR (i, 0, 8) {
|
|
carry += (u64)x[i] + (~xr[i] & 0xffffffff);
|
|
xr[i] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
// Final reduction modulo L (conditional subtraction)
|
|
remove_l(xr, xr);
|
|
store32_le_buf(reduced, xr, 8);
|
|
|
|
WIPE_BUFFER(xr);
|
|
}
|
|
|
|
void crypto_eddsa_reduce(u8 reduced[32], const u8 expanded[64])
|
|
{
|
|
u32 x[16];
|
|
load32_le_buf(x, expanded, 16);
|
|
mod_l(reduced, x);
|
|
WIPE_BUFFER(x);
|
|
}
|
|
|
|
// r = (a * b) + c
|
|
void crypto_eddsa_mul_add(u8 r[32],
|
|
const u8 a[32], const u8 b[32], const u8 c[32])
|
|
{
|
|
u32 A[8]; load32_le_buf(A, a, 8);
|
|
u32 B[8]; load32_le_buf(B, b, 8);
|
|
u32 p[16]; load32_le_buf(p, c, 8); ZERO(p + 8, 8);
|
|
multiply(p, A, B);
|
|
mod_l(r, p);
|
|
WIPE_BUFFER(p);
|
|
WIPE_BUFFER(A);
|
|
WIPE_BUFFER(B);
|
|
}
|
|
|
|
///////////////
|
|
/// Ed25519 ///
|
|
///////////////
|
|
|
|
// Point (group element, ge) in a twisted Edwards curve,
|
|
// in extended projective coordinates.
|
|
// ge : x = X/Z, y = Y/Z, T = XY/Z
|
|
// ge_cached : Yp = X+Y, Ym = X-Y, T2 = T*D2
|
|
// ge_precomp: Z = 1
|
|
typedef struct { fe X; fe Y; fe Z; fe T; } ge;
|
|
typedef struct { fe Yp; fe Ym; fe Z; fe T2; } ge_cached;
|
|
typedef struct { fe Yp; fe Ym; fe T2; } ge_precomp;
|
|
|
|
static void ge_zero(ge *p)
|
|
{
|
|
fe_0(p->X);
|
|
fe_1(p->Y);
|
|
fe_1(p->Z);
|
|
fe_0(p->T);
|
|
}
|
|
|
|
static void ge_tobytes(u8 s[32], const ge *h)
|
|
{
|
|
fe recip, x, y;
|
|
fe_invert(recip, h->Z);
|
|
fe_mul(x, h->X, recip);
|
|
fe_mul(y, h->Y, recip);
|
|
fe_tobytes(s, y);
|
|
s[31] ^= fe_isodd(x) << 7;
|
|
|
|
WIPE_BUFFER(recip);
|
|
WIPE_BUFFER(x);
|
|
WIPE_BUFFER(y);
|
|
}
|
|
|
|
// h = -s, where s is a point encoded in 32 bytes
|
|
//
|
|
// Variable time! Inputs must not be secret!
|
|
// => Use only to *check* signatures.
|
|
//
|
|
// From the specifications:
|
|
// The encoding of s contains y and the sign of x
|
|
// x = sqrt((y^2 - 1) / (d*y^2 + 1))
|
|
// In extended coordinates:
|
|
// X = x, Y = y, Z = 1, T = x*y
|
|
//
|
|
// Note that num * den is a square iff num / den is a square
|
|
// If num * den is not a square, the point was not on the curve.
|
|
// From the above:
|
|
// Let num = y^2 - 1
|
|
// Let den = d*y^2 + 1
|
|
// x = sqrt((y^2 - 1) / (d*y^2 + 1))
|
|
// x = sqrt(num / den)
|
|
// x = sqrt(num^2 / (num * den))
|
|
// x = num * sqrt(1 / (num * den))
|
|
//
|
|
// Therefore, we can just compute:
|
|
// num = y^2 - 1
|
|
// den = d*y^2 + 1
|
|
// isr = invsqrt(num * den) // abort if not square
|
|
// x = num * isr
|
|
// Finally, negate x if its sign is not as specified.
|
|
static int ge_frombytes_neg_vartime(ge *h, const u8 s[32])
|
|
{
|
|
fe_frombytes(h->Y, s);
|
|
fe_1(h->Z);
|
|
fe_sq (h->T, h->Y); // t = y^2
|
|
fe_mul(h->X, h->T, d ); // x = d*y^2
|
|
fe_sub(h->T, h->T, h->Z); // t = y^2 - 1
|
|
fe_add(h->X, h->X, h->Z); // x = d*y^2 + 1
|
|
fe_mul(h->X, h->T, h->X); // x = (y^2 - 1) * (d*y^2 + 1)
|
|
int is_square = invsqrt(h->X, h->X);
|
|
if (!is_square) {
|
|
return -1; // Not on the curve, abort
|
|
}
|
|
fe_mul(h->X, h->T, h->X); // x = sqrt((y^2 - 1) / (d*y^2 + 1))
|
|
if (fe_isodd(h->X) == (s[31] >> 7)) {
|
|
fe_neg(h->X, h->X);
|
|
}
|
|
fe_mul(h->T, h->X, h->Y);
|
|
return 0;
|
|
}
|
|
|
|
static void ge_cache(ge_cached *c, const ge *p)
|
|
{
|
|
fe_add (c->Yp, p->Y, p->X);
|
|
fe_sub (c->Ym, p->Y, p->X);
|
|
fe_copy(c->Z , p->Z );
|
|
fe_mul (c->T2, p->T, D2 );
|
|
}
|
|
|
|
// Internal buffers are not wiped! Inputs must not be secret!
|
|
// => Use only to *check* signatures.
|
|
static void ge_add(ge *s, const ge *p, const ge_cached *q)
|
|
{
|
|
fe a, b;
|
|
fe_add(a , p->Y, p->X );
|
|
fe_sub(b , p->Y, p->X );
|
|
fe_mul(a , a , q->Yp);
|
|
fe_mul(b , b , q->Ym);
|
|
fe_add(s->Y, a , b );
|
|
fe_sub(s->X, a , b );
|
|
|
|
fe_add(s->Z, p->Z, p->Z );
|
|
fe_mul(s->Z, s->Z, q->Z );
|
|
fe_mul(s->T, p->T, q->T2);
|
|
fe_add(a , s->Z, s->T );
|
|
fe_sub(b , s->Z, s->T );
|
|
|
|
fe_mul(s->T, s->X, s->Y);
|
|
fe_mul(s->X, s->X, b );
|
|
fe_mul(s->Y, s->Y, a );
|
|
fe_mul(s->Z, a , b );
|
|
}
|
|
|
|
// Internal buffers are not wiped! Inputs must not be secret!
|
|
// => Use only to *check* signatures.
|
|
static void ge_sub(ge *s, const ge *p, const ge_cached *q)
|
|
{
|
|
ge_cached neg;
|
|
fe_copy(neg.Ym, q->Yp);
|
|
fe_copy(neg.Yp, q->Ym);
|
|
fe_copy(neg.Z , q->Z );
|
|
fe_neg (neg.T2, q->T2);
|
|
ge_add(s, p, &neg);
|
|
}
|
|
|
|
static void ge_madd(ge *s, const ge *p, const ge_precomp *q, fe a, fe b)
|
|
{
|
|
fe_add(a , p->Y, p->X );
|
|
fe_sub(b , p->Y, p->X );
|
|
fe_mul(a , a , q->Yp);
|
|
fe_mul(b , b , q->Ym);
|
|
fe_add(s->Y, a , b );
|
|
fe_sub(s->X, a , b );
|
|
|
|
fe_add(s->Z, p->Z, p->Z );
|
|
fe_mul(s->T, p->T, q->T2);
|
|
fe_add(a , s->Z, s->T );
|
|
fe_sub(b , s->Z, s->T );
|
|
|
|
fe_mul(s->T, s->X, s->Y);
|
|
fe_mul(s->X, s->X, b );
|
|
fe_mul(s->Y, s->Y, a );
|
|
fe_mul(s->Z, a , b );
|
|
}
|
|
|
|
// Internal buffers are not wiped! Inputs must not be secret!
|
|
// => Use only to *check* signatures.
|
|
static void ge_msub(ge *s, const ge *p, const ge_precomp *q, fe a, fe b)
|
|
{
|
|
ge_precomp neg;
|
|
fe_copy(neg.Ym, q->Yp);
|
|
fe_copy(neg.Yp, q->Ym);
|
|
fe_neg (neg.T2, q->T2);
|
|
ge_madd(s, p, &neg, a, b);
|
|
}
|
|
|
|
static void ge_double(ge *s, const ge *p, ge *q)
|
|
{
|
|
fe_sq (q->X, p->X);
|
|
fe_sq (q->Y, p->Y);
|
|
fe_sq (q->Z, p->Z); // qZ = pZ^2
|
|
fe_mul_small(q->Z, q->Z, 2); // qZ = pZ^2 * 2
|
|
fe_add(q->T, p->X, p->Y);
|
|
fe_sq (s->T, q->T);
|
|
fe_add(q->T, q->Y, q->X);
|
|
fe_sub(q->Y, q->Y, q->X);
|
|
fe_sub(q->X, s->T, q->T);
|
|
fe_sub(q->Z, q->Z, q->Y);
|
|
|
|
fe_mul(s->X, q->X , q->Z);
|
|
fe_mul(s->Y, q->T , q->Y);
|
|
fe_mul(s->Z, q->Y , q->Z);
|
|
fe_mul(s->T, q->X , q->T);
|
|
}
|
|
|
|
// 5-bit signed window in cached format (Niels coordinates, Z=1)
|
|
static const ge_precomp b_window[8] = {
|
|
{{25967493,-14356035,29566456,3660896,-12694345,
|
|
4014787,27544626,-11754271,-6079156,2047605,},
|
|
{-12545711,934262,-2722910,3049990,-727428,
|
|
9406986,12720692,5043384,19500929,-15469378,},
|
|
{-8738181,4489570,9688441,-14785194,10184609,
|
|
-12363380,29287919,11864899,-24514362,-4438546,},},
|
|
{{15636291,-9688557,24204773,-7912398,616977,
|
|
-16685262,27787600,-14772189,28944400,-1550024,},
|
|
{16568933,4717097,-11556148,-1102322,15682896,
|
|
-11807043,16354577,-11775962,7689662,11199574,},
|
|
{30464156,-5976125,-11779434,-15670865,23220365,
|
|
15915852,7512774,10017326,-17749093,-9920357,},},
|
|
{{10861363,11473154,27284546,1981175,-30064349,
|
|
12577861,32867885,14515107,-15438304,10819380,},
|
|
{4708026,6336745,20377586,9066809,-11272109,
|
|
6594696,-25653668,12483688,-12668491,5581306,},
|
|
{19563160,16186464,-29386857,4097519,10237984,
|
|
-4348115,28542350,13850243,-23678021,-15815942,},},
|
|
{{5153746,9909285,1723747,-2777874,30523605,
|
|
5516873,19480852,5230134,-23952439,-15175766,},
|
|
{-30269007,-3463509,7665486,10083793,28475525,
|
|
1649722,20654025,16520125,30598449,7715701,},
|
|
{28881845,14381568,9657904,3680757,-20181635,
|
|
7843316,-31400660,1370708,29794553,-1409300,},},
|
|
{{-22518993,-6692182,14201702,-8745502,-23510406,
|
|
8844726,18474211,-1361450,-13062696,13821877,},
|
|
{-6455177,-7839871,3374702,-4740862,-27098617,
|
|
-10571707,31655028,-7212327,18853322,-14220951,},
|
|
{4566830,-12963868,-28974889,-12240689,-7602672,
|
|
-2830569,-8514358,-10431137,2207753,-3209784,},},
|
|
{{-25154831,-4185821,29681144,7868801,-6854661,
|
|
-9423865,-12437364,-663000,-31111463,-16132436,},
|
|
{25576264,-2703214,7349804,-11814844,16472782,
|
|
9300885,3844789,15725684,171356,6466918,},
|
|
{23103977,13316479,9739013,-16149481,817875,
|
|
-15038942,8965339,-14088058,-30714912,16193877,},},
|
|
{{-33521811,3180713,-2394130,14003687,-16903474,
|
|
-16270840,17238398,4729455,-18074513,9256800,},
|
|
{-25182317,-4174131,32336398,5036987,-21236817,
|
|
11360617,22616405,9761698,-19827198,630305,},
|
|
{-13720693,2639453,-24237460,-7406481,9494427,
|
|
-5774029,-6554551,-15960994,-2449256,-14291300,},},
|
|
{{-3151181,-5046075,9282714,6866145,-31907062,
|
|
-863023,-18940575,15033784,25105118,-7894876,},
|
|
{-24326370,15950226,-31801215,-14592823,-11662737,
|
|
-5090925,1573892,-2625887,2198790,-15804619,},
|
|
{-3099351,10324967,-2241613,7453183,-5446979,
|
|
-2735503,-13812022,-16236442,-32461234,-12290683,},},
|
|
};
|
|
|
|
// Incremental sliding windows (left to right)
|
|
// Based on Roberto Maria Avanzi[2005]
|
|
typedef struct {
|
|
i16 next_index; // position of the next signed digit
|
|
i8 next_digit; // next signed digit (odd number below 2^window_width)
|
|
u8 next_check; // point at which we must check for a new window
|
|
} slide_ctx;
|
|
|
|
static void slide_init(slide_ctx *ctx, const u8 scalar[32])
|
|
{
|
|
// scalar is guaranteed to be below L, either because we checked (s),
|
|
// or because we reduced it modulo L (h_ram). L is under 2^253, so
|
|
// so bits 253 to 255 are guaranteed to be zero. No need to test them.
|
|
//
|
|
// Note however that L is very close to 2^252, so bit 252 is almost
|
|
// always zero. If we were to start at bit 251, the tests wouldn't
|
|
// catch the off-by-one error (constructing one that does would be
|
|
// prohibitively expensive).
|
|
//
|
|
// We should still check bit 252, though.
|
|
int i = 252;
|
|
while (i > 0 && scalar_bit(scalar, i) == 0) {
|
|
i--;
|
|
}
|
|
ctx->next_check = (u8)(i + 1);
|
|
ctx->next_index = -1;
|
|
ctx->next_digit = -1;
|
|
}
|
|
|
|
static int slide_step(slide_ctx *ctx, int width, int i, const u8 scalar[32])
|
|
{
|
|
if (i == ctx->next_check) {
|
|
if (scalar_bit(scalar, i) == scalar_bit(scalar, i - 1)) {
|
|
ctx->next_check--;
|
|
} else {
|
|
// compute digit of next window
|
|
int w = MC_MIN(width, i + 1);
|
|
int v = -(scalar_bit(scalar, i) << (w-1));
|
|
FOR_T (int, j, 0, w-1) {
|
|
v += scalar_bit(scalar, i-(w-1)+j) << j;
|
|
}
|
|
v += scalar_bit(scalar, i-w);
|
|
int lsb = v & (~v + 1); // smallest bit of v
|
|
int s = // log2(lsb)
|
|
(((lsb & 0xAA) != 0) << 0) |
|
|
(((lsb & 0xCC) != 0) << 1) |
|
|
(((lsb & 0xF0) != 0) << 2);
|
|
ctx->next_index = (i16)(i-(w-1)+s);
|
|
ctx->next_digit = (i8) (v >> s );
|
|
ctx->next_check -= (u8) w;
|
|
}
|
|
}
|
|
return i == ctx->next_index ? ctx->next_digit: 0;
|
|
}
|
|
|
|
#define P_W_WIDTH 3 // Affects the size of the stack
|
|
#define B_W_WIDTH 5 // Affects the size of the binary
|
|
#define P_W_SIZE (1<<(P_W_WIDTH-2))
|
|
|
|
int crypto_eddsa_check_equation(const u8 signature[64], const u8 public_key[32],
|
|
const u8 h[32])
|
|
{
|
|
ge minus_A; // -public_key
|
|
ge minus_R; // -first_half_of_signature
|
|
const u8 *s = signature + 32;
|
|
|
|
// Check that A and R are on the curve
|
|
// Check that 0 <= S < L (prevents malleability)
|
|
// *Allow* non-cannonical encoding for A and R
|
|
{
|
|
u32 s32[8];
|
|
load32_le_buf(s32, s, 8);
|
|
if (ge_frombytes_neg_vartime(&minus_A, public_key) ||
|
|
ge_frombytes_neg_vartime(&minus_R, signature) ||
|
|
is_above_l(s32)) {
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
// look-up table for minus_A
|
|
ge_cached lutA[P_W_SIZE];
|
|
{
|
|
ge minus_A2, tmp;
|
|
ge_double(&minus_A2, &minus_A, &tmp);
|
|
ge_cache(&lutA[0], &minus_A);
|
|
FOR (i, 1, P_W_SIZE) {
|
|
ge_add(&tmp, &minus_A2, &lutA[i-1]);
|
|
ge_cache(&lutA[i], &tmp);
|
|
}
|
|
}
|
|
|
|
// sum = [s]B - [h]A
|
|
// Merged double and add ladder, fused with sliding
|
|
slide_ctx h_slide; slide_init(&h_slide, h);
|
|
slide_ctx s_slide; slide_init(&s_slide, s);
|
|
int i = MC_MAX(h_slide.next_check, s_slide.next_check);
|
|
ge *sum = &minus_A; // reuse minus_A for the sum
|
|
ge_zero(sum);
|
|
while (i >= 0) {
|
|
ge tmp;
|
|
ge_double(sum, sum, &tmp);
|
|
int h_digit = slide_step(&h_slide, P_W_WIDTH, i, h);
|
|
int s_digit = slide_step(&s_slide, B_W_WIDTH, i, s);
|
|
if (h_digit > 0) { ge_add(sum, sum, &lutA[ h_digit / 2]); }
|
|
if (h_digit < 0) { ge_sub(sum, sum, &lutA[-h_digit / 2]); }
|
|
fe t1, t2;
|
|
if (s_digit > 0) { ge_madd(sum, sum, b_window + s_digit/2, t1, t2); }
|
|
if (s_digit < 0) { ge_msub(sum, sum, b_window + -s_digit/2, t1, t2); }
|
|
i--;
|
|
}
|
|
|
|
// Compare [8](sum-R) and the zero point
|
|
// The multiplication by 8 eliminates any low-order component
|
|
// and ensures consistency with batched verification.
|
|
ge_cached cached;
|
|
u8 check[32];
|
|
static const u8 zero_point[32] = {1}; // Point of order 1
|
|
ge_cache(&cached, &minus_R);
|
|
ge_add(sum, sum, &cached);
|
|
ge_double(sum, sum, &minus_R); // reuse minus_R as temporary
|
|
ge_double(sum, sum, &minus_R); // reuse minus_R as temporary
|
|
ge_double(sum, sum, &minus_R); // reuse minus_R as temporary
|
|
ge_tobytes(check, sum);
|
|
return crypto_verify32(check, zero_point);
|
|
}
|
|
|
|
// 5-bit signed comb in cached format (Niels coordinates, Z=1)
|
|
static const ge_precomp b_comb_low[8] = {
|
|
{{-6816601,-2324159,-22559413,124364,18015490,
|
|
8373481,19993724,1979872,-18549925,9085059,},
|
|
{10306321,403248,14839893,9633706,8463310,
|
|
-8354981,-14305673,14668847,26301366,2818560,},
|
|
{-22701500,-3210264,-13831292,-2927732,-16326337,
|
|
-14016360,12940910,177905,12165515,-2397893,},},
|
|
{{-12282262,-7022066,9920413,-3064358,-32147467,
|
|
2927790,22392436,-14852487,2719975,16402117,},
|
|
{-7236961,-4729776,2685954,-6525055,-24242706,
|
|
-15940211,-6238521,14082855,10047669,12228189,},
|
|
{-30495588,-12893761,-11161261,3539405,-11502464,
|
|
16491580,-27286798,-15030530,-7272871,-15934455,},},
|
|
{{17650926,582297,-860412,-187745,-12072900,
|
|
-10683391,-20352381,15557840,-31072141,-5019061,},
|
|
{-6283632,-2259834,-4674247,-4598977,-4089240,
|
|
12435688,-31278303,1060251,6256175,10480726,},
|
|
{-13871026,2026300,-21928428,-2741605,-2406664,
|
|
-8034988,7355518,15733500,-23379862,7489131,},},
|
|
{{6883359,695140,23196907,9644202,-33430614,
|
|
11354760,-20134606,6388313,-8263585,-8491918,},
|
|
{-7716174,-13605463,-13646110,14757414,-19430591,
|
|
-14967316,10359532,-11059670,-21935259,12082603,},
|
|
{-11253345,-15943946,10046784,5414629,24840771,
|
|
8086951,-6694742,9868723,15842692,-16224787,},},
|
|
{{9639399,11810955,-24007778,-9320054,3912937,
|
|
-9856959,996125,-8727907,-8919186,-14097242,},
|
|
{7248867,14468564,25228636,-8795035,14346339,
|
|
8224790,6388427,-7181107,6468218,-8720783,},
|
|
{15513115,15439095,7342322,-10157390,18005294,
|
|
-7265713,2186239,4884640,10826567,7135781,},},
|
|
{{-14204238,5297536,-5862318,-6004934,28095835,
|
|
4236101,-14203318,1958636,-16816875,3837147,},
|
|
{-5511166,-13176782,-29588215,12339465,15325758,
|
|
-15945770,-8813185,11075932,-19608050,-3776283,},
|
|
{11728032,9603156,-4637821,-5304487,-7827751,
|
|
2724948,31236191,-16760175,-7268616,14799772,},},
|
|
{{-28842672,4840636,-12047946,-9101456,-1445464,
|
|
381905,-30977094,-16523389,1290540,12798615,},
|
|
{27246947,-10320914,14792098,-14518944,5302070,
|
|
-8746152,-3403974,-4149637,-27061213,10749585,},
|
|
{25572375,-6270368,-15353037,16037944,1146292,
|
|
32198,23487090,9585613,24714571,-1418265,},},
|
|
{{19844825,282124,-17583147,11004019,-32004269,
|
|
-2716035,6105106,-1711007,-21010044,14338445,},
|
|
{8027505,8191102,-18504907,-12335737,25173494,
|
|
-5923905,15446145,7483684,-30440441,10009108,},
|
|
{-14134701,-4174411,10246585,-14677495,33553567,
|
|
-14012935,23366126,15080531,-7969992,7663473,},},
|
|
};
|
|
|
|
static const ge_precomp b_comb_high[8] = {
|
|
{{33055887,-4431773,-521787,6654165,951411,
|
|
-6266464,-5158124,6995613,-5397442,-6985227,},
|
|
{4014062,6967095,-11977872,3960002,8001989,
|
|
5130302,-2154812,-1899602,-31954493,-16173976,},
|
|
{16271757,-9212948,23792794,731486,-25808309,
|
|
-3546396,6964344,-4767590,10976593,10050757,},},
|
|
{{2533007,-4288439,-24467768,-12387405,-13450051,
|
|
14542280,12876301,13893535,15067764,8594792,},
|
|
{20073501,-11623621,3165391,-13119866,13188608,
|
|
-11540496,-10751437,-13482671,29588810,2197295,},
|
|
{-1084082,11831693,6031797,14062724,14748428,
|
|
-8159962,-20721760,11742548,31368706,13161200,},},
|
|
{{2050412,-6457589,15321215,5273360,25484180,
|
|
124590,-18187548,-7097255,-6691621,-14604792,},
|
|
{9938196,2162889,-6158074,-1711248,4278932,
|
|
-2598531,-22865792,-7168500,-24323168,11746309,},
|
|
{-22691768,-14268164,5965485,9383325,20443693,
|
|
5854192,28250679,-1381811,-10837134,13717818,},},
|
|
{{-8495530,16382250,9548884,-4971523,-4491811,
|
|
-3902147,6182256,-12832479,26628081,10395408,},
|
|
{27329048,-15853735,7715764,8717446,-9215518,
|
|
-14633480,28982250,-5668414,4227628,242148,},
|
|
{-13279943,-7986904,-7100016,8764468,-27276630,
|
|
3096719,29678419,-9141299,3906709,11265498,},},
|
|
{{11918285,15686328,-17757323,-11217300,-27548967,
|
|
4853165,-27168827,6807359,6871949,-1075745,},
|
|
{-29002610,13984323,-27111812,-2713442,28107359,
|
|
-13266203,6155126,15104658,3538727,-7513788,},
|
|
{14103158,11233913,-33165269,9279850,31014152,
|
|
4335090,-1827936,4590951,13960841,12787712,},},
|
|
{{1469134,-16738009,33411928,13942824,8092558,
|
|
-8778224,-11165065,1437842,22521552,-2792954,},
|
|
{31352705,-4807352,-25327300,3962447,12541566,
|
|
-9399651,-27425693,7964818,-23829869,5541287,},
|
|
{-25732021,-6864887,23848984,3039395,-9147354,
|
|
6022816,-27421653,10590137,25309915,-1584678,},},
|
|
{{-22951376,5048948,31139401,-190316,-19542447,
|
|
-626310,-17486305,-16511925,-18851313,-12985140,},
|
|
{-9684890,14681754,30487568,7717771,-10829709,
|
|
9630497,30290549,-10531496,-27798994,-13812825,},
|
|
{5827835,16097107,-24501327,12094619,7413972,
|
|
11447087,28057551,-1793987,-14056981,4359312,},},
|
|
{{26323183,2342588,-21887793,-1623758,-6062284,
|
|
2107090,-28724907,9036464,-19618351,-13055189,},
|
|
{-29697200,14829398,-4596333,14220089,-30022969,
|
|
2955645,12094100,-13693652,-5941445,7047569,},
|
|
{-3201977,14413268,-12058324,-16417589,-9035655,
|
|
-7224648,9258160,1399236,30397584,-5684634,},},
|
|
};
|
|
|
|
static void lookup_add(ge *p, ge_precomp *tmp_c, fe tmp_a, fe tmp_b,
|
|
const ge_precomp comb[8], const u8 scalar[32], int i)
|
|
{
|
|
u8 teeth = (u8)((scalar_bit(scalar, i) ) +
|
|
(scalar_bit(scalar, i + 32) << 1) +
|
|
(scalar_bit(scalar, i + 64) << 2) +
|
|
(scalar_bit(scalar, i + 96) << 3));
|
|
u8 high = teeth >> 3;
|
|
u8 index = (teeth ^ (high - 1)) & 7;
|
|
FOR (j, 0, 8) {
|
|
i32 select = 1 & (((j ^ index) - 1) >> 8);
|
|
fe_ccopy(tmp_c->Yp, comb[j].Yp, select);
|
|
fe_ccopy(tmp_c->Ym, comb[j].Ym, select);
|
|
fe_ccopy(tmp_c->T2, comb[j].T2, select);
|
|
}
|
|
fe_neg(tmp_a, tmp_c->T2);
|
|
fe_cswap(tmp_c->T2, tmp_a , high ^ 1);
|
|
fe_cswap(tmp_c->Yp, tmp_c->Ym, high ^ 1);
|
|
ge_madd(p, p, tmp_c, tmp_a, tmp_b);
|
|
}
|
|
|
|
// p = [scalar]B, where B is the base point
|
|
static void ge_scalarmult_base(ge *p, const u8 scalar[32])
|
|
{
|
|
// twin 4-bits signed combs, from Mike Hamburg's
|
|
// Fast and compact elliptic-curve cryptography (2012)
|
|
// 1 / 2 modulo L
|
|
static const u8 half_mod_L[32] = {
|
|
247,233,122,46,141,49,9,44,107,206,123,81,239,124,111,10,
|
|
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,8,
|
|
};
|
|
// (2^256 - 1) / 2 modulo L
|
|
static const u8 half_ones[32] = {
|
|
142,74,204,70,186,24,118,107,184,231,190,57,250,173,119,99,
|
|
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,7,
|
|
};
|
|
|
|
// All bits set form: 1 means 1, 0 means -1
|
|
u8 s_scalar[32];
|
|
crypto_eddsa_mul_add(s_scalar, scalar, half_mod_L, half_ones);
|
|
|
|
// Double and add ladder
|
|
fe tmp_a, tmp_b; // temporaries for addition
|
|
ge_precomp tmp_c; // temporary for comb lookup
|
|
ge tmp_d; // temporary for doubling
|
|
fe_1(tmp_c.Yp);
|
|
fe_1(tmp_c.Ym);
|
|
fe_0(tmp_c.T2);
|
|
|
|
// Save a double on the first iteration
|
|
ge_zero(p);
|
|
lookup_add(p, &tmp_c, tmp_a, tmp_b, b_comb_low , s_scalar, 31);
|
|
lookup_add(p, &tmp_c, tmp_a, tmp_b, b_comb_high, s_scalar, 31+128);
|
|
// Regular double & add for the rest
|
|
for (int i = 30; i >= 0; i--) {
|
|
ge_double(p, p, &tmp_d);
|
|
lookup_add(p, &tmp_c, tmp_a, tmp_b, b_comb_low , s_scalar, i);
|
|
lookup_add(p, &tmp_c, tmp_a, tmp_b, b_comb_high, s_scalar, i+128);
|
|
}
|
|
// Note: we could save one addition at the end if we assumed the
|
|
// scalar fit in 252 bits. Which it does in practice if it is
|
|
// selected at random. However, non-random, non-hashed scalars
|
|
// *can* overflow 252 bits in practice. Better account for that
|
|
// than leaving that kind of subtle corner case.
|
|
|
|
WIPE_BUFFER(tmp_a); WIPE_CTX(&tmp_d);
|
|
WIPE_BUFFER(tmp_b); WIPE_CTX(&tmp_c);
|
|
WIPE_BUFFER(s_scalar);
|
|
}
|
|
|
|
void crypto_eddsa_scalarbase(u8 point[32], const u8 scalar[32])
|
|
{
|
|
ge P;
|
|
ge_scalarmult_base(&P, scalar);
|
|
ge_tobytes(point, &P);
|
|
WIPE_CTX(&P);
|
|
}
|
|
|
|
void crypto_eddsa_key_pair(u8 secret_key[64], u8 public_key[32], u8 seed[32])
|
|
{
|
|
// To allow overlaps, observable writes happen in this order:
|
|
// 1. seed
|
|
// 2. secret_key
|
|
// 3. public_key
|
|
u8 a[64];
|
|
COPY(a, seed, 32);
|
|
crypto_wipe(seed, 32);
|
|
COPY(secret_key, a, 32);
|
|
crypto_blake2b(a, 64, a, 32);
|
|
crypto_eddsa_trim_scalar(a, a);
|
|
crypto_eddsa_scalarbase(secret_key + 32, a);
|
|
COPY(public_key, secret_key + 32, 32);
|
|
WIPE_BUFFER(a);
|
|
}
|
|
|
|
static void hash_reduce(u8 h[32],
|
|
const u8 *a, size_t a_size,
|
|
const u8 *b, size_t b_size,
|
|
const u8 *c, size_t c_size)
|
|
{
|
|
u8 hash[64];
|
|
crypto_blake2b_ctx ctx;
|
|
crypto_blake2b_init (&ctx, 64);
|
|
crypto_blake2b_update(&ctx, a, a_size);
|
|
crypto_blake2b_update(&ctx, b, b_size);
|
|
crypto_blake2b_update(&ctx, c, c_size);
|
|
crypto_blake2b_final (&ctx, hash);
|
|
crypto_eddsa_reduce(h, hash);
|
|
}
|
|
|
|
// Digital signature of a message with from a secret key.
|
|
//
|
|
// The secret key comprises two parts:
|
|
// - The seed that generates the key (secret_key[ 0..31])
|
|
// - The public key (secret_key[32..63])
|
|
//
|
|
// The seed and the public key are bundled together to make sure users
|
|
// don't use mismatched seeds and public keys, which would instantly
|
|
// leak the secret scalar and allow forgeries (allowing this to happen
|
|
// has resulted in critical vulnerabilities in the wild).
|
|
//
|
|
// The seed is hashed to derive the secret scalar and a secret prefix.
|
|
// The sole purpose of the prefix is to generate a secret random nonce.
|
|
// The properties of that nonce must be as follows:
|
|
// - Unique: we need a different one for each message.
|
|
// - Secret: third parties must not be able to predict it.
|
|
// - Random: any detectable bias would break all security.
|
|
//
|
|
// There are two ways to achieve these properties. The obvious one is
|
|
// to simply generate a random number. Here that would be a parameter
|
|
// (Monocypher doesn't have an RNG). It works, but then users may reuse
|
|
// the nonce by accident, which _also_ leaks the secret scalar and
|
|
// allows forgeries. This has happened in the wild too.
|
|
//
|
|
// This is no good, so instead we generate that nonce deterministically
|
|
// by reducing modulo L a hash of the secret prefix and the message.
|
|
// The secret prefix makes the nonce unpredictable, the message makes it
|
|
// unique, and the hash/reduce removes all bias.
|
|
//
|
|
// The cost of that safety is hashing the message twice. If that cost
|
|
// is unacceptable, there are two alternatives:
|
|
//
|
|
// - Signing a hash of the message instead of the message itself. This
|
|
// is fine as long as the hash is collision resistant. It is not
|
|
// compatible with existing "pure" signatures, but at least it's safe.
|
|
//
|
|
// - Using a random nonce. Please exercise **EXTREME CAUTION** if you
|
|
// ever do that. It is absolutely **critical** that the nonce is
|
|
// really an unbiased random number between 0 and L-1, never reused,
|
|
// and wiped immediately.
|
|
//
|
|
// To lower the likelihood of complete catastrophe if the RNG is
|
|
// either flawed or misused, you can hash the RNG output together with
|
|
// the secret prefix and the beginning of the message, and use the
|
|
// reduction of that hash instead of the RNG output itself. It's not
|
|
// foolproof (you'd need to hash the whole message) but it helps.
|
|
//
|
|
// Signing a message involves the following operations:
|
|
//
|
|
// scalar, prefix = HASH(secret_key)
|
|
// r = HASH(prefix || message) % L
|
|
// R = [r]B
|
|
// h = HASH(R || public_key || message) % L
|
|
// S = ((h * a) + r) % L
|
|
// signature = R || S
|
|
void crypto_eddsa_sign(u8 signature [64], const u8 secret_key[64],
|
|
const u8 *message, size_t message_size)
|
|
{
|
|
u8 a[64]; // secret scalar and prefix
|
|
u8 r[32]; // secret deterministic "random" nonce
|
|
u8 h[32]; // publically verifiable hash of the message (not wiped)
|
|
u8 R[32]; // first half of the signature (allows overlapping inputs)
|
|
|
|
crypto_blake2b(a, 64, secret_key, 32);
|
|
crypto_eddsa_trim_scalar(a, a);
|
|
hash_reduce(r, a + 32, 32, message, message_size, 0, 0);
|
|
crypto_eddsa_scalarbase(R, r);
|
|
hash_reduce(h, R, 32, secret_key + 32, 32, message, message_size);
|
|
COPY(signature, R, 32);
|
|
crypto_eddsa_mul_add(signature + 32, h, a, r);
|
|
|
|
WIPE_BUFFER(a);
|
|
WIPE_BUFFER(r);
|
|
}
|
|
|
|
// To check the signature R, S of the message M with the public key A,
|
|
// there are 3 steps:
|
|
//
|
|
// compute h = HASH(R || A || message) % L
|
|
// check that A is on the curve.
|
|
// check that R == [s]B - [h]A
|
|
//
|
|
// The last two steps are done in crypto_eddsa_check_equation()
|
|
int crypto_eddsa_check(const u8 signature[64], const u8 public_key[32],
|
|
const u8 *message, size_t message_size)
|
|
{
|
|
u8 h[32];
|
|
hash_reduce(h, signature, 32, public_key, 32, message, message_size);
|
|
return crypto_eddsa_check_equation(signature, public_key, h);
|
|
}
|
|
|
|
/////////////////////////
|
|
/// EdDSA <--> X25519 ///
|
|
/////////////////////////
|
|
void crypto_eddsa_to_x25519(u8 x25519[32], const u8 eddsa[32])
|
|
{
|
|
// (u, v) = ((1+y)/(1-y), sqrt(-486664)*u/x)
|
|
// Only converting y to u, the sign of x is ignored.
|
|
fe t1, t2;
|
|
fe_frombytes(t2, eddsa);
|
|
fe_add(t1, fe_one, t2);
|
|
fe_sub(t2, fe_one, t2);
|
|
fe_invert(t2, t2);
|
|
fe_mul(t1, t1, t2);
|
|
fe_tobytes(x25519, t1);
|
|
WIPE_BUFFER(t1);
|
|
WIPE_BUFFER(t2);
|
|
}
|
|
|
|
void crypto_x25519_to_eddsa(u8 eddsa[32], const u8 x25519[32])
|
|
{
|
|
// (x, y) = (sqrt(-486664)*u/v, (u-1)/(u+1))
|
|
// Only converting u to y, x is assumed positive.
|
|
fe t1, t2;
|
|
fe_frombytes(t2, x25519);
|
|
fe_sub(t1, t2, fe_one);
|
|
fe_add(t2, t2, fe_one);
|
|
fe_invert(t2, t2);
|
|
fe_mul(t1, t1, t2);
|
|
fe_tobytes(eddsa, t1);
|
|
WIPE_BUFFER(t1);
|
|
WIPE_BUFFER(t2);
|
|
}
|
|
|
|
/////////////////////////////////////////////
|
|
/// Dirty ephemeral public key generation ///
|
|
/////////////////////////////////////////////
|
|
|
|
// Those functions generates a public key, *without* clearing the
|
|
// cofactor. Sending that key over the network leaks 3 bits of the
|
|
// private key. Use only to generate ephemeral keys that will be hidden
|
|
// with crypto_curve_to_hidden().
|
|
//
|
|
// The public key is otherwise compatible with crypto_x25519(), which
|
|
// properly clears the cofactor.
|
|
//
|
|
// Note that the distribution of the resulting public keys is almost
|
|
// uniform. Flipping the sign of the v coordinate (not provided by this
|
|
// function), covers the entire key space almost perfectly, where
|
|
// "almost" means a 2^-128 bias (undetectable). This uniformity is
|
|
// needed to ensure the proper randomness of the resulting
|
|
// representatives (once we apply crypto_curve_to_hidden()).
|
|
//
|
|
// Recall that Curve25519 has order C = 2^255 + e, with e < 2^128 (not
|
|
// to be confused with the prime order of the main subgroup, L, which is
|
|
// 8 times less than that).
|
|
//
|
|
// Generating all points would require us to multiply a point of order C
|
|
// (the base point plus any point of order 8) by all scalars from 0 to
|
|
// C-1. Clamping limits us to scalars between 2^254 and 2^255 - 1. But
|
|
// by negating the resulting point at random, we also cover scalars from
|
|
// -2^255 + 1 to -2^254 (which modulo C is congruent to e+1 to 2^254 + e).
|
|
//
|
|
// In practice:
|
|
// - Scalars from 0 to e + 1 are never generated
|
|
// - Scalars from 2^255 to 2^255 + e are never generated
|
|
// - Scalars from 2^254 + 1 to 2^254 + e are generated twice
|
|
//
|
|
// Since e < 2^128, detecting this bias requires observing over 2^100
|
|
// representatives from a given source (this will never happen), *and*
|
|
// recovering enough of the private key to determine that they do, or do
|
|
// not, belong to the biased set (this practically requires solving
|
|
// discrete logarithm, which is conjecturally intractable).
|
|
//
|
|
// In practice, this means the bias is impossible to detect.
|
|
|
|
// s + (x*L) % 8*L
|
|
// Guaranteed to fit in 256 bits iff s fits in 255 bits.
|
|
// L < 2^253
|
|
// x%8 < 2^3
|
|
// L * (x%8) < 2^255
|
|
// s < 2^255
|
|
// s + L * (x%8) < 2^256
|
|
static void add_xl(u8 s[32], u8 x)
|
|
{
|
|
u64 mod8 = x & 7;
|
|
u64 carry = 0;
|
|
FOR (i , 0, 8) {
|
|
carry = carry + load32_le(s + 4*i) + L[i] * mod8;
|
|
store32_le(s + 4*i, (u32)carry);
|
|
carry >>= 32;
|
|
}
|
|
}
|
|
|
|
// "Small" dirty ephemeral key.
|
|
// Use if you need to shrink the size of the binary, and can afford to
|
|
// slow down by a factor of two (compared to the fast version)
|
|
//
|
|
// This version works by decoupling the cofactor from the main factor.
|
|
//
|
|
// - The trimmed scalar determines the main factor
|
|
// - The clamped bits of the scalar determine the cofactor.
|
|
//
|
|
// Cofactor and main factor are combined into a single scalar, which is
|
|
// then multiplied by a point of order 8*L (unlike the base point, which
|
|
// has prime order). That "dirty" base point is the addition of the
|
|
// regular base point (9), and a point of order 8.
|
|
void crypto_x25519_dirty_small(u8 public_key[32], const u8 secret_key[32])
|
|
{
|
|
// Base point of order 8*L
|
|
// Raw scalar multiplication with it does not clear the cofactor,
|
|
// and the resulting public key will reveal 3 bits of the scalar.
|
|
//
|
|
// The low order component of this base point has been chosen
|
|
// to yield the same results as crypto_x25519_dirty_fast().
|
|
static const u8 dirty_base_point[32] = {
|
|
0xd8, 0x86, 0x1a, 0xa2, 0x78, 0x7a, 0xd9, 0x26,
|
|
0x8b, 0x74, 0x74, 0xb6, 0x82, 0xe3, 0xbe, 0xc3,
|
|
0xce, 0x36, 0x9a, 0x1e, 0x5e, 0x31, 0x47, 0xa2,
|
|
0x6d, 0x37, 0x7c, 0xfd, 0x20, 0xb5, 0xdf, 0x75,
|
|
};
|
|
// separate the main factor & the cofactor of the scalar
|
|
u8 scalar[32];
|
|
crypto_eddsa_trim_scalar(scalar, secret_key);
|
|
|
|
// Separate the main factor and the cofactor
|
|
//
|
|
// The scalar is trimmed, so its cofactor is cleared. The three
|
|
// least significant bits however still have a main factor. We must
|
|
// remove it for X25519 compatibility.
|
|
//
|
|
// cofactor = lsb * L (modulo 8*L)
|
|
// combined = scalar + cofactor (modulo 8*L)
|
|
add_xl(scalar, secret_key[0]);
|
|
scalarmult(public_key, scalar, dirty_base_point, 256);
|
|
WIPE_BUFFER(scalar);
|
|
}
|
|
|
|
// Select low order point
|
|
// We're computing the [cofactor]lop scalar multiplication, where:
|
|
//
|
|
// cofactor = tweak & 7.
|
|
// lop = (lop_x, lop_y)
|
|
// lop_x = sqrt((sqrt(d + 1) + 1) / d)
|
|
// lop_y = -lop_x * sqrtm1
|
|
//
|
|
// The low order point has order 8. There are 4 such points. We've
|
|
// chosen the one whose both coordinates are positive (below p/2).
|
|
// The 8 low order points are as follows:
|
|
//
|
|
// [0]lop = ( 0 , 1 )
|
|
// [1]lop = ( lop_x , lop_y)
|
|
// [2]lop = ( sqrt(-1), -0 )
|
|
// [3]lop = ( lop_x , -lop_y)
|
|
// [4]lop = (-0 , -1 )
|
|
// [5]lop = (-lop_x , -lop_y)
|
|
// [6]lop = (-sqrt(-1), 0 )
|
|
// [7]lop = (-lop_x , lop_y)
|
|
//
|
|
// The x coordinate is either 0, sqrt(-1), lop_x, or their opposite.
|
|
// The y coordinate is either 0, -1 , lop_y, or their opposite.
|
|
// The pattern for both is the same, except for a rotation of 2 (modulo 8)
|
|
//
|
|
// This helper function captures the pattern, and we can use it thus:
|
|
//
|
|
// select_lop(x, lop_x, sqrtm1, cofactor);
|
|
// select_lop(y, lop_y, fe_one, cofactor + 2);
|
|
//
|
|
// This is faster than an actual scalar multiplication,
|
|
// and requires less code than naive constant time look up.
|
|
static void select_lop(fe out, const fe x, const fe k, u8 cofactor)
|
|
{
|
|
fe tmp;
|
|
fe_0(out);
|
|
fe_ccopy(out, k , (cofactor >> 1) & 1); // bit 1
|
|
fe_ccopy(out, x , (cofactor >> 0) & 1); // bit 0
|
|
fe_neg (tmp, out);
|
|
fe_ccopy(out, tmp, (cofactor >> 2) & 1); // bit 2
|
|
WIPE_BUFFER(tmp);
|
|
}
|
|
|
|
// "Fast" dirty ephemeral key
|
|
// We use this one by default.
|
|
//
|
|
// This version works by performing a regular scalar multiplication,
|
|
// then add a low order point. The scalar multiplication is done in
|
|
// Edwards space for more speed (*2 compared to the "small" version).
|
|
// The cost is a bigger binary for programs that don't also sign messages.
|
|
void crypto_x25519_dirty_fast(u8 public_key[32], const u8 secret_key[32])
|
|
{
|
|
// Compute clean scalar multiplication
|
|
u8 scalar[32];
|
|
ge pk;
|
|
crypto_eddsa_trim_scalar(scalar, secret_key);
|
|
ge_scalarmult_base(&pk, scalar);
|
|
|
|
// Compute low order point
|
|
fe t1, t2;
|
|
select_lop(t1, lop_x, sqrtm1, secret_key[0]);
|
|
select_lop(t2, lop_y, fe_one, secret_key[0] + 2);
|
|
ge_precomp low_order_point;
|
|
fe_add(low_order_point.Yp, t2, t1);
|
|
fe_sub(low_order_point.Ym, t2, t1);
|
|
fe_mul(low_order_point.T2, t2, t1);
|
|
fe_mul(low_order_point.T2, low_order_point.T2, D2);
|
|
|
|
// Add low order point to the public key
|
|
ge_madd(&pk, &pk, &low_order_point, t1, t2);
|
|
|
|
// Convert to Montgomery u coordinate (we ignore the sign)
|
|
fe_add(t1, pk.Z, pk.Y);
|
|
fe_sub(t2, pk.Z, pk.Y);
|
|
fe_invert(t2, t2);
|
|
fe_mul(t1, t1, t2);
|
|
|
|
fe_tobytes(public_key, t1);
|
|
|
|
WIPE_BUFFER(t1); WIPE_CTX(&pk);
|
|
WIPE_BUFFER(t2); WIPE_CTX(&low_order_point);
|
|
WIPE_BUFFER(scalar);
|
|
}
|
|
|
|
///////////////////
|
|
/// Elligator 2 ///
|
|
///////////////////
|
|
static const fe A = {486662};
|
|
|
|
// Elligator direct map
|
|
//
|
|
// Computes the point corresponding to a representative, encoded in 32
|
|
// bytes (little Endian). Since positive representatives fits in 254
|
|
// bits, The two most significant bits are ignored.
|
|
//
|
|
// From the paper:
|
|
// w = -A / (fe(1) + non_square * r^2)
|
|
// e = chi(w^3 + A*w^2 + w)
|
|
// u = e*w - (fe(1)-e)*(A//2)
|
|
// v = -e * sqrt(u^3 + A*u^2 + u)
|
|
//
|
|
// We ignore v because we don't need it for X25519 (the Montgomery
|
|
// ladder only uses u).
|
|
//
|
|
// Note that e is either 0, 1 or -1
|
|
// if e = 0 u = 0 and v = 0
|
|
// if e = 1 u = w
|
|
// if e = -1 u = -w - A = w * non_square * r^2
|
|
//
|
|
// Let r1 = non_square * r^2
|
|
// Let r2 = 1 + r1
|
|
// Note that r2 cannot be zero, -1/non_square is not a square.
|
|
// We can (tediously) verify that:
|
|
// w^3 + A*w^2 + w = (A^2*r1 - r2^2) * A / r2^3
|
|
// Therefore:
|
|
// chi(w^3 + A*w^2 + w) = chi((A^2*r1 - r2^2) * (A / r2^3))
|
|
// chi(w^3 + A*w^2 + w) = chi((A^2*r1 - r2^2) * (A / r2^3)) * 1
|
|
// chi(w^3 + A*w^2 + w) = chi((A^2*r1 - r2^2) * (A / r2^3)) * chi(r2^6)
|
|
// chi(w^3 + A*w^2 + w) = chi((A^2*r1 - r2^2) * (A / r2^3) * r2^6)
|
|
// chi(w^3 + A*w^2 + w) = chi((A^2*r1 - r2^2) * A * r2^3)
|
|
// Corollary:
|
|
// e = 1 if (A^2*r1 - r2^2) * A * r2^3) is a non-zero square
|
|
// e = -1 if (A^2*r1 - r2^2) * A * r2^3) is not a square
|
|
// Note that w^3 + A*w^2 + w (and therefore e) can never be zero:
|
|
// w^3 + A*w^2 + w = w * (w^2 + A*w + 1)
|
|
// w^3 + A*w^2 + w = w * (w^2 + A*w + A^2/4 - A^2/4 + 1)
|
|
// w^3 + A*w^2 + w = w * (w + A/2)^2 - A^2/4 + 1)
|
|
// which is zero only if:
|
|
// w = 0 (impossible)
|
|
// (w + A/2)^2 = A^2/4 - 1 (impossible, because A^2/4-1 is not a square)
|
|
//
|
|
// Let isr = invsqrt((A^2*r1 - r2^2) * A * r2^3)
|
|
// isr = sqrt(1 / ((A^2*r1 - r2^2) * A * r2^3)) if e = 1
|
|
// isr = sqrt(sqrt(-1) / ((A^2*r1 - r2^2) * A * r2^3)) if e = -1
|
|
//
|
|
// if e = 1
|
|
// let u1 = -A * (A^2*r1 - r2^2) * A * r2^2 * isr^2
|
|
// u1 = w
|
|
// u1 = u
|
|
//
|
|
// if e = -1
|
|
// let ufactor = -non_square * sqrt(-1) * r^2
|
|
// let vfactor = sqrt(ufactor)
|
|
// let u2 = -A * (A^2*r1 - r2^2) * A * r2^2 * isr^2 * ufactor
|
|
// u2 = w * -1 * -non_square * r^2
|
|
// u2 = w * non_square * r^2
|
|
// u2 = u
|
|
void crypto_elligator_map(u8 curve[32], const u8 hidden[32])
|
|
{
|
|
fe r, u, t1, t2, t3;
|
|
fe_frombytes_mask(r, hidden, 2); // r is encoded in 254 bits.
|
|
fe_sq(r, r);
|
|
fe_add(t1, r, r);
|
|
fe_add(u, t1, fe_one);
|
|
fe_sq (t2, u);
|
|
fe_mul(t3, A2, t1);
|
|
fe_sub(t3, t3, t2);
|
|
fe_mul(t3, t3, A);
|
|
fe_mul(t1, t2, u);
|
|
fe_mul(t1, t3, t1);
|
|
int is_square = invsqrt(t1, t1);
|
|
fe_mul(u, r, ufactor);
|
|
fe_ccopy(u, fe_one, is_square);
|
|
fe_sq (t1, t1);
|
|
fe_mul(u, u, A);
|
|
fe_mul(u, u, t3);
|
|
fe_mul(u, u, t2);
|
|
fe_mul(u, u, t1);
|
|
fe_neg(u, u);
|
|
fe_tobytes(curve, u);
|
|
|
|
WIPE_BUFFER(t1); WIPE_BUFFER(r);
|
|
WIPE_BUFFER(t2); WIPE_BUFFER(u);
|
|
WIPE_BUFFER(t3);
|
|
}
|
|
|
|
// Elligator inverse map
|
|
//
|
|
// Computes the representative of a point, if possible. If not, it does
|
|
// nothing and returns -1. Note that the success of the operation
|
|
// depends only on the point (more precisely its u coordinate). The
|
|
// tweak parameter is used only upon success
|
|
//
|
|
// The tweak should be a random byte. Beyond that, its contents are an
|
|
// implementation detail. Currently, the tweak comprises:
|
|
// - Bit 1 : sign of the v coordinate (0 if positive, 1 if negative)
|
|
// - Bit 2-5: not used
|
|
// - Bits 6-7: random padding
|
|
//
|
|
// From the paper:
|
|
// Let sq = -non_square * u * (u+A)
|
|
// if sq is not a square, or u = -A, there is no mapping
|
|
// Assuming there is a mapping:
|
|
// if v is positive: r = sqrt(-u / (non_square * (u+A)))
|
|
// if v is negative: r = sqrt(-(u+A) / (non_square * u ))
|
|
//
|
|
// We compute isr = invsqrt(-non_square * u * (u+A))
|
|
// if it wasn't a square, abort.
|
|
// else, isr = sqrt(-1 / (non_square * u * (u+A))
|
|
//
|
|
// If v is positive, we return isr * u:
|
|
// isr * u = sqrt(-1 / (non_square * u * (u+A)) * u
|
|
// isr * u = sqrt(-u / (non_square * (u+A))
|
|
//
|
|
// If v is negative, we return isr * (u+A):
|
|
// isr * (u+A) = sqrt(-1 / (non_square * u * (u+A)) * (u+A)
|
|
// isr * (u+A) = sqrt(-(u+A) / (non_square * u)
|
|
int crypto_elligator_rev(u8 hidden[32], const u8 public_key[32], u8 tweak)
|
|
{
|
|
fe t1, t2, t3;
|
|
fe_frombytes(t1, public_key); // t1 = u
|
|
|
|
fe_add(t2, t1, A); // t2 = u + A
|
|
fe_mul(t3, t1, t2);
|
|
fe_mul_small(t3, t3, -2);
|
|
int is_square = invsqrt(t3, t3); // t3 = sqrt(-1 / non_square * u * (u+A))
|
|
if (is_square) {
|
|
// The only variable time bit. This ultimately reveals how many
|
|
// tries it took us to find a representable key.
|
|
// This does not affect security as long as we try keys at random.
|
|
|
|
fe_ccopy (t1, t2, tweak & 1); // multiply by u if v is positive,
|
|
fe_mul (t3, t1, t3); // multiply by u+A otherwise
|
|
fe_mul_small(t1, t3, 2);
|
|
fe_neg (t2, t3);
|
|
fe_ccopy (t3, t2, fe_isodd(t1));
|
|
fe_tobytes(hidden, t3);
|
|
|
|
// Pad with two random bits
|
|
hidden[31] |= tweak & 0xc0;
|
|
}
|
|
|
|
WIPE_BUFFER(t1);
|
|
WIPE_BUFFER(t2);
|
|
WIPE_BUFFER(t3);
|
|
return is_square - 1;
|
|
}
|
|
|
|
void crypto_elligator_key_pair(u8 hidden[32], u8 secret_key[32], u8 seed[32])
|
|
{
|
|
u8 pk [32]; // public key
|
|
u8 buf[64]; // seed + representative
|
|
COPY(buf + 32, seed, 32);
|
|
do {
|
|
crypto_chacha20_djb(buf, 0, 64, buf+32, zero, 0);
|
|
crypto_x25519_dirty_fast(pk, buf); // or the "small" version
|
|
} while(crypto_elligator_rev(buf+32, pk, buf[32]));
|
|
// Note that the return value of crypto_elligator_rev() is
|
|
// independent from its tweak parameter.
|
|
// Therefore, buf[32] is not actually reused. Either we loop one
|
|
// more time and buf[32] is used for the new seed, or we succeeded,
|
|
// and buf[32] becomes the tweak parameter.
|
|
|
|
crypto_wipe(seed, 32);
|
|
COPY(hidden , buf + 32, 32);
|
|
COPY(secret_key, buf , 32);
|
|
WIPE_BUFFER(buf);
|
|
WIPE_BUFFER(pk);
|
|
}
|
|
|
|
///////////////////////
|
|
/// Scalar division ///
|
|
///////////////////////
|
|
|
|
// Montgomery reduction.
|
|
// Divides x by (2^256), and reduces the result modulo L
|
|
//
|
|
// Precondition:
|
|
// x < L * 2^256
|
|
// Constants:
|
|
// r = 2^256 (makes division by r trivial)
|
|
// k = (r * (1/r) - 1) // L (1/r is computed modulo L )
|
|
// Algorithm:
|
|
// s = (x * k) % r
|
|
// t = x + s*L (t is always a multiple of r)
|
|
// u = (t/r) % L (u is always below 2*L, conditional subtraction is enough)
|
|
static void redc(u32 u[8], u32 x[16])
|
|
{
|
|
static const u32 k[8] = {
|
|
0x12547e1b, 0xd2b51da3, 0xfdba84ff, 0xb1a206f2,
|
|
0xffa36bea, 0x14e75438, 0x6fe91836, 0x9db6c6f2,
|
|
};
|
|
|
|
// s = x * k (modulo 2^256)
|
|
// This is cheaper than the full multiplication.
|
|
u32 s[8] = {0};
|
|
FOR (i, 0, 8) {
|
|
u64 carry = 0;
|
|
FOR (j, 0, 8-i) {
|
|
carry += s[i+j] + (u64)x[i] * k[j];
|
|
s[i+j] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
}
|
|
u32 t[16] = {0};
|
|
multiply(t, s, L);
|
|
|
|
// t = t + x
|
|
u64 carry = 0;
|
|
FOR (i, 0, 16) {
|
|
carry += (u64)t[i] + x[i];
|
|
t[i] = (u32)carry;
|
|
carry >>= 32;
|
|
}
|
|
|
|
// u = (t / 2^256) % L
|
|
// Note that t / 2^256 is always below 2*L,
|
|
// So a constant time conditional subtraction is enough
|
|
remove_l(u, t+8);
|
|
|
|
WIPE_BUFFER(s);
|
|
WIPE_BUFFER(t);
|
|
}
|
|
|
|
void crypto_x25519_inverse(u8 blind_salt [32], const u8 private_key[32],
|
|
const u8 curve_point[32])
|
|
{
|
|
static const u8 Lm2[32] = { // L - 2
|
|
0xeb, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,
|
|
0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
|
|
};
|
|
// 1 in Montgomery form
|
|
u32 m_inv [8] = {
|
|
0x8d98951d, 0xd6ec3174, 0x737dcf70, 0xc6ef5bf4,
|
|
0xfffffffe, 0xffffffff, 0xffffffff, 0x0fffffff,
|
|
};
|
|
|
|
u8 scalar[32];
|
|
crypto_eddsa_trim_scalar(scalar, private_key);
|
|
|
|
// Convert the scalar in Montgomery form
|
|
// m_scl = scalar * 2^256 (modulo L)
|
|
u32 m_scl[8];
|
|
{
|
|
u32 tmp[16];
|
|
ZERO(tmp, 8);
|
|
load32_le_buf(tmp+8, scalar, 8);
|
|
mod_l(scalar, tmp);
|
|
load32_le_buf(m_scl, scalar, 8);
|
|
WIPE_BUFFER(tmp); // Wipe ASAP to save stack space
|
|
}
|
|
|
|
// Compute the inverse
|
|
u32 product[16];
|
|
for (int i = 252; i >= 0; i--) {
|
|
ZERO(product, 16);
|
|
multiply(product, m_inv, m_inv);
|
|
redc(m_inv, product);
|
|
if (scalar_bit(Lm2, i)) {
|
|
ZERO(product, 16);
|
|
multiply(product, m_inv, m_scl);
|
|
redc(m_inv, product);
|
|
}
|
|
}
|
|
// Convert the inverse *out* of Montgomery form
|
|
// scalar = m_inv / 2^256 (modulo L)
|
|
COPY(product, m_inv, 8);
|
|
ZERO(product + 8, 8);
|
|
redc(m_inv, product);
|
|
store32_le_buf(scalar, m_inv, 8); // the *inverse* of the scalar
|
|
|
|
// Clear the cofactor of scalar:
|
|
// cleared = scalar * (3*L + 1) (modulo 8*L)
|
|
// cleared = scalar + scalar * 3 * L (modulo 8*L)
|
|
// Note that (scalar * 3) is reduced modulo 8, so we only need the
|
|
// first byte.
|
|
add_xl(scalar, scalar[0] * 3);
|
|
|
|
// Recall that 8*L < 2^256. However it is also very close to
|
|
// 2^255. If we spanned the ladder over 255 bits, random tests
|
|
// wouldn't catch the off-by-one error.
|
|
scalarmult(blind_salt, scalar, curve_point, 256);
|
|
|
|
WIPE_BUFFER(scalar); WIPE_BUFFER(m_scl);
|
|
WIPE_BUFFER(product); WIPE_BUFFER(m_inv);
|
|
}
|
|
|
|
////////////////////////////////
|
|
/// Authenticated encryption ///
|
|
////////////////////////////////
|
|
static void lock_auth(u8 mac[16], const u8 auth_key[32],
|
|
const u8 *ad , size_t ad_size,
|
|
const u8 *cipher_text, size_t text_size)
|
|
{
|
|
u8 sizes[16]; // Not secret, not wiped
|
|
store64_le(sizes + 0, ad_size);
|
|
store64_le(sizes + 8, text_size);
|
|
crypto_poly1305_ctx poly_ctx; // auto wiped...
|
|
crypto_poly1305_init (&poly_ctx, auth_key);
|
|
crypto_poly1305_update(&poly_ctx, ad , ad_size);
|
|
crypto_poly1305_update(&poly_ctx, zero , gap(ad_size, 16));
|
|
crypto_poly1305_update(&poly_ctx, cipher_text, text_size);
|
|
crypto_poly1305_update(&poly_ctx, zero , gap(text_size, 16));
|
|
crypto_poly1305_update(&poly_ctx, sizes , 16);
|
|
crypto_poly1305_final (&poly_ctx, mac); // ...here
|
|
}
|
|
|
|
void crypto_aead_init_x(crypto_aead_ctx *ctx,
|
|
u8 const key[32], const u8 nonce[24])
|
|
{
|
|
crypto_chacha20_h(ctx->key, key, nonce);
|
|
COPY(ctx->nonce, nonce + 16, 8);
|
|
ctx->counter = 0;
|
|
}
|
|
|
|
void crypto_aead_init_djb(crypto_aead_ctx *ctx,
|
|
const u8 key[32], const u8 nonce[8])
|
|
{
|
|
COPY(ctx->key , key , 32);
|
|
COPY(ctx->nonce, nonce, 8);
|
|
ctx->counter = 0;
|
|
}
|
|
|
|
void crypto_aead_init_ietf(crypto_aead_ctx *ctx,
|
|
const u8 key[32], const u8 nonce[12])
|
|
{
|
|
COPY(ctx->key , key , 32);
|
|
COPY(ctx->nonce, nonce + 4, 8);
|
|
ctx->counter = (u64)load32_le(nonce) << 32;
|
|
}
|
|
|
|
void crypto_aead_write(crypto_aead_ctx *ctx, u8 *cipher_text, u8 mac[16],
|
|
const u8 *ad, size_t ad_size,
|
|
const u8 *plain_text, size_t text_size)
|
|
{
|
|
u8 auth_key[64]; // the last 32 bytes are used for rekeying.
|
|
crypto_chacha20_djb(auth_key, 0, 64, ctx->key, ctx->nonce, ctx->counter);
|
|
crypto_chacha20_djb(cipher_text, plain_text, text_size,
|
|
ctx->key, ctx->nonce, ctx->counter + 1);
|
|
lock_auth(mac, auth_key, ad, ad_size, cipher_text, text_size);
|
|
COPY(ctx->key, auth_key + 32, 32);
|
|
WIPE_BUFFER(auth_key);
|
|
}
|
|
|
|
int crypto_aead_read(crypto_aead_ctx *ctx, u8 *plain_text, const u8 mac[16],
|
|
const u8 *ad, size_t ad_size,
|
|
const u8 *cipher_text, size_t text_size)
|
|
{
|
|
u8 auth_key[64]; // the last 32 bytes are used for rekeying.
|
|
u8 real_mac[16];
|
|
crypto_chacha20_djb(auth_key, 0, 64, ctx->key, ctx->nonce, ctx->counter);
|
|
lock_auth(real_mac, auth_key, ad, ad_size, cipher_text, text_size);
|
|
int mismatch = crypto_verify16(mac, real_mac);
|
|
if (!mismatch) {
|
|
crypto_chacha20_djb(plain_text, cipher_text, text_size,
|
|
ctx->key, ctx->nonce, ctx->counter + 1);
|
|
COPY(ctx->key, auth_key + 32, 32);
|
|
}
|
|
WIPE_BUFFER(auth_key);
|
|
WIPE_BUFFER(real_mac);
|
|
return mismatch;
|
|
}
|
|
|
|
void crypto_aead_lock(u8 *cipher_text, u8 mac[16], const u8 key[32],
|
|
const u8 nonce[24], const u8 *ad, size_t ad_size,
|
|
const u8 *plain_text, size_t text_size)
|
|
{
|
|
crypto_aead_ctx ctx;
|
|
crypto_aead_init_x(&ctx, key, nonce);
|
|
crypto_aead_write(&ctx, cipher_text, mac, ad, ad_size,
|
|
plain_text, text_size);
|
|
crypto_wipe(&ctx, sizeof(ctx));
|
|
}
|
|
|
|
int crypto_aead_unlock(u8 *plain_text, const u8 mac[16], const u8 key[32],
|
|
const u8 nonce[24], const u8 *ad, size_t ad_size,
|
|
const u8 *cipher_text, size_t text_size)
|
|
{
|
|
crypto_aead_ctx ctx;
|
|
crypto_aead_init_x(&ctx, key, nonce);
|
|
int mismatch = crypto_aead_read(&ctx, plain_text, mac, ad, ad_size,
|
|
cipher_text, text_size);
|
|
crypto_wipe(&ctx, sizeof(ctx));
|
|
return mismatch;
|
|
}
|
|
|
|
#ifdef MONOCYPHER_CPP_NAMESPACE
|
|
}
|
|
#endif
|