lokinet/crypto/xchacha20/hchacha.c

#include <stdint.h>
#include <stdlib.h>

#include <sodium/crypto_core_hchacha20.h>
#include <sodium/private/common.h>

#define QUARTERROUND(A, B, C, D) \
  do                             \
  {                              \
    A += B;                      \
    D = ROTL32(D ^ A, 16);       \
    C += D;                      \
    B = ROTL32(B ^ C, 12);       \
    A += B;                      \
    D = ROTL32(D ^ A, 8);        \
    C += D;                      \
    B = ROTL32(B ^ C, 7);        \
  } while(0)

int
crypto_core_hchacha20(unsigned char *out, const unsigned char *in,
                      const unsigned char *k, const unsigned char *c)
{
  int i;
  uint32_t x0, x1, x2, x3, x4, x5, x6, x7;
  uint32_t x8, x9, x10, x11, x12, x13, x14, x15;

  if(c == NULL)
  {
    x0 = 0x61707865;
    x1 = 0x3320646e;
    x2 = 0x79622d32;
    x3 = 0x6b206574;
  }
  else
  {
    x0 = LOAD32_LE(c + 0);
    x1 = LOAD32_LE(c + 4);
    x2 = LOAD32_LE(c + 8);
    x3 = LOAD32_LE(c + 12);
  }
  x4  = LOAD32_LE(k + 0);
  x5  = LOAD32_LE(k + 4);
  x6  = LOAD32_LE(k + 8);
  x7  = LOAD32_LE(k + 12);
  x8  = LOAD32_LE(k + 16);
  x9  = LOAD32_LE(k + 20);
  x10 = LOAD32_LE(k + 24);
  x11 = LOAD32_LE(k + 28);
  x12 = LOAD32_LE(in + 0);
  x13 = LOAD32_LE(in + 4);
  x14 = LOAD32_LE(in + 8);
  x15 = LOAD32_LE(in + 12);

  for(i = 0; i < 10; i++)
  {
    QUARTERROUND(x0, x4, x8, x12);
    QUARTERROUND(x1, x5, x9, x13);
    QUARTERROUND(x2, x6, x10, x14);
    QUARTERROUND(x3, x7, x11, x15);
    QUARTERROUND(x0, x5, x10, x15);
    QUARTERROUND(x1, x6, x11, x12);
    QUARTERROUND(x2, x7, x8, x13);
    QUARTERROUND(x3, x4, x9, x14);
  }

  STORE32_LE(out + 0, x0);
  STORE32_LE(out + 4, x1);
  STORE32_LE(out + 8, x2);
  STORE32_LE(out + 12, x3);
  STORE32_LE(out + 16, x12);
  STORE32_LE(out + 20, x13);
  STORE32_LE(out + 24, x14);
  STORE32_LE(out + 28, x15);

  return 0;
}

size_t
crypto_core_hchacha20_outputbytes(void)
{
  return crypto_core_hchacha20_OUTPUTBYTES;
}

size_t
crypto_core_hchacha20_inputbytes(void)
{
  return crypto_core_hchacha20_INPUTBYTES;
}

size_t
crypto_core_hchacha20_keybytes(void)
{
  return crypto_core_hchacha20_KEYBYTES;
}

size_t
crypto_core_hchacha20_constbytes(void)
{
  return crypto_core_hchacha20_CONSTBYTES;
}