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76 lines
1.5 KiB
Go
76 lines
1.5 KiB
Go
// Copyright (c) 2021 Tulir Asokan
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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// Package keys contains a utility struct for elliptic curve keypairs.
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package keys
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import (
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"crypto/rand"
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"fmt"
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"go.mau.fi/libsignal/ecc"
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"golang.org/x/crypto/curve25519"
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)
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type KeyPair struct {
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Pub *[32]byte
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Priv *[32]byte
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}
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var _ ecc.ECPublicKeyable
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func NewKeyPairFromPrivateKey(priv [32]byte) *KeyPair {
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var kp KeyPair
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kp.Priv = &priv
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var pub [32]byte
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curve25519.ScalarBaseMult(&pub, kp.Priv)
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kp.Pub = &pub
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return &kp
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}
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func NewKeyPair() *KeyPair {
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var priv [32]byte
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_, err := rand.Read(priv[:])
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if err != nil {
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panic(fmt.Errorf("failed to generate curve25519 private key: %w", err))
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}
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priv[0] &= 248
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priv[31] &= 127
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priv[31] |= 64
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return NewKeyPairFromPrivateKey(priv)
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}
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func (kp *KeyPair) CreateSignedPreKey(keyID uint32) *PreKey {
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newKey := NewPreKey(keyID)
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newKey.Signature = kp.Sign(&newKey.KeyPair)
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return newKey
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}
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func (kp *KeyPair) Sign(keyToSign *KeyPair) *[64]byte {
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pubKeyForSignature := make([]byte, 33)
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pubKeyForSignature[0] = ecc.DjbType
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copy(pubKeyForSignature[1:], keyToSign.Pub[:])
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signature := ecc.CalculateSignature(ecc.NewDjbECPrivateKey(*kp.Priv), pubKeyForSignature)
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return &signature
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}
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type PreKey struct {
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KeyPair
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KeyID uint32
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Signature *[64]byte
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}
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func NewPreKey(keyID uint32) *PreKey {
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return &PreKey{
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KeyPair: *NewKeyPair(),
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KeyID: keyID,
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}
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}
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