1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "net/quic/crypto/curve25519_key_exchange.h"
7 #include "base/logging.h"
8 #include "crypto/curve25519.h"
9 #include "net/quic/crypto/quic_random.h"
11 using base::StringPiece;
16 Curve25519KeyExchange::Curve25519KeyExchange() {}
18 Curve25519KeyExchange::~Curve25519KeyExchange() {}
21 Curve25519KeyExchange* Curve25519KeyExchange::New(
22 const StringPiece& private_key) {
23 Curve25519KeyExchange* ka;
24 // We don't want to #include the NaCl headers in the public header file, so
25 // we use literals for the sizes of private_key_ and public_key_. Here we
26 // assert that those values are equal to the values from the NaCl header.
28 sizeof(ka->private_key_) == crypto::curve25519::kScalarBytes,
30 COMPILE_ASSERT(sizeof(ka->public_key_) == crypto::curve25519::kBytes,
33 if (private_key.size() != crypto::curve25519::kScalarBytes) {
37 ka = new Curve25519KeyExchange();
38 memcpy(ka->private_key_, private_key.data(),
39 crypto::curve25519::kScalarBytes);
40 crypto::curve25519::ScalarBaseMult(ka->private_key_, ka->public_key_);
45 string Curve25519KeyExchange::NewPrivateKey(QuicRandom* rand) {
46 uint8 private_key[crypto::curve25519::kScalarBytes];
47 rand->RandBytes(private_key, sizeof(private_key));
49 // This makes |private_key| a valid scalar, as specified on
50 // http://cr.yp.to/ecdh.html
51 private_key[0] &= 248;
52 private_key[31] &= 127;
53 private_key[31] |= 64;
54 return string(reinterpret_cast<char*>(private_key), sizeof(private_key));
57 KeyExchange* Curve25519KeyExchange::NewKeyPair(QuicRandom* rand) const {
58 const string private_value = NewPrivateKey(rand);
59 return Curve25519KeyExchange::New(private_value);
62 bool Curve25519KeyExchange::CalculateSharedKey(
63 const StringPiece& peer_public_value,
64 string* out_result) const {
65 if (peer_public_value.size() != crypto::curve25519::kBytes) {
69 uint8 result[crypto::curve25519::kBytes];
70 crypto::curve25519::ScalarMult(
72 reinterpret_cast<const uint8*>(peer_public_value.data()),
74 out_result->assign(reinterpret_cast<char*>(result), sizeof(result));
79 StringPiece Curve25519KeyExchange::public_value() const {
80 return StringPiece(reinterpret_cast<const char*>(public_key_),
84 QuicTag Curve25519KeyExchange::tag() const { return kC255; }