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/basictypes.h"
8 #include "base/logging.h"
9 #include "crypto/curve25519.h"
10 #include "net/quic/crypto/quic_random.h"
12 using base::StringPiece;
17 Curve25519KeyExchange::Curve25519KeyExchange() {}
19 Curve25519KeyExchange::~Curve25519KeyExchange() {}
22 Curve25519KeyExchange* Curve25519KeyExchange::New(
23 const StringPiece& private_key) {
24 Curve25519KeyExchange* ka;
25 // We don't want to #include the NaCl headers in the public header file, so
26 // we use literals for the sizes of private_key_ and public_key_. Here we
27 // assert that those values are equal to the values from the NaCl header.
29 sizeof(ka->private_key_) == crypto::curve25519::kScalarBytes,
31 COMPILE_ASSERT(sizeof(ka->public_key_) == crypto::curve25519::kBytes,
34 if (private_key.size() != crypto::curve25519::kScalarBytes) {
38 ka = new Curve25519KeyExchange();
39 memcpy(ka->private_key_, private_key.data(),
40 crypto::curve25519::kScalarBytes);
41 crypto::curve25519::ScalarBaseMult(ka->private_key_, ka->public_key_);
46 string Curve25519KeyExchange::NewPrivateKey(QuicRandom* rand) {
47 uint8 private_key[crypto::curve25519::kScalarBytes];
48 rand->RandBytes(private_key, sizeof(private_key));
50 // This makes |private_key| a valid scalar, as specified on
51 // http://cr.yp.to/ecdh.html
52 private_key[0] &= 248;
53 private_key[31] &= 127;
54 private_key[31] |= 64;
55 return string(reinterpret_cast<char*>(private_key), sizeof(private_key));
58 KeyExchange* Curve25519KeyExchange::NewKeyPair(QuicRandom* rand) const {
59 const string private_value = NewPrivateKey(rand);
60 return Curve25519KeyExchange::New(private_value);
63 bool Curve25519KeyExchange::CalculateSharedKey(
64 const StringPiece& peer_public_value,
65 string* out_result) const {
66 if (peer_public_value.size() != crypto::curve25519::kBytes) {
70 uint8 result[crypto::curve25519::kBytes];
71 crypto::curve25519::ScalarMult(
73 reinterpret_cast<const uint8*>(peer_public_value.data()),
75 out_result->assign(reinterpret_cast<char*>(result), sizeof(result));
80 StringPiece Curve25519KeyExchange::public_value() const {
81 return StringPiece(reinterpret_cast<const char*>(public_key_),
85 QuicTag Curve25519KeyExchange::tag() const { return kC255; }