aead_base_encrypter_openssl.cc revision a1401311d1ab56c4ed0a474bd38c108f75cb0cd9 
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.
4
5#include "net/quic/crypto/aead_base_encrypter.h"
6
7#include <openssl/err.h>
8#include <openssl/evp.h>
9#include <string.h>
10
11#include "base/memory/scoped_ptr.h"
12
13using base::StringPiece;
14
15namespace net {
16
17namespace {
18
19// Clear OpenSSL error stack.
20void ClearOpenSslErrors() {
21#ifdef NDEBUG
22  while (ERR_get_error()) {}
23#else
24  while (unsigned long error = ERR_get_error()) {
25    char buf[120];
26    ERR_error_string_n(error, buf, arraysize(buf));
27    DLOG(ERROR) << "OpenSSL error: " << buf;
28  }
29#endif
30}
31
32}  // namespace
33
34AeadBaseEncrypter::AeadBaseEncrypter(const EVP_AEAD* aead_alg,
35                                     size_t key_size,
36                                     size_t auth_tag_size,
37                                     size_t nonce_prefix_size)
38    : aead_alg_(aead_alg),
39      key_size_(key_size),
40      auth_tag_size_(auth_tag_size),
41      nonce_prefix_size_(nonce_prefix_size) {
42  DCHECK_LE(key_size_, sizeof(key_));
43  DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
44}
45
46AeadBaseEncrypter::~AeadBaseEncrypter() {}
47
48bool AeadBaseEncrypter::SetKey(StringPiece key) {
49  DCHECK_EQ(key.size(), key_size_);
50  if (key.size() != key_size_) {
51    return false;
52  }
53  memcpy(key_, key.data(), key.size());
54
55  EVP_AEAD_CTX_cleanup(ctx_.get());
56
57  if (!EVP_AEAD_CTX_init(ctx_.get(), aead_alg_, key_, key_size_,
58                         auth_tag_size_, NULL)) {
59    ClearOpenSslErrors();
60    return false;
61  }
62
63  return true;
64}
65
66bool AeadBaseEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
67  DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
68  if (nonce_prefix.size() != nonce_prefix_size_) {
69    return false;
70  }
71  memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
72  return true;
73}
74
75bool AeadBaseEncrypter::Encrypt(StringPiece nonce,
76                                StringPiece associated_data,
77                                StringPiece plaintext,
78                                unsigned char* output) {
79  if (nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketSequenceNumber)) {
80    return false;
81  }
82
83  ssize_t len = EVP_AEAD_CTX_seal(
84      ctx_.get(), output, plaintext.size() + auth_tag_size_,
85      reinterpret_cast<const uint8_t*>(nonce.data()), nonce.size(),
86      reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size(),
87      reinterpret_cast<const uint8_t*>(associated_data.data()),
88      associated_data.size());
89
90  if (len < 0) {
91    ClearOpenSslErrors();
92    return false;
93  }
94
95  return true;
96}
97
98QuicData* AeadBaseEncrypter::EncryptPacket(
99    QuicPacketSequenceNumber sequence_number,
100    StringPiece associated_data,
101    StringPiece plaintext) {
102  size_t ciphertext_size = GetCiphertextSize(plaintext.length());
103  scoped_ptr<char[]> ciphertext(new char[ciphertext_size]);
104
105  // TODO(ianswett): Introduce a check to ensure that we don't encrypt with the
106  // same sequence number twice.
107  uint8 nonce[sizeof(nonce_prefix_) + sizeof(sequence_number)];
108  const size_t nonce_size = nonce_prefix_size_ + sizeof(sequence_number);
109  DCHECK_LE(nonce_size, sizeof(nonce));
110  memcpy(nonce, nonce_prefix_, nonce_prefix_size_);
111  memcpy(nonce + nonce_prefix_size_, &sequence_number, sizeof(sequence_number));
112  if (!Encrypt(StringPiece(reinterpret_cast<char*>(nonce), nonce_size),
113               associated_data, plaintext,
114               reinterpret_cast<unsigned char*>(ciphertext.get()))) {
115    return NULL;
116  }
117
118  return new QuicData(ciphertext.release(), ciphertext_size, true);
119}
120
121size_t AeadBaseEncrypter::GetKeySize() const { return key_size_; }
122
123size_t AeadBaseEncrypter::GetNoncePrefixSize() const {
124  return nonce_prefix_size_;
125}
126
127size_t AeadBaseEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
128  return ciphertext_size - auth_tag_size_;
129}
130
131size_t AeadBaseEncrypter::GetCiphertextSize(size_t plaintext_size) const {
132  return plaintext_size + auth_tag_size_;
133}
134
135StringPiece AeadBaseEncrypter::GetKey() const {
136  return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
137}
138
139StringPiece AeadBaseEncrypter::GetNoncePrefix() const {
140  if (nonce_prefix_size_ == 0) {
141    return StringPiece();
142  }
143  return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
144                     nonce_prefix_size_);
145}
146
147}  // namespace net
148