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// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/quic/crypto/aead_base_encrypter.h"
#include <openssl/err.h>
#include <openssl/evp.h>
#include <string.h>
#include "base/memory/scoped_ptr.h"
#include "net/quic/quic_flags.h"
#include "net/quic/quic_utils.h"
using base::StringPiece;
namespace net {
namespace {
// The maximum size in bytes of the nonce, including 8 bytes of sequence number.
// ChaCha20 uses only the 8 byte sequence number and AES-GCM uses 12 bytes.
const size_t kMaxNonceSize = 12;
// In debug builds only, log OpenSSL error stack. Then clear OpenSSL error
// stack.
void DLogOpenSslErrors() {
#ifdef NDEBUG
while (ERR_get_error()) {
}
#else
while (unsigned long error = ERR_get_error()) {
char buf[120];
ERR_error_string_n(error, buf, arraysize(buf));
DLOG(ERROR) << "OpenSSL error: " << buf;
}
#endif
}
} // namespace
AeadBaseEncrypter::AeadBaseEncrypter(const EVP_AEAD* aead_alg,
size_t key_size,
size_t auth_tag_size,
size_t nonce_prefix_size)
: aead_alg_(aead_alg),
key_size_(key_size),
auth_tag_size_(auth_tag_size),
nonce_prefix_size_(nonce_prefix_size) {
DCHECK_LE(key_size_, sizeof(key_));
DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
DCHECK_GE(kMaxNonceSize, nonce_prefix_size_);
}
AeadBaseEncrypter::~AeadBaseEncrypter() {}
bool AeadBaseEncrypter::SetKey(StringPiece key) {
DCHECK_EQ(key.size(), key_size_);
if (key.size() != key_size_) {
return false;
}
memcpy(key_, key.data(), key.size());
EVP_AEAD_CTX_cleanup(ctx_.get());
if (!EVP_AEAD_CTX_init(ctx_.get(), aead_alg_, key_, key_size_, auth_tag_size_,
nullptr)) {
DLogOpenSslErrors();
return false;
}
return true;
}
bool AeadBaseEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
if (nonce_prefix.size() != nonce_prefix_size_) {
return false;
}
memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
return true;
}
bool AeadBaseEncrypter::Encrypt(StringPiece nonce,
StringPiece associated_data,
StringPiece plaintext,
unsigned char* output) {
if (nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketNumber)) {
return false;
}
size_t ciphertext_len;
if (!EVP_AEAD_CTX_seal(
ctx_.get(), output, &ciphertext_len,
plaintext.size() + auth_tag_size_,
reinterpret_cast<const uint8_t*>(nonce.data()), nonce.size(),
reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size(),
reinterpret_cast<const uint8_t*>(associated_data.data()),
associated_data.size())) {
DLogOpenSslErrors();
return false;
}
return true;
}
bool AeadBaseEncrypter::EncryptPacket(QuicPathId path_id,
QuicPacketNumber packet_number,
StringPiece associated_data,
StringPiece plaintext,
char* output,
size_t* output_length,
size_t max_output_length) {
size_t ciphertext_size = GetCiphertextSize(plaintext.length());
if (max_output_length < ciphertext_size) {
return false;
}
// TODO(ianswett): Introduce a check to ensure that we don't encrypt with the
// same packet number twice.
const size_t nonce_size = nonce_prefix_size_ + sizeof(packet_number);
ALIGNAS(4) char nonce_buffer[kMaxNonceSize];
memcpy(nonce_buffer, nonce_prefix_, nonce_prefix_size_);
uint64_t path_id_packet_number =
QuicUtils::PackPathIdAndPacketNumber(path_id, packet_number);
memcpy(nonce_buffer + nonce_prefix_size_, &path_id_packet_number,
sizeof(path_id_packet_number));
if (!Encrypt(StringPiece(nonce_buffer, nonce_size), associated_data,
plaintext, reinterpret_cast<unsigned char*>(output))) {
return false;
}
*output_length = ciphertext_size;
return true;
}
size_t AeadBaseEncrypter::GetKeySize() const {
return key_size_;
}
size_t AeadBaseEncrypter::GetNoncePrefixSize() const {
return nonce_prefix_size_;
}
size_t AeadBaseEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
return ciphertext_size - auth_tag_size_;
}
size_t AeadBaseEncrypter::GetCiphertextSize(size_t plaintext_size) const {
return plaintext_size + auth_tag_size_;
}
StringPiece AeadBaseEncrypter::GetKey() const {
return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
}
StringPiece AeadBaseEncrypter::GetNoncePrefix() const {
if (nonce_prefix_size_ == 0) {
return StringPiece();
}
return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
nonce_prefix_size_);
}
} // namespace net
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