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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 "quiche/quic/core/crypto/aead_base_decrypter.h"
#include <cstdint>
#include <string>
#include "absl/base/macros.h"
#include "absl/strings/string_view.h"
#include "openssl/crypto.h"
#include "openssl/err.h"
#include "openssl/evp.h"
#include "quiche/quic/core/quic_utils.h"
#include "quiche/quic/platform/api/quic_bug_tracker.h"
#include "quiche/quic/platform/api/quic_logging.h"
#include "quiche/common/quiche_crypto_logging.h"
namespace quic {
using ::quiche::ClearOpenSslErrors;
using ::quiche::DLogOpenSslErrors;
namespace {
const EVP_AEAD* InitAndCall(const EVP_AEAD* (*aead_getter)()) {
// Ensure BoringSSL is initialized before calling |aead_getter|. In Chromium,
// the static initializer is disabled.
CRYPTO_library_init();
return aead_getter();
}
} // namespace
AeadBaseDecrypter::AeadBaseDecrypter(const EVP_AEAD* (*aead_getter)(),
size_t key_size, size_t auth_tag_size,
size_t nonce_size,
bool use_ietf_nonce_construction)
: aead_alg_(InitAndCall(aead_getter)),
key_size_(key_size),
auth_tag_size_(auth_tag_size),
nonce_size_(nonce_size),
use_ietf_nonce_construction_(use_ietf_nonce_construction),
have_preliminary_key_(false) {
QUICHE_DCHECK_GT(256u, key_size);
QUICHE_DCHECK_GT(256u, auth_tag_size);
QUICHE_DCHECK_GT(256u, nonce_size);
QUICHE_DCHECK_LE(key_size_, sizeof(key_));
QUICHE_DCHECK_LE(nonce_size_, sizeof(iv_));
}
AeadBaseDecrypter::~AeadBaseDecrypter() {}
bool AeadBaseDecrypter::SetKey(absl::string_view key) {
QUICHE_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 AeadBaseDecrypter::SetNoncePrefix(absl::string_view nonce_prefix) {
if (use_ietf_nonce_construction_) {
QUIC_BUG(quic_bug_10709_1)
<< "Attempted to set nonce prefix on IETF QUIC crypter";
return false;
}
QUICHE_DCHECK_EQ(nonce_prefix.size(), nonce_size_ - sizeof(QuicPacketNumber));
if (nonce_prefix.size() != nonce_size_ - sizeof(QuicPacketNumber)) {
return false;
}
memcpy(iv_, nonce_prefix.data(), nonce_prefix.size());
return true;
}
bool AeadBaseDecrypter::SetIV(absl::string_view iv) {
if (!use_ietf_nonce_construction_) {
QUIC_BUG(quic_bug_10709_2) << "Attempted to set IV on Google QUIC crypter";
return false;
}
QUICHE_DCHECK_EQ(iv.size(), nonce_size_);
if (iv.size() != nonce_size_) {
return false;
}
memcpy(iv_, iv.data(), iv.size());
return true;
}
bool AeadBaseDecrypter::SetPreliminaryKey(absl::string_view key) {
QUICHE_DCHECK(!have_preliminary_key_);
SetKey(key);
have_preliminary_key_ = true;
return true;
}
bool AeadBaseDecrypter::SetDiversificationNonce(
const DiversificationNonce& nonce) {
if (!have_preliminary_key_) {
return true;
}
std::string key, nonce_prefix;
size_t prefix_size = nonce_size_;
if (!use_ietf_nonce_construction_) {
prefix_size -= sizeof(QuicPacketNumber);
}
DiversifyPreliminaryKey(
absl::string_view(reinterpret_cast<const char*>(key_), key_size_),
absl::string_view(reinterpret_cast<const char*>(iv_), prefix_size), nonce,
key_size_, prefix_size, &key, &nonce_prefix);
if (!SetKey(key) ||
(!use_ietf_nonce_construction_ && !SetNoncePrefix(nonce_prefix)) ||
(use_ietf_nonce_construction_ && !SetIV(nonce_prefix))) {
QUICHE_DCHECK(false);
return false;
}
have_preliminary_key_ = false;
return true;
}
bool AeadBaseDecrypter::DecryptPacket(uint64_t packet_number,
absl::string_view associated_data,
absl::string_view ciphertext,
char* output, size_t* output_length,
size_t max_output_length) {
if (ciphertext.length() < auth_tag_size_) {
return false;
}
if (have_preliminary_key_) {
QUIC_BUG(quic_bug_10709_3)
<< "Unable to decrypt while key diversification is pending";
return false;
}
uint8_t nonce[kMaxNonceSize];
memcpy(nonce, iv_, nonce_size_);
size_t prefix_len = nonce_size_ - sizeof(packet_number);
if (use_ietf_nonce_construction_) {
for (size_t i = 0; i < sizeof(packet_number); ++i) {
nonce[prefix_len + i] ^=
(packet_number >> ((sizeof(packet_number) - i - 1) * 8)) & 0xff;
}
} else {
memcpy(nonce + prefix_len, &packet_number, sizeof(packet_number));
}
if (!EVP_AEAD_CTX_open(
ctx_.get(), reinterpret_cast<uint8_t*>(output), output_length,
max_output_length, reinterpret_cast<const uint8_t*>(nonce),
nonce_size_, reinterpret_cast<const uint8_t*>(ciphertext.data()),
ciphertext.size(),
reinterpret_cast<const uint8_t*>(associated_data.data()),
associated_data.size())) {
// Because QuicFramer does trial decryption, decryption errors are expected
// when encryption level changes. So we don't log decryption errors.
ClearOpenSslErrors();
return false;
}
return true;
}
size_t AeadBaseDecrypter::GetKeySize() const { return key_size_; }
size_t AeadBaseDecrypter::GetNoncePrefixSize() const {
return nonce_size_ - sizeof(QuicPacketNumber);
}
size_t AeadBaseDecrypter::GetIVSize() const { return nonce_size_; }
absl::string_view AeadBaseDecrypter::GetKey() const {
return absl::string_view(reinterpret_cast<const char*>(key_), key_size_);
}
absl::string_view AeadBaseDecrypter::GetNoncePrefix() const {
return absl::string_view(reinterpret_cast<const char*>(iv_),
nonce_size_ - sizeof(QuicPacketNumber));
}
} // namespace quic
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