blob: 2be495d92cc91b92edadaeed865b32e1607f1af7 [file] [log] [blame]
// 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/crypto_secret_boxer.h"
#include <cstdint>
#include <string>
#include "absl/strings/string_view.h"
#include "openssl/aead.h"
#include "openssl/err.h"
#include "quiche/quic/core/crypto/quic_random.h"
#include "quiche/quic/platform/api/quic_logging.h"
namespace quic {
// kSIVNonceSize contains the number of bytes of nonce in each AES-GCM-SIV box.
// AES-GCM-SIV takes a 12-byte nonce and, since the messages are so small, each
// key is good for more than 2^64 source-address tokens. See table 1 of
static const size_t kSIVNonceSize = 12;
// AES-GCM-SIV comes in AES-128 and AES-256 flavours. The AES-256 version is
// used here so that the key size matches the 256-bit XSalsa20 keys that we
// used to use.
static const size_t kBoxKeySize = 32;
struct CryptoSecretBoxer::State {
// ctxs are the initialised AEAD contexts. These objects contain the
// scheduled AES state for each of the keys.
std::vector<bssl::UniquePtr<EVP_AEAD_CTX>> ctxs;
CryptoSecretBoxer::CryptoSecretBoxer() {}
CryptoSecretBoxer::~CryptoSecretBoxer() {}
// static
size_t CryptoSecretBoxer::GetKeySize() { return kBoxKeySize; }
// kAEAD is the AEAD used for boxing: AES-256-GCM-SIV.
static const EVP_AEAD* (*const kAEAD)() = EVP_aead_aes_256_gcm_siv;
bool CryptoSecretBoxer::SetKeys(const std::vector<std::string>& keys) {
if (keys.empty()) {
QUIC_LOG(DFATAL) << "No keys supplied!";
return false;
const EVP_AEAD* const aead = kAEAD();
std::unique_ptr<State> new_state(new State);
for (const std::string& key : keys) {
QUICHE_DCHECK_EQ(kBoxKeySize, key.size());
bssl::UniquePtr<EVP_AEAD_CTX> ctx(
EVP_AEAD_CTX_new(aead, reinterpret_cast<const uint8_t*>(,
if (!ctx) {
QUIC_LOG(DFATAL) << "EVP_AEAD_CTX_init failed";
return false;
QuicWriterMutexLock l(&lock_);
state_ = std::move(new_state);
return true;
std::string CryptoSecretBoxer::Box(QuicRandom* rand,
absl::string_view plaintext) const {
// The box is formatted as:
// 12 bytes of random nonce
// n bytes of ciphertext
// 16 bytes of authenticator
size_t out_len =
kSIVNonceSize + plaintext.size() + EVP_AEAD_max_overhead(kAEAD());
std::string ret;
uint8_t* out = reinterpret_cast<uint8_t*>(const_cast<char*>(;
// Write kSIVNonceSize bytes of random nonce to the beginning of the output
// buffer.
rand->RandBytes(out, kSIVNonceSize);
const uint8_t* const nonce = out;
out += kSIVNonceSize;
out_len -= kSIVNonceSize;
size_t bytes_written;
QuicReaderMutexLock l(&lock_);
if (!EVP_AEAD_CTX_seal(state_->ctxs[0].get(), out, &bytes_written, out_len,
nonce, kSIVNonceSize,
reinterpret_cast<const uint8_t*>(,
plaintext.size(), nullptr, 0)) {
QUIC_LOG(DFATAL) << "EVP_AEAD_CTX_seal failed";
return "";
QUICHE_DCHECK_EQ(out_len, bytes_written);
return ret;
bool CryptoSecretBoxer::Unbox(absl::string_view in_ciphertext,
std::string* out_storage,
absl::string_view* out) const {
if (in_ciphertext.size() < kSIVNonceSize) {
return false;
const uint8_t* const nonce =
reinterpret_cast<const uint8_t*>(;
const uint8_t* const ciphertext = nonce + kSIVNonceSize;
const size_t ciphertext_len = in_ciphertext.size() - kSIVNonceSize;
bool ok = false;
QuicReaderMutexLock l(&lock_);
for (const bssl::UniquePtr<EVP_AEAD_CTX>& ctx : state_->ctxs) {
size_t bytes_written;
if (EVP_AEAD_CTX_open(ctx.get(),
&bytes_written, ciphertext_len, nonce,
kSIVNonceSize, ciphertext, ciphertext_len, nullptr,
0)) {
ok = true;
*out = absl::string_view(out_storage->data(), bytes_written);
return ok;
} // namespace quic