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// Copyright (c) 2011 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 "crypto/symmetric_key.h"
#include <openssl/evp.h>
#include <openssl/rand.h>
#include <algorithm>
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/strings/string_util.h"
#include "crypto/openssl_util.h"
namespace crypto {
SymmetricKey::~SymmetricKey() {
std::fill(key_.begin(), key_.end(), '\0'); // Zero out the confidential key.
}
// static
SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm,
size_t key_size_in_bits) {
DCHECK_EQ(AES, algorithm);
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (key_size_in_bits != 128 && key_size_in_bits != 256)
return NULL;
size_t key_size_in_bytes = key_size_in_bits / 8;
DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
if (key_size_in_bytes == 0)
return NULL;
OpenSSLErrStackTracer err_tracer(FROM_HERE);
scoped_ptr<SymmetricKey> key(new SymmetricKey);
uint8* key_data = reinterpret_cast<uint8*>(
base::WriteInto(&key->key_, key_size_in_bytes + 1));
int rv = RAND_bytes(key_data, static_cast<int>(key_size_in_bytes));
return rv == 1 ? key.release() : NULL;
}
// static
SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm,
const std::string& password,
const std::string& salt,
size_t iterations,
size_t key_size_in_bits) {
DCHECK(algorithm == AES || algorithm == HMAC_SHA1);
if (algorithm == AES) {
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (key_size_in_bits != 128 && key_size_in_bits != 256)
return NULL;
}
size_t key_size_in_bytes = key_size_in_bits / 8;
DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
if (key_size_in_bytes == 0)
return NULL;
OpenSSLErrStackTracer err_tracer(FROM_HERE);
scoped_ptr<SymmetricKey> key(new SymmetricKey);
uint8* key_data = reinterpret_cast<uint8*>(
base::WriteInto(&key->key_, key_size_in_bytes + 1));
int rv = PKCS5_PBKDF2_HMAC_SHA1(password.data(), password.length(),
reinterpret_cast<const uint8*>(salt.data()),
salt.length(), iterations,
static_cast<int>(key_size_in_bytes),
key_data);
return rv == 1 ? key.release() : NULL;
}
// static
SymmetricKey* SymmetricKey::Import(Algorithm algorithm,
const std::string& raw_key) {
if (algorithm == AES) {
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (raw_key.size() != 128/8 && raw_key.size() != 256/8)
return NULL;
}
scoped_ptr<SymmetricKey> key(new SymmetricKey);
key->key_ = raw_key;
return key.release();
}
bool SymmetricKey::GetRawKey(std::string* raw_key) {
*raw_key = key_;
return true;
}
} // namespace crypto
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