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// Copyright (c) 2012 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.
#ifndef CRYPTO_SYMMETRIC_KEY_H_
#define CRYPTO_SYMMETRIC_KEY_H_
#include <stddef.h>
#include <memory>
#include <string>
#include "base/macros.h"
#include "build/build_config.h"
#include "crypto/crypto_export.h"
namespace crypto {
// Wraps a platform-specific symmetric key and allows it to be held in a
// scoped_ptr.
class CRYPTO_EXPORT SymmetricKey {
public:
// Defines the algorithm that a key will be used with. See also
// classs Encrptor.
enum Algorithm {
AES,
HMAC_SHA1,
};
virtual ~SymmetricKey();
// Generates a random key suitable to be used with |algorithm| and of
// |key_size_in_bits| bits. |key_size_in_bits| must be a multiple of 8.
// The caller is responsible for deleting the returned SymmetricKey.
static std::unique_ptr<SymmetricKey> GenerateRandomKey(
Algorithm algorithm,
size_t key_size_in_bits);
// Derives a key from the supplied password and salt using PBKDF2, suitable
// for use with specified |algorithm|. Note |algorithm| is not the algorithm
// used to derive the key from the password. |key_size_in_bits| must be a
// multiple of 8. The caller is responsible for deleting the returned
// SymmetricKey.
static std::unique_ptr<SymmetricKey> DeriveKeyFromPasswordUsingPbkdf2(
Algorithm algorithm,
const std::string& password,
const std::string& salt,
size_t iterations,
size_t key_size_in_bits);
// Derives a key from the supplied password and salt using scrypt, suitable
// for use with specified |algorithm|. Note |algorithm| is not the algorithm
// used to derive the key from the password. |cost_parameter|, |block_size|,
// and |parallelization_parameter| correspond to the parameters |N|, |r|, and
// |p| from the scrypt specification (see RFC 7914). |key_size_in_bits| must
// be a multiple of 8. The caller is responsible for deleting the returned
// SymmetricKey.
static std::unique_ptr<SymmetricKey> DeriveKeyFromPasswordUsingScrypt(
Algorithm algorithm,
const std::string& password,
const std::string& salt,
size_t cost_parameter,
size_t block_size,
size_t parallelization_parameter,
size_t max_memory_bytes,
size_t key_size_in_bits);
// Imports an array of key bytes in |raw_key|. This key may have been
// generated by GenerateRandomKey or DeriveKeyFromPassword{Pbkdf2,Scrypt} and
// exported with key(). The key must be of suitable size for use with
// |algorithm|. The caller owns the returned SymmetricKey.
static std::unique_ptr<SymmetricKey> Import(Algorithm algorithm,
const std::string& raw_key);
// Returns the raw platform specific key data.
const std::string& key() const { return key_; }
private:
SymmetricKey();
std::string key_;
DISALLOW_COPY_AND_ASSIGN(SymmetricKey);
};
} // namespace crypto
#endif // CRYPTO_SYMMETRIC_KEY_H_