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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 <string>
#include "base/basictypes.h"
#include "crypto/crypto_export.h"
#if defined(NACL_WIN64)
// See comments for crypto_nacl_win64 in crypto.gyp.
// Must test for NACL_WIN64 before OS_WIN since former is a subset of latter.
#include "crypto/scoped_capi_types.h"
#elif defined(USE_NSS) || defined(OS_WIN) || defined(OS_MACOSX)
#include "crypto/scoped_nss_types.h"
#endif
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 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 SymmetricKey* DeriveKeyFromPassword(Algorithm algorithm,
const std::string& password,
const std::string& salt,
size_t iterations,
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 and exported with
// GetRawKey, or via another compatible method. The key must be of suitable
// size for use with |algorithm|. The caller owns the returned SymmetricKey.
static SymmetricKey* Import(Algorithm algorithm, const std::string& raw_key);
#if defined(USE_OPENSSL)
const std::string& key() { return key_; }
#elif defined(NACL_WIN64)
HCRYPTKEY key() const { return key_.get(); }
#elif defined(USE_NSS) || defined(OS_WIN) || defined(OS_MACOSX)
PK11SymKey* key() const { return key_.get(); }
#endif
// Extracts the raw key from the platform specific data.
// Warning: |raw_key| holds the raw key as bytes and thus must be handled
// carefully.
bool GetRawKey(std::string* raw_key);
#if defined(OS_CHROMEOS)
// Creates symmetric key from NSS key. Takes over the ownership of |key|.
static SymmetricKey* CreateFromKey(PK11SymKey* key);
#endif
private:
#if defined(USE_OPENSSL)
SymmetricKey() {}
std::string key_;
#elif defined(NACL_WIN64)
SymmetricKey(HCRYPTPROV provider, HCRYPTKEY key,
const void* key_data, size_t key_size_in_bytes);
ScopedHCRYPTPROV provider_;
ScopedHCRYPTKEY key_;
// Contains the raw key, if it is known during initialization and when it
// is likely that the associated |provider_| will be unable to export the
// |key_|. This is the case of HMAC keys when the key size exceeds 16 bytes
// when using the default RSA provider.
// TODO(rsleevi): See if KP_EFFECTIVE_KEYLEN is the reason why CryptExportKey
// fails with NTE_BAD_KEY/NTE_BAD_LEN
std::string raw_key_;
#elif defined(USE_NSS) || defined(OS_WIN) || defined(OS_MACOSX)
explicit SymmetricKey(PK11SymKey* key);
ScopedPK11SymKey key_;
#endif
DISALLOW_COPY_AND_ASSIGN(SymmetricKey);
};
} // namespace crypto
#endif // CRYPTO_SYMMETRIC_KEY_H_
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