1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "crypto/symmetric_key.h"
6
7 #include <openssl/evp.h>
8 #include <openssl/rand.h>
9
10 #include <algorithm>
11
12 #include "base/logging.h"
13 #include "base/memory/scoped_ptr.h"
14 #include "base/string_util.h"
15 #include "crypto/openssl_util.h"
16
17 namespace crypto {
18
~SymmetricKey()19 SymmetricKey::~SymmetricKey() {
20 std::fill(key_.begin(), key_.end(), '\0'); // Zero out the confidential key.
21 }
22
23 // static
GenerateRandomKey(Algorithm algorithm,size_t key_size_in_bits)24 SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm,
25 size_t key_size_in_bits) {
26 DCHECK_EQ(AES, algorithm);
27 int key_size_in_bytes = key_size_in_bits / 8;
28 DCHECK_EQ(static_cast<int>(key_size_in_bits), key_size_in_bytes * 8);
29
30 if (key_size_in_bits == 0)
31 return NULL;
32
33 OpenSSLErrStackTracer err_tracer(FROM_HERE);
34 scoped_ptr<SymmetricKey> key(new SymmetricKey);
35 uint8* key_data =
36 reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
37
38 int rv = RAND_bytes(key_data, key_size_in_bytes);
39 return rv == 1 ? key.release() : NULL;
40 }
41
42 // static
DeriveKeyFromPassword(Algorithm algorithm,const std::string & password,const std::string & salt,size_t iterations,size_t key_size_in_bits)43 SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm,
44 const std::string& password,
45 const std::string& salt,
46 size_t iterations,
47 size_t key_size_in_bits) {
48 DCHECK(algorithm == AES || algorithm == HMAC_SHA1);
49 int key_size_in_bytes = key_size_in_bits / 8;
50 DCHECK_EQ(static_cast<int>(key_size_in_bits), key_size_in_bytes * 8);
51
52 OpenSSLErrStackTracer err_tracer(FROM_HERE);
53 scoped_ptr<SymmetricKey> key(new SymmetricKey);
54 uint8* key_data =
55 reinterpret_cast<uint8*>(WriteInto(&key->key_, key_size_in_bytes + 1));
56 int rv = PKCS5_PBKDF2_HMAC_SHA1(password.data(), password.length(),
57 reinterpret_cast<const uint8*>(salt.data()),
58 salt.length(), iterations,
59 key_size_in_bytes, key_data);
60 return rv == 1 ? key.release() : NULL;
61 }
62
63 // static
Import(Algorithm algorithm,const std::string & raw_key)64 SymmetricKey* SymmetricKey::Import(Algorithm algorithm,
65 const std::string& raw_key) {
66 scoped_ptr<SymmetricKey> key(new SymmetricKey);
67 key->key_ = raw_key;
68 return key.release();
69 }
70
GetRawKey(std::string * raw_key)71 bool SymmetricKey::GetRawKey(std::string* raw_key) {
72 *raw_key = key_;
73 return true;
74 }
75
76 } // namespace crypto
77