1 // Copyright 2011 The Chromium Authors
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 <stddef.h>
8 #include <stdint.h>
9
10 #include <algorithm>
11 #include <utility>
12
13 #include "base/check_op.h"
14 #include "base/notreached.h"
15 #include "base/strings/string_util.h"
16 #include "crypto/openssl_util.h"
17 #include "third_party/boringssl/src/include/openssl/evp.h"
18 #include "third_party/boringssl/src/include/openssl/rand.h"
19
20 namespace crypto {
21
22 namespace {
23
CheckDerivationParameters(SymmetricKey::Algorithm algorithm,size_t key_size_in_bits)24 bool CheckDerivationParameters(SymmetricKey::Algorithm algorithm,
25 size_t key_size_in_bits) {
26 switch (algorithm) {
27 case SymmetricKey::AES:
28 // Check for supported key sizes. Historically, NSS supported AES-192
29 // while BoringSSL did not and this check aligned their behavior.
30 return key_size_in_bits == 128 || key_size_in_bits == 256;
31 case SymmetricKey::HMAC_SHA1:
32 return key_size_in_bits % 8 == 0 && key_size_in_bits != 0;
33 }
34
35 NOTREACHED();
36 return false;
37 }
38
39 } // namespace
40
~SymmetricKey()41 SymmetricKey::~SymmetricKey() {
42 std::fill(key_.begin(), key_.end(), '\0'); // Zero out the confidential key.
43 }
44
45 // static
GenerateRandomKey(Algorithm algorithm,size_t key_size_in_bits)46 std::unique_ptr<SymmetricKey> SymmetricKey::GenerateRandomKey(
47 Algorithm algorithm,
48 size_t key_size_in_bits) {
49 DCHECK_EQ(AES, algorithm);
50
51 // Check for supported key sizes. Historically, NSS supported AES-192 while
52 // BoringSSL did not and this check aligned their behavior.
53 if (key_size_in_bits != 128 && key_size_in_bits != 256)
54 return nullptr;
55
56 size_t key_size_in_bytes = key_size_in_bits / 8;
57 DCHECK_EQ(key_size_in_bits, key_size_in_bytes * 8);
58
59 if (key_size_in_bytes == 0)
60 return nullptr;
61
62 OpenSSLErrStackTracer err_tracer(FROM_HERE);
63 std::unique_ptr<SymmetricKey> key(new SymmetricKey);
64 uint8_t* key_data = reinterpret_cast<uint8_t*>(
65 base::WriteInto(&key->key_, key_size_in_bytes + 1));
66
67 int rv = RAND_bytes(key_data, static_cast<int>(key_size_in_bytes));
68 return rv == 1 ? std::move(key) : nullptr;
69 }
70
71 // static
DeriveKeyFromPasswordUsingPbkdf2(Algorithm algorithm,const std::string & password,const std::string & salt,size_t iterations,size_t key_size_in_bits)72 std::unique_ptr<SymmetricKey> SymmetricKey::DeriveKeyFromPasswordUsingPbkdf2(
73 Algorithm algorithm,
74 const std::string& password,
75 const std::string& salt,
76 size_t iterations,
77 size_t key_size_in_bits) {
78 if (!CheckDerivationParameters(algorithm, key_size_in_bits))
79 return nullptr;
80
81 size_t key_size_in_bytes = key_size_in_bits / 8;
82
83 OpenSSLErrStackTracer err_tracer(FROM_HERE);
84 std::unique_ptr<SymmetricKey> key(new SymmetricKey);
85 uint8_t* key_data = reinterpret_cast<uint8_t*>(
86 base::WriteInto(&key->key_, key_size_in_bytes + 1));
87
88 int rv = PKCS5_PBKDF2_HMAC_SHA1(
89 password.data(), password.length(),
90 reinterpret_cast<const uint8_t*>(salt.data()), salt.length(),
91 static_cast<unsigned>(iterations),
92 key_size_in_bytes, key_data);
93 return rv == 1 ? std::move(key) : nullptr;
94 }
95
96 // static
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)97 std::unique_ptr<SymmetricKey> SymmetricKey::DeriveKeyFromPasswordUsingScrypt(
98 Algorithm algorithm,
99 const std::string& password,
100 const std::string& salt,
101 size_t cost_parameter,
102 size_t block_size,
103 size_t parallelization_parameter,
104 size_t max_memory_bytes,
105 size_t key_size_in_bits) {
106 if (!CheckDerivationParameters(algorithm, key_size_in_bits))
107 return nullptr;
108
109 size_t key_size_in_bytes = key_size_in_bits / 8;
110
111 OpenSSLErrStackTracer err_tracer(FROM_HERE);
112 std::unique_ptr<SymmetricKey> key(new SymmetricKey);
113 uint8_t* key_data = reinterpret_cast<uint8_t*>(
114 base::WriteInto(&key->key_, key_size_in_bytes + 1));
115
116 int rv = EVP_PBE_scrypt(password.data(), password.length(),
117 reinterpret_cast<const uint8_t*>(salt.data()),
118 salt.length(), cost_parameter, block_size,
119 parallelization_parameter, max_memory_bytes, key_data,
120 key_size_in_bytes);
121 return rv == 1 ? std::move(key) : nullptr;
122 }
123
124 // static
Import(Algorithm algorithm,const std::string & raw_key)125 std::unique_ptr<SymmetricKey> SymmetricKey::Import(Algorithm algorithm,
126 const std::string& raw_key) {
127 if (algorithm == AES) {
128 // Check for supported key sizes. Historically, NSS supported AES-192 while
129 // BoringSSL did not and this check aligned their behavior.
130 if (raw_key.size() != 128/8 && raw_key.size() != 256/8)
131 return nullptr;
132 }
133
134 std::unique_ptr<SymmetricKey> key(new SymmetricKey);
135 key->key_ = raw_key;
136 return key;
137 }
138
139 SymmetricKey::SymmetricKey() = default;
140
141 } // namespace crypto
142