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1 // Copyright (c) 2010 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 "base/crypto/symmetric_key.h" | |
6 | |
7 #include <CommonCrypto/CommonCryptor.h> | |
8 #include <CoreFoundation/CFString.h> | |
9 #include <Security/cssm.h> | |
10 | |
11 #include "base/crypto/cssm_init.h" | |
12 #include "base/logging.h" | |
13 | |
14 namespace { | |
15 | |
16 CSSM_KEY_TYPE CheckKeyParams(base::SymmetricKey::Algorithm algorithm, | |
17 size_t key_size_in_bits) { | |
18 if (algorithm == base::SymmetricKey::AES) { | |
19 CHECK(key_size_in_bits == 128 || | |
20 key_size_in_bits == 192 || | |
21 key_size_in_bits == 256) | |
22 << "Invalid key size " << key_size_in_bits << " bits"; | |
23 return CSSM_ALGID_AES; | |
24 } else { | |
25 // FIPS 198 Section 3 requires a HMAC-SHA-1 derived keys to be at least | |
26 // (HMAC-SHA-1 output size / 2) to be compliant. Since the ouput size of | |
27 // HMAC-SHA-1 is 160 bits, we require at least 80 bits here. | |
28 CHECK(algorithm == base::SymmetricKey::HMAC_SHA1); | |
29 CHECK(key_size_in_bits >= 80 && (key_size_in_bits % 8) == 0) | |
30 << "Invalid key size " << key_size_in_bits << " bits"; | |
31 return CSSM_ALGID_SHA1HMAC_LEGACY; | |
32 } | |
33 } | |
34 | |
35 void* CreateRandomBytes(size_t size) { | |
36 CSSM_RETURN err; | |
37 CSSM_CC_HANDLE ctx; | |
38 err = CSSM_CSP_CreateRandomGenContext(base::GetSharedCSPHandle(), | |
39 CSSM_ALGID_APPLE_YARROW, | |
40 NULL, | |
41 size, &ctx); | |
42 if (err) { | |
43 base::LogCSSMError("CSSM_CSP_CreateRandomGenContext", err); | |
44 return NULL; | |
45 } | |
46 CSSM_DATA random_data = {}; | |
47 err = CSSM_GenerateRandom(ctx, &random_data); | |
48 if (err) { | |
49 base::LogCSSMError("CSSM_GenerateRandom", err); | |
50 random_data.Data = NULL; | |
51 } | |
52 CSSM_DeleteContext(ctx); | |
53 return random_data.Data; // Caller responsible for freeing this | |
54 } | |
55 | |
56 inline CSSM_DATA StringToData(const std::string& str) { | |
57 CSSM_DATA data = { | |
58 str.size(), | |
59 reinterpret_cast<uint8_t*>(const_cast<char*>(str.data())) | |
60 }; | |
61 return data; | |
62 } | |
63 | |
64 } // namespace | |
65 | |
66 namespace base { | |
67 | |
68 SymmetricKey::~SymmetricKey() {} | |
69 | |
70 // static | |
71 SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm, | |
72 size_t key_size_in_bits) { | |
73 CheckKeyParams(algorithm, key_size_in_bits); | |
74 void* random_bytes = CreateRandomBytes((key_size_in_bits + 7) / 8); | |
75 if (!random_bytes) | |
76 return NULL; | |
77 SymmetricKey *key = new SymmetricKey(random_bytes, key_size_in_bits); | |
78 free(random_bytes); | |
79 return key; | |
80 } | |
81 | |
82 // static | |
83 SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm, | |
84 const std::string& password, | |
85 const std::string& salt, | |
86 size_t iterations, | |
87 size_t key_size_in_bits) { | |
88 // Derived (haha) from cdsaDeriveKey() in Apple's CryptoSample. | |
89 CSSM_KEY_TYPE key_type = CheckKeyParams(algorithm, key_size_in_bits); | |
90 SymmetricKey* derived_key = NULL; | |
91 CSSM_KEY cssm_key = {}; | |
92 | |
93 CSSM_CC_HANDLE ctx = 0; | |
94 CSSM_ACCESS_CREDENTIALS credentials = {}; | |
95 CSSM_RETURN err; | |
96 CSSM_DATA salt_data = StringToData(salt); | |
97 err = CSSM_CSP_CreateDeriveKeyContext(GetSharedCSPHandle(), | |
98 CSSM_ALGID_PKCS5_PBKDF2, | |
99 key_type, key_size_in_bits, | |
100 &credentials, | |
101 NULL, | |
102 iterations, | |
103 &salt_data, | |
104 NULL, | |
105 &ctx); | |
106 if (err) { | |
107 LogCSSMError("CSSM_CSP_CreateDeriveKeyContext", err); | |
108 return NULL; | |
109 } | |
110 | |
111 CSSM_PKCS5_PBKDF2_PARAMS params = {}; | |
112 params.Passphrase = StringToData(password); | |
113 params.PseudoRandomFunction = CSSM_PKCS5_PBKDF2_PRF_HMAC_SHA1; | |
114 CSSM_DATA param_data = {sizeof(params), reinterpret_cast<uint8_t*>(¶ms)}; | |
115 err = CSSM_DeriveKey(ctx, | |
116 ¶m_data, | |
117 CSSM_KEYUSE_ANY, | |
118 CSSM_KEYATTR_RETURN_DATA | CSSM_KEYATTR_EXTRACTABLE, | |
119 NULL, | |
120 NULL, | |
121 &cssm_key); | |
122 if (err) { | |
123 LogCSSMError("CSSM_DeriveKey", err); | |
124 goto exit; | |
125 } | |
126 | |
127 DCHECK_EQ(cssm_key.KeyData.Length, key_size_in_bits / 8); | |
128 derived_key = new SymmetricKey(cssm_key.KeyData.Data, key_size_in_bits); | |
129 | |
130 exit: | |
131 CSSM_DeleteContext(ctx); | |
132 CSSM_FreeKey(GetSharedCSPHandle(), &credentials, &cssm_key, false); | |
133 return derived_key; | |
134 } | |
135 | |
136 // static | |
137 SymmetricKey* SymmetricKey::Import(Algorithm algorithm, | |
138 const std::string& raw_key) { | |
139 return new SymmetricKey(raw_key.data(), raw_key.size() * 8); | |
140 } | |
141 | |
142 SymmetricKey::SymmetricKey(const void *key_data, size_t key_size_in_bits) | |
143 : key_(reinterpret_cast<const char*>(key_data), | |
144 key_size_in_bits / 8) {} | |
145 | |
146 bool SymmetricKey::GetRawKey(std::string* raw_key) { | |
147 *raw_key = key_; | |
148 return true; | |
149 } | |
150 | |
151 CSSM_DATA SymmetricKey::cssm_data() const { | |
152 return StringToData(key_); | |
153 } | |
154 | |
155 } // namespace base | |
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