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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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