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1 // Copyright 2014 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 "components/rappor/byte_vector_utils.h" | |
6 | |
7 #include <string> | |
8 | |
9 #include "base/logging.h" | |
10 #include "base/rand_util.h" | |
11 #include "base/strings/string_number_conversions.h" | |
12 #include "crypto/random.h" | |
13 | |
14 namespace rappor { | |
15 | |
16 ByteVector* ByteVectorOr(const ByteVector& lhs, ByteVector* rhs) { | |
17 DCHECK_EQ(lhs.size(), rhs->size()); | |
18 for (size_t i = 0, len = lhs.size(); i < len; ++i) { | |
19 (*rhs)[i] = lhs[i] | (*rhs)[i]; | |
20 } | |
21 return rhs; | |
22 } | |
23 | |
24 ByteVector* ByteVectorMerge(const ByteVector& mask, | |
25 const ByteVector& lhs, | |
26 ByteVector* rhs) { | |
27 DCHECK_EQ(lhs.size(), rhs->size()); | |
28 for (size_t i = 0, len = lhs.size(); i < len; ++i) { | |
29 (*rhs)[i] = (lhs[i] & ~mask[i]) | ((*rhs)[i] & mask[i]); | |
30 } | |
31 return rhs; | |
32 } | |
33 | |
34 int CountBits(const ByteVector& vector) { | |
35 int bit_count = 0; | |
36 for(size_t i = 0; i < vector.size(); ++i) { | |
37 uint8_t byte = vector[i]; | |
38 for (int j = 0; j < 8 ; ++j) { | |
39 if (byte & (1 << j)) | |
40 bit_count++; | |
41 } | |
42 } | |
43 return bit_count; | |
44 } | |
45 | |
46 ByteVectorGenerator::ByteVectorGenerator(size_t byte_count) | |
47 : byte_count_(byte_count) {} | |
48 | |
49 ByteVectorGenerator::~ByteVectorGenerator() {} | |
50 | |
51 ByteVector ByteVectorGenerator::GetRandomByteVector() { | |
52 ByteVector bytes(byte_count_); | |
53 crypto::RandBytes(&bytes[0], bytes.size()); | |
54 return bytes; | |
55 } | |
56 | |
57 ByteVector ByteVectorGenerator::GetWeightedRandomByteVector( | |
58 Probability probability) { | |
59 ByteVector bytes = GetRandomByteVector(); | |
60 switch (probability) { | |
61 case PROBABILITY_75: | |
62 return *ByteVectorOr(GetRandomByteVector(), &bytes); | |
63 case PROBABILITY_50: | |
64 return bytes; | |
65 } | |
66 NOTREACHED(); | |
67 return bytes; | |
68 } | |
69 | |
70 HmacByteVectorGenerator::HmacByteVectorGenerator( | |
71 size_t byte_count, | |
72 const std::string& entropy_input, | |
73 const std::string& personalization_string) | |
74 : ByteVectorGenerator(byte_count), | |
75 hmac_(crypto::HMAC::SHA256), | |
76 value_(hmac_.DigestLength(), 0x01), | |
77 requested_bytes_(0) { | |
78 // HMAC_DRBG Instantiate Process | |
79 // 1. seed_material = entropy_input + nonce + personalization_string | |
80 // Note: We are using the 8.6.7 interpretation, where the entropy_input and | |
81 // nonce are acquired at the same time from the same source. | |
82 std::string seed_material(entropy_input + personalization_string); | |
edknapp
2014/02/12 00:27:17
DCHECK(entropy_input.length() == kEntropyInputSize
Steven Holte
2014/02/12 04:02:55
Done.
| |
83 // 2. Key = 0x00 00...00 | |
84 ByteVector key(hmac_.DigestLength(), 0x00); | |
85 // 3. V = 0x01 01...01 | |
86 // (value_ in initializer list) | |
87 | |
88 // 4. (Key, V) = HMAC_DRBG_Update(seed_material, Key, V) | |
89 Update(seed_material, key); | |
90 } | |
91 | |
92 HmacByteVectorGenerator::~HmacByteVectorGenerator() {} | |
93 | |
94 // static | |
95 std::string HmacByteVectorGenerator::GenerateEntropyInput() { | |
96 return base::RandBytesAsString(kEntropyInputSize); | |
97 } | |
98 | |
99 void HmacByteVectorGenerator::Update(const std::string& provided_data, | |
100 const ByteVector& key) { | |
101 std::string initial_value(value_.begin(), value_.end()); | |
102 // HMAC_DRBG Update Process | |
103 // 1. K = HMAC(K, V || 0x00 || provided_data) | |
104 ByteVector generated_key(hmac_.DigestLength()); | |
105 crypto::HMAC keygen_hmac(crypto::HMAC::SHA256); | |
106 if (!keygen_hmac.Init(std::string(key.begin(), key.end()))) | |
107 NOTREACHED(); | |
108 if (!keygen_hmac.Sign(initial_value + char(0x00) + provided_data, | |
109 &generated_key[0], generated_key.size())) { | |
110 NOTREACHED(); | |
111 } | |
112 // 2. V = HMAC(K, V) | |
113 if (!hmac_.Init(std::string(generated_key.begin(), generated_key.end()))) | |
114 NOTREACHED(); | |
115 if (!hmac_.Sign(initial_value, &value_[0], value_.size())) | |
116 NOTREACHED(); | |
117 } | |
edknapp
2014/02/12 00:27:17
Steps 3-6:
if (provided_data.length() > 0) {
K =
Steven Holte
2014/02/12 04:02:55
Done.
| |
118 | |
119 ByteVector HmacByteVectorGenerator::GetRandomByteVector() { | |
120 ByteVector bytes(byte_count_); | |
121 uint8_t* data = bytes.data(); | |
122 size_t digest_length = hmac_.DigestLength(); | |
123 size_t bytes_to_go = byte_count_; | |
124 while (bytes_to_go > 0) { | |
125 size_t requested_byte_in_digest = requested_bytes_ % digest_length; | |
126 if (requested_byte_in_digest == 0) { | |
127 // Do step 4.1 of the HMAC_DRBG Generate Process for more bits. | |
128 // V = HMAC(Key, V) | |
129 if (!hmac_.Sign(std::string(value_.begin(), value_.end()), | |
130 &value_[0], value_.size())) { | |
131 NOTREACHED(); | |
132 } | |
133 } | |
134 size_t n = std::min(bytes_to_go, | |
135 digest_length - requested_byte_in_digest); | |
136 memcpy(data, &value_[requested_byte_in_digest], n); | |
137 data += n; | |
138 bytes_to_go -= n; | |
139 requested_bytes_ += n; | |
140 // Check max_number_of_bits_per_request from 10.1 Table 2 | |
141 // max_number_of_bits_per_request == 2^19 bits == 2^16 bytes | |
142 DCHECK_LT(requested_bytes_, 1U << 16); | |
143 } | |
144 return bytes; | |
145 } | |
146 | |
147 } // namespace rappor | |
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