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1 // Copyright (c) 2013 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/strings/string_number_conversions.h" | |
11 #include "crypto/hmac.h" | |
12 #include "crypto/random.h" | |
13 | |
14 namespace rappor { | |
15 | |
16 ByteVector* ByteVectorAnd(ByteVector* lhs, const ByteVector& rhs) { | |
17 DCHECK_EQ(lhs->size(), rhs.size()); | |
18 for (size_t i = 0, len = rhs.size(); i < len; i++) { | |
19 (*lhs)[i] = (*lhs)[i] & rhs[i]; | |
20 } | |
21 return lhs; | |
22 } | |
23 | |
24 ByteVector* ByteVectorOr(ByteVector* lhs, const ByteVector& rhs) { | |
25 DCHECK_EQ(lhs->size(), rhs.size()); | |
26 for (size_t i = 0, len = rhs.size(); i < len; i++) { | |
27 (*lhs)[i] = (*lhs)[i] | rhs[i]; | |
28 } | |
29 return lhs; | |
30 } | |
31 | |
32 ByteVector* ByteVectorMerge(ByteVector* lhs, | |
33 const ByteVector& rhs, | |
34 const ByteVector& mask) { | |
35 DCHECK_EQ(lhs->size(), rhs.size()); | |
36 for (size_t i = 0, len = rhs.size(); i < len; i++) { | |
37 (*lhs)[i] = ((*lhs)[i] & ~mask[i]) | (rhs[i] & mask[i]); | |
38 } | |
39 return lhs; | |
40 } | |
41 | |
42 ByteVectorGenerator::ByteVectorGenerator(size_t byte_count) | |
43 : byte_count_(byte_count) {} | |
44 | |
45 uint8_t ByteVectorGenerator::RandByte() { | |
46 uint8_t random_bits; | |
47 crypto::RandBytes(&random_bits, sizeof(uint8_t)); | |
48 return random_bits; | |
49 } | |
50 | |
51 ByteVector ByteVectorGenerator::GetRandomByteVector() { | |
52 ByteVector bytes(byte_count_); | |
53 for (size_t i = 0; i < byte_count_; i++) { | |
54 bytes[i] = RandByte(); | |
55 } | |
56 return bytes; | |
57 } | |
58 | |
59 ByteVector ByteVectorGenerator::GetWeightedRandomByteVector( | |
60 Probability probability) { | |
61 ByteVector bytes = GetRandomByteVector(); | |
62 switch (probability) { | |
63 case PROBABILITY_87_5: | |
64 return *ByteVectorOr(ByteVectorOr(&bytes, GetRandomByteVector()), | |
65 GetRandomByteVector()); | |
66 case PROBABILITY_75: | |
67 return *ByteVectorOr(&bytes, GetRandomByteVector()); | |
68 case PROBABILITY_50: | |
69 return bytes; | |
70 case PROBABILITY_25: | |
71 return *ByteVectorAnd(&bytes, GetRandomByteVector()); | |
72 case PROBABILITY_12_5: | |
73 return *ByteVectorAnd(ByteVectorAnd(&bytes, GetRandomByteVector()), | |
74 GetRandomByteVector()); | |
75 default: | |
76 // Invalid probability for coin flips | |
77 abort(); | |
78 } | |
79 } | |
80 | |
81 HmacByteVectorGenerator::HmacByteVectorGenerator(size_t byte_count, | |
82 const std::string& secret) | |
83 : ByteVectorGenerator(byte_count), hmac_(crypto::HMAC::SHA256) { | |
84 // A completely arbitrary value for the initial value of an | |
85 // HmacByteVectorGenerator's state. The initial digits of pi. | |
86 const uint64_t kHmacInitialState = 3141592653589793; | |
87 | |
88 if (!hmac_.Init(secret)) { | |
89 abort(); | |
Alexei Svitkine (slow)
2014/01/09 19:23:09
Don't use abort() in Chrome code. You probably wan
Steven Holte
2014/01/09 22:03:01
Done.
| |
90 }; | |
91 assert(hmac_.DigestLength() > sizeof(uint64_t)); | |
92 hmac_state_ = kHmacInitialState; | |
93 } | |
94 | |
95 uint8_t HmacByteVectorGenerator::RandByte() { | |
96 uint8_t random_bits; | |
97 std::string state = base::Uint64ToString(hmac_state_); | |
98 if (!hmac_.Sign(state, &random_bits, sizeof(uint8_t))) { | |
99 abort(); | |
100 } | |
101 ++hmac_state_; | |
102 return random_bits; | |
103 } | |
104 | |
105 } // namespace rappor | |
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