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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/strings/string_number_conversions.h" | |
11 #include "crypto/random.h" | |
12 | |
13 namespace rappor { | |
14 | |
15 ByteVector* ByteVectorOr(const ByteVector& lhs, ByteVector* rhs) { | |
16 DCHECK_EQ(lhs.size(), rhs->size()); | |
17 for (size_t i = 0, len = lhs.size(); i < len; ++i) { | |
18 (*rhs)[i] = lhs[i] | (*rhs)[i]; | |
19 } | |
20 return rhs; | |
21 } | |
22 | |
23 ByteVector* ByteVectorMerge(const ByteVector& mask, | |
24 const ByteVector& lhs, | |
25 ByteVector* rhs) { | |
26 DCHECK_EQ(lhs.size(), rhs->size()); | |
27 for (size_t i = 0, len = lhs.size(); i < len; ++i) { | |
28 (*rhs)[i] = (lhs[i] & ~mask[i]) | ((*rhs)[i] & mask[i]); | |
29 } | |
30 return rhs; | |
31 } | |
32 | |
33 ByteVectorGenerator::ByteVectorGenerator(size_t byte_count) | |
34 : byte_count_(byte_count) {} | |
35 | |
36 ByteVectorGenerator::~ByteVectorGenerator() {} | |
37 | |
38 uint8_t ByteVectorGenerator::RandByte() { | |
39 uint8_t random_bits; | |
40 crypto::RandBytes(&random_bits, sizeof(uint8_t)); | |
41 return random_bits; | |
42 } | |
43 | |
44 ByteVector ByteVectorGenerator::GetRandomByteVector() { | |
45 ByteVector bytes(byte_count_); | |
46 for (size_t i = 0; i < byte_count_; ++i) { | |
47 bytes[i] = RandByte(); | |
48 } | |
49 return bytes; | |
50 } | |
51 | |
52 ByteVector ByteVectorGenerator::GetWeightedRandomByteVector( | |
53 Probability probability) { | |
54 ByteVector bytes = GetRandomByteVector(); | |
55 switch (probability) { | |
56 case PROBABILITY_75: | |
57 return *ByteVectorOr(GetRandomByteVector(), &bytes); | |
58 case PROBABILITY_50: | |
59 return bytes; | |
60 } | |
61 NOTREACHED(); | |
62 return bytes; | |
63 } | |
64 | |
65 HmacByteVectorGenerator::HmacByteVectorGenerator(size_t byte_count, | |
66 const std::string& secret) | |
67 : ByteVectorGenerator(byte_count), | |
68 hmac_(crypto::HMAC::SHA256) { | |
69 // "Nothing up my sleeve" number for the initial value of an | |
70 // HmacByteVectorGenerator's state. The initial digits of pi. | |
71 const uint64_t kHmacInitialState = 3141592653589793; | |
72 | |
73 if (!hmac_.Init(secret)) | |
74 NOTREACHED(); | |
75 | |
76 DCHECK(hmac_.DigestLength() > sizeof(uint8_t)); | |
Alexei Svitkine (slow)
2014/01/21 18:14:04
DCHECK_GT
Steven Holte
2014/01/21 20:25:14
Done.
| |
77 hmac_state_ = kHmacInitialState; | |
78 } | |
79 | |
80 HmacByteVectorGenerator::~HmacByteVectorGenerator() {} | |
81 | |
82 uint8_t HmacByteVectorGenerator::RandByte() { | |
83 uint8_t random_bits; | |
84 std::string state = base::Uint64ToString(hmac_state_); | |
85 if (!hmac_.Sign(state, &random_bits, sizeof(uint8_t))) | |
86 NOTREACHED(); | |
87 | |
88 ++hmac_state_; | |
89 return random_bits; | |
90 } | |
91 | |
92 } // namespace rappor | |
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