Index: components/rappor/byte_vector_utils.cc |
diff --git a/components/rappor/byte_vector_utils.cc b/components/rappor/byte_vector_utils.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..560e591c0b93069305368fc86a888ad513664780 |
--- /dev/null |
+++ b/components/rappor/byte_vector_utils.cc |
@@ -0,0 +1,104 @@ |
+// Copyright 2014 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "components/rappor/byte_vector_utils.h" |
+ |
+#include <string> |
+ |
+#include "base/logging.h" |
+#include "base/strings/string_number_conversions.h" |
+#include "crypto/random.h" |
+ |
+namespace rappor { |
+ |
+ByteVector* ByteVectorOr(const ByteVector& lhs, ByteVector* rhs) { |
+ DCHECK_EQ(lhs.size(), rhs->size()); |
+ for (size_t i = 0, len = lhs.size(); i < len; ++i) { |
+ (*rhs)[i] = lhs[i] | (*rhs)[i]; |
+ } |
+ return rhs; |
+} |
+ |
+ByteVector* ByteVectorMerge(const ByteVector& mask, |
+ const ByteVector& lhs, |
+ ByteVector* rhs) { |
+ DCHECK_EQ(lhs.size(), rhs->size()); |
+ for (size_t i = 0, len = lhs.size(); i < len; ++i) { |
+ (*rhs)[i] = (lhs[i] & ~mask[i]) | ((*rhs)[i] & mask[i]); |
+ } |
+ return rhs; |
+} |
+ |
+int CountBits(const ByteVector& vector) { |
+ int bit_count = 0; |
+ for(size_t i = 0; i < vector.size(); ++i) { |
+ uint8_t byte = vector[i]; |
+ for (int j = 0; j < 8 ; ++j) { |
+ if (byte & (1 << j)) |
+ bit_count++; |
+ } |
+ } |
+ return bit_count; |
+} |
+ |
+ByteVectorGenerator::ByteVectorGenerator(size_t byte_count) |
+ : byte_count_(byte_count) {} |
+ |
+ByteVectorGenerator::~ByteVectorGenerator() {} |
+ |
+uint8_t ByteVectorGenerator::RandByte() { |
+ uint8_t random_bits; |
+ crypto::RandBytes(&random_bits, sizeof(uint8_t)); |
+ return random_bits; |
+} |
+ |
+ByteVector ByteVectorGenerator::GetRandomByteVector() { |
+ ByteVector bytes(byte_count_); |
+ for (size_t i = 0; i < byte_count_; ++i) { |
+ bytes[i] = RandByte(); |
+ } |
+ return bytes; |
+} |
+ |
+ByteVector ByteVectorGenerator::GetWeightedRandomByteVector( |
+ Probability probability) { |
+ ByteVector bytes = GetRandomByteVector(); |
+ switch (probability) { |
+ case PROBABILITY_75: |
+ return *ByteVectorOr(GetRandomByteVector(), &bytes); |
+ case PROBABILITY_50: |
+ return bytes; |
+ } |
+ NOTREACHED(); |
+ return bytes; |
+} |
+ |
+HmacByteVectorGenerator::HmacByteVectorGenerator(size_t byte_count, |
+ const std::string& secret) |
+ : ByteVectorGenerator(byte_count), |
+ hmac_(crypto::HMAC::SHA256) { |
+ // "Nothing up my sleeve" number for the initial value of an |
+ // HmacByteVectorGenerator's state. The initial digits of pi. |
+ const uint64_t kHmacInitialState = 3141592653589793; |
+ |
+ if (!hmac_.Init(secret)) |
+ NOTREACHED(); |
+ |
+ DCHECK_GT(hmac_.DigestLength(), sizeof(uint8_t)); |
+ hmac_state_ = kHmacInitialState; |
+} |
+ |
+HmacByteVectorGenerator::~HmacByteVectorGenerator() {} |
+ |
+uint8_t HmacByteVectorGenerator::RandByte() { |
+ uint8_t random_bits; |
+ std::string state = base::Uint64ToString(hmac_state_); |
+ if (!hmac_.Sign(state, &random_bits, sizeof(uint8_t))) |
+ NOTREACHED(); |
+ |
+ ++hmac_state_; |
ulfar
2014/02/07 20:19:02
Actually, we should do something a bit fancier, to
Steven Holte
2014/02/07 21:08:16
Will update this next pass.
|
+ return random_bits; |
+} |
+ |
+} // namespace rappor |