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..10e91046d5b7fb49702f9ff898b2858675d9d8b8 |
--- /dev/null |
+++ b/components/rappor/byte_vector_utils.cc |
@@ -0,0 +1,124 @@ |
+// 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) { |
wtc
2014/02/10 20:12:54
This operation is called "population count" or "po
Steven Holte
2014/02/10 22:50:54
Since I'm only using this function for testing, I'
|
+ 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() { |
wtc
2014/02/10 20:12:54
Requesting only one byte at a time from the PRNG c
Steven Holte
2014/02/10 22:50:54
Done.
|
+ 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(); |
wtc
2014/02/10 20:12:54
This error probably needs to be detected in releas
Steven Holte
2014/02/10 22:50:54
This should be prevented by compiler errors due to
|
+ return bytes; |
+} |
+ |
+HmacByteVectorGenerator::HmacByteVectorGenerator(size_t byte_count, |
+ const std::string& secret) |
+ : ByteVectorGenerator(byte_count), |
+ hmac_(crypto::HMAC::SHA256), |
+ value_(hmac_.DigestLength(), 0x01), |
+ requested_bytes_(0) { |
+ // HMAC_DRBG Instantiate Process |
+ // 2. Key = 0x00 00...00 |
+ // 3. V = 0x01 01...01 |
+ ByteVector key(hmac_.DigestLength(), 0x00); |
+ std::string initial_value(value_.begin(), value_.end()); |
+ |
+ // 4. (Key, V) = HMAC_DRBG_Update(seed_material, Key, V) |
+ // HMAC_DRBG Update Process inlined |
+ // 1. K = HMAC(K, V || 0x00 || provided_data) |
+ crypto::HMAC keygen_hmac(crypto::HMAC::SHA256); |
+ if (!keygen_hmac.Init(std::string(key.begin(), key.end()))) |
+ NOTREACHED(); |
+ if (!keygen_hmac.Sign(initial_value + char(0x00) + secret, |
+ key.data(), key.size())) |
+ NOTREACHED(); |
+ // 2. V = HMAC(K, V) |
+ if (!hmac_.Init(std::string(key.begin(), key.end()))) |
+ NOTREACHED(); |
+ if (!hmac_.Sign(initial_value, value_.data(), value_.size())) |
+ NOTREACHED(); |
+} |
+ |
+HmacByteVectorGenerator::~HmacByteVectorGenerator() {} |
+ |
+uint8_t HmacByteVectorGenerator::RandByte() { |
+ size_t requested_byte_in_digest = requested_bytes_ % hmac_.DigestLength(); |
+ if (requested_byte_in_digest == 0) { |
+ // Do step 4.1 of the HMAC_DRBG Generate Process for more bits. |
+ // V = HMAC(Key, V) |
+ if(!hmac_.Sign(std::string(value_.begin(), value_.end()), |
+ value_.data(), value_.size())) |
+ NOTREACHED(); |
+ } |
+ uint8_t result = value_[requested_byte_in_digest]; |
+ requested_bytes_++; |
+ // Check max_number_of_bits_per_request from 10.1 Table 2 |
+ // max_number_of_bits_per_request == 2^19 bits == 2^16 bytes |
+ DCHECK_LT(requested_bytes_, 1U << 16); |
+ return result; |
+} |
+ |
+} // namespace rappor |