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..846227f9daad0008d688b5bbc464c599ba5993c5 |
--- /dev/null |
+++ b/components/rappor/byte_vector_utils.cc |
@@ -0,0 +1,161 @@ |
+// 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/rand_util.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) { |
Alexei Svitkine (slow)
2014/02/12 18:13:05
Nit: space after for
Steven Holte
2014/02/12 22:28:50
Done.
|
+ 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() {} |
+ |
+ByteVector ByteVectorGenerator::GetRandomByteVector() { |
+ ByteVector bytes(byte_count_); |
+ crypto::RandBytes(&bytes[0], bytes.size()); |
+ 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& entropy_input, |
+ const std::string& personalization_string) |
+ : ByteVectorGenerator(byte_count), |
+ hmac_(crypto::HMAC::SHA256), |
+ value_(hmac_.DigestLength(), 0x01), |
+ requested_bytes_(0) { |
+ // HMAC_DRBG Instantiate Process |
+ // 1. seed_material = entropy_input + nonce + personalization_string |
+ // Note: We are using the 8.6.7 interpretation, where the entropy_input and |
+ // nonce are acquired at the same time from the same source. |
+ DCHECK_EQ(entropy_input.size(), kEntropyInputSize); |
Alexei Svitkine (slow)
2014/02/12 18:13:05
Nit: expected value should be on the left
Steven Holte
2014/02/12 22:28:50
Done.
|
+ std::string seed_material(entropy_input + personalization_string); |
+ // 2. Key = 0x00 00...00 |
+ ByteVector key(hmac_.DigestLength(), 0x00); |
+ // 3. V = 0x01 01...01 |
+ // (value_ in initializer list) |
+ |
+ // 4. (Key, V) = HMAC_DRBG_Update(seed_material, Key, V) |
+ Update(seed_material, key); |
+} |
+ |
+HmacByteVectorGenerator::~HmacByteVectorGenerator() {} |
+ |
+const size_t HmacByteVectorGenerator::kEntropyInputSize = (128 / 8) * 3 / 2; |
+ |
+// static |
+std::string HmacByteVectorGenerator::GenerateEntropyInput() { |
+ return base::RandBytesAsString(kEntropyInputSize); |
+} |
+ |
+void HmacByteVectorGenerator::Update(const std::string& provided_data, |
+ const ByteVector& key1) { |
+ std::string value1(value_.begin(), value_.end()); |
+ // HMAC_DRBG Update Process |
+ // 1. K = HMAC(K, V || 0x00 || provided_data) |
+ ByteVector key2(hmac_.DigestLength()); |
+ crypto::HMAC hmac1(crypto::HMAC::SHA256); |
+ if (!hmac1.Init(std::string(key1.begin(), key1.end()))) |
Alexei Svitkine (slow)
2014/02/12 18:13:05
I'm not super happy with the amount of copying of
Steven Holte
2014/02/12 22:28:50
Using StringPiece.
|
+ NOTREACHED(); |
+ if (!hmac1.Sign(value1 + char(0x00) + provided_data, &key2[0], key2.size())) |
+ NOTREACHED(); |
+ // 2. V = HMAC(K, V) |
+ crypto::HMAC hmac2(crypto::HMAC::SHA256); |
+ if (!hmac2.Init(std::string(key2.begin(), key2.end()))) |
+ NOTREACHED(); |
+ if (!hmac2.Sign(value1, &value_[0], value_.size())) |
+ NOTREACHED(); |
+ // 3. If (provided_data = Null), then return K and V. |
+ DCHECK_GE(provided_data.size(), kEntropyInputSize); |
+ // 4. K = HMAC(K, V || 0x01 || provided_data) |
+ std::string value2(value_.begin(), value_.end()); |
+ ByteVector key3(hmac_.DigestLength()); |
+ if (!hmac2.Sign(value2 + char(0x01) + provided_data, &key3[0], key3.size())) |
Alexei Svitkine (slow)
2014/02/12 18:13:05
This logic seems very similar to what you do for t
Steven Holte
2014/02/12 22:28:50
Added helper function for K = HMAC(K, data)
Alexei Svitkine (slow)
2014/02/12 22:42:36
Thanks, this is much cleaner!
|
+ NOTREACHED(); |
+ // 5. V = HMAC(K, V) |
+ if (!hmac_.Init(std::string(key3.begin(), key3.end()))) |
+ NOTREACHED(); |
+ if (!hmac_.Sign(value2, &value_[0], value_.size())) |
+ NOTREACHED(); |
+} |
+ |
+ByteVector HmacByteVectorGenerator::GetRandomByteVector() { |
+ ByteVector bytes(byte_count_); |
+ uint8_t* data = bytes.data(); |
+ size_t digest_length = hmac_.DigestLength(); |
Alexei Svitkine (slow)
2014/02/12 18:13:05
Nit: const
I'd also put this at the top of the fu
Steven Holte
2014/02/12 22:28:50
Done.
|
+ size_t bytes_to_go = byte_count_; |
+ while (bytes_to_go > 0) { |
+ size_t requested_byte_in_digest = requested_bytes_ % digest_length; |
+ 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_[0], value_.size())) { |
+ NOTREACHED(); |
+ } |
+ } |
+ size_t n = std::min(bytes_to_go, |
+ digest_length - requested_byte_in_digest); |
+ memcpy(data, &value_[requested_byte_in_digest], n); |
+ data += n; |
+ bytes_to_go -= n; |
+ requested_bytes_ += n; |
+ // 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 bytes; |
+} |
+ |
+} // namespace rappor |