RAPPOR implementation

components/rappor/byte_vector_utils_unittest.cc

+// 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 "base/rand_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace rappor {
+
+namespace {
+
+class SecondRequest : public HmacByteVectorGenerator {
+ public:
+  SecondRequest(const HmacByteVectorGenerator& first_request)
+      : HmacByteVectorGenerator(first_request) {}
+};
+
+std::string HexToString(const char* hex) {
+  ByteVector bv;
+  base::HexStringToBytes(hex, &bv);
+  return std::string(bv.begin(), bv.end());
+}
+
+}  // namespace
+
+TEST(ByteVectorTest, ByteVectorOr) {
+  ByteVector lhs(2);
+  lhs[1] = 0x12;
+  ByteVector rhs(2);
+  rhs[1] = 0x03;
+
+  EXPECT_EQ(0x13, (*ByteVectorOr(lhs, &rhs))[1]);
+}
+
+TEST(ByteVectorTest, ByteVectorMerge) {
+  ByteVector lhs(2);
+  lhs[1] = 0x33;
+  ByteVector rhs(2);
+  rhs[1] = 0x55;
+  ByteVector mask(2);
+  mask[1] = 0x0f;
+
+  EXPECT_EQ(0x35, (*ByteVectorMerge(mask, lhs, &rhs))[1]);
+}
+
+TEST(ByteVectorTest, ByteVectorGenerator) {
+  ByteVectorGenerator generator(2u);
+  ByteVector random_50 = generator.GetWeightedRandomByteVector(PROBABILITY_50);
+  EXPECT_EQ(random_50.size(), 2u);
+  ByteVector random_75 = generator.GetWeightedRandomByteVector(PROBABILITY_75);
+  EXPECT_EQ(random_75.size(), 2u);
+}
+
+TEST(ByteVectorTest, HmacByteVectorGenerator) {
+  HmacByteVectorGenerator generator(1u,
+      std::string(HmacByteVectorGenerator::kEntropyInputSize, 0x00), "");
+  ByteVector random_50 = generator.GetWeightedRandomByteVector(PROBABILITY_50);
+  EXPECT_EQ(random_50.size(), 1u);
+  EXPECT_EQ(random_50[0], 0x0B);
+  ByteVector random_75 = generator.GetWeightedRandomByteVector(PROBABILITY_75);
+  EXPECT_EQ(random_75.size(), 1u);
+  EXPECT_EQ(random_75[0], 0xdf);
+}
+
+TEST(ByteVectorTest, HmacNist) {
+  // Test case 0 for SHA-256 HMAC_DRBG no reseed tests from
+  // http://csrc.nist.gov/groups/STM/cavp/
+  const char entropy[] =
+      "ca851911349384bffe89de1cbdc46e6831e44d34a4fb935ee285dd14b71a7488";
+  const char nonce[] = "659ba96c601dc69fc902940805ec0ca8";
+  const char expected[] =
+      "e528e9abf2dece54d47c7e75e5fe302149f817ea9fb4bee6f4199697d04d5b89"
+      "d54fbb978a15b5c443c9ec21036d2460b6f73ebad0dc2aba6e624abf07745bc1"
+      "07694bb7547bb0995f70de25d6b29e2d3011bb19d27676c07162c8b5ccde0668"
+      "961df86803482cb37ed6d5c0bb8d50cf1f50d476aa0458bdaba806f48be9dcb8";
+
+  std::string entropy_input = HexToString(entropy) + HexToString(nonce);
+  HmacByteVectorGenerator generator(1024u / 8, entropy_input, "");
+  generator.GetWeightedRandomByteVector(PROBABILITY_50);
+  SecondRequest generator2(generator);
+  ByteVector random_50 = generator2.GetWeightedRandomByteVector(PROBABILITY_50);
+
+  EXPECT_EQ(HexToString(expected),
+      std::string(random_50.begin(), random_50.end()));
+}
+
+TEST(ByteVectorTest, WeightedRandomStatistics50) {
+  ByteVectorGenerator generator(50u);
+  ByteVector random = generator.GetWeightedRandomByteVector(PROBABILITY_50);
+  int bit_count = CountBits(random);
+  // Check bounds on bit counts that are true with 99.999% probability.
+  EXPECT_GT(bit_count, 155); // Binomial(400, .5) CDF(155) ~= 0.000004
+  EXPECT_LE(bit_count, 244); // Binomial(400, .5) CDF(244) ~= 0.999996
+}
+
+TEST(ByteVectorTest, WeightedRandomStatistics75) {
+  ByteVectorGenerator generator(50u);
+  ByteVector random = generator.GetWeightedRandomByteVector(PROBABILITY_75);
+  int bit_count = CountBits(random);
+  // Check bounds on bit counts that are true with 99.999% probability.
+  EXPECT_GT(bit_count, 259); // Binomial(400, .75) CDF(259) ~= 0.000003
+  EXPECT_LE(bit_count, 337); // Binomial(400, .75) CDF(337) ~= 0.999997
+}
+
+TEST(ByteVectorTest, HmacWeightedRandomStatistics50) {
+  HmacByteVectorGenerator generator(50u,
+      HmacByteVectorGenerator::GenerateEntropyInput(), "");
+  ByteVector random = generator.GetWeightedRandomByteVector(PROBABILITY_50);
+  int bit_count = CountBits(random);
+  // Check bounds on bit counts that are true with 99.999% probability.
+  EXPECT_GT(bit_count, 155); // Binomial(400, .5) CDF(155) ~= 0.000004
+  EXPECT_LE(bit_count, 244); // Binomial(400, .5) CDF(244) ~= 0.999996
+}
+
+TEST(ByteVectorTest, HmacWeightedRandomStatistics75) {
+  HmacByteVectorGenerator generator(50u,
+      HmacByteVectorGenerator::GenerateEntropyInput(), "");
+  ByteVector random = generator.GetWeightedRandomByteVector(PROBABILITY_75);
+  int bit_count = CountBits(random);
+  // Check bounds on bit counts that are true with 99.999% probability.
+  EXPECT_GT(bit_count, 259); // Binomial(400, .75) CDF(259) ~= 0.000003
+  EXPECT_LE(bit_count, 337); // Binomial(400, .75) CDF(337) ~= 0.999997
+}
+
+}  // namespace rappor