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Diffstat (limited to 'absl/random/internal/seed_material_test.cc')
| -rw-r--r-- | absl/random/internal/seed_material_test.cc | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/absl/random/internal/seed_material_test.cc b/absl/random/internal/seed_material_test.cc new file mode 100644 index 00000000..0de6c4c6 --- /dev/null +++ b/absl/random/internal/seed_material_test.cc @@ -0,0 +1,201 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/random/internal/seed_material.h" + +#include <bitset> +#include <cstdlib> +#include <cstring> +#include <random> + +#include "gmock/gmock.h" +#include "gtest/gtest.h" + +#ifdef __ANDROID__ +// Android assert messages only go to system log, so death tests cannot inspect +// the message for matching. +#define ABSL_EXPECT_DEATH_IF_SUPPORTED(statement, regex) \ + EXPECT_DEATH_IF_SUPPORTED(statement, ".*") +#else +#define ABSL_EXPECT_DEATH_IF_SUPPORTED EXPECT_DEATH_IF_SUPPORTED +#endif + +namespace { + +using testing::Each; +using testing::ElementsAre; +using testing::Eq; +using testing::Ne; +using testing::Pointwise; + +TEST(SeedBitsToBlocks, VerifyCases) { + EXPECT_EQ(0, absl::random_internal::SeedBitsToBlocks(0)); + EXPECT_EQ(1, absl::random_internal::SeedBitsToBlocks(1)); + EXPECT_EQ(1, absl::random_internal::SeedBitsToBlocks(31)); + EXPECT_EQ(1, absl::random_internal::SeedBitsToBlocks(32)); + EXPECT_EQ(2, absl::random_internal::SeedBitsToBlocks(33)); + EXPECT_EQ(4, absl::random_internal::SeedBitsToBlocks(127)); + EXPECT_EQ(4, absl::random_internal::SeedBitsToBlocks(128)); + EXPECT_EQ(5, absl::random_internal::SeedBitsToBlocks(129)); +} + +TEST(ReadSeedMaterialFromOSEntropy, SuccessiveReadsAreDistinct) { + constexpr size_t kSeedMaterialSize = 64; + uint32_t seed_material_1[kSeedMaterialSize] = {}; + uint32_t seed_material_2[kSeedMaterialSize] = {}; + + EXPECT_TRUE(absl::random_internal::ReadSeedMaterialFromOSEntropy( + absl::Span<uint32_t>(seed_material_1, kSeedMaterialSize))); + EXPECT_TRUE(absl::random_internal::ReadSeedMaterialFromOSEntropy( + absl::Span<uint32_t>(seed_material_2, kSeedMaterialSize))); + + EXPECT_THAT(seed_material_1, Pointwise(Ne(), seed_material_2)); +} + +TEST(ReadSeedMaterialFromOSEntropy, ReadZeroBytesIsNoOp) { + uint32_t seed_material[32] = {}; + std::memset(seed_material, 0xAA, sizeof(seed_material)); + EXPECT_TRUE(absl::random_internal::ReadSeedMaterialFromOSEntropy( + absl::Span<uint32_t>(seed_material, 0))); + + EXPECT_THAT(seed_material, Each(Eq(0xAAAAAAAA))); +} + +TEST(ReadSeedMaterialFromOSEntropy, NullPtrVectorArgument) { +#ifdef NDEBUG + EXPECT_FALSE(absl::random_internal::ReadSeedMaterialFromOSEntropy( + absl::Span<uint32_t>(nullptr, 32))); +#else + bool result; + ABSL_EXPECT_DEATH_IF_SUPPORTED( + result = absl::random_internal::ReadSeedMaterialFromOSEntropy( + absl::Span<uint32_t>(nullptr, 32)), + "!= nullptr"); + (void)result; // suppress unused-variable warning +#endif +} + +TEST(ReadSeedMaterialFromURBG, SeedMaterialEqualsVariateSequence) { + // Two default-constructed instances of std::mt19937_64 are guaranteed to + // produce equal variate-sequences. + std::mt19937 urbg_1; + std::mt19937 urbg_2; + constexpr size_t kSeedMaterialSize = 1024; + uint32_t seed_material[kSeedMaterialSize] = {}; + + EXPECT_TRUE(absl::random_internal::ReadSeedMaterialFromURBG( + &urbg_1, absl::Span<uint32_t>(seed_material, kSeedMaterialSize))); + for (uint32_t seed : seed_material) { + EXPECT_EQ(seed, urbg_2()); + } +} + +TEST(ReadSeedMaterialFromURBG, ReadZeroBytesIsNoOp) { + std::mt19937_64 urbg; + uint32_t seed_material[32]; + std::memset(seed_material, 0xAA, sizeof(seed_material)); + EXPECT_TRUE(absl::random_internal::ReadSeedMaterialFromURBG( + &urbg, absl::Span<uint32_t>(seed_material, 0))); + + EXPECT_THAT(seed_material, Each(Eq(0xAAAAAAAA))); +} + +TEST(ReadSeedMaterialFromURBG, NullUrbgArgument) { + constexpr size_t kSeedMaterialSize = 32; + uint32_t seed_material[kSeedMaterialSize]; +#ifdef NDEBUG + EXPECT_FALSE(absl::random_internal::ReadSeedMaterialFromURBG<std::mt19937_64>( + nullptr, absl::Span<uint32_t>(seed_material, kSeedMaterialSize))); +#else + bool result; + ABSL_EXPECT_DEATH_IF_SUPPORTED( + result = absl::random_internal::ReadSeedMaterialFromURBG<std::mt19937_64>( + nullptr, absl::Span<uint32_t>(seed_material, kSeedMaterialSize)), + "!= nullptr"); + (void)result; // suppress unused-variable warning +#endif +} + +TEST(ReadSeedMaterialFromURBG, NullPtrVectorArgument) { + std::mt19937_64 urbg; +#ifdef NDEBUG + EXPECT_FALSE(absl::random_internal::ReadSeedMaterialFromURBG( + &urbg, absl::Span<uint32_t>(nullptr, 32))); +#else + bool result; + ABSL_EXPECT_DEATH_IF_SUPPORTED( + result = absl::random_internal::ReadSeedMaterialFromURBG( + &urbg, absl::Span<uint32_t>(nullptr, 32)), + "!= nullptr"); + (void)result; // suppress unused-variable warning +#endif +} + +// The avalanche effect is a desirable cryptographic property of hashes in which +// changing a single bit in the input causes each bit of the output to be +// changed with probability near 50%. +// +// https://en.wikipedia.org/wiki/Avalanche_effect + +TEST(MixSequenceIntoSeedMaterial, AvalancheEffectTestOneBitLong) { + std::vector<uint32_t> seed_material = {1, 2, 3, 4, 5, 6, 7, 8}; + + // For every 32-bit number with exactly one bit set, verify the avalanche + // effect holds. In order to reduce flakiness of tests, accept values + // anywhere in the range of 30%-70%. + for (uint32_t v = 1; v != 0; v <<= 1) { + std::vector<uint32_t> seed_material_copy = seed_material; + absl::random_internal::MixIntoSeedMaterial( + absl::Span<uint32_t>(&v, 1), + absl::Span<uint32_t>(seed_material_copy.data(), + seed_material_copy.size())); + + uint32_t changed_bits = 0; + for (size_t i = 0; i < seed_material.size(); i++) { + std::bitset<sizeof(uint32_t) * 8> bitset(seed_material[i] ^ + seed_material_copy[i]); + changed_bits += bitset.count(); + } + + EXPECT_LE(changed_bits, 0.7 * sizeof(uint32_t) * 8 * seed_material.size()); + EXPECT_GE(changed_bits, 0.3 * sizeof(uint32_t) * 8 * seed_material.size()); + } +} + +TEST(MixSequenceIntoSeedMaterial, AvalancheEffectTestOneBitShort) { + std::vector<uint32_t> seed_material = {1}; + + // For every 32-bit number with exactly one bit set, verify the avalanche + // effect holds. In order to reduce flakiness of tests, accept values + // anywhere in the range of 30%-70%. + for (uint32_t v = 1; v != 0; v <<= 1) { + std::vector<uint32_t> seed_material_copy = seed_material; + absl::random_internal::MixIntoSeedMaterial( + absl::Span<uint32_t>(&v, 1), + absl::Span<uint32_t>(seed_material_copy.data(), + seed_material_copy.size())); + + uint32_t changed_bits = 0; + for (size_t i = 0; i < seed_material.size(); i++) { + std::bitset<sizeof(uint32_t) * 8> bitset(seed_material[i] ^ + seed_material_copy[i]); + changed_bits += bitset.count(); + } + + EXPECT_LE(changed_bits, 0.7 * sizeof(uint32_t) * 8 * seed_material.size()); + EXPECT_GE(changed_bits, 0.3 * sizeof(uint32_t) * 8 * seed_material.size()); + } +} + +} // namespace |