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