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Diffstat (limited to 'third_party/abseil_cpp/absl/random/internal/seed_material.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/random/internal/seed_material.h | 104 |
1 files changed, 0 insertions, 104 deletions
diff --git a/third_party/abseil_cpp/absl/random/internal/seed_material.h b/third_party/abseil_cpp/absl/random/internal/seed_material.h deleted file mode 100644 index 4be10e925685..000000000000 --- a/third_party/abseil_cpp/absl/random/internal/seed_material.h +++ /dev/null @@ -1,104 +0,0 @@ -// 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. - -#ifndef ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_ -#define ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_ - -#include <cassert> -#include <cstdint> -#include <cstdlib> -#include <string> -#include <vector> - -#include "absl/base/attributes.h" -#include "absl/random/internal/fast_uniform_bits.h" -#include "absl/types/optional.h" -#include "absl/types/span.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace random_internal { - -// Returns the number of 32-bit blocks needed to contain the given number of -// bits. -constexpr size_t SeedBitsToBlocks(size_t seed_size) { - return (seed_size + 31) / 32; -} - -// Amount of entropy (measured in bits) used to instantiate a Seed Sequence, -// with which to create a URBG. -constexpr size_t kEntropyBitsNeeded = 256; - -// Amount of entropy (measured in 32-bit blocks) used to instantiate a Seed -// Sequence, with which to create a URBG. -constexpr size_t kEntropyBlocksNeeded = - random_internal::SeedBitsToBlocks(kEntropyBitsNeeded); - -static_assert(kEntropyBlocksNeeded > 0, - "Entropy used to seed URBGs must be nonzero."); - -// Attempts to fill a span of uint32_t-values using an OS-provided source of -// true entropy (eg. /dev/urandom) into an array of uint32_t blocks of data. The -// resulting array may be used to initialize an instance of a class conforming -// to the C++ Standard "Seed Sequence" concept [rand.req.seedseq]. -// -// If values.data() == nullptr, the behavior is undefined. -ABSL_MUST_USE_RESULT -bool ReadSeedMaterialFromOSEntropy(absl::Span<uint32_t> values); - -// Attempts to fill a span of uint32_t-values using variates generated by an -// existing instance of a class conforming to the C++ Standard "Uniform Random -// Bit Generator" concept [rand.req.urng]. The resulting data may be used to -// initialize an instance of a class conforming to the C++ Standard -// "Seed Sequence" concept [rand.req.seedseq]. -// -// If urbg == nullptr or values.data() == nullptr, the behavior is undefined. -template <typename URBG> -ABSL_MUST_USE_RESULT bool ReadSeedMaterialFromURBG( - URBG* urbg, absl::Span<uint32_t> values) { - random_internal::FastUniformBits<uint32_t> distr; - - assert(urbg != nullptr && values.data() != nullptr); - if (urbg == nullptr || values.data() == nullptr) { - return false; - } - - for (uint32_t& seed_value : values) { - seed_value = distr(*urbg); - } - return true; -} - -// Mixes given sequence of values with into given sequence of seed material. -// Time complexity of this function is O(sequence.size() * -// seed_material.size()). -// -// Algorithm is based on code available at -// https://gist.github.com/imneme/540829265469e673d045 -// by Melissa O'Neill. -void MixIntoSeedMaterial(absl::Span<const uint32_t> sequence, - absl::Span<uint32_t> seed_material); - -// Returns salt value. -// -// Salt is obtained only once and stored in static variable. -// -// May return empty value if optaining the salt was not possible. -absl::optional<uint32_t> GetSaltMaterial(); - -} // namespace random_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_ |