fc8dc48020
git-subtree-dir: third_party/abseil_cpp git-subtree-mainline:ffb2ae54begit-subtree-split:768eb2ca28
102 lines
3.2 KiB
C++
102 lines
3.2 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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#ifndef ABSL_RANDOM_INTERNAL_RANDEN_H_
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#define ABSL_RANDOM_INTERNAL_RANDEN_H_
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#include <cstddef>
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#include "absl/random/internal/platform.h"
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#include "absl/random/internal/randen_hwaes.h"
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#include "absl/random/internal/randen_slow.h"
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#include "absl/random/internal/randen_traits.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace random_internal {
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// RANDen = RANDom generator or beetroots in Swiss German.
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// 'Strong' (well-distributed, unpredictable, backtracking-resistant) random
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// generator, faster in some benchmarks than std::mt19937_64 and pcg64_c32.
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//
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// Randen implements the basic state manipulation methods.
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class Randen {
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public:
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static constexpr size_t kStateBytes = RandenTraits::kStateBytes;
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static constexpr size_t kCapacityBytes = RandenTraits::kCapacityBytes;
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static constexpr size_t kSeedBytes = RandenTraits::kSeedBytes;
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~Randen() = default;
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Randen();
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// Generate updates the randen sponge. The outer portion of the sponge
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// (kCapacityBytes .. kStateBytes) may be consumed as PRNG state.
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template <typename T, size_t N>
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void Generate(T (&state)[N]) const {
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static_assert(N * sizeof(T) == kStateBytes,
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"Randen::Generate() requires kStateBytes of state");
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#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
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// HW AES Dispatch.
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if (has_crypto_) {
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RandenHwAes::Generate(keys_, state);
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} else {
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RandenSlow::Generate(keys_, state);
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}
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#elif ABSL_HAVE_ACCELERATED_AES
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// HW AES is enabled.
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RandenHwAes::Generate(keys_, state);
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#else
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// HW AES is disabled.
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RandenSlow::Generate(keys_, state);
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#endif
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}
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// Absorb incorporates additional seed material into the randen sponge. After
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// absorb returns, Generate must be called before the state may be consumed.
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template <typename S, size_t M, typename T, size_t N>
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void Absorb(const S (&seed)[M], T (&state)[N]) const {
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static_assert(M * sizeof(S) == RandenTraits::kSeedBytes,
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"Randen::Absorb() requires kSeedBytes of seed");
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static_assert(N * sizeof(T) == RandenTraits::kStateBytes,
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"Randen::Absorb() requires kStateBytes of state");
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#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
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// HW AES Dispatch.
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if (has_crypto_) {
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RandenHwAes::Absorb(seed, state);
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} else {
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RandenSlow::Absorb(seed, state);
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}
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#elif ABSL_HAVE_ACCELERATED_AES
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// HW AES is enabled.
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RandenHwAes::Absorb(seed, state);
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#else
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// HW AES is disabled.
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RandenSlow::Absorb(seed, state);
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#endif
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}
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private:
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const void* keys_;
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#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
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bool has_crypto_;
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#endif
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};
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} // namespace random_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_RANDOM_INTERNAL_RANDEN_H_
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