|
|
|
|
// 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_RANDEN_TRAITS_H_
|
|
|
|
|
#define ABSL_RANDOM_INTERNAL_RANDEN_TRAITS_H_
|
|
|
|
|
|
|
|
|
|
// HERMETIC NOTE: The randen_hwaes target must not introduce duplicate
|
|
|
|
|
// symbols from arbitrary system and other headers, since it may be built
|
|
|
|
|
// with different flags from other targets, using different levels of
|
|
|
|
|
// optimization, potentially introducing ODR violations.
|
|
|
|
|
|
|
|
|
|
#include <cstddef>
|
|
|
|
|
|
|
|
|
|
#include "absl/base/config.h"
|
|
|
|
|
|
|
|
|
|
namespace absl {
|
|
|
|
|
ABSL_NAMESPACE_BEGIN
|
|
|
|
|
namespace random_internal {
|
|
|
|
|
|
|
|
|
|
// RANDen = RANDom generator or beetroots in Swiss German.
|
|
|
|
|
// 'Strong' (well-distributed, unpredictable, backtracking-resistant) random
|
|
|
|
|
// generator, faster in some benchmarks than std::mt19937_64 and pcg64_c32.
|
|
|
|
|
//
|
|
|
|
|
// RandenTraits contains the basic algorithm traits, such as the size of the
|
|
|
|
|
// state, seed, sponge, etc.
|
|
|
|
|
struct RandenTraits {
|
|
|
|
|
// Size of the entire sponge / state for the randen PRNG.
|
|
|
|
|
static constexpr size_t kStateBytes = 256; // 2048-bit
|
|
|
|
|
|
|
|
|
|
// Size of the 'inner' (inaccessible) part of the sponge. Larger values would
|
|
|
|
|
// require more frequent calls to RandenGenerate.
|
|
|
|
|
static constexpr size_t kCapacityBytes = 16; // 128-bit
|
|
|
|
|
|
|
|
|
|
// Size of the default seed consumed by the sponge.
|
|
|
|
|
static constexpr size_t kSeedBytes = kStateBytes - kCapacityBytes;
|
|
|
|
|
|
|
|
|
|
// Largest size for which security proofs are known.
|
|
|
|
|
static constexpr size_t kFeistelBlocks = 16;
|
|
|
|
|
|
|
|
|
|
// Type-2 generalized Feistel => one round function for every two blocks.
|
|
|
|
|
static constexpr size_t kFeistelFunctions = kFeistelBlocks / 2; // = 8
|
|
|
|
|
|
|
|
|
|
// Ensures SPRP security and two full subblock diffusions.
|
|
|
|
|
// Must be > 4 * log2(kFeistelBlocks).
|
|
|
|
|
static constexpr size_t kFeistelRounds = 16 + 1;
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
} // namespace random_internal
|
|
|
|
|
ABSL_NAMESPACE_END
|
|
|
|
|
} // namespace absl
|
|
|
|
|
|
|
|
|
|
#endif // ABSL_RANDOM_INTERNAL_RANDEN_TRAITS_H_
|
