randen_slow.cc | Explore in Territory

// 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/randen_slow.h"

#include <cstddef>
#include <cstdint>
#include <cstring>

#include "absl/base/attributes.h"
#include "absl/base/internal/endian.h"
#include "absl/numeric/int128.h"
#include "absl/random/internal/platform.h"
#include "absl/random/internal/randen_traits.h"

#if ABSL_HAVE_ATTRIBUTE(always_inline) || \
    (defined(__GNUC__) && !defined(__clang__))
#define ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE …
#elif defined(_MSC_VER)
// We can achieve something similar to attribute((always_inline)) with MSVC by
// using the __forceinline keyword, however this is not perfect. MSVC is
// much less aggressive about inlining, and even with the __forceinline keyword.
#define ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE …
#else
#define ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE
#endif

namespace {

// AES portions based on rijndael-alg-fst.c,
// https://fastcrypto.org/front/misc/rijndael-alg-fst.c, and modified for
// platform-endianness.
//
// Implementation of
// http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf
constexpr uint32_t te0[256] = …;

constexpr uint32_t te1[256] = …;

constexpr uint32_t te2[256] = …;

constexpr uint32_t te3[256] = …;

// Software implementation of the Vector128 class, using uint32_t
// as an underlying vector register.
struct alignas(16) Vector128 { … };

inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE Vector128
Vector128Load(const void* from) { … }

inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE void Vector128Store(
    const Vector128& v, void* to) { … }

// One round of AES. "round_key" is a public constant for breaking the
// symmetry of AES (ensures previously equal columns differ afterwards).
inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE Vector128
AesRound(const Vector128& state, const Vector128& round_key) { … }

RandenTraits;

// The improved Feistel block shuffle function for 16 blocks.
inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE void BlockShuffle(
    absl::uint128* state) { … }

// Feistel round function using two AES subrounds. Very similar to F()
// from Simpira v2, but with independent subround keys. Uses 17 AES rounds
// per 16 bytes (vs. 10 for AES-CTR). Computing eight round functions in
// parallel hides the 7-cycle AESNI latency on HSW. Note that the Feistel
// XORs are 'free' (included in the second AES instruction).
inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE const absl::uint128*
FeistelRound(absl::uint128* ABSL_RANDOM_INTERNAL_RESTRICT state,
             const absl::uint128* ABSL_RANDOM_INTERNAL_RESTRICT keys) { … }

// Cryptographic permutation based via type-2 Generalized Feistel Network.
// Indistinguishable from ideal by chosen-ciphertext adversaries using less than
// 2^64 queries if the round function is a PRF. This is similar to the b=8 case
// of Simpira v2, but more efficient than its generic construction for b=16.
inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE void Permute(
    absl::uint128* state,
    const absl::uint128* ABSL_RANDOM_INTERNAL_RESTRICT keys) { … }

// Enables native loads in the round loop by pre-swapping.
inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE void SwapEndian(
    absl::uint128* state) { … }

}  // namespace

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {

const void* RandenSlow::GetKeys() { … }

void RandenSlow::Absorb(const void* seed_void, void* state_void) { … }

void RandenSlow::Generate(const void* keys_void, void* state_void) { … }

}  // namespace random_internal
ABSL_NAMESPACE_END
}  // namespace absl
chromium/third_party/abseil-cpp/absl/random/internal/randen_slow.cc
