randen_slow.h

// 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_SLOW_H_
#define ABSL_RANDOM_INTERNAL_RANDEN_SLOW_H_

#include <cstddef>

#include "absl/base/config.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {

// RANDen = RANDom generator or beetroots in Swiss German.
// RandenSlow implements the basic state manipulation methods for
// architectures lacking AES hardware acceleration intrinsics.
class RandenSlow {
 public:
  // 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

  static void Generate(const void* keys, void* state_void);
  static void Absorb(const void* seed_void, void* state_void);
  static const void* GetKeys();
};

}  // namespace random_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_RANDOM_INTERNAL_RANDEN_SLOW_H_