sha3_reference.h

// Copyright 2025 Google LLC.
//
// 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
//
//     http://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 PRIVACY_PROOFS_ZK_LIB_CIRCUITS_SHA3_SHA3_REFERENCE_H_
#define PRIVACY_PROOFS_ZK_LIB_CIRCUITS_SHA3_SHA3_REFERENCE_H_
 
// !!!!! DO NOT USE IN PRODUCTION !!!!!
 
/* This is a simple reference implementation of sha3
   to be used to design zero-knowledge circuits.  DO NOT USE
   THIS CODE IN PRODUCTION. */
#include <cstdint>
#include <cstdlib>
 
namespace proofs {
class Sha3Reference {
  size_t mdlen_;
  size_t rate_;
  size_t wrptr_;
  uint8_t buf_[200];
  uint64_t a_[5][5];
 
  static void keccak_f_1600(uint64_t A[5][5]);
 
 public:
  explicit Sha3Reference(size_t mdlen)
      : mdlen_(mdlen), rate_(200 - 2 * mdlen), wrptr_(0), buf_{}, a_{} {}
 
  void update(const char* data, size_t n);
  void final(uint8_t digest[/*mdlen*/]);
 
  static void keccak_f_1600_DEBUG_ONLY(uint64_t A[5][5]);
};
}  // namespace proofs
#endif  // PRIVACY_PROOFS_ZK_LIB_CIRCUITS_SHA3_SHA3_REFERENCE_H_