text: // Copyright (c) 2019-2020 The Bitkincoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  
  #include <bench/bench.h>
  #include <crypto/chacha_poly_aead.h>
  #include <crypto/poly1305.h> // for the POLY1305_TAGLEN constant
  #include <hash.h>
  
  #include <assert.h>
  #include <limits>
  
  /* Number of bytes to process per iteration */
  static constexpr uint64_t BUFFER_SIZE_TINY = 64;
  static constexpr uint64_t BUFFER_SIZE_SMALL = 256;
  static constexpr uint64_t BUFFER_SIZE_LARGE = 1024 * 1024;
  
  static const unsigned char k1[32] = {0};
  static const unsigned char k2[32] = {0};
  
  static ChaCha20Poly1305AEAD aead(k1, 32, k2, 32);
  
  static void CHACHA20_POLY1305_AEAD(benchmark::Bench& bench, size_t buffersize, bool include_decryption)
  {
      std::vector<unsigned char> in(buffersize + CHACHA20_POLY1305_AEAD_AAD_LEN + POLY1305_TAGLEN, 0);
      std::vector<unsigned char> out(buffersize + CHACHA20_POLY1305_AEAD_AAD_LEN + POLY1305_TAGLEN, 0);
      uint64_t seqnr_payload = 0;
      uint64_t seqnr_aad = 0;
      int aad_pos = 0;
      uint32_t len = 0;
      bench.batch(buffersize).unit("byte").run([&] {
          // encrypt or decrypt the buffer with a static key
          assert(aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, out.data(), out.size(), in.data(), buffersize, true));
  
          if (include_decryption) {
              // if we decrypt, include the GetLength
              assert(aead.GetLength(&len, seqnr_aad, aad_pos, in.data()));
              assert(aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, out.data(), out.size(), in.data(), buffersize, true));
          }
  
          // increase main sequence number
          seqnr_payload++;
          // increase aad position (position in AAD keystream)
          aad_pos += CHACHA20_POLY1305_AEAD_AAD_LEN;
          if (aad_pos + CHACHA20_POLY1305_AEAD_AAD_LEN > CHACHA20_ROUND_OUTPUT) {
              aad_pos = 0;
              seqnr_aad++;
          }
          if (seqnr_payload + 1 == std::numeric_limits<uint64_t>::max()) {
              // reuse of nonce+key is okay while benchmarking.
              seqnr_payload = 0;
              seqnr_aad = 0;
              aad_pos = 0;
          }
      });
  }
  
  static void CHACHA20_POLY1305_AEAD_64BYTES_ONLY_ENCRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_TINY, false);
  }
  
  static void CHACHA20_POLY1305_AEAD_256BYTES_ONLY_ENCRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_SMALL, false);
  }
  
  static void CHACHA20_POLY1305_AEAD_1MB_ONLY_ENCRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_LARGE, false);
  }
  
  static void CHACHA20_POLY1305_AEAD_64BYTES_ENCRYPT_DECRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_TINY, true);
  }
  
  static void CHACHA20_POLY1305_AEAD_256BYTES_ENCRYPT_DECRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_SMALL, true);
  }
  
  static void CHACHA20_POLY1305_AEAD_1MB_ENCRYPT_DECRYPT(benchmark::Bench& bench)
  {
      CHACHA20_POLY1305_AEAD(bench, BUFFER_SIZE_LARGE, true);
  }
  
  // Add Hash() (dbl-sha256) bench for comparison
  
  static void HASH(benchmark::Bench& bench, size_t buffersize)
  {
      uint8_t hash[CHash256::OUTPUT_SIZE];
      std::vector<uint8_t> in(buffersize,0);
      bench.batch(in.size()).unit("byte").run([&] {
          CHash256().Write(in).Finalize(hash);
      });
  }
  
  static void HASH_64BYTES(benchmark::Bench& bench)
  {
      HASH(bench, BUFFER_SIZE_TINY);
  }
  
  static void HASH_256BYTES(benchmark::Bench& bench)
  {
      HASH(bench, BUFFER_SIZE_SMALL);
  }
  
  static void HASH_1MB(benchmark::Bench& bench)
  {
      HASH(bench, BUFFER_SIZE_LARGE);
  }
  
  BENCHMARK(CHACHA20_POLY1305_AEAD_64BYTES_ONLY_ENCRYPT);
  BENCHMARK(CHACHA20_POLY1305_AEAD_256BYTES_ONLY_ENCRYPT);
  BENCHMARK(CHACHA20_POLY1305_AEAD_1MB_ONLY_ENCRYPT);
  BENCHMARK(CHACHA20_POLY1305_AEAD_64BYTES_ENCRYPT_DECRYPT);
  BENCHMARK(CHACHA20_POLY1305_AEAD_256BYTES_ENCRYPT_DECRYPT);
  BENCHMARK(CHACHA20_POLY1305_AEAD_1MB_ENCRYPT_DECRYPT);
  BENCHMARK(HASH_64BYTES);
  BENCHMARK(HASH_256BYTES);
  BENCHMARK(HASH_1MB);
  