text: // Copyright (c) 2014-2018, The Monero Project
  // 
  // All rights reserved.
  // 
  // Redistribution and use in source and binary forms, with or without modification, are
  // permitted provided that the following conditions are met:
  // 
  // 1. Redistributions of source code must retain the above copyright notice, this list of
  //    conditions and the following disclaimer.
  // 
  // 2. Redistributions in binary form must reproduce the above copyright notice, this list
  //    of conditions and the following disclaimer in the documentation and/or other
  //    materials provided with the distribution.
  // 
  // 3. Neither the name of the copyright holder nor the names of its contributors may be
  //    used to endorse or promote products derived from this software without specific
  //    prior written permission.
  // 
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  // 
  // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
  
  #pragma once
  
  #include <stdint.h>
  #include <stddef.h>
  
  #define CHACHA_KEY_SIZE 32
  #define CHACHA_IV_SIZE 8
  
  #if defined(__cplusplus)
  #include <memory.h>
  
  #include "memwipe.h"
  #include "mlocker.h"
  #include "hash.h"
  
  namespace crypto {
    extern "C" {
  #endif
      void chacha8(const void* data, size_t length, const uint8_t* key, const uint8_t* iv, char* cipher);
      void chacha20(const void* data, size_t length, const uint8_t* key, const uint8_t* iv, char* cipher);
  #if defined(__cplusplus)
    }
  
    using chacha_key = epee::mlocked<tools::scrubbed_arr<uint8_t, CHACHA_KEY_SIZE>>;
  
  #pragma pack(push, 1)
    // MS VC 2012 doesn't interpret `class chacha_iv` as POD in spite of [9.0.10], so it is a struct
    struct chacha_iv {
      uint8_t data[CHACHA_IV_SIZE];
    };
  #pragma pack(pop)
  
    static_assert(sizeof(chacha_key) == CHACHA_KEY_SIZE && sizeof(chacha_iv) == CHACHA_IV_SIZE, "Invalid structure size");
  
    inline void chacha8(const void* data, std::size_t length, const chacha_key& key, const chacha_iv& iv, char* cipher) {
      chacha8(data, length, key.data(), reinterpret_cast<const uint8_t*>(&iv), cipher);
    }
  
    inline void chacha20(const void* data, std::size_t length, const chacha_key& key, const chacha_iv& iv, char* cipher) {
      chacha20(data, length, key.data(), reinterpret_cast<const uint8_t*>(&iv), cipher);
    }
  
    inline void generate_chacha_key(const void *data, size_t size, chacha_key& key, uint64_t kdf_rounds) {
      static_assert(sizeof(chacha_key) <= sizeof(hash), "Size of hash must be at least that of chacha_key");
      epee::mlocked<tools::scrubbed_arr<char, HASH_SIZE>> pwd_hash;
      crypto::cn_slow_hash(data, size, pwd_hash.data(), 0);
      for (uint64_t n = 1; n < kdf_rounds; ++n)
        crypto::cn_slow_hash(pwd_hash.data(), pwd_hash.size(), pwd_hash.data(), 0);
      memcpy(&unwrap(unwrap(key)), pwd_hash.data(), sizeof(key));
    }
  
    inline void generate_chacha_key_prehashed(const void *data, size_t size, chacha_key& key, uint64_t kdf_rounds) {
      static_assert(sizeof(chacha_key) <= sizeof(hash), "Size of hash must be at least that of chacha_key");
      epee::mlocked<tools::scrubbed_arr<char, HASH_SIZE>> pwd_hash;
      crypto::cn_slow_hash(data, size, pwd_hash.data(), 1);
      for (uint64_t n = 1; n < kdf_rounds; ++n)
        crypto::cn_slow_hash(pwd_hash.data(), pwd_hash.size(), pwd_hash.data(), 0);
      memcpy(&unwrap(unwrap(key)), pwd_hash.data(), sizeof(key));
    }
  
    inline void generate_chacha_key(std::string password, chacha_key& key, uint64_t kdf_rounds) {
      return generate_chacha_key(password.data(), password.size(), key, kdf_rounds);
    }
  }
  
  #endif
  