text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2012 The Bitcoin developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  #ifndef BITCOIN_HASH_H
  #define BITCOIN_HASH_H
  
  #include "uint256.h"
  #include "serialize.h"
  
  #include <openssl/sha.h>
  #include <openssl/ripemd.h>
  
  #include "crypto/ripemd160.h"
  #include "crypto/sha256.h"
  
  #include <vector>
  
  /** A hasher class for MTI's 256-bit hash (double SHA-256). */
  class CHash256 {
  private:
      CSHA256 sha;
  public:
      static const size_t OUTPUT_SIZE = CSHA256::OUTPUT_SIZE;
  
      void Finalize(unsigned char hash[OUTPUT_SIZE]) {
          unsigned char buf[sha.OUTPUT_SIZE];
          sha.Finalize(buf);
          sha.Reset().Write(buf, sha.OUTPUT_SIZE).Finalize(hash);
      }
  
      CHash256& Write(const unsigned char *data, size_t len) {
          sha.Write(data, len);
          return *this;
      }
  
      CHash256& Reset() {
          sha.Reset();
          return *this;
      }
  };
  
  /** A hasher class for MTI's 160-bit hash (SHA-256 + RIPEMD-160). */
  class CHash160 {
  private:
      CSHA256 sha;
  public:
      static const size_t OUTPUT_SIZE = CRIPEMD160::OUTPUT_SIZE;
  
      void Finalize(unsigned char hash[OUTPUT_SIZE]) {
          unsigned char buf[sha.OUTPUT_SIZE];
          sha.Finalize(buf);
          CRIPEMD160().Write(buf, sha.OUTPUT_SIZE).Finalize(hash);
      }
  
      CHash160& Write(const unsigned char *data, size_t len) {
          sha.Write(data, len);
          return *this;
      }
  
      CHash160& Reset() {
          sha.Reset();
          return *this;
      }
  };
  
  
  template<typename T1>
  inline uint256 Hash(const T1 pbegin, const T1 pend)
  {
      static unsigned char pblank[1];
      uint256 hash1;
      SHA256((pbegin == pend ? pblank : (unsigned char*)&pbegin[0]), (pend - pbegin) * sizeof(pbegin[0]), (unsigned char*)&hash1);
      uint256 hash2;
      SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
      return hash2;
  }
  
  class CHashWriter
  {
  private:
      SHA256_CTX ctx;
  
  public:
      int nType;
      int nVersion;
  
      void Init() {
          SHA256_Init(&ctx);
      }
  
      CHashWriter(int nTypeIn, int nVersionIn) : nType(nTypeIn), nVersion(nVersionIn) {
          Init();
      }
  
      CHashWriter& write(const char *pch, size_t size) {
          SHA256_Update(&ctx, pch, size);
          return (*this);
      }
  
      // invalidates the object
      uint256 GetHash() {
          uint256 hash1;
          SHA256_Final((unsigned char*)&hash1, &ctx);
          uint256 hash2;
          SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
          return hash2;
      }
  
      template<typename T>
      CHashWriter& operator<<(const T& obj) {
          // Serialize to this stream
          ::Serialize(*this, obj, nType, nVersion);
          return (*this);
      }
  };
  
  
  template<typename T1, typename T2>
  inline uint256 Hash(const T1 p1begin, const T1 p1end,
                      const T2 p2begin, const T2 p2end)
  {
      static unsigned char pblank[1];
      uint256 hash1;
      SHA256_CTX ctx;
      SHA256_Init(&ctx);
      SHA256_Update(&ctx, (p1begin == p1end ? pblank : (unsigned char*)&p1begin[0]), (p1end - p1begin) * sizeof(p1begin[0]));
      SHA256_Update(&ctx, (p2begin == p2end ? pblank : (unsigned char*)&p2begin[0]), (p2end - p2begin) * sizeof(p2begin[0]));
      SHA256_Final((unsigned char*)&hash1, &ctx);
      uint256 hash2;
      SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
      return hash2;
  }
  
  template<typename T1, typename T2, typename T3>
  inline uint256 Hash(const T1 p1begin, const T1 p1end,
                      const T2 p2begin, const T2 p2end,
                      const T3 p3begin, const T3 p3end)
  {
      static unsigned char pblank[1];
      uint256 hash1;
      SHA256_CTX ctx;
      SHA256_Init(&ctx);
      SHA256_Update(&ctx, (p1begin == p1end ? pblank : (unsigned char*)&p1begin[0]), (p1end - p1begin) * sizeof(p1begin[0]));
      SHA256_Update(&ctx, (p2begin == p2end ? pblank : (unsigned char*)&p2begin[0]), (p2end - p2begin) * sizeof(p2begin[0]));
      SHA256_Update(&ctx, (p3begin == p3end ? pblank : (unsigned char*)&p3begin[0]), (p3end - p3begin) * sizeof(p3begin[0]));
      SHA256_Final((unsigned char*)&hash1, &ctx);
      uint256 hash2;
      SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
      return hash2;
  }
  
  template<typename T>
  uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL_VERSION)
  {
      CHashWriter ss(nType, nVersion);
      ss << obj;
      return ss.GetHash();
  }
  
  template<typename T1>
  inline uint160 Hash160(const T1 pbegin, const T1 pend)
  {
      static unsigned char pblank[1];
      uint256 hash1;
      SHA256((pbegin == pend ? pblank : (unsigned char*)&pbegin[0]), (pend - pbegin) * sizeof(pbegin[0]), (unsigned char*)&hash1);
      uint160 hash2;
      RIPEMD160((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
      return hash2;
  }
  
  inline uint160 Hash160(const std::vector<unsigned char>& vch)
  {
      return Hash160(vch.begin(), vch.end());
  }
  
  typedef struct
  {
      SHA512_CTX ctxInner;
      SHA512_CTX ctxOuter;
  } HMAC_SHA512_CTX;
  
  int HMAC_SHA512_Init(HMAC_SHA512_CTX *pctx, const void *pkey, size_t len);
  int HMAC_SHA512_Update(HMAC_SHA512_CTX *pctx, const void *pdata, size_t len);
  int HMAC_SHA512_Final(unsigned char *pmd, HMAC_SHA512_CTX *pctx);
  void BIP32Hash(const unsigned char chainCode[32], unsigned int nChild, unsigned char header, const unsigned char data[32], unsigned char output[64]);
  #endif
  