text: // Copyright (c) 2009-2012 The blazecoin Developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <openssl/aes.h>
  #include <openssl/evp.h>
  #include <vector>
  #include <string>
  #ifdef WIN32
  #include <windows.h>
  #endif
  
  #include "crypter.h"
  
  bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod)
  {
      if (nRounds < 1 || chSalt.size() != WALLET_CRYPTO_SALT_SIZE)
          return false;
  
      int i = 0;
      if (nDerivationMethod == 0)
          i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha512(), &chSalt[0],
                            (unsigned char *)&strKeyData[0], strKeyData.size(), nRounds, chKey, chIV);
  
      if (i != (int)WALLET_CRYPTO_KEY_SIZE)
      {
          OPENSSL_cleanse(chKey, sizeof(chKey));
          OPENSSL_cleanse(chIV, sizeof(chIV));
          return false;
      }
  
      fKeySet = true;
      return true;
  }
  
  bool CCrypter::SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV)
  {
      if (chNewKey.size() != WALLET_CRYPTO_KEY_SIZE || chNewIV.size() != WALLET_CRYPTO_KEY_SIZE)
          return false;
  
      memcpy(&chKey[0], &chNewKey[0], sizeof chKey);
      memcpy(&chIV[0], &chNewIV[0], sizeof chIV);
  
      fKeySet = true;
      return true;
  }
  
  bool CCrypter::Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext)
  {
      if (!fKeySet)
          return false;
  
      // max ciphertext len for a n bytes of plaintext is
      // n + AES_BLOCK_SIZE - 1 bytes
      int nLen = vchPlaintext.size();
      int nCLen = nLen + AES_BLOCK_SIZE, nFLen = 0;
      vchCiphertext = std::vector<unsigned char> (nCLen);
  
      EVP_CIPHER_CTX ctx;
  
      bool fOk = true;
  
      EVP_CIPHER_CTX_init(&ctx);
      if (fOk) fOk = EVP_EncryptInit_ex(&ctx, EVP_aes_256_cbc(), NULL, chKey, chIV);
      if (fOk) fOk = EVP_EncryptUpdate(&ctx, &vchCiphertext[0], &nCLen, &vchPlaintext[0], nLen);
      if (fOk) fOk = EVP_EncryptFinal_ex(&ctx, (&vchCiphertext[0])+nCLen, &nFLen);
      EVP_CIPHER_CTX_cleanup(&ctx);
  
      if (!fOk) return false;
  
      vchCiphertext.resize(nCLen + nFLen);
      return true;
  }
  
  bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext)
  {
      if (!fKeySet)
          return false;
  
      // plaintext will always be equal to or lesser than length of ciphertext
      int nLen = vchCiphertext.size();
      int nPLen = nLen, nFLen = 0;
  
      vchPlaintext = CKeyingMaterial(nPLen);
  
      EVP_CIPHER_CTX ctx;
  
      bool fOk = true;
  
      EVP_CIPHER_CTX_init(&ctx);
      if (fOk) fOk = EVP_DecryptInit_ex(&ctx, EVP_aes_256_cbc(), NULL, chKey, chIV);
      if (fOk) fOk = EVP_DecryptUpdate(&ctx, &vchPlaintext[0], &nPLen, &vchCiphertext[0], nLen);
      if (fOk) fOk = EVP_DecryptFinal_ex(&ctx, (&vchPlaintext[0])+nPLen, &nFLen);
      EVP_CIPHER_CTX_cleanup(&ctx);
  
      if (!fOk) return false;
  
      vchPlaintext.resize(nPLen + nFLen);
      return true;
  }
  
  
  bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext)
  {
      CCrypter cKeyCrypter;
      std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
      memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
      if(!cKeyCrypter.SetKey(vMasterKey, chIV))
          return false;
      return cKeyCrypter.Encrypt(*((const CKeyingMaterial*)&vchPlaintext), vchCiphertext);
  }
  
  bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CKeyingMaterial& vchPlaintext)
  {
      CCrypter cKeyCrypter;
      std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
      memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
      if(!cKeyCrypter.SetKey(vMasterKey, chIV))
          return false;
      return cKeyCrypter.Decrypt(vchCiphertext, *((CKeyingMaterial*)&vchPlaintext));
  }
  