1  // Copyright (c) 2009-2021 The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #include <wallet/crypter.h>
  6  
  7  #include <common/system.h>
  8  #include <crypto/aes.h>
  9  #include <crypto/sha512.h>
 10  
 11  #include <vector>
 12  
 13  namespace wallet {
 14  int CCrypter::BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, const SecureString& strKeyData, int count, unsigned char *key,unsigned char *iv) const
 15  {
 16      // This mimics the behavior of openssl's EVP_BytesToKey with an aes256cbc
 17      // cipher and sha512 message digest. Because sha512's output size (64b) is
 18      // greater than the aes256 block size (16b) + aes256 key size (32b),
 19      // there's no need to process more than once (D_0).
 20  
 21      if(!count || !key || !iv)
 22          return 0;
 23  
 24      unsigned char buf[CSHA512::OUTPUT_SIZE];
 25      CSHA512 di;
 26  
 27      di.Write((const unsigned char*)strKeyData.data(), strKeyData.size());
 28      di.Write(chSalt.data(), chSalt.size());
 29      di.Finalize(buf);
 30  
 31      for(int i = 0; i != count - 1; i++)
 32          di.Reset().Write(buf, sizeof(buf)).Finalize(buf);
 33  
 34      memcpy(key, buf, WALLET_CRYPTO_KEY_SIZE);
 35      memcpy(iv, buf + WALLET_CRYPTO_KEY_SIZE, WALLET_CRYPTO_IV_SIZE);
 36      memory_cleanse(buf, sizeof(buf));
 37      return WALLET_CRYPTO_KEY_SIZE;
 38  }
 39  
 40  bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod)
 41  {
 42      if (nRounds < 1 || chSalt.size() != WALLET_CRYPTO_SALT_SIZE)
 43          return false;
 44  
 45      int i = 0;
 46      if (nDerivationMethod == 0)
 47          i = BytesToKeySHA512AES(chSalt, strKeyData, nRounds, vchKey.data(), vchIV.data());
 48  
 49      if (i != (int)WALLET_CRYPTO_KEY_SIZE)
 50      {
 51          memory_cleanse(vchKey.data(), vchKey.size());
 52          memory_cleanse(vchIV.data(), vchIV.size());
 53          return false;
 54      }
 55  
 56      fKeySet = true;
 57      return true;
 58  }
 59  
 60  bool CCrypter::SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV)
 61  {
 62      if (chNewKey.size() != WALLET_CRYPTO_KEY_SIZE || chNewIV.size() != WALLET_CRYPTO_IV_SIZE)
 63          return false;
 64  
 65      memcpy(vchKey.data(), chNewKey.data(), chNewKey.size());
 66      memcpy(vchIV.data(), chNewIV.data(), chNewIV.size());
 67  
 68      fKeySet = true;
 69      return true;
 70  }
 71  
 72  bool CCrypter::Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext) const
 73  {
 74      if (!fKeySet)
 75          return false;
 76  
 77      // max ciphertext len for a n bytes of plaintext is
 78      // n + AES_BLOCKSIZE bytes
 79      vchCiphertext.resize(vchPlaintext.size() + AES_BLOCKSIZE);
 80  
 81      AES256CBCEncrypt enc(vchKey.data(), vchIV.data(), true);
 82      size_t nLen = enc.Encrypt(vchPlaintext.data(), vchPlaintext.size(), vchCiphertext.data());
 83      if(nLen < vchPlaintext.size())
 84          return false;
 85      vchCiphertext.resize(nLen);
 86  
 87      return true;
 88  }
 89  
 90  bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext) const
 91  {
 92      if (!fKeySet)
 93          return false;
 94  
 95      // plaintext will always be equal to or lesser than length of ciphertext
 96      int nLen = vchCiphertext.size();
 97  
 98      vchPlaintext.resize(nLen);
 99  
100      AES256CBCDecrypt dec(vchKey.data(), vchIV.data(), true);
101      nLen = dec.Decrypt(vchCiphertext.data(), vchCiphertext.size(), vchPlaintext.data());
102      if(nLen == 0)
103          return false;
104      vchPlaintext.resize(nLen);
105      return true;
106  }
107  
108  bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext)
109  {
110      CCrypter cKeyCrypter;
111      std::vector<unsigned char> chIV(WALLET_CRYPTO_IV_SIZE);
112      memcpy(chIV.data(), &nIV, WALLET_CRYPTO_IV_SIZE);
113      if(!cKeyCrypter.SetKey(vMasterKey, chIV))
114          return false;
115      return cKeyCrypter.Encrypt(vchPlaintext, vchCiphertext);
116  }
117  
118  bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CKeyingMaterial& vchPlaintext)
119  {
120      CCrypter cKeyCrypter;
121      std::vector<unsigned char> chIV(WALLET_CRYPTO_IV_SIZE);
122      memcpy(chIV.data(), &nIV, WALLET_CRYPTO_IV_SIZE);
123      if(!cKeyCrypter.SetKey(vMasterKey, chIV))
124          return false;
125      return cKeyCrypter.Decrypt(vchCiphertext, vchPlaintext);
126  }
127  
128  bool DecryptKey(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCryptedSecret, const CPubKey& vchPubKey, CKey& key)
129  {
130      CKeyingMaterial vchSecret;
131      if(!DecryptSecret(vMasterKey, vchCryptedSecret, vchPubKey.GetHash(), vchSecret))
132          return false;
133  
134      if (vchSecret.size() != 32)
135          return false;
136  
137      key.Set(vchSecret.begin(), vchSecret.end(), vchPubKey.IsCompressed());
138      return key.VerifyPubKey(vchPubKey);
139  }
140  } // namespace wallet