src/crypter.cpp

   1 // Copyright (c) 2009-2012 The Bitcoin Developers
   2 // Distributed under the MIT/X11 software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #include <openssl/aes.h>
   6 #include <openssl/evp.h>
   7 #include <vector>
   8 #include <string>
   9 #ifdef WIN32
  10 #include <windows.h>
  11 #endif
  12
  13 #include "crypter.h"
  14
  15 bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod)
  16 {
  17     if (nRounds < 1 || chSalt.size() != WALLET_CRYPTO_SALT_SIZE)
  18         return false;
  19
  20     // Try to keep the keydata out of swap (and be a bit over-careful to keep the IV that we don't even use out of swap)
  21     // Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
  22     // Note as well that at no point in this program is any attempt made to prevent stealing of keys by reading the memory of the running process.
  23     mlock(&chKey[0], sizeof chKey);
  24     mlock(&chIV[0], sizeof chIV);
  25
  26     int i = 0;
  27     if (nDerivationMethod == 0)
  28         i = EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha512(), &chSalt[0],
  29                           (unsigned char *)&strKeyData[0], strKeyData.size(), nRounds, chKey, chIV);
  30
  31     if (i != (int)WALLET_CRYPTO_KEY_SIZE)
  32     {
  33         memset(&chKey, 0, sizeof chKey);
  34         memset(&chIV, 0, sizeof chIV);
  35         return false;
  36     }
  37
  38     fKeySet = true;
  39     return true;
  40 }
  41
  42 bool CCrypter::SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV)
  43 {
  44     if (chNewKey.size() != WALLET_CRYPTO_KEY_SIZE || chNewIV.size() != WALLET_CRYPTO_KEY_SIZE)
  45         return false;
  46
  47     // Try to keep the keydata out of swap
  48     // Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
  49     // Note as well that at no point in this program is any attempt made to prevent stealing of keys by reading the memory of the running process.
  50     mlock(&chKey[0], sizeof chKey);
  51     mlock(&chIV[0], sizeof chIV);
  52
  53     memcpy(&chKey[0], &chNewKey[0], sizeof chKey);
  54     memcpy(&chIV[0], &chNewIV[0], sizeof chIV);
  55
  56     fKeySet = true;
  57     return true;
  58 }
  59
  60 bool CCrypter::Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext)
  61 {
  62     if (!fKeySet)
  63         return false;
  64
  65     // max ciphertext len for a n bytes of plaintext is
  66     // n + AES_BLOCK_SIZE - 1 bytes
  67     int nLen = vchPlaintext.size();
  68     int nCLen = nLen + AES_BLOCK_SIZE, nFLen = 0;
  69     vchCiphertext = std::vector<unsigned char> (nCLen);
  70
  71     EVP_CIPHER_CTX ctx;
  72
  73     bool fOk = true;
  74
  75     EVP_CIPHER_CTX_init(&ctx);
  76     if (fOk) fOk = EVP_EncryptInit_ex(&ctx, EVP_aes_256_cbc(), NULL, chKey, chIV);
  77     if (fOk) fOk = EVP_EncryptUpdate(&ctx, &vchCiphertext[0], &nCLen, &vchPlaintext[0], nLen);
  78     if (fOk) fOk = EVP_EncryptFinal_ex(&ctx, (&vchCiphertext[0])+nCLen, &nFLen);
  79     EVP_CIPHER_CTX_cleanup(&ctx);
  80
  81     if (!fOk) return false;
  82
  83     vchCiphertext.resize(nCLen + nFLen);
  84     return true;
  85 }
  86
  87 bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext)
  88 {
  89     if (!fKeySet)
  90         return false;
  91
  92     // plaintext will always be equal to or lesser than length of ciphertext
  93     int nLen = vchCiphertext.size();
  94     int nPLen = nLen, nFLen = 0;
  95
  96     vchPlaintext = CKeyingMaterial(nPLen);
  97
  98     EVP_CIPHER_CTX ctx;
  99
 100     bool fOk = true;
 101
 102     EVP_CIPHER_CTX_init(&ctx);
 103     if (fOk) fOk = EVP_DecryptInit_ex(&ctx, EVP_aes_256_cbc(), NULL, chKey, chIV);
 104     if (fOk) fOk = EVP_DecryptUpdate(&ctx, &vchPlaintext[0], &nPLen, &vchCiphertext[0], nLen);
 105     if (fOk) fOk = EVP_DecryptFinal_ex(&ctx, (&vchPlaintext[0])+nPLen, &nFLen);
 106     EVP_CIPHER_CTX_cleanup(&ctx);
 107
 108     if (!fOk) return false;
 109
 110     vchPlaintext.resize(nPLen + nFLen);
 111     return true;
 112 }
 113
 114
 115 bool EncryptSecret(CKeyingMaterial& vMasterKey, const CSecret &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext)
 116 {
 117     CCrypter cKeyCrypter;
 118     std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
 119     memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
 120     if(!cKeyCrypter.SetKey(vMasterKey, chIV))
 121         return false;
 122     return cKeyCrypter.Encrypt((CKeyingMaterial)vchPlaintext, vchCiphertext);
 123 }
 124
 125 bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CSecret& vchPlaintext)
 126 {
 127     CCrypter cKeyCrypter;
 128     std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
 129     memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
 130     if(!cKeyCrypter.SetKey(vMasterKey, chIV))
 131         return false;
 132     return cKeyCrypter.Decrypt(vchCiphertext, *((CKeyingMaterial*)&vchPlaintext));
 133 }