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// 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.
#include <openssl/aes.h>
#include <openssl/evp.h>
#include <vector>
#include <string>
#ifdef WIN32
#include <windows.h>
#endif
#include "crypter.h"
#include "util.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;
// 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)
// Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
// 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.
mlock(&chKey[0], sizeof chKey);
mlock(&chIV[0], sizeof chIV);
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)
{
memset(&chKey, 0, sizeof chKey);
memset(&chIV, 0, 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;
// Try to keep the keydata out of swap
// Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
// 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.
mlock(&chKey[0], sizeof chKey);
mlock(&chIV[0], sizeof chIV);
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(CKeyingMaterial& vMasterKey, const CSecret &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((CKeyingMaterial)vchPlaintext, vchCiphertext);
}
bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CSecret& 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));
}
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