bool DecryptAES256(const SecureString& sKey, const std::string& sCiphertext, const std::string& sIV, SecureString& sPlaintext)
{
// plaintext will always be equal to or lesser than length of ciphertext
int nLen = sCiphertext.size();
int nPLen = nLen, nFLen = 0;
// Verify key sizes
if(sKey.size() != 32 || sIV.size() != AES_BLOCK_SIZE) {
LogPrintf("crypter DecryptAES256 - Invalid key or block size\n");
return false;
}
sPlaintext.resize(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, (const unsigned char*) &sKey[0], (const unsigned char*) &sIV[0]);
if (fOk) fOk = EVP_DecryptUpdate(&ctx, (unsigned char *) &sPlaintext[0], &nPLen, (const unsigned char *) &sCiphertext[0], nLen);
if (fOk) fOk = EVP_DecryptFinal_ex(&ctx, (unsigned char *) (&sPlaintext[0])+nPLen, &nFLen);
EVP_CIPHER_CTX_cleanup(&ctx);
if (!fOk) return false;
sPlaintext.resize(nPLen + nFLen);
return true;
}
SecureString CKeePassIntegrator::generateRandomKey(size_t nSize)
{
// Generates random key
SecureString key;
key.resize(nSize);
RandAddSeedPerfmon();
RAND_bytes((unsigned char *) &key[0], nSize);
return key;
}