private static byte[] CheckHmac(byte[] dataToDecrypt, byte[] salt, AesCryptoServiceProvider aes)
{
var hmac = ByteHelpers.CreateSpecialByteArray(32);
var encryptedData = ByteHelpers.CreateSpecialByteArray(dataToDecrypt.Length - 32);
Buffer.BlockCopy(dataToDecrypt, 0, hmac, 0, 32);
Buffer.BlockCopy(dataToDecrypt, 32, encryptedData, 0, dataToDecrypt.Length - 32);
var newHmac = CreateHmac(salt, aes, encryptedData);
if (!ByteHelpers.ByteArrayCompare(hmac, newHmac))
{
throw new CryptographicException("The authenticated message code doesn't match. \n\nThe message may have been corrupted or tampered with.");
}
return(encryptedData);
}
public static byte[] DecryptByteBlock(byte[] dataToDecrypt, byte[] password)
{
if (dataToDecrypt == null)
{
throw new ArgumentNullException("dataToDecrypt");
}
if (password == null)
{
throw new ArgumentNullException("password");
}
var aes = new Aes();
var salt = ByteHelpers.CreateSpecialByteArray(32);
var message = ByteHelpers.CreateSpecialByteArray(dataToDecrypt.Length - 32);
Buffer.BlockCopy(dataToDecrypt, 0, salt, 0, 32);
Buffer.BlockCopy(dataToDecrypt, 32, message, 0, dataToDecrypt.Length - 32);
var deCompressed = Compressor.Decompress(aes.Decrypt(message, password, salt, 70000));
return(deCompressed);
}