public byte[] EncryptBytes(byte[] data, string shared_key)
{
if (data.Length < 1)
{
throw new ArgumentNullException("data should be more than 1 bytes");
}
byte[] timestamp = BitConverter.GetBytes(this.GetTimestamp());
byte[] dataBlock = new byte[28 + data.Length];
Buffer.BlockCopy(m_salt, 0, dataBlock, 0, 20);
Buffer.BlockCopy(timestamp, 0, dataBlock, 20, 8);
Buffer.BlockCopy(data, 0, dataBlock, 28, data.Length);
byte[] signature = this.SHA1(dataBlock);
byte[] aes_key = Encoding.UTF8.GetBytes(shared_key + this.ToHex(signature).ToLower());
byte[] key, iv;
CryptoUtility.PassphraseToDefaultKeyAndIV(aes_key, null, 1, out key, out iv);
byte[] encryptData = AES256CTR.EncryptBytes(dataBlock, key, iv);
byte[] result = new byte[20 + encryptData.Length];
Buffer.BlockCopy(signature, 0, result, 0, 20);
Buffer.BlockCopy(encryptData, 0, result, 20, encryptData.Length);
return(result);
}
public byte[] DecryptBytes(byte[] data, string shared_key, bool skiptTmestamp, out int exipe_on)
{
if (data.Length <= 20)
{
throw new ArgumentNullException("data should be more than 20 bytes");
}
byte[] signature = new byte[20];
Buffer.BlockCopy(data, 0, signature, 0, 20);
byte[] aes_key = Encoding.UTF8.GetBytes(shared_key + this.ToHex(signature).ToLower());
byte[] cryptData = new byte[data.Length - 20];
Buffer.BlockCopy(data, 20, cryptData, 0, data.Length - 20);
byte[] key, iv;
CryptoUtility.PassphraseToDefaultKeyAndIV(aes_key, null, 1, out key, out iv);
byte[] decryptData = AES256CTR.DecryptBytes(cryptData, key, iv);
byte[] _slat = new byte[20];
byte[] _timestamp = new byte[8];
byte[] _dataBlock = new byte[decryptData.Length - 28];
Buffer.BlockCopy(decryptData, 0, _slat, 0, 20);
Buffer.BlockCopy(decryptData, 20, _timestamp, 0, 8);
Buffer.BlockCopy(decryptData, 28, _dataBlock, 0, decryptData.Length - 28);
exipe_on = Convert.ToInt32(BitConverter.ToDouble(_timestamp, 0) - GetTimestamp());
if (ToHex(SHA1(decryptData)) != ToHex(signature))
{
throw new Exception("Signature of data not valid.");
}
else if (ToHex(m_salt) != ToHex(_slat))
{
throw new Exception("Salt of data not valid.");
}
else if (!skiptTmestamp && (exipe_on < 0 || exipe_on > BLOCK_EXIPE_TIME))
{
throw new Exception("Timestamp of data has expired.");
}
return(_dataBlock);
}
