[AS3/C#] Byte encryption ( DES-CBC zero pad )
- by mark_dj
Hi there,
Currently writing my own AMF TcpSocketServer. Everything works good so far i can send and recieve objects and i use some serialization/deserialization code. Now i started working on the encryption code and i am not so familiar with this stuff.
I work with bytes , is DES-CBC a good
way to encrypt this stuff? Or are
there other more performant/secure
ways to send my data? Note that
performance is a must :).
When i call: ReadAmf3Object with the decrypter specified i get an: InvalidOperationException thrown by my ReadAmf3Object function when i read out the first byte the Amf3TypeCode isn't specified ( they range from 0 to 16 i believe (Bool, String, Int, DateTime, etc) ). I got Typecodes varying from 97 to 254? Anyone knows whats going wrong? I think it has something to do with the encryption part. Since the deserializer works fine w/o the encryption. I am using the right padding/mode/key?
I used: http://code.google.com/p/as3crypto/ as as3 encryption/decryption library. And i wrote an Async tcp server with some abuse of the threadpool ;)
Anyway here some code:
C# crypter initalization code
System.Security.Cryptography.DESCryptoServiceProvider crypter = new DESCryptoServiceProvider();
crypter.Padding = PaddingMode.Zeros;
crypter.Mode = CipherMode.CBC;
crypter.Key = Encoding.ASCII.GetBytes("TESTTEST");
AS3
private static var _KEY:ByteArray = Hex.toArray(Hex.fromString("TESTTEST"));
private static var _TYPE:String = "des-cbc";
public static function encrypt(array:ByteArray):ByteArray
{
var pad:IPad = new NullPad;
var mode:ICipher = Crypto.getCipher(_TYPE, _KEY, pad);
pad.setBlockSize(mode.getBlockSize());
mode.encrypt(array);
return array;
}
public static function decrypt(array:ByteArray):ByteArray
{
var pad:IPad = new NullPad;
var mode:ICipher = Crypto.getCipher(_TYPE, _KEY, pad);
pad.setBlockSize(mode.getBlockSize());
mode.decrypt(array);
return array;
}
C# read/unserialize/decrypt code
public override object Read(int length)
{
object d;
using (MemoryStream stream = new MemoryStream())
{
stream.Write(this._readBuffer, 0, length);
stream.Position = 0;
if (this.Decrypter != null)
{
using (CryptoStream c = new CryptoStream(stream, this.Decrypter, CryptoStreamMode.Read))
using (AmfReader reader = new AmfReader(c))
{
d = reader.ReadAmf3Object();
}
}
else
{
using (AmfReader reader = new AmfReader(stream))
{
d = reader.ReadAmf3Object();
}
}
}
return d;
}
