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POByte encryption ( DES-CBC zero pad )
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copied!<p>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.</p> <ul> <li>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 :).</li> <li>When i call: <strong>ReadAmf3Object</strong> 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?</li> </ul> <p>I used: <a href="http://code.google.com/p/as3crypto/" rel="nofollow noreferrer">http://code.google.com/p/as3crypto/</a> as as3 encryption/decryption library. And i wrote an Async tcp server with some abuse of the threadpool ;)</p> <p>Anyway here some code:</p> <p><strong>C# crypter initalization code</strong></p> <pre><code>System.Security.Cryptography.DESCryptoServiceProvider crypter = new DESCryptoServiceProvider(); crypter.Padding = PaddingMode.Zeros; crypter.Mode = CipherMode.CBC; crypter.Key = Encoding.ASCII.GetBytes("TESTTEST"); </code></pre> <p><strong>AS3</strong></p> <pre><code>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; } </code></pre> <p><strong>C# read/unserialize/decrypt code</strong></p> <pre><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; } </code></pre>

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