AES 256 encryption between .NET and PHP

I finally got around to creating some sample code to demonstrate how to do Rijndael (AES-256) encryption between PHP and .NET servers.

They key probelm I found was that mcrypt pads the key with zeroes, where the default behaviour in .NET is PKCS7 padding. Use this line in your/net project to mimic the PHP behaviour.

symmetricKey.Padding = PaddingMode.Zeros;

You also have to remove the padded nulls from the end of string after you do the decryption:

result= result.TrimEnd('\0');

The complete working C# and PHP projects are here:
https://github.com/dchymko/.NET–PHP-encryption