.Net AES Encryption - Universally Accepted Pad Setting

Question

I have a .Net web service that processes AES encrypted data. The consumers of my service agree on a key/IV pair with me and that way we can pass data securely. I have a consumer using PHP that is using mcrypt to encrypt. mcrypt is padding with NULLs. I was not setting a pad (NONE) and therefore not able to decrypt the strings. I changed my padding to Zero and was able to decrypt the mcrypt values.

I want to change my web service to use a universally accepted pad setting. And tell all my consumers to use that pad setting. However, I can't seem to find that universal pad setting. I have also read a few post that talk about some pad settings being "less secure". And equally bad, I have seen some post about some pad settings not translating across systems reliably.

Is there a universally accepted, secure and reliable pad setting for AES encryption?

Please let me know.

Answer 1

Not realy. There is PKCS padding, Zeros, Ansi X923, ISO10126, all are well supported and accepted standards. You and your WWW service just have to aggree on what to use, just as you agree on the cipher block mode, IV value and so on and so forth (ie. make it part of the protocol if needed).