php async crypt

Question

I'm looking for an asynchronous crypt algorithm to digitally sign a string with php and verify the signature by using a mobile app (mostly ios or android).

What could be the most simple and effective way to do so? Can I trust RSA or it is slow and difficoult to implement in both sides (mobile and php server side)? In case RSA is good enough, can you suggest me a good implementation?

Answer 1

phpseclib, a pure PHP RSA implementation is the best PHP RSA implementation I've come across. It supports PKCS#1 signatures and PSS signatures - the two most widely used padding schemes for RSA. ie. it, unlike most other PHP RSA implementations, is interoperable with OpenSSL, OpenSSH, .NET, etc. And from your post it sounds like interoperability is going to be quite important.