PHP mcrypt usage class?

I'm pretty new at this. Tried to make sense of the manual page for mcrypt at PHP.net when I thought a good tutorial would do a better job. So I searched yet without anything substantial.

I also tried one of the examples of using mcrypt to perform the encryption and decryption with 2 functions, but it gives a warning of "Size of key is too large for this algorithm".

Can anyone please write me a two-way class to do the encryption / decryption using mcrypt so 开发者_运维知识库I can make sense of the library? Thanks!

See this SO thread: PHP Mcrypt - Encrypting / Decrypting file

FYI, it's very uncool to ask people to do your work for you. At least show an effort. We're here to help, not be slave labor.