Cryptography on your MacOS X program

For this first tip, I just want to help you performing basic operations like generating digests (MD5, SHA1, …) or dealing with asymetric keys in your programs.

On the Mac OS X platform, there are basically two libraries providing these crypto capabilities :

1 - openSSL
2 - Apple CDSA

For the first one, just import the header(s) you need from /usr/include/openssl and then link your product with the /usr/lib/libsecurity.dylib.
With CDSA, you have to add the /System/Library/Frameworks/Security.framework to your Xcode project and then link your product with it.

It seems to me that openSSL is easier to use but the choice between these two libraries may be triggered by politics.

For the CDSA documentation, I strongly recommend you to download and read the examples provided by Apple : CryptoSample