• Symmetric Encryption: AES, DES, 3DES, CAST, RC4, RC2, and Blowfish. (The algorithm selection is poorly documented in the man pages, I'm reading source here.)
It has an API that would not surprise anyone who has used a similar library.
It's only deprecated in the sense that Apple are no longer going to supply it. You can either switch to CommonCrypto (if it's appropriate) or bring your own OpenSSL.