What blockcipher should I use with OCB?
You can use OCB with any blockcipher that you like. But the obvious choice is AES. AES actually comes in three flavors: AES128, AES192, and AES256. I like AES128. If you use OCB with a blockcipher having a 64-bit blocklength instead of a 128-bit blocklength, beware that you’ll get a worse security bound. You’ll need to change keys well before you encrypt 232 blocks (as with all well-known modes that use a 64-bit blockcipher).
