# cypher algorithm

**MindFuq
**
mindfuq@comcast.net

*Sun Nov 3 17:18:01 2002*

* Peter C. Chapin <pchapin@ecet.vtc.edu> [2002-11-02 10:00]:
>*
*>* I believe you want the --cipher-algo option. It requires a cipher name.
*>* Use "gpg --version" to see the list of supported names. I'm not sure if
*>* the list is case sensitive or not but, for example, you might do
*>*
*>* $ gpg -c --cipher-algo BLOWFISH afile.txt
*
It's not case sensitive. Also, the -c isn't necessary, unless you
really want a purely symmetric conventional encryption.
>* The public key algorithm used depends on the type of key used and you can
*>* select that when the key is generated. I haven't played with that much so
*>* I'm not so sure how to get, for example, RSA.
*
Yes Peter, that's right on the money. The key dictates what
asymmetric algorithm is used. This is because unlike symmetric
crypto, an asymmetric key is actually a number with meaning that
satisfies an equation with the other key. With symmetric crypto, the
key can be any set of random bits and any algorithm can be used with
any key, provided that the key is the right length for the algorithm.
So if you want to create an RSA encrypted message, you must encrypt it
with an RSA key, which is an option when you generate the key. Note
that you may have to use the --expert switch in order to get the RSA
option, I don't recall off the top of my head.