Trying to get a clue about 3DES

[Thiago Jung Bauermann]

Hello all,

I don't know much about crypto (perhaps you can tell that from my questions),
and was trying to play a little with 3DES using the cipher/des.c
implementation provided by GnuPG (I decided to use 3DES because it was the
only one with comments in the source on how to use it :-) ).

I have some questions about the thing (sorry to ask so much at the same time):
It needs keys with 8 chars in size to work, but how can I make it so that the
user can specify shorter keys? I padded them with spaces, is that secure? I
also guess that the keys are not null terminated, right? Also, it encrypts
8 chars at a time, but how can I work with shorter blocks? And are they null
terminated also?

I tried to get those answers by looking how GPG uses it, but a rgrep in
the sources didn't reveal where GPG is using the thing... Also, what happened
to that gcrypt library that was announced here some time ago? My initial
thought was to play with it, instead of des.c.

Thanks for your time!
-- 
Thiago Jung Bauermann jungmann at cwb.matrix.com.br  Ask for OpenPGP key
                 "How do you power off this machine?"
             (Linus, when upgrading linux.cs.helsinki.fi)