"unusable public key" on encryption

[David Shaw]

On Sun, Dec 28, 2003 at 11:43:38PM -0800, Douglas Choma wrote:
> I've run into a bit of a snag this evening.  I'm desperately trying to 
> encrypt something using an RSA public key that someone sent me via 
> email.  After importing the key successfully(???), I am still unable to 
> use it for encryption.  This has never been a problem in the past, but 
> it is also the first RSA key that I've tried working with.
> 
> If I run "gpg --list-keys", the key shows up as follows:
> pub  1024R/3006DF31 2003-12-16 SWsoft Support Team (Generated for 
> Rusoffice) <support at sw-soft.com>
> 
> So, that looks okay...I think?

It's probably a sign-only key.  Do this:

 gpg --export 3006DF31 | gpg --list-packets | grep flags

David