"unusable public key" on encryption

[Douglas Choma]

> > 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

The results are:
hashed subpkt 27 len 1 (key flags: 03)

I'm afraid I don't know what that means though.  :-)