Hi. We have a client who wants to sign web pages using GPG, even when
we're using SSL already. Right now we're using separate keys for both
tasks, but I think the same RSA keys can be used (I know some sites
that do that, but don't know how). The SSL certificate is already
signed, so it can't be modified. I have private and public keys from
the SSL certificate in ASCII format.

This is what I've tried so far: I unencrypted the private key (RSA) of
the SSL certificate (it was DES-encrypted). I replaced the OpenSSL
headers with the GPG ones (i.e., -----BEGIN RSA PRIVATE KEY-----
replaced with -----BEGIN PGP PRIVATE KEY BLOCK-----, and such). I
calculated the checksum of the RSA key and put it on the last line of
the key.

It didn't work. The software I'm using (Cryptix Java libraries)
complains that the key has an "invalid packet type" when it reads the
private key.

How can I use the SSL RSA key for GPG signing?

Thanks in advance