The JPackage Project GPG key can be downloaded here: jpackage.asc
It is recommended to make this key available to RPM; we use it to sign all our packages as well as some other files in the repository (apt-rpm in particular). First, change to the user account you use RPM with (usually root) and optionally download the key.
If your rpm supports the --import option
(you might need version 4.1), do this:
rpm --import /path/to/jpackage.asc
Or if you didn't download the key:
rpm --import http://www.jpackage.org/jpackage.asc
For older versions of RPM, you'll need to use GPG for importing the key. Note that if you're using apt-get, you should import with GPG and RPM (if your RPM supports this, of course). apt-get uses the key from GPG for verifying repository files, whereas RPM may handle it internally for verifying package signatures.
gpg --import /path/to/jpackage.asc
Or if you didn't download the key and have Wget, Lynx, curl or lwp-get:
wget -O- http://www.jpackage.org/jpackage.asc | gpg --import
lynx -source http://www.jpackage.org/jpackage.asc | gpg --import
curl http://www.jpackage.org/jpackage.asc | gpg --import
lwp-get http://www.jpackage.org/jpackage.asc | gpg --import
The key is also available from public keyservers. Oh, and here's the key fingerprint.
1F81 C0FB C2B8 22B3 DE12 33A4 5C6C FFF7 C431 416D