Here’s a quick bash script I used to generated a “vanity” PGP key with the last two bytes (four characters) set to FFFF.

#!/usr/bin/env bash

while :
do
gpg --debug-quick-random -q --batch --gen-key << EOF
Key-Type: RSA
Key-Length: 2048
Name-Email: user@domain
Name-Real: Real Name
Passphrase: yourverylongpassphrasegoeshere
EOF

if gpg -q --list-keys | head -4 | tail -c 5 | grep FFFF
then
        echo Break
        exit 1
else
        gpg2 --batch -q --yes --delete-secret-and-public-key `gpg -q --list-keys
| head -4 | tail -n 1`
fi

done

I also added no-secmem-warning to ~/.gnupg/options to suppress the insecure memory warnings. When I set it to a 1024-bit key, it only took about 3 hours, while 2048-bit took 20 hours across.

It goes without saying, my use of insecure randomness is a terrible idea for those facing a serious threat model. Also, you’re basically picking a number at random out of 65,535 hoping for the right combination – but I’m just having fun with it.