Well there is some mixing up of terms in your post.
The KeyID is simply a way to identify the key.
You encrypt using the public key of the recipient (and the recipient decrypts using their private key).
You sign using your private key (and verify using the public key of signer).
When encrypting or signing the output will always be the same. The short or long key ID is simply a way to identify the key. There is only one key.
Kinda first name or full legal name both identify the same person.
Are you just asking how to get the extender (16 digit) keyID for your keypair? If so I assume this is for Bitcoin-OTC?If so this should help. I don't believe GPA has an option to show 16 digit keyID so you will need the GPG CLI tool. You can keep using GPA or any other client once you have the keyID because it won't change.
GPG command line tool:
http://ftp://ftp.gnupg.org/gcrypt/binary/gnupg-w32cli-1.4.11.exeGPG clients find all keys from the same user store so if you already created or imported a key using GPA (or another client) it can be "seen" from the CLI tool.
To get extended keyID
gpg --list-keys --keyid-format long
Example:
C:\Program Files (x86)\GNU\GnuPG>gpg --list-keys --keyid-format long
C:/Users/<USERNAME>/AppData/Roaming/gnupg\pubring.gpg
-------------------------------------------------------
pub 2048R/28BB715FC26C17CD 2012-06-10
uid Tangible Cryptography LLC <info@tangiblecryptography.com>
sub 2048R/73A6FE7F86DA949B 2012-06-10
is the 16 digit KeyID for our company master key. You may or may not have "sub" keys listed. Sub keys are linked to the master key. You can google GPG subkey for more info but the simple version if the master KeyID is your full identity. It was what you want to provide the counterparty.
