Is it possible to change PGP / GPG Key Size on an exisiting key? Is it possible for myself to change the key size (say from 2048 to 4096) on an EXISTING PGP / GPG key, and just republishing that key?

Or do I have to generate a new key all together?

I want to say that you have to create a new key pair, but I don't have enough documentation either way to support a claim.
Thanks for the info Jens Erat



There is no way to "upgrade" an OpenPGP key. You will have to create a new one, and you will loose your reputation in the web of trust.

Think about:


Giving your new key with the old one, so other could follow the signatures
Revoking the old one after some time
Using a seemingly unnecessary large key as primary key and smaller subkeys for day-to-day usage. You will never need the primary key for anything but signing other keys (which is rare) and others verifying your signatures (cheap anyway).


Source