Magic Wormhole: get things from one computer to another, safely

author here.. happy to answer any questions!

I use wormhole a lot, but I've been too lazy to figure out if it's as secure as ssh/scp, so I always gpg the file I'm transferring before putting it into wormhole.

Is that paranoid behavior?

It can't hurt, but it shouldn't be necessary. The client-side software establishes an encrypted connection with its peer, using an encryption scheme that should be just as secure [but see below] as what GPG or SSH will give you.

For GPG to add security, you also have to make sure the GPG key is transferred safely, which adds work to the transfer process. Either you're GPG-encrypting to a public key (which you must have copied from the receiving side to the sending side at some point), or you're using a symmetric-key passphrase (which you must generate randomly, to be secure, and then copy it from one side to the other).

I should note that magic-wormhole's encryption scheme is not post-quantum -secure. So if you've managed to get a GPG symmetric key transferred to both sides via PQ-secure pathways (I see that current SSH 9.8 includes "kex: algorithm: sntrup761x25519-sha512@openssh.com", where NTRU is PQ-secure), then your extra GPG encryption will indeed provide you with security against a sufficiently-large quantum computer, whereas just magic-wormhole would be vulnerable.