I need a command-line tool that does public key encryption of a few KB of data with an ASCII-armored file format. For convenient auditing, it needs to be non-repudiable, and easy to find out which keys can decrypt.

As far as I could see, the closest this article gets is saltpack, but that is an unstable alpha, and it does not appear to have a command line interface.

So no, this is not a modern alternative to PGP for my use case :-(