Alternative implementation with filippo.io/age instead of PGP

[warkadiusz]

Hello,

First of all, thank you for maintaining that fork. The tool, while maybe niche, is very useful.

Last days, while trying to use crypt for one of my projects, I had an idea to replace PGP as it's encryption/decryption engine with modern, purpose-built encryption library age.
The reasons behind that were: 1. troublesome keys management with gpg, 2. deprecation of golang.org/x/crypto/opengpg, 3. apparently general problems with PGP

Working experimental version is available in my fork: https://github.com/warkadiusz/crypt

For compatibility reasons, I did not remove the PGP implementation out of it. Instead, a new flag -encryption-engine is available, accepting either pgp or age as a value, with default being pgp. The implementation at the moment is little dirty, not tested etc., but it's working.

Is this something you would see as a part of crypt? If you'd be interested, I could prepare a proper implementation and open a PR. If your fork is just for security updates/maintenance and not further developments, it's also fine – in this case I'll keep my fork separate.

Thank you and best regards,