Support post-quantum encryption

[myfirstnameispaul]

I can think of the following places MiaB should probably be configured to support post-quantum encryption:

1. Postfix
2. Dovecot
3. Nginx
4. NSD
5. OpenDKIM (Assuming DKIM and the project will be updated to support PQC)
6. OpenSSH
7. Cerbot

I have not researched deeply enough, but maybe others have so I'm posting just a starter issue here.

[downtownallday]

How about the AES256 encryption used with duplicity backups. AES256 is considered resistant, but backups could be stored and decrypted later with quantum advances.

Also, are you thinking ML-KEM key exchange without supporting multiple certificates? That seems to be what could be implemented relatively easily once Openssl 3.5 is available. Adding support for multiple certificates would be tougher due to the MiaB changes needed (think management/ssl_certificates.py). Dovecot, postfix and nginx all support multiple certificates now so that shouldn't be an issue, but don't know about the others.

Openssl 3.5 is needed for any of this but isn't part of Ubuntu until Resolute (26.04 LTS) comes out in a couple of weeks. Maybe adding some support would be a good addition to the MiaB-on-Resolute effort.

[myfirstnameispaul]

Thanks, I hadn't gotten to symmetrical encryption. I had thought the advantage of quantum computing was more for attacking asymmetrical public keys to obtain private keys. I may end up browsing through project discussions to see what duplicity, cryptsetup (LUKS), rclone, etc., teams are posting on the topic.

Possibly an aside, but something that I never learned is why there are experts who argue that AES-128 can be considered better than AES-256 because there are other differences in the standard, maybe something left out of AES-256? Initial searches aren't helping me here.

I was also just thinking we might consider something like a system message after implementing PQC that is strongly worded to advise password changes on all accounts.