On the Subject of Feed Identities; I propose the following:

1. Generate a Private/Public ED25519 key pair
   
2. Use this key pair to sign your Twtxt feed
   
3. Use it as your feed’s identity in place of # url = as # key = ...
   

For example:

$ ssh-keygen -f prologic@twtxt.net
$ ssh-keygen -Y sign -n prologic@twtxt.net -f prologic@twtxt.net twtxt.txt

And your feed would looke like:

# nick        = prologic
# key         = SHA256:23OiSfuPC4zT0lVh1Y+XKh+KjP59brhZfxFHIYZkbZs
# sig         = twtxt.txt.sig
# prev        = j6bmlgq twtxt.txt/1
# avatar      = https://twtxt.net/user/prologic/avatar#gdoicerjkh3nynyxnxawwwkearr4qllkoevtwb3req4hojx5z43q
# description = "Problems are Solved by Method" 🇦🇺👨‍💻👨‍🦯🏹♔ 🏓⚯ 👨‍👩‍👧‍👧🛥 -- James Mills (operator of twtxt.net / creator of Yarn.social 🧶)

2024-06-14T18:22:17Z	(#nef6byq) @<bender https://twtxt.net/user/bender/twtxt.txt>  Hehe thanks! 😅 Still gotta sort out some other bugs, but that's tomorrows job 🤞
...

Twt Hash extension would change of course to use a feed’s ED25519 public key fingerprint.

@prologic@twtxt.net Some criticisms and a possible alternative direction:

1. Key rotation. I’m not a security person, but my understanding is that it’s good to be able to give keys an expiry date and replace them with new ones periodically.

2. It makes maintaining a feed more complicated. Now instead of just needing to put a file on a web server (and scan the logs for user agents) I also need to do this. What brought me to twtxt was its radical simplicity.

Instead, maybe we should think about a way to allow old urls to be rotated out? Like, my metadata could somehow say that X used to be my primary URL, but going forward from date D onward my primary url is Y. (Or, if you really want to use public key cryptography, maybe something similar could be used for key rotation there.)

It’s nice that your scheme would add a way to verify the twts you download, but https is supposed to do that anyway. If you don’t trust https to do that (maybe you don’t like relying on root CAs?) then maybe your preferred solution should be reflected by your primary feed url. E.g. if you prefer the security offered by IPFS, then maybe an IPNS url would do the trick. The fact that feed locations are URLs gives some flexibility. (But then rotation is still an issue, if I understand ipns right.)

In fact, maybe your public key idea is compatible with my last point. Just come up with a url scheme that means “this feed’s primary URL is actually a public key”, and then feed authors can optionally switch to that.