So really your argument is just that switching to a location-based addressing “just makes sense”. Why? Without concrete pros/cons of each approach this isn’t really a strong argument I’m afraid. In fact I probably need to just sit down and detail the properties of both approaches and the pros/cons of both.

I also don’t really buy the argument of simplicity either personally, because I don’t technically see it much more difficult to take a echo -e "<url>\t<timestamp>\t<content>" | sha256sum | base64 as the Twt Subject or concatenating the <url> <timestamp> – The “effort” is the same. If we’re going to argue that SHA256 or cryptographic hashes are “too complicated” then I’m not really sure how to support that argument.

@falsifian@www.falsifian.org I believe the preserve means to include the original subject hash in the start of the twt such as (#somehash)

@bender@twtxt.net

Sorry, you’re right, I should have used numbers!

I’m don’t understand what “preserve the original hash” could mean other than “make sure there’s still a twt in the feed with that hash”. Maybe the text could be clarified somehow.

I’m also not sure what you mean by markdown already being part of it. Of course people can already use Markdown, just like presumably nothing stopped people from using (twt subjects) before they were formally described. But it’s not universal; e.g. as a jenny user I just see the plain text.

@prologic@twtxt.net Thanks for writing that up!

I hope it can remain a living document (or sequence of draft revisions) for a good long time while we figure out how this stuff works in practice.

I am not sure how I feel about all this being done at once, vs. letting conventions arise.

For example, even today I could reply to twt abc1234 with “(#abc1234) Edit: …” and I think all you humans would understand it as an edit to (#abc1234). Maybe eventually it would become a common enough convention that clients would start to support it explicitly.

Similarly we could just start using 11-digit hashes. We should iron out whether it’s sha256 or whatever but there’s no need get all the other stuff right at the same time.

I have similar thoughts about how some users could try out location-based replies in a backward-compatible way (append the replyto: stuff after the legacy (#hash) style).

However I recognize that I’m not the one implementing this stuff, and it’s less work to just have everything determined up front.

Misc comments (I haven’t read the whole thing):

• Did you mean to make hashes hexadecimal? You lose 11 bits that way compared to base32. I’d suggest gaining 11 bits with base64 instead.

• “Clients MUST preserve the original hash” — do you mean they MUST preserve the original twt?

• Thanks for phrasing the bit about deletions so neutrally.

• I don’t like the MUST in “Clients MUST follow the chain of reply-to references…”. If someone writes a client as a 40-line shell script that requires the user to piece together the threading themselves, IMO we shouldn’t declare the client non-conforming just because they didn’t get to all the bells and whistles.

• Similarly I don’t like the MUST for user agents. For one thing, you might want to fetch a feed without revealing your identty. Also, it raises the bar for a minimal implementation (I’m again thinking again of the 40-line shell script).

• For “who follows” lists: why must the long, random tokens be only valid for a limited time? Do you have a scenario in mind where they could leak?

• Why can’t feeds be served over HTTP/1.0? Again, thinking about simple software. I recently tried implementing HTTP/1.1 and it wasn’t too bad, but 1.0 would have been slightly simpler.

• Why get into the nitty-gritty about caching headers? This seems like generic advice for HTTP servers and clients.

• I’m a little sad about other protocols being not recommended.

• I don’t know how I feel about including markdown. I don’t mind too much that yarn users emit twts full of markdown, but I’m more of a plain text kind of person. Also it adds to the length. I wonder if putting a separate document would make more sense; that would also help with the length.

Had to build a list of all feeds (that I follow) and all twts in them and there are two collisions already:

$ ./stats
Saw 58263 hashes
7fqcxaa
  https://twtxt.net/user/justamoment/twtxt.txt
  https://twtxt.net/user/prologic/twtxt.txt
ntnakqa
  https://twtxt.net/user/prologic/twtxt.txt
  https://twtxt.net/user/thecanine/twtxt.txt

Namely:

$ jenny -D https://twtxt.net/user/justamoment/twtxt.txt | grep 7fqcxaa

[7fqcxaa] [2022-12-28 04:53:30+00:00] [(#pmuqoca) @prologic@twtxt.net I checked the GitHub discussion, it became a request to join forces.

Do you plan on having them join?

Also for the name, how about:

• “progit” or “prologit” (prologic official hard fork)
  
• “git-stance” (git instance)
  
• “GitTree” (Gitea inspired, maybe to related)
  
• “Gitomata” (git automata)
  
• “Git.Source”
  
• “Forgor” (forgit is taken so I forgor) 🤣
  
• “SweetGit” (as salty chat)
  
• “Pepper Git” (other ingredients) 😉
  
• “GitHeart” (core of git with a GitHub sounding name)
  
• “GitTaka” (With music in mind)
  

Ok, enough fun… Hope this helps sprout some ideas from others if nothing is to your taste.]

$ jenny -D https://twtxt.net/user/prologic/twtxt.txt/5 | grep 7fqcxaa

[7fqcxaa] [2022-02-25 21:14:45+00:00] [(#bqq6fxq) It’s handled by blue Monday]

And:

$ jenny -D https://twtxt.net/user/thecanine/twtxt.txt | grep ntnakqa
[ntnakqa] [2022-01-23 10:24:09+00:00] [(#2wh7r4q) <a href="https://yarn.girlonthemoon.xyz/external?uri=https://twtxt.net/user/prologic/twtxt.txt">@prologic<em>@twtxt.net</em></a> I know, I was just hoping it might have also gotten fixed by that change, by some kind of backend miracles. 😂]

$ jenny -D https://twtxt.net/user/prologic/twtxt.txt/1 | grep ntnakqa
[ntnakqa] [2024-02-27 05:51:50+00:00] [(#otuupfq) <a href="https://yarn.girlonthemoon.xyz/external?uri=https://twtxt.net/user/shreyan/twtxt.txt">@shreyan<em>@twtxt.net</em></a>  Ahh 👌]

I wrote some code to try out non-hash reply subjects formatted as (replyto ), while keeping the ability to use the existing hash style.

I don’t think we need to decide all at once. If clients add support for a new method then people can use it if they like. The downside of course is that this costs developer time, so I decided to invest a few hours of my own time into a proof of concept.

With apologies to @movq@www.uninformativ.de for corrupting jenny’s beautiful code. I don’t write this expecting you to incorporate the patch, because it does complicate things and might not be a direction you want to go in. But if you like any part of this approach feel free to use bits of it; I release the patch under jenny’s current LICENCE.

Supporting both kinds of reply in jenny was complicated because each email can only have one Message-Id, and because it’s possible the target twt will not be seen until after the twt referencing it. The following patch uses an sqlite database to keep track of known (url, timestamp) pairs, as well as a separate table of (url, timestamp) pairs that haven’t been seen yet but are wanted. When one of those “wanted” twts is finally seen, the mail file gets rewritten to include the appropriate In-Reply-To header.

Patch based on jenny commit 73a5ea81.

https://www.falsifian.org/a/oDtr/patch0.txt

Not implemented:

• Composing twts using the (replyto …) format.
  
• Probably other important things I’m forgetting.

@prologic@twtxt.net I read it. I understand it. Hopefully a solution can be agreed upon that solves the editing issue, whilst maintaining the cryptographic hash.

@prologic@twtxt.net I know the role of the current hash is to allow referencing (replies and, thus, threads), and it also represents a “unique” way to verify a twtxt hasn’t been tampered with. Is that second so important, if we are trying to allow edits? I know if feels good to be able to verify, but in reality, how often one does it?

@prologic@twtxt.net how about hashing a combination of nick/timestamp, or url/timestamp only, and not the twtxt content? On edit those will not change, so no breaking of threads. I know, I know, just adding noise here. :-P

@quark@ferengi.one It does not. That is why I’m advocating for not using hashes for treads, but a simpler link-back scheme.

the stem matching is the same as how GIT does its branch hashes. i think you can stem it down to 2 or 3 sha bytes.

if a client sees someone in a yarn using a byte longer hash it can lengthen to match since it can assume that maybe the other client has a collision that it doesnt know about.

@prologic@twtxt.net the basic idea was to stem the hash.. so you have a hash abcdef0123456789... any sub string of that hash after the first 6 will match. so abcdef, abcdef012, abcdef0123456 all match the same. on the case of a collision i think we decided on matching the newest since we archive off older threads anyway. the third rule was about growing the minimum hash size after some threshold of collisions were detected.

@prologic@twtxt.net Wikipedia claims sha1 is vulnerable to a “chosen-prefix attack”, which I gather means I can write any two twts I like, and then cause them to have the exact same sha1 hash by appending something. I guess a twt ending in random junk might look suspcious, but perhaps the junk could be worked into an image URL like . If that’s not possible now maybe it will be later.

git only uses sha1 because they’re stuck with it: migrating is very hard. There was an effort to move git to sha256 but I don’t know its status. I think there is progress being made with Game Of Trees, a git clone that uses the same on-disk format.

I can’t imagine any benefit to using sha1, except that maybe some very old software might support sha1 but not sha256.

@movq@www.uninformativ.de going a little sideways on this, “*If twtxt/Yarn was to grow bigger, then this would become a concern again. But even Mastodon allows editing, so how much of a problem can it really be? 😅*”, wouldn’t it preparing for a potential (even if very, very, veeeeery remote) growth be a good thing? Mastodon signs all messages, keeps a history of edits, and it doesn’t break threads. It isn’t a problem there.😉 It is here.

I think keeping hashes is a must. If anything for that “feels good” feeling.

@movq@www.uninformativ.de Agreed that hashes have a benefit. I came up with a similar example where when I twted about an 11-character hash collision. Perhaps hashes could be made optional somehow. Like, you could use the “replyto” idea and then additionally put a hash somewhere if you want to lock in which version of the twt you are replying to.

There is nothing wrong with how we currently run a diff to see what has been removed. if i build a merkle tree off all the twt hashes in a feed i can use that to verify a twt should be in a feed or not. and gossip that to my peers.

isn’t the benefit of blake2b that it is a more efficient algo than sha1 and has the same or similar entropy to sha3? i thought we had partially solved this with some type of expanding hash size? additionally we could increase bit density by using base36 or base64/url-safe…

I’m not advocating in either direction, btw. I haven’t made up my mind yet. 😅 Just braindumping here.

The (replyto:…) proposal is definitely more in the spirit of twtxt, I’d say. It’s much simpler, anyone can use it even with the simplest tools, no need for any client code. That is certainly a great property, if you ask me, and it’s things like that that brought me to twtxt in the first place.

I’d also say that in our tiny little community, message integrity simply doesn’t matter. Signed feeds don’t matter. I signed my feed for a while using GPG, someone else did the same, but in the end, nobody cares. The community is so tiny, there’s enough “implicit trust” or whatever you want to call it.

If twtxt/Yarn was to grow bigger, then this would become a concern again. But even Mastodon allows editing, so how much of a problem can it really be? 😅

I do have to “admit”, though, that hashes feel better. It feels good to know that we can clearly identify a certain twt. It feels more correct and stable.

Hm.

I suspect that the (replyto:…) proposal would work just as well in practice.

Regarding jenny development: There have been enough changes in the last few weeks, imo. I want to let things settle for a while (potential bugfixes aside) and then I’m going to cut a new release.

And I guess the release after that is going to include all the threading/hashing stuff – if we can decide on one of the proposals. 😂

@prologic@twtxt.net

There’s a simple reason all the current hashes end in a or q: the hash is 256 bits, the base32 encoding chops that into groups of 5 bits, and 256 isn’t divisible by 5. The last character of the base32 encoding just has that left-over single bit (256 mod 5 = 1).

So I agree with #3 below, but do you have a source for #1, #2 or #4? I would expect any lack of variability in any part of a hash function’s output would make it more vulnerable to attacks, so designers of hash functions would want to make the whole output vary as much as possible.

Other than the divisible-by-5 thing, my current intuition is it doesn’t matter what part you take.

1. Hash Structure: Hashes are typically designed so that their outputs have specific statistical properties. The first few characters often have more entropy or variability, meaning they are less likely to have patterns. The last characters may not maintain this randomness, especially if the encoding method has a tendency to produce less varied endings.

2. Collision Resistance: When using hashes, the goal is to minimize the risk of collisions (different inputs producing the same output). By using the first few characters, you leverage the full distribution of the hash. The last characters may not distribute in the same way, potentially increasing the likelihood of collisions.

3. Encoding Characteristics: Base32 encoding has a specific structure and padding that might influence the last characters more than the first. If the data being hashed is similar, the last characters may be more similar across different hashes.

4. Use Cases: In many applications (like generating unique identifiers), the beginning of the hash is often the most informative and varied. Relying on the end might reduce the uniqueness of generated identifiers, especially if a prefix has a specific context or meaning.

An alternate idea for supporting (properly) Twt Edits is to denoate as such and extend the meaning of a Twt Subject (which would need to be called something better?); For example, let’s say I produced the following Twt:

2024-09-18T23:08:00+10:00	Hllo World

And my feed’s URI is https://example.com/twtxt.txt. The hash for this Twt is therefore 229d24612a2:

$ echo -n "https://example.com/twtxt.txt\n2024-09-18T23:08:00+10:00\nHllo World" | sha1sum | head -c 11
229d24612a2

You wish to correct your mistake, so you make an amendment to that Twt like so:

2024-09-18T23:10:43+10:00	(edit:#229d24612a2) Hello World

Which would then have a new Twt hash value of 026d77e03fa:

$ echo -n "https://example.com/twtxt.txt\n2024-09-18T23:10:43+10:00\nHello World" | sha1sum | head -c 11
026d77e03fa

Clients would then take this edit:#229d24612a2 to mean, this Twt is an edit of 229d24612a2 and should be replaced in the client’s cache, or indicated as such to the user that this is the intended content.

@quark@ferengi.one My money is on a SHA1SUM hash encoding to keep things much simpler:

$ echo -n "https://twtxt.net/user/prologic/twtxt.txt\n2020-07-18T12:39:52Z\nHello World! 😊" | sha1sum | head -c 11
87fd9b0ae4e

Taking the last n characters of a base32 encoded hash instead of the first n can be problematic for several reasons:

1. Hash Structure: Hashes are typically designed so that their outputs have specific statistical properties. The first few characters often have more entropy or variability, meaning they are less likely to have patterns. The last characters may not maintain this randomness, especially if the encoding method has a tendency to produce less varied endings.

2. Collision Resistance: When using hashes, the goal is to minimize the risk of collisions (different inputs producing the same output). By using the first few characters, you leverage the full distribution of the hash. The last characters may not distribute in the same way, potentially increasing the likelihood of collisions.

3. Encoding Characteristics: Base32 encoding has a specific structure and padding that might influence the last characters more than the first. If the data being hashed is similar, the last characters may be more similar across different hashes.

4. Use Cases: In many applications (like generating unique identifiers), the beginning of the hash is often the most informative and varied. Relying on the end might reduce the uniqueness of generated identifiers, especially if a prefix has a specific context or meaning.

In summary, using the first n characters generally preserves the intended randomness and collision resistance of the hash, making it a safer choice in most cases.

@prologic@twtxt.net I saw those, yes. I tried using yarnc, and it would work for a simple twtxt. Now, for a more convoluted one it truly becomes a nightmare using that tool for the job. I know there are talks about changing this hash, so this might be a moot point right now, but it would be nice to have a tool that:

1. Would calculate the hash of a twtxt in a file.
   
2. Would calculate all hashes on a twtxt.txt (local and remote).
   

Again, something lovely to have after any looming changes occur.

Could someone knowledgable reply with the steps a grandpa will take to calculate the hash of a twtxt from the CLI, using out-of-the-box tools? I swear I read about it somewhere, but can’t find it.

@falsifian@www.falsifian.org based on Twt Subject Extension, your subject is invalid. You can have custom subjects, that is, not a valid hash, but you simply can’t put anything, and expect it to be treated as a TwtSubject, me thinks.

yarnd just doesn’t render the subject. Fair enough. It’s (replyto http://darch.dk/twtxt.txt 2024-09-15T12:50:17Z), and if you don’t want to go on a hunt, the twt hash is weadxga: https://twtxt.net/twt/weadxga

@sorenpeter@darch.dk I like this idea. Just for fun, I’m using a variant in this twt. (Also because I’m curious how it non-hash subjects appear in jenny and yarn.)

URLs can contain commas so I suggest a different character to separate the url from the date. Is this twt I’ve used space (also after “replyto”, for symmetry).

I think this solves:

• Changing feed identities: although @mckinley@twtxt.net points out URLs can change, I think this syntax should be okay as long as the feed at that URL can be fetched, and as long as the current canonical URL for the feed lists this one as an alternate.
  
• editing, if you don’t care about message integrity
  
• finding the root of a thread, if you’re not following the author
  

An optional hash could be added if message integrity is desired. (E.g. if you don’t trust the feed author not to make a misleading edit.) Other recent suggestions about how to deal with edits and hashes might be applicable then.

People publishing multiple twts per second should include sub-second precision in their timestamps. As you suggested, the timestamp could just be copied verbatim.

@prologic@twtxt.net I have some ideas:

• Add smartypants rendering, just like Yarn has.
  
• Add the ability to create individual twtxts, each named after their hash.
  
• Fix the formatting of the help. :-P

@movq@www.uninformativ.de

Maybe I’m being a bit too purist/minimalistic here. As I said before (in one of the 1372739 posts on this topic – or maybe I didn’t even send that twt, I don’t remember 😅), I never really liked hashes to begin with. They aren’t super hard to implement but they are kind of against the beauty of the original twtxt – because you need special client support for them. It’s not something that you could write manually in your twtxt.txt file. With @sorenpeter@darch.dk’s proposal, though, that would be possible.

Tangentially related, I was a bit disappointed to learn that the twt subject extension is now never used except with hashes. Manually-written subjects sounded so beautifully ad-hoc and organic as a way to disambiguate replies. Maybe I’ll try it some time just for fun.

@prologic@twtxt.net

() @falsifian@www.falsifian.org You mean the idea of being able to inline # url = changes in your feed?

Yes, that one. But @lyse@lyse.isobeef.org pointed out suffers a compatibility issue, since currently the first listed url is used for hashing, not the last. Unless your feed is in reverse chronological order. Heh, I guess another metadata field could indicate which version to use.

Or maybe url changes could somehow be combined with the archive feeds extension? Could the url metadata field be local to each archive file, so that to switch to a new url all you need to do is archive everything you’ve got and start a new file at the new url?

I don’t think it’s that likely my feed url will change.

@prologic@twtxt.net Yeah, that thing with (#hash;#originalHash) would also work.

Maybe I’m being a bit too purist/minimalistic here. As I said before (in one of the 1372739 posts on this topic – or maybe I didn’t even send that twt, I don’t remember 😅), I never really liked hashes to begin with. They aren’t super hard to implement but they are kind of against the beauty of the original twtxt – because you need special client support for them. It’s not something that you could write manually in your twtxt.txt file. With @sorenpeter@darch.dk’s proposal, though, that would be possible.

I don’t know … maybe it’s just me. 🥴

I’m also being a bit selfish, to be honest: Implementing (#hash;#originalHash) in jenny for editing your own feed would not be a no-brainer. (Editing is already kind of unsupported, actually.) It wouldn’t be a problem to implement it for fetching other people’s feeds, though.

@movq@www.uninformativ.de I figured it will be something like this, yet, you were able to reply just fine, and I wasn’t. Looking at your twtxt.txt I see this line:

2024-09-16T17:37:14+00:00	(#o6dsrga) @<prologic https://twtxt.net/user/prologic/twtxt.txt>

@<quark https://ferengi.one/twtxt.txt> This is what I get. 🤔

Which is using the right hash. Mine, on the other hand, when I replied to the original, old style message (Message-Id: <o6dsrga>), looks like this:

2024-09-16T16:42:27+00:00	(#o) @<prologic https://twtxt.net/user/prologic/twtxt.txt> this was your first twtxt. Cool! :-P

What did you do to make yours work? I simply went to the oldest @prologic@twtxt.net’s entry on my Maildir, and replied to it (jenny set the reply-to hash to #o, even though the Message-Id is o6dsrga). Since jenny can’t fetch archived twtxts, how could I go to re-fetch everything? And, most importantly, would re-fetching fix the Message-Id:?

Hmm… I replied to this message:

From: prologic <prologic>
Subject: Hello World! 😊
Date: Sat, 18 Jul 2020 08:39:52 -0400
Message-Id: <o6dsrga>
X-twtxt-feed-url: https://twtxt.net/user/prologic/twtxt.txt

Hello World! 😊

And see how the hash shows… Is it because that hash isn’t longer used?

@sorenpeter@darch.dk

1. (replyto:http://darch.dk/twtxt.txt,2024-09-15T12:06:27Z)
   

I think I like this a lot. 🤔

The problem with using hashes always was that they’re “one-directional”: You can construct a hash from URL + timestamp + twt, but you cannot do the inverse. When I see “, I have no idea what that could possibly refer to.

But of course something like (replyto:http://darch.dk/twtxt.txt,2024-09-15T12:06:27Z) has all the information you need. This could simplify twt/feed discovery quite a bit, couldn’t it? 🤔 That thing that I just implemented – jenny asking some Yarn pod for some twt hash – would not be necessary anymore. Clients could easily and automatically fetch complete threads instead of requiring the user to follow all relevant feeds.

Only using the timestamp to identify a twt also solves the edit problem.

It even is better for non-Yarn clients, because you now don’t have to read, understand, and implement a “twt hash specification” before you can reply to someone.

The only problem, really, is that (replyto:http://darch.dk/twtxt.txt,2024-09-15T12:06:27Z) is so long. Clients would have to try harder to hide this. 😅

@prologic@twtxt.net by the way and just in case… is the metadata in tour twtxt.txt file, pointing at your rotated feed files formatted as prev = hash twtxt.txt/n instead of a link by design? I couldn’t fetch any, nor can I do a –fetch-context on replays to your old twts.

@aelaraji@aelaraji.com no, it is not just you. Do fetch the parent with jenny, and you will see there are two messages with different hash. Soren did something funky, for sure.

Alright, I saw enough broken threads lately to be motivated enough to extend the --fetch-context thingy: It can now ask Yarn pods for twt hashes.

https://www.uninformativ.de/git/jenny/commit/eefd3fa09083e2206ed0d71887d2ef2884684a71.html

This is only done as a last resort if there’s no other way to find the missing twt. Like, when there’s a twt that begins with just a hash and no user mention, there’s no way for jenny to know on which feed that twt can be found, so it’ll ask some Yarn pod in that case.

@prologic@twtxt.net Brute force. I just hashed a bunch of versions of both tweets until I found a collision.

I mostly just wanted an excuse to write the program. I don’t know how I feel about actually using super-long hashes; could make the twts annoying to read if you prefer to view them untransformed.

@prologic@twtxt.net earlier you suggested extending hashes to 11 characters, but here’s an argument that they should be even longer than that.

Imagine I found this twt one day at https://example.com/twtxt.txt :

2024-09-14T22:00Z Useful backup command: rsync -a “$HOME” /mnt/backup

and I responded with “(#5dgoirqemeq) Thanks for the tip!”. Then I’ve endorsed the twt, but it could latter get changed to

2024-09-14T22:00Z Useful backup command: rm -rf /some_important_directory

which also has an 11-character base32 hash of 5dgoirqemeq. (I’m using the existing hashing method with https://example.com/twtxt.txt as the feed url, but I’m taking 11 characters instead of 7 from the end of the base32 encoding.)

That’s what I meant by “spoofing” in an earlier twt.

I don’t know if preventing this sort of attack should be a goal, but if it is, the number of bits in the hash should be at least two times log2(number of attempts we want to defend against), where the “two times” is because of the birthday paradox.

Side note: current hashes always end with “a” or “q”, which is a bit wasteful. Maybe we should take the first N characters of the base32 encoding instead of the last N.

Code I used for the above example: https://fossil.falsifian.org/misc/file?name=src/twt_collision/find_collision.c
I only needed to compute 43394987 hashes to find it.

I was not suggesting to that everyone need to setup a working webfinger endpoint, but that we take the format of nick+(sub)domain as base for generating the hashed together with the message date and content.

If we omit the protocol prefix from the way we do things now will that not solve most of the problems? In the case of gemini://gemini.ctrl-c.club/~nristen/twtxt.txt they also have a working twtxt.txt at https://ctrl-c.club/~nristen/twtxt.txt … damn I just notice the gemini. subdomain.

Okay what about defining a prefers protocol as part of the hash schema? so 1: https , 2: http 3: gemini 4: gopher ?

@sorenpeter@darch.dk There was a client that would generate a unique hash for each twt. It didn’t get wide adoption.

So this is a great thread. I have been thinking about this too.. and what if we are coming at it from the wrong direction? Identity being tied to a given URL has always been a pain point. If i get a new URL its almost as if i have a new identity because not only am I serving at a new location but all my previous communications are broken because the hashes are all wrong.

What if instead we used this idea of signatures to thread the URLs together into one identity? We keep the URL to Hash in place. Changing that now is basically a no go. But we can create a signature chain that can link identities together. So if i move to a new URL i update the chain hosted by my primary identity to include the new URL. If i have an archived feed that the old URL is now dead, we can point to where it is now hosted and use the current convention of hashing based on the first url:

The signature chain can also be used to rotate to new keys over time. Just sign in a new key or revoke an old one. The prior signatures remain valid within the scope of time the signatures were made and the keys were active.

The signature file can be hosted anywhere as long as it can be fetched by a reasonable protocol. So say we could use a webfinger that directs to the signature file? you have an identity like frank@beans.co that will discover a feed at some URL and a signature chain at another URL. Maybe even include the most recent signing key?

From there the client can auto discover old feeds to link them together into one complete timeline. And the signatures can validate that its all correct.

I like the idea of maybe putting the chain in the feed preamble and keeping the single self contained file.. but wonder if that would cause lots of clutter? The signature chain would be something like a log with what is changing (new key, revoke, add url) and a signature of the change + the previous signature.

# chain: ADDKEY kex14zwrx68cfkg28kjdstvcw4pslazwtgyeueqlg6z7y3f85h29crjsgfmu0w 
# sig: BEGIN SALTPACK SIGNED MESSAGE. ... 
# chain: ADDURL https://txt.sour.is/user/xuu
# sig: BEGIN SALTPACK SIGNED MESSAGE. ...
# chain: REVKEY kex14zwrx68cfkg28kjdstvcw4pslazwtgyeueqlg6z7y3f85h29crjsgfmu0w
# sig: ...

@mckinley@twtxt.net To answer some of your questions:

Are SSH signatures standardized and are there robust software libraries that can handle them? We’ll need a library in at least Python and Go to provide verified feed support with the currently used clients.

We already have this. Ed25519 libraries exist for all major languages. Aside from using ssh-keygen -Y sign and ssh-keygen -Y verify, you can also use the salty CLI itself (https://git.mills.io/prologic/salty), and I’m sure there are other command-line tools that could be used too.

If we all implemented this, every twt hash would suddenly change and every conversation thread we’ve ever had would at least lose its opening post.

Yes. This would happen, so we’d have to make a decision around this, either a) a cut-off point or b) some way to progressively transition.

how little data is needed for generating the hashes? Instead of the full URL, can we makedo with just the domain (example.net) so we avoid the conflicts with gemini://, https:// and only http:// (like in my own twtxt.txt) or construct something like like a webfinger id nick@domain (also used by mastodon etc.) from the domain and nick if there, else use domain as nick as well

@lyse@lyse.isobeef.org This looks like a nice way to do it.

Another thought: if clients can’t agree on the url (for example, if we switch to this new way, but some old clients still do it the old way), that could be mitigated by computing many hashes for each twt: one for every url in the feed. So, if a feed has three URLs, every twt is associated with three hashes when it comes time to put threads together.

A client stills need to choose one url to use for the hash when composing a reply, but this might add some breathing room if there’s a period when clients are doing different things.

(From what I understand of jenny, this would be difficult to implement there since each pseudo-email can only have one msgid to match to the in-reply-to headers. I don’t know about other clients.)

@falsifian@www.falsifian.org In my opinion it was a mistake that we defined the first url field in the feed to define the URL for hashing. It should have been the last encountered one. Then, assuming append-style feeds, you could override the old URL with a new one from a certain point on:

# url = https://example.com/alias/txtxt.txt
# url = https://example.com/initial/twtxt.txt
<message 1 uses the initial URL>
<message 2 uses the initial URL, too>
# url = https://example.com/new/twtxt.txt
<message 3 uses the new URL>
# url = https://example.com/brand-new/twtxt.txt
<message 4 uses the brand new URL>

In theory, the same could be done for prepend-style feeds. They do exist, I’ve come around them. The parser would just have to calculate the hashes afterwards and not immediately.

@movq@www.uninformativ.de Another idea: just hash the feed url and time, without the message content. And don’t twt more than once per second.

Maybe you could even just use the time, and rely on @-mentions to disambiguate. Not sure how that would work out.

Though I kind of like the idea of twts being immutable. At least, it’s clear which version of a twt you’re replying to (assuming nobody is engineering hash collisions).

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.

@bender@twtxt.net Sorry, trust was the wrong word. Trust as in, you do not have to check with anything or anyone that the hash is valid. You can verify the hash is valid by recomputing the hash from the content of what it points to, etc.