ActivityPub over ATProto (2023)
berjon.com
berjon.com
I have a Bluesky identity that I registered primarily to follow someone that I happened to meet in person while stumping for the Rio Grande Plan[0]. I only have like five posts on it, but I would like to migrate that over to the same domain I already self-host Mastodon on. Bluesky has an option to have your handle on a custom domain, but that involves publishing a DNS record containing a did:plc whose keys are custodially owned by Bluesky. This is not so much an exit as it is an overcomplicated verification scheme.
My assumption is that if Bluesky wanted a better credible exit than ActivityPub, then we would need some way to rotate keys so that I could have my own PDS publish new posts on my existing identity and have other AppViews recognize that as the same kmeisthax that was previously using Bluesky as a PDS. The Mastodon exit is woefully inadequate, but at least if the admin cooperates, you can redirect your account and export your data. Everyone else on any other ActivityPub instance will see the same thing. As it currently stands, ATProto has a great way to migrate between AppViews[1], but no way to migrate off an uncompliant PDS.
[0] The Rio Grande Plan is a citizen-led movement calling for burying the heavy rail corridor going through Salt Lake City.
[1] ActivityPub is actually really lousy at cross-app interaction. If you're on a Mastodon instance, there is no way to participate in a Lemmy forum. Mastodon does not understand how to send the correct ActivityPub messages that Lemmy expects; and there's no protocol for Lemmy to tell Mastodon to publish certain ActivityPub messages on its behalf.
The fact that BlueSky runs the PLC central server is supposed to be fixed by them creating a swiss association to run and control it instead, but while they announced this, it is unclear if it went anywhere.
If you migrate to a self hosted PDS using the all-in-one migration `goat account migrate` command, it will temporarily change your handle to a subdomain of your new PDS, and leave the new PDS managing the PLC. You can instead perform each step manually via goat or raw API calls, either of which would let you transition to direct PLC key management, and/or a new domain based handle as a single atomic plc update, as part of the overall migration process.
See https://atproto.com/guides/account-migration for a discussion of the process at the protocol level. See https://whtwnd.com/bnewbold.net/3l5ii332pf32u for a breakdown of both the automated, and step by step process via `goat`. It does not go into the details of switching to self managed, but it basically requires crafting your new PLC document, sending that one to the old PDS to sign, and then submitting the result. There are manual PLC signing, and submission commands available as `goat plc` subcommands, for use once you have manual control.
The option to register and manage PLC rotation keys should be built into the Bluesky Appview itself, sitting right next to the existing option to verify a domain with your did:plc string. Having the option only exist as a command line tool means most people aren't going to use it and third-party PDS hosts are going to be a pain in the ass to use for people with data already on Bluesky's PDS.
I'm also not happy about the existence of the PLC directory at all, mostly because it's not really explained all that well in the Bluesky interface. I assumed PDSes were just identified by their domain name (like a Mastodon instance is) - and while that is an option with did:web, it's not the default option, and you cannot migrate an identity between PLC and DNS governance. Hopefully that will change.
That I didn't know! So... Basically the whole solution is still "trust me bro"?
There are also read-only mirrors of the PLC, but that doesn't really matter, given that the whole point of the PLC is to be a trusted[1] entity for arbitrating identity conflicts. This is necessary because the PLC is what lets you register new signing keys to overrule an uncooperative PDS - otherwise, you have the moral equivalent of Mastodon instances where an instance admin can hold your identity hostage.
And, technically speaking, did:web is also "trust-me-bro", in the sense that it ultimately relies on DNS to resolve names to servers. DNS and PLC are moral equivalents[0] in that ultimately there is a central authority to arbitrate disputes over who owns what identities. In fact, there kind of has to be. Every proposal for a true distributed identity system ultimately boils down to either pinning a self-signed key or web-of-trust, both of which have undesirable failure modes due to the lack of a central trusted authority.
Ultimately, the choice comes down to: do you want to pay the DNS people $15/yr for a zone to host your DID on, or do you trust Bluesky's PLC server to offer that hosting for free?
[0] Almost. In practice, DNS is a recursively nested set of central governors; every TLD imposes an additional governor on top of ICANN root zone management. In practice, almost all DNS shenanigans happen at registrars; and of the shenanigans not caused by registrars, most of them happen at the TLD operators and not the root zone itself.
[1] PLC stores all identity updates in an append-only log. I'd call it a blockchain, but the Bitcoin people ruined that term. Practically speaking, if the PLC were to "turn evil" and mess with people's identities there'd be irrefutable proof of it. How much this assuages your concern depends on what you think about Certificate Transparency.
That's the one part you can't migrate; everything else you can change while retaining your followers, posts, etc.
Setting your handle to a domain name via DNS[1] is intended to be easy for non-technical users (especially with registrars adding one-click forms for doing so) and also decoupled from actual PDS hosting. Many users just want their handle to reflect their identity on the web, and are ok trusting BlueSky to host their PDS for free.
Migrating to a new PDS is possible in both the cooperative case[2] or in the adversarial case[3]. The gist is that A: you should take regular backups by exporting your account data, and B: if you're using did:plc instead of did:web, you should register a backup key that has a higher priority than the key held by your PDS, so a malicious PDS can't simply migrate you back.
[0] https://github.com/bluesky-social/atproto/discussions/2705
[1] Alternatively there's an option for HTTP handle resolution instead via `/.well-known/atproto-did`
[2] https://atproto.com/specs/account#pds-account-migration
[3] https://www.da.vidbuchanan.co.uk/blog/adversarial-pds-migrat...
All of these things require engineering and social work to grow and it's hit and miss to gather momentum and stickiness.
The Fediverse Is Not the Way Forward
https://news.ycombinator.com/item?id=48785077
There are no instances in ATProto
What Bluesky and AT Proto in general do is make it easy for people to either get a domain (a *.bsky.social subdomain) or use their own as their handle.
And AT Proto also lets you change your domain while preserving your identity, since the actual identity is a DID.
That makes it very easy to move your data and your handle around and not lose followers. If you change your RSS server's domain name, your subscribers don't come with you.
Show me the ATProto server that can integrate with BlueSky.
Honestly my main question here is "If you disagree with various ActivityPub instances' defederations, you can get around this by starting your own instance that federates with everything; is there an equivalent for bypassing Bluesky's moderation decisions?"
Can you? The same Glitch that shut down last year? https://blog.glitch.com/post/goodbye-glitch
Regardless, ActivityPub and ATProto have different designs and goals. Your question is akin to comparing a helicopter and an airplane.
There's no such thing as a "ATProto server". How complicated it is, and the trade-offs it made are valid criticisms of it. It all depends on what exactly your goal is as a participant of a distributed social network.
If the thing you want to own is your identity and data, you can fairly easy run a PDS yourself. If the thing you care about is different moderation decisions, you can run your own labeller (moderation system) or subscribe to another someone else has made.
To 'own your data' you just need a PDS, which should be cheaper to run than an ActivityPub server
To build an app you need some of the more expensive parts
People really do ask where "The AT Proto server is" as evidenced by this thread, and the really is no "AT Proto server" or "instance". AT Proto and BlueSky are a collection of services with no 1-1 relationship to a Mastodon or RSS server.
There's absolutely nothing misleading about that.