What We Build On

When someone you trust vouches for a person they’ve worked beside, something valuable has happened: testimony has traveled. The decisions that matter most, from who gets hired to who gets trusted, still turn on testimony, and almost none of it leaves a record the next stranger can check. The Attestation Notary protocol is a set of rules for writing that testimony down. Extol authored it, maintains its reference implementation, and operates the first production network built on it.

This essay is the protocol’s family tree. Nothing in it is a clean-sheet invention, and every part descends from work someone else published, tested, and in several cases watched fail. We have written elsewhere about the graveyard of reputation systems and the laws it taught us.¹ What follows is the other half of the inheritance: the traditions that got something right, what each one solved, and the one layer none of them built.

The notary: Solana Attestation Service

Start at the bottom of the stack, with the least human question: where does a signed record physically live? A signed claim needs to be durably recorded somewhere a verifier can check it, without trusting the recorder. This problem is solved. The protocol binds its notarization layer to the Solana Attestation Service (SAS), and it publishes the criteria that made SAS the right choice.

The chain is the protocol’s notary, not its religion. One criterion outranks the rest: the substrate must refuse to be a directory. Nothing in how records are stored may let a stranger assemble everything Alice ever signed, or everyone who ever signed something about Bob. The SAS binding enforces that refusal, and it is the bar any future replacement must clear. A companion implementation, backed by nothing more than a Postgres database, shows the signing layer working with no chain at all, and documents what that choice gives up.

  ┌───────────────────────────────┐
  │                               │
  │            Extol              │
  │                               │
  ╞═══════════════════════════════╡
  │  ATTESTATION NOTARY PROTOCOL  │
  │                               │
  │  disclosure:                  │ ← Elinor Ostrom
  │    shown, never pulled        │
  │                               │
  │  the constraint:              │ ← soulbound tokens
  │    standing is not for sale   │
  │                               │
  │  the envelope:                │ ← W3C VCs, Open Badges
  │    the signed claim           │ 
  │                               │
  │  the notary:                  │ ← Solana Attestation
  │    the public record          │   Service
  └───────────────────────────────┘

The stack, bottom to top: each layer, and the tradition that supplied it.

The envelope: W3C Verifiable Credentials and Open Badges

One layer up sits the data format. The fields a portable, cryptographically signed claim about a person must carry. This problem was solved by a decade of serious work. The W3C Verifiable Credentials standard established the full model: signed claims about a subject, expressed in a portable envelope, verifiable by any conforming implementation.² Open Badges built the peer-attested credential pattern at real scale in education, with over a thousand issuing organizations and millions of badges minted.³

The protocol inherits the signed-claim shape from both. It departs in one structural place: Verifiable Credentials assume issuer authority hierarchies. A school issues a diploma, a government issues a license. The Attestation Notary protocol treats every signer as equal and lets weight derive from graph structure at read time, not from institutional privilege at write time. What a signature is worth depends on who signed, what they staked, and what the graph shows about them, decided when the record is read, not when it was written.

The deeper inheritance from these two projects is a warning: millions of badges were minted, and employers did not check them. The full post-mortem is the first law of our field guide. What matters for the lineage is what that failure revealed: the envelope existed, and what did not exist was a protocol governing who may fill it, at what cost to themselves, and under whose control it is shown.

The constraint: soulbound tokens

In 2022, Ohlhaver, Weyl, and Buterin published “Decentralized Society: Finding Web3’s Soul,” and ruled something out.⁴ Their observation was structural: any reputation primitive tradable in a fungible market will, over time, come to represent what someone was willing to pay for the appearance of standing rather than what the holder actually did. Their proposal, soulbound tokens, identity-bound and permanently non-transferable, moved the fix from instinct to design principle.

The protocol honors the constraint by not over-promising it. Any implementer can wrap a record in a token and trade the token, and no rule about bytes can stop them. A protocol that promised non-transferable standing would be making a promise it cannot keep. So the constraint lives where it can be kept, in the commitments adopters publish.

Extol’s guardrails answer it directly: standing is non-transferable, any conversion of standing into transferable value happens in the open, and a firewall stops records from ever being wrapped into tokens. Other implementers may commit differently, and the protocol does not choose for them.

The protocol is deliberately silent on a further set of questions implementers will face immediately: voting weight, delegation, how standing converts to influence. That silence is not an oversight; it is a boundary. The protocol’s job is to make signatures verifiable, not to prescribe how downstream systems read the graph those signatures build. Posner and Weyl’s Radical Markets provides a hint of where to find such prescriptions.⁵

The reasoning tradition: Ostrom

Elinor Ostrom never wrote a line about credentials, and her work governs more of the protocol’s design than any document that did. Governing the Commons demonstrated that communities can steward shared resources durably, without privatization and without a central authority, when the rules meet certain design conditions: defined boundaries, locally fitted rules, community monitoring, graduated sanctions.⁶ Trust is such a resource; we make that argument in full elsewhere. A community’s willingness to vouch is depletable: it can be over-harvested by costless endorsement, polluted by paid attestation, and enclosed by any platform that custodies it.

Ostrom’s principles are why the protocol’s disclosure rule reads the way it does: records move only with the person they concern, shown by them, never pulled in bulk, never searched by strangers. Any protocol that permits pulling records about a person without them converts that person’s reputation from a commons they co-govern into an extractable resource they cannot defend. Ostrom’s work is what tells us this failure is structural, not incidental. Where the earlier projects in this lineage gave us mechanisms, she gave us the criteria for judging them.

The closest relative: PCARE

One predecessor enters the family tree differently. Every ancestor so far shaped the protocol. Puja Ohlhaver’s 2025 community-currency model, PCARE, shaped what Extol built on top of Attestation Notary: the token layer, which lives in one implementer’s products rather than in the protocol every implementer shares.⁷ We credit it in the most detail anyway, because the work shapes important parts of what Extol builds, just not the open half.

PCARE offers a currency design for the economics of power: each community issues its own currency, and members choose between permanently locking it for influence or keeping it liquid to exchange outward. Community currencies are an old idea; two of PCARE’s mechanisms for them are not, and Extol inherits both openly. The locked/liquid split is hers. And the subsidiarity condition is hers: local stake, meaning voice and standing, must weigh more heavily inside a community than global money does, or outside capital can simply buy local outcomes. Extol builds that requirement into how its communities draw their boundaries.

The two models answer different questions. PCARE prices influence: the weight a member’s locked currency carries in a community’s decisions. The protocol governs the record: who did what, witnessed by whom. Extol runs them side by side and never lets one pay for the other. Attesting earns no tokens, because the moment a signature makes money for its signer, the signal dies.

Influence weighted per person also invites the oldest attack in the genre: one person splitting into several accounts to be counted more than once. The durable defense has always been in-person, high-context community, where one body cannot show up as two, and witnessed attestation makes that defense native to the protocol. A trail crew that watched you swing a tool all season cannot be persuaded to sign for a person who does not exist. Extol’s deployments are field data on whether that defense holds. We expect to keep reporting what we find.

The composition

Lay the ancestry end to end and what remains is not a missing idea but a missing integration. SAS notarizes. Verifiable Credentials and Open Badges define the envelope. Soulbound tokens supply the non-transferability constraint. PCARE structures influence within and between communities. Ostrom tells us how to judge the whole arrangement. Every piece exists somewhere in this lineage. No one had composed them into a single specification: testimony a person earns from witnesses, keeps for life, and shows on their own terms.

What the protocol adds is not novel cryptography and not a novel idea. It is the requirement that the pieces come as a set, because each one fails without the others. A signature without stake is cheap talk. A record anyone can pull is not reputation, it is a dossier. And a substrate that acts as a directory turns even a well-designed record into surveillance infrastructure. Each ancestor solved its piece. The protocol’s work was choosing them, requiring all of them, and publishing the arrangement as a protocol rather than a product so that anyone can build on it.

Extol holds three roles today, author, reference maintainer, and first production network, because that is how specifications begin, not how they should end. If the protocol does its job, other implementations, networks, and maintainers will emerge alongside it. The specification is on GitHub now. Review happens where specifications live: in issues, in pull requests, and in the implementations that decide to build against it. That is how this family grows, one review and one implementation at a time.

Ken Leiserson builds tools for trust between people who work together. He can be reached at extol.work or on X @kenserson.