Levarac

ETHGlobal Tokyo 2026

Mizar and Alcor

Eligibility, recomputable from published inputs.

An event key qualifies when it has signed mutual observations with at least N distinct Alcor-credentialed partner keys, in at least B time windows per partner, and the claimant holds an Alcor distinct-human credential.

This proves the published rule was met under its evidence and credential trust assumptions. It does not prove physical attendance.

Try it Read the source
Four phones meeting over two time windows Phones A, B and C see each other in both windows, so each has two partners with two windows and passes. The passer-by D meets C in one window only and fails. WINDOW 1 OF 2 WINDOW 2 OF 2 RESULT · N = 2, B = 2 1 window A PASS 2/2 partners B PASS 2/2 partners C PASS 2/2 partners D FAIL
Illustration of the rule with the published demo values N = 2, B = 2. D, a passer-by, meets one phone once.

Try it

Six ways in, from a phone or a terminal.

Demo video

Video coming soon

A walkthrough of the join, encounter and claim flow. The link will appear here once it is published.

Not yet available

iOS app

Install Beid through TestFlight

The ETHGlobal Tokyo demo build of Beid. Beid, Levarac's reference app, implements the Parallax protocol end to end: it senses nearby devices over Barnard, signs observations with its event key and submits them for anchoring.

Join the TestFlight

Human check

Open the Alcor join page

Binds one World ID to an event key. The full flow needs the Beid app, which signs the check with its event key.

alcor-human-check.levarac.workers.dev

EAS schema

Claim attestation schema

0x858edbfff167feaa82c4bb29f3ce4a62ed06024ccdd8377f4f0b26619ccd65d3

bytes32 eventId, address eventKey, uint64 snapshotId, bytes32 manifestDigest

View on EASScan

Run locally

Reproduce in one command

From e2e/ in a Mizar checkout. It evaluates the fixture, posts a root on a local Anvil chain and claims against MockEAS.

pnpm install --frozen-lockfile && pnpm e2e
README: Local E2E

What has and has not been verified live, including the claim page and the first snapshot, is kept current in the README deployment record.

How it works

From a handshake of radios to a claim in your wallet.

  1. 01

    Join and pass the human check

    Beid signs a typed challenge with its event key. Alcor binds one World ID to that event key for the event and publishes a signed credential.

  2. 02

    Phones observe each other

    Beid signs BLE observations, and Parallax anchors their commitments on Sepolia. A pair counts only when both phones report each other's rotating identifiers in the same time window.

  3. 03

    A fixed N/B rule

    Each eligible key needs N distinct credentialed partners, each seen in at least B time windows (300 s by default). The published demo parameters set N = 2 and B = 2, and were published before any snapshot.

  4. 04

    Posting a snapshot root on Sepolia

    The evaluator writes a manifest, the eligible list and Merkle proofs. Once a snapshot is taken, the configured root poster posts its root, the manifest's SHA-256 digest and a cutoff block to the claim contract.

  5. 05

    Claim to your own wallet

    Once a snapshot root is posted, a claim checks against it. You choose a recipient wallet and Beid signs for it. The contract checks membership and the signature, allows one claim per event key and issues a non-revocable EAS attestation. Each claim is its own transaction.

Once a snapshot root is posted, anyone with the published inputs can rerun the evaluator and compare the result with that root.

Components

Two new pieces on three existing ones.

Built at ETHGlobal Tokyo 2026

Mizar

Participation-rule evaluator and EAS claim system.

public repository

Alcor

Human-check service and join page.

public repository

Pre-existing before the hackathon

Parallax

Protocol for signed BLE observations and anchored evidence.

private repository

Beid

Beid, Levarac's reference app, implements the Parallax protocol end to end: it senses nearby devices over Barnard, signs observations with its event key and submits them for anchoring. Its typed event-key signing entry point was added during the hackathon.

public repository

Barnard

BLE sensing library and SDK.

public repository

Rule comparison

Same evidence, three rules. Only the full rule excludes both.

The same signed inputs, evaluated with the human check switched off, with the encounter rule switched off, and with both. Recorded synthetic data. Not live, not posted.

Eligible event keys / event keys in the case. N = 2, B = 2.
CaseNo human checkNo encounter ruleFull rule
Honest attendees3 / 33 / 33 / 3
Mallory: one human, three phones3 / 31 / 30 / 3
Walk-in: credential, no encounters0 / 11 / 10 / 1

Counts are eligible event keys, not issued on-chain records. Synthetic signatures test the rule and replay mechanics; they do not establish live World ID verification, physical presence or chain anchoring. Full report and one-command reproduction.

Evidence replay: honest participants A, B and C pass with two partners each; Mallory's three phones fail; the walk-in fails. 3 of 7 keys pass.
The evaluator's graph export for the same recorded synthetic data, replayed window by window. Open the interactive replay

Source

Read the code.

Trust assumptions

Alcor is a trusted attester: the service verifies World ID off-chain, and Mizar checks Alcor's signed credential rather than rerunning World's verification. Signed observations do not prove physical location.

Relayed or colluding devices can still manufacture encounters; the human check limits each person to one key but does not stop collusion.

What the result does and does not establish