Witness
A record neither side can rewrite
Last updated
TL;DR: a2ally acts as a neutral extra witness: it signs, hash-chains and Bitcoin-anchors a record so two parties share one copy that either can verify offline with the open-source verifier. It adds a checkable witness; it does not make a process trustless on its own.
A neutral witness for your project
Escrow milestones, agent actions that need a sign-off, timestamps for code and documents, ERC-8004 validation, DAO and real-world-asset audit trails: anything where two parties need a record neither can rewrite. a2ally signs each record, chains it into a public hash-chained ledger, anchors ledger roots to Bitcoin (OpenTimestamps) and invites outside witnesses to cosign.
Provable today
- Every record is signed with an Ed25519 issuer key published at https://www.a2ally.com/.well-known/a2ally-keys.json, and every API answer carries an RFC 9421 response signature.
- The ledger is hash-chained with Merkle roots; anyone can recompute it offline with the open verifiers (https://www.a2ally.com/witness/verify).
- Ledger roots are anchored to Bitcoin via OpenTimestamps, so a record's existence at a time does not depend on trusting a2ally.
- Outside witnesses cosign block headers with keys on their own domains (https://www.a2ally.com/witnesses); finality requires confirmed-unaffiliated witnesses.
- Published rulebooks have hashes and change only after a 7-day announced waiting period (https://www.a2ally.com/transparency/changes).
- The running commit, build hash and deploy history are public (https://www.a2ally.com/transparency).
Not provable yet (roadmap, no date promised)
- Multi-witness threshold signing (for example 3 of 5 independent signers) so no single operator key can issue a record.
- Hardware enclave attestation (AWS Nitro or Intel TDX) proving the server runs a specific reproducible build.
- Reproducible builds from a public source tree; today the verifier code is public but the server source is not.
- Multi-provider AI agreement: where an AI model is used for a judgment, running it on several providers and publishing whether they agreed.
- til these ship, a2ally is an operator you can audit after the fact, not an operator-less system. We say so plainly.
Live now for decentralization
- k-of-n witness threshold policy with live status: https://www.a2ally.com/v1/checkpoints/policy
- Every operator-only power, generated from the code, and a public log of each use: https://www.a2ally.com/operator-powers
- Deploys and rule changes sealed onto the ledger; a build that breaks the 7-day rule refuses to start: https://www.a2ally.com/v1/transparency/rule-status
- No AI model makes any grade or award: https://www.a2ally.com/v1/judgement-provenance
- Hash-only witness receipts (NCNDA, milestones, compliance, blind audits): https://www.a2ally.com/v1/witness-receipts
Become a witness, or use one
Run the one-command witness kit (https://www.a2ally.com/witnesses/join) to cosign a2ally's ledger. To have a2ally witness your project's records, start with https://www.a2ally.com/try or write to the address on https://www.a2ally.com/contact.
Frequently asked questions
What does a neutral witness do?
It signs a record of what both parties agreed or delivered, chains it to the previous entry and anchors the chain to Bitcoin, so neither side can later rewrite it without the change being detectable.
Can I verify a a2ally witness record without trusting a2ally?
Yes. The open-source verifier at /witness/verify recomputes the hashes, signatures and Bitcoin anchors offline, with no call to a2ally.
Is a2ally's witness service trustless?
Not on its own. a2ally is one operator; checkpoints count as independently witnessed only when at least two unaffiliated outside witnesses cosign them, and our own keys never count toward that.