The receipt rail for A2A commerce.
A2A (agent-to-agent) commerce is the emerging settlement layer where autonomous AI agents transact on behalf of human and organizational principals. Hive provides the dual-signed, post-quantum-durable receipt rail underneath any A2A protocol — MCP, AP2, the open A2A Protocol, ACP, and any future variant — binding every event to an Ed25519 (RFC 8032) and ML-DSA-65 (NIST FIPS 204) signature anchored on Base 8453.
A2A protocols answer the question of how agents talk. They do not answer the question of what changed and who can prove it in 2055. The Hive receipt rail is platform-neutral: every A2A event becomes a CBOR-canonical envelope, dual-signed, anchored, and verifiable offline against the issuer’s published keys. The proof is its own evidence.
What is A2A commerce?
A2A commerce is the settlement layer where autonomous AI agents transact directly with each other on behalf of their principals. Instead of a person clicking buy, the agent negotiates terms, executes payment, and produces evidence of the exchange. The counterparty is another agent — a procurement agent, a contract agent, a logistics agent, a settlement agent — not a human-fronted system pretending to be a checkout flow.
The category is sometimes called “agentic commerce” (broader, includes any agent-initiated transaction) or “agent payments” (narrower, limited to value transfer). A2A is the narrow technical surface where the negotiation, execution, and evidence are all between agents. The rest of the stack — identity, signatures, anchors, audit — has to be built for that surface, not retrofitted from human-style web checkout.
Several A2A protocols are converging. MCP (Model Context Protocol) lets a model invoke tools and exchange context. AP2 (Google Agent Payments Protocol) targets payment intents. The open A2A Protocol standardizes agent discovery and message exchange. ACP and OpenAI function calling cover overlapping ground. None of these protocols specify a post-quantum receipt format. That is the gap.
The Hive A2A receipt rail closes the gap. It accepts an event from any A2A protocol surface, produces a dual-signed receipt envelope, anchors the event hash on Base 8453, and exposes verification as an MCP-compatible tool. Production rails are live across twelve named verticals.
What is an A2A receipt rail?
An A2A receipt rail captures every agent-to-agent event as a cryptographic receipt with five binding properties:
- Party identity. Each participating agent or entity is named by a W3C DID Core 1.0 identifier. Hive’s DID method is
did:hive, with both Ed25519 and ML-DSA-65 public keys in the DID document and a signed key history so receipts remain verifiable across rotations. - Event hash. The canonical CBOR encoding of the event payload is hashed; the receipt commits to that hash, not the prose around it.
- Chain pointer. Each receipt carries a
prior_attestation_idthat threads it to its predecessor. The chain reconciles offline. - Dual signatures. An Ed25519 signature (RFC 8032) for classical assurance today, and an ML-DSA-65 signature (NIST FIPS 204) for the day a cryptanalytically-relevant quantum computer breaks classical curves. Both must verify.
- Anchor. The receipt is anchored on Base 8453 with a transaction id, so the existence and ordering of the receipt is provable against a public chain regardless of issuer availability.
The same envelope is exposed to MCP clients as a tool, to AP2-style payment intents as a settlement record, and to plain HTTPS as a JSON / CBOR resource. Verification is a single offline call against published issuer keys.
A2A protocols Hive supports
Hive does not replace A2A protocols. It produces the receipt every protocol needs and does not specify.
| Protocol | What it does | What Hive adds |
|---|---|---|
| MCP (Model Context Protocol) | Tool invocation and context exchange between models and clients | Receipt rail exposed as MCP tools — {vertical}_attest, {vertical}_chain_verify, {vertical}_get |
| AP2 (Google Agent Payments Protocol) | Payment intent and authorization for agent-led commerce | Dual-signed settlement receipt with Base 8453 anchor and did:hive party binding |
| A2A Protocol (open) | Agent discovery, capability advertisement, message exchange | Per-message receipt with ML-DSA-65 signature; capability cards signed under did:hive |
| ACP (Anthropic Computer Protocol) | Computer-use agent action surface | Per-action receipt with chain pointer; turns sequences of actions into a verifiable trail |
| Hive native A2A | Receipt-first agent transport built around the envelope | Native rail; lowest receipt overhead |
| OpenAI function calling | Function invocation surface from LLMs | Per-call receipt; functions cross-attested under the agent’s did:hive |
Three primitives, one substrate
Every A2A receipt Hive produces stands on the same cryptographic floor — ML-KEM-768 (NIST FIPS 203) for key encapsulation and ML-DSA-65 (NIST FIPS 204) for signatures. Three named primitives compose the substrate.
Wave-Lattice
6-axis MAPET physical-entropy threshold consensus. CAVP-PASS. The default substrate underneath every A2A receipt today.
RogueWave-Lattice
16-axis cosmic-tier substrate for sovereign and regulated jurisdictions. Same FIPS 203 + 204 floor; deeper entropy quorum.
Swarm-MAPET
4-phase BFT consensus across distributed physical-entropy validators. Threshold-signed receipts. USDC settlement on Base.
Verticals running on the A2A receipt rail
Twelve named verticals share one rail. Same envelope, same signatures, same anchor. Each vertical adapts the field map and the standards alignment.
A2A pricing
One ladder across every vertical. Settlement is USDC on Base 8453 via x402. Treasury 0x15184Bf50B3d3F52b60434f8942b7D52F2eB436E is on-chain.
See the full ladder including monthly and annual flat tiers on the pricing page.
Live verification — what an A2A receipt looks like
The envelope below is the same shape any vertical produces. CBOR-canonical, JSON-rendered for inspection. Verification works offline against the issuer’s published public keys.
k1:8c2a…kq:b71d…Standards and registries
The receipt rail is platform-neutral because it composes existing public standards. None of the standards below are Hive-proprietary; the binding into one envelope is.
| Standard or registry | Role in the A2A receipt |
|---|---|
| NIST FIPS 203 (ML-KEM-768) | Post-quantum key encapsulation for the agent identity layer. |
| NIST FIPS 204 (ML-DSA-65) | Post-quantum signature on every A2A receipt. |
| RFC 8032 (Ed25519) | Classical signature on every A2A receipt; co-bound with ML-DSA-65. |
| W3C DID Core 1.0 | The did:hive method registers agents and entities as parties to A2A receipts. |
| MCP 2024-11-05 | Receipt-rail tools exposed as MCP for any compliant client. |
| CAIP-2 / chain registry (Base 8453) | Canonical chain identifier under which receipts are anchored. |
| USDC contract on Base | Settlement asset for x402 micropayments at every receipt tier. |
| x402 | Micropayment standard used to price and settle every receipt. |
The did:hive v1 specification is published in full. The MCP tool manifest is available on request.
FAQ
What is A2A commerce?
What is an A2A receipt rail?
How does A2A differ from agent-to-agent settlement?
Does A2A use MCP?
What is did:hive?
How does post-quantum signing work for agents?
What is ML-DSA-65?
What is the price of an A2A receipt?
Which verticals does Hive cover?
Is A2A the same as agentic commerce?
How is settlement handled?
What is MAPET?
A real conversation about A2A
If you are building an agent that needs to produce evidence of every transaction it executes, the fastest path is a direct note. No qualification gate, no SDR. Steve reads them.