RCPT Protocol is an open cryptographic standard for verifiable agent action receipts — signed, timestamped, tamper-evident records that any agent can generate and any system can verify. Built on W3C DIDs, Ed25519 signatures, and JSON Canonicalization Scheme (JCS, RFC 8785).
When a human sends an email, signs a contract, or executes a trade, there is an implicit accountability chain. Identity is established. The action is logged. Consequences follow. When an AI agent does the same things, there is nothing — no verifiable identity, no tamper-evident log, no standard by which one system can prove to another what happened.
No existing standard addresses all three cohesively. RCPT Protocol is designed to close this gap.
The atomic unit of the protocol — a cryptographically signed, tamper-evident record of a single agent action. Signed with Ed25519 (RFC 8032) over JCS-canonicalized bytes (RFC 8785). No pre-hashing. Inputs and outputs are stored as SHA-256 hashes only — RCPT is audit infrastructure, not surveillance infrastructure.
Identity is expressed via W3C DIDs: did:key for agents (public key is the identifier), did:web for enterprise environments with organizational anchoring. Receipt IDs are ULIDs — lexicographically sortable and globally unique. Full schema in the specification.
RCPT separates proof of existence from receipt content. Full receipts are stored off-chain. Merkle roots covering batches of receipts are periodically anchored to a blockchain, providing trustless timestamp proof at minimal cost. The reference implementation anchors to Solana (~$0.26 per batch of up to 10,000 receipts).
RCPT complements existing identity, authorization, and transparency frameworks. It occupies the gap between IETF AIMS Layer 6 (Authorization) and Layer 7 (Monitoring) — providing cryptographic proof that an authorized action was actually performed.
Detailed comparison in the whitepaper §7.
A Cryptographic Trust Standard for the Agentic Internet
This document specifies the RCPT Protocol data model, cryptographic requirements, receipt chaining semantics, agent identity model, storage architecture, delegation framework, and implementation guidance for developers and enterprises.
RCPT Protocol v0.x is governed by RCPT Labs. Upon v1.0 stability, stewardship will transfer to an appropriate open standards body. The protocol uses semantic versioning: minor increments are backwards compatible (new optional fields); major increments may introduce breaking changes with a minimum six-month migration window. Proposed changes follow an RFC process with 30-day public comment periods via GitHub.