MCP and A2A are not solving one crucial challenge in the post-AGI world – Trust

The VACT-P protocol, a decentralized, model-independent standard for secure coordination among autonomous agents, has been released as a reference implementation (VACT-P-RFC-0001, Core 0.1) to address trust challenges in the post-AGI world. It provides cryptographic accountability, fine-grained delegation, and tamper-evident auditing using DIDs, RFC 8785, and Ed25519 signatures, with SDKs for Python and TypeScript and a three-agent demo. The protocol aims to ensure every agent action is provable and tied to a human or organizational principal, addressing the insufficiency of raw API keys or OAuth tokens for autonomous agents.

Every agent action, provable.VACT is a decentralized, model-independent protocol for secure coordination, delegation, audit, and economic exchange among autonomous agents. This repository is the reference implementation of VACT-P-RFC-0001 Core 0.1 . It implements the Phase 1 roadmap: signed envelopes, Agent Passports, Mandates, Delegations, the task state machine, receipts, revocation, and Python + TypeScript SDKs — plus a reference HTTP gateway and a runnable three-agent end-to-end demo spec §32 . As autonomous agents begin to act independently—hiring other agents, spending money, executing business processes, and reading sensitive files—they transition from tools to autonomous actors. In this environment, raw API keys or standard OAuth tokens are insufficient because they do not verify context or provenance of actions. VACT-P introduces a standard, cryptographic, fail-closed trust model that solves these key challenges: - Accountability & Non-Repudiation :- Every action can be mathematically tied back to a human or organizational Principal who authorized it. - You can verify the exact chain of authorization DIDs and signatures from the principal down through each intermediary agent. - Every action can be mathematically tied back to a human or organizational - Fine-Grained Dynamic Authorization Delegation :- Instead of sharing master API keys, agents delegate restricted authority using Delegations . - These constraints actions, resources, budget limit, time bounds are evaluated and narrowed at each hop. Any attempt to expand authority fails closed automatically. - Instead of sharing master API keys, agents delegate - Tamper-Evident Auditing :- The protocol produces a sequence of signed Receipts Policy, Execution, Evaluation, Settlement linked via a cryptographic hash-chain. - If an agent tampers with a single byte of execution data or violates a policy, the verification chain breaks. - The protocol produces a sequence of signed - Decentralized & Multi-Agent Standard :- Built entirely on open standards: DIDs Decentralized Identifiers , JSON Canonicalization Scheme RFC 8785 , and Ed25519 signatures. - No central database or broker required. Works across different model providers, hosting infrastructure, and programming languages. - Built entirely on open standards: Mandate → Delegation → Offer/Quote → Task Contract → Policy Decision → Execution Receipt → Evaluation Receipt → Settlement Receipt VACT-P is designed to be overlayed on top of your existing software, identity, and payment systems without requiring a rewrite: did:web : Bind agent identities to DNS domains you already control e.g. did:web:agent.yourcompany.com . The public key is served under /.well-known/did.json . did:key / did:ion : Integrate with other decentralized identity standards. Service Mesh / SPIFFE : Map your internal Kubernetes SPIFFE IDs to DIDs to bridge internal cluster authentication with VACT-P's agent authorization framework. API Gateways : Deploy the reference HTTP gateway or build custom middleware behind API gateways like Kong, Traefik, or AWS API Gateway. Envelope Wrapping : Intercept incoming HTTPS requests, unpack the VACT-P envelope, verify the signature, and map the headers e.g. X-VACT-P-Task-Id to downstream trace headers. LangChain / AutoGen / CrewAI : Integrate the Python or TypeScript SDK into the tools and action hooks of your agent frameworks. Before executing an external tool e.g., database write , wrap the action in a signed VACT-P task request envelope. Stripe / Payment Rails : Map the Settlement Receipt schema to payment processors. When a task evaluates to PASS , trigger Stripe/ACH charges programmatically using the captured task budget. vact-p/ ├── spec/ VACT-P-RFC-0001, JSON Schemas, signed test vectors ├── sdk-python/ vact-p-sdk Python ≥3.10 ├── sdk-typescript/ @vact-p-protocol/sdk Node ≥18, zero runtime deps ├── gateway/ Reference HTTP gateway spec §25 — stdlib only ├── examples/ Three-agent reference flow spec §32 └── Makefile cd sdk-python && pip install -e ". dev " && pytest python from vact p sdk import Keypair, sign object, verify object, make envelope controller = Keypair.generate kid="did:web:example.com key-1" env = make envelope type="vact p.task.request", mode="async", sender="did:web:client.example", recipients= "did:web:provider.example" , payload={"task": "summarize", "input": "urn:sha256:..."}, ttl seconds=300, signed = sign object env, controller JCS + Ed25519 spec §9.2 assert verify object signed, controller.public key cd sdk-typescript && npm install && npm test js import { generateKeypair, signObject, verifyObject, makeEnvelope } from "@vact-p-protocol/sdk"; const kp = generateKeypair "did:web:example.com key-1" ; const env = makeEnvelope { type: "vact p.task.request", mode: "sync", sender: "did:web:client.example", recipients: "did:web:provider.example" , payload: { hello: "world" }, ttlSeconds: 300, } ; const signed = signObject env, kp ; verifyObject signed, kp.publicKey ; // true Both SDKs produce byte-identical canonical forms — see spec/test-vectors/ , which are generated by the Python SDK and verified by the TypeScript test suite. make demo Principal → Requester → Research Agent → Evaluator → Settlement, with a fully reconstructable audit chain printed at the end. Every step is a signed VACT-P object; tampering with any byte breaks the chain. make demo-langchain Demonstrates how to wrap standard LangChain tools with cryptographic VACT-P validation. The agent reads data and publishes summaries if allowed by the delegation chain, and is blocked automatically with PERMISSION DENIED if it attempts unauthorized tool execution. make gateway serves http://localhost:8402 curl http://localhost:8402/.well-known/vact-agent.json Endpoints: /.well-known/vact-agent.json , POST /vact-p/v0.1/messages , GET /vact-p/v0.1/tasks/{id} , POST /vact-p/v0.1/tasks/{id}/cancel , GET /vact-p/v0.1/receipts/{id} , GET /vact-p/v0.1/revocations/{id} . Signing — RFC 8785 JCS canonicalization + Ed25519, top-level proof §9.2 Envelope — required fields, expiry, nonce, replay defense §9.5, §10 Authority — effective-authority intersection; delegation can never expand actions, resources, time, budget, or depth; fails closed §11 State machine — the 17 task states with transition validation §15 Receipts — execution / policy / evaluation / settlement / revocation builders §21 Revocation — objects + priority semantics; indeterminate ⇒ deny for material actions §24 0.1.0-draft — tracks VACT-P-RFC-0001 Public Design Draft. Not production audited. Contributions via VACT-P Enhancement Proposals VEPs — see CONTRIBUTING.md /mindify-ai/VACT-P/blob/main/CONTRIBUTING.md . MIT License