EVIDIQ Notary MCP

<p align="center"> <img src="https://raw.githubusercontent.com/evidiq/evidiq/main/assets/evidiq.png" width="88" alt="EVIDIQ" /> </p>

<h1 align="center">EVIDIQ Notary MCP</h1>

<p align="center"><strong>Cryptographic receipts for AI outputs.</strong></p>

<p align="center"> Sign · Anchor · Verify — every inference provably existed, exactly as recorded. </p>

<p align="center"> <a href="https://evidiq.dev">evidiq.dev</a> · <a href="https://github.com/evidiq/evidiq">EVIDIQ Main</a> · <a href="https://github.com/evidiq/evidiq-notary-mcp">Notary MCP</a> </p>

<p align="center"> <a href="https://mcp.evidiq.dev/notary/mcp"><img src="https://img.shields.io/badge/MCP%20Server-Live-6E56CF?style=flat-square" alt="MCP Server" /></a> <a href="https://0g.ai"><img src="https://img.shields.io/badge/0G-Storage-00C2A8?style=flat-square" alt="0G Storage" /></a> <a href="https://www.oklink.com/xlayer"><img src="https://img.shields.io/badge/X%20Layer-Settlement-3CCF4E?style=flat-square" alt="X Layer" /></a> <a href="https://mcp.evidiq.dev/notary/x402"><img src="https://img.shields.io/badge/x402-pay--per--call-2563EB?style=flat-square" alt="x402" /></a> <a href="https://okx.ai"><img src="https://img.shields.io/badge/OKX.AI-A2MCP-121212?style=flat-square&logo=okx&logoColor=white" alt="OKX.AI" /></a> <a href="./LICENSE"><img src="https://img.shields.io/badge/License-MIT-3DA639?style=flat-square" alt="License: MIT" /></a> </p>

---

AI agents generate outputs at scale, but nothing proves what a model said, when, or whether it was altered afterward. EVIDIQ Notary is the cryptographic receipt layer for AI inferences — delivered as a remote MCP server, billed per call over x402. Submit a prompt + response + model id; receive a signed, timestamped, 0G-anchored receipt that anyone can verify offline.

What it does

Every notarization returns a receipt that proves four things at once:

• Existence — this exact prompt/response existed at this timestamp.
• Integrity — change one character and the hash changes; verification fails.
• Provenance — the model id, notary address, and optional trust report are bound into the signature.
• Independence — verify a receipt offline with the notary's EVM address; batch Merkle roots are anchored on 0G Storage.

Use it from any agent

# Read the live pricing discovery
curl -s https://mcp.evidiq.dev/notary/x402

# Or connect the remote MCP server (Claude Code)
claude mcp add --transport http evidiq-notary https://mcp.evidiq.dev/notary/mcp

verify_attestation, get_receipt, notary_stats, and notary_pubkey are free. notarize_inference and notarize_batch are pay-per-call over x402: unauthenticated requests receive an HTTP 402 challenge; sign it and retry.

MCP Tools

Tool	Cost	Description
notarize_inference	$0.001 USDT0	Single AI output notarization — signed receipt + 0G anchor
notarize_batch	$0.005 USDT0	Up to 20 inferences in one call (audit trails)
verify_attestation	Free	Verify receipt: EIP-191 signature + content hash + Merkle proof
get_receipt	Free	Fetch proof material for an attestation
notary_stats	Free	Live volume, top models, notary address
notary_pubkey	Free	Notary EVM address + algorithm (offline verify)

How it settles

EVIDIQ Notary owns signing, anchoring, and verification, and settles on open infrastructure:

• 0G Storage — every receipt is anchored on 0G mainnet (Aristotle, chain 16661) via the @0gfoundation/0g-ts-sdk. Tamper-evident, durable, and fetchable by anyone.
• x402 v2 — per-call settlement (EIP-3009 exact / transferWithAuthorization), gasless for the payer, settled on-chain by the notary's X402_SETTLE_KEY.
• X Layer / USDT0 — the OKX A2MCP settlement token (0x779ded…, 6 decimals). Per-tool pricing: $0.001 = 1000 atomic (single), $0.005 = 5000 atomic (batch).
• EIP-191 — receipts are signed with the notary's EVM key (OG_PRIVATE_KEY). The same signature any verifier can recover offline.

Proven on-chain

Every notarization is verifiable end-to-end — the payment settles on X Layer and the receipt is anchored on 0G Storage. Both from live calls, not mockups.

1 · Payment — x402 settlement on X Layer

Amount	0.001 USDT0 on X Layer (eip155:196) — per-tool pricing (batch: 0.005)
Flow	HTTP 402 → EIP-3009 signature → transferWithAuthorization (gasless for the payer)
Tx	0x53f72073…0070f2 · SUCCESS

2 · Receipt — 0G Storage anchor

Signer	0x8a3c7524…3ee7D (EIP-191, the EVIDIQ attester key)
Anchor	receipt JSON uploaded to 0G Storage mainnet via @0gfoundation/0g-ts-sdk
Anchor tx	0xa43c8186…1a5e1 · SUCCESS

3 · Verification — EIP-191 + Merkle proof

verify_attestation	recompute keccak256(prompt ‖ response) → recover EIP-191 signer → brute-force Merkle proof against merkleRoot
Live result	valid: true, contentMatch: true, signatureValid: true, merkleValid: true

# Reproduce a paid notarization end-to-end (free tools need no payment)
curl -s https://mcp.evidiq.dev/notary/x402 | python3 -m json.tool

Payment on one chain, tamper-evident proof on 0G — the whole receipt is auditable end to end.

Pricing

Per-tool pricing — notarize_inference and notarize_batch are paid (x402); receipts are anchor + signed; everything else is free.

Operation	Cost	Token	Chain	Atomic
notarize_inference (single)	$0.001	USDT0	X Layer (eip155:196)	1000
notarize_batch (≤20 items)	$0.005	USDT0	X Layer (eip155:196)	5000
verify_attestation	Free	—	—	—
get_receipt	Free	—	—	—
notary_stats	Free	—	—	—
notary_pubkey	Free	—	—	—

Payment: x402 v2 protocol (EIP-3009 transferWithAuthorization on X Layer). No API keys, no accounts — the challenge quotes the right price per tool; sign it and retry.

Live discovery: GET https://mcp.evidiq.dev/notary/x402 returns the full per-tool pricing table.

Architecture

┌─────────────────┐     ┌──────────────────┐     ┌─────────────┐
│   AI Agent      │────▶│  EVIDIQ Notary   │────▶│  0G Storage │
│ (MCP Client)    │     │   MCP Server     │     │  (anchoring)│
└─────────────────┘     └──────────────────┘     └─────────────┘
                               │
                               ▼
                      ┌──────────────────┐     ┌──────────────┐
                      │  x402 v2 gate    │────▶│  X Layer     │
                      │  (EIP-3009)      │     │  USDT0 settle│
                      └──────────────────┘     └──────────────┘
                               │
                               ▼
                      ┌──────────────────┐
                      │  EIP-191 sign    │
                      │  + Merkle tree   │
                      └──────────────────┘

Self-host

# Build & run (Docker)
docker build -t evidiq-notary .
docker run -d -p 3000:3000 --env-file .env evidiq-notary

# Or from source
npm install && npm run build
PORT=3000 node dist/start-server.js

Endpoint: POST /mcp · Discovery: GET /x402 · Health: GET /

Configuration

# Notary signing key (EVM, EIP-191) — reuses the EVIDIQ 0G attester key
NOTARY_PRIVATE_KEY=0x...
OG_PRIVATE_KEY=0x...

# x402 payment config (X Layer mainnet, USDT0)
X402_CHAIN=x-layer
X402_ASSET=0x779ded0c9e1022225f8e0630b35a9b54be713736
X402_PAY_TO=0x2a8efe3093278bb4bd3b2d9c7b5ba992ca4fc9b0
X402_PRICE=1000                   # $0.001 USDT0 per single notarization (6 decimals)
X402_BATCH_PRICE=5000             # $0.005 USDT0 per batch (≤20 items)
X402_DOMAIN_NAME=USD₮0
X402_DOMAIN_VERSION=1
X402_SETTLE_KEY=0x...             # Gas-funded X Layer wallet
X402_RPC=https://rpc.xlayer.tech

# 0G Storage (mainnet Aristotle, chain 16661)
OG_STORAGE_RPC=https://evmrpc.0g.ai
OG_STORAGE_INDEXER=https://indexer-storage-turbo.0g.ai

Receipt structure

{
  "attestationId": "0xfbd95c81…eeb1",
  "contentHash": "0xfbd95c81…eeb1",
  "promptHash": "0x…",
  "responseHash": "0x…",
  "signature": "0x2f012d7f… (EIP-191)",
  "notaryAddress": "0x8a3c7524Aaed081825aC88eC7f4cCECFc583ee7D",
  "timestamp": "2026-07-17T00:41:15.303Z",
  "modelId": "glm-5.2",
  "merkleRoot": "0xfbd95c81…eeb1",
  "merkleProof": ["0x…"],
  "storageRoot": "0xae8526f7…e894",
  "storageTx": "0xa43c8186…1a5e1"
}

Verification (offline)

Anyone can verify a receipt without contacting the notary:

1. Fetch the notary address: notary_pubkey tool (0x8a3c7524…3ee7D).
2. Recompute contentHash = keccak256(prompt ‖ response).
3. Recover the EIP-191 signer from signature over attestationMessage(reportHash, merkleRoot) — must equal notaryAddress.
4. Verify the Merkle proof against merkleRoot (anchored on 0G).

Development

npm install      # install deps
npm run build    # tsc → dist/
npm run dev      # tsx watch server.ts
npm test         # vitest

Links

• Live endpoint — https://mcp.evidiq.dev/notary/mcp
• Pricing discovery — https://mcp.evidiq.dev/notary/x402
• EVIDIQ main — https://github.com/evidiq/evidiq
• EVIDIQ skill — https://github.com/evidiq/evidiq-skill
• 0G Labs — https://0g.ai
• x402 Protocol — https://x402.org
• OKX.AI — https://okx.ai

License

MIT © 2026 EVIDIQ — see LICENSE. Part of the EVIDIQ trust layer for the AI agent economy.