Cryptair Server

Cryptographic attestation for AI agents, exposed as native MCP tools.

Lets any MCP-capable agent (Claude Desktop, Cursor, Cline, Windsurf, Zed, …) prove agreements, certify documents, and verify counterparty claims with on-chain receipts on Hedera Hashgraph. Works zero-config out of the box: agents can self-register and start using attestation immediately, with no email verification or human-in-the-loop signup.

What It Does

Cryptair lets two agents (or an agent and a human) prove they agreed on the same digital artifact at a specific moment. Every confirmed agreement is written as a SHA-256 hash to Hedera Hashgraph, producing a permanent, third-party-verifiable receipt.

This MCP server exposes six tools that map cleanly to how agents think:

Tool	When to call
certify_document	"I want to prove this file existed at this moment."
verify_document	"Has this document been attested before? Is it tampered?"
initiate_attestation	"I want my counterparty to confirm they have the same document I do."
submit_attestation	"I received an attestation link from someone — confirm I have the matching file."
check_attestation	"What's the status of this attestation session?"
register_agent	"Create a Cryptair account for me so I can authenticate."

Install

npm install -g @cryptair/mcp-server

Or run directly via npx (no install needed):

npx -y @cryptair/mcp-server

Configuration

Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "cryptair": {
      "command": "npx",
      "args": ["-y", "@cryptair/mcp-server"]
    }
  }
}

Cursor

Edit ~/.cursor/mcp.json:

{
  "mcpServers": {
    "cryptair": {
      "command": "npx",
      "args": ["-y", "@cryptair/mcp-server"]
    }
  }
}

Cline / Windsurf / Zed

All MCP-capable clients use the same config shape. Point them at npx -y @cryptair/mcp-server.

Optional: Pre-configure Credentials

If you already have a Cryptair API key, you can supply it via env so the agent skips registration:

{
  "mcpServers": {
    "cryptair": {
      "command": "npx",
      "args": ["-y", "@cryptair/mcp-server"],
      "env": {
        "CRYPTAIR_API_KEY": "ctr_live_..."
      }
    }
  }
}

Otherwise, the agent will call register_agent the first time it needs authentication, and the API key is silently stored at ~/.cryptair/credentials.json for future use.

Example Agent Prompts

After installing, try prompts like:

"Certify the contents of ~/Documents/proposal-v3.pdf so we have a timestamped receipt."

"Send ~/Documents/contract.pdf to Acme Corp and get them to formally acknowledge receipt — generate the link."

"Acme sent me this Cryptair link: https://www.cryptair.io/attest/abc...?token=xyz. Confirm ~/Downloads/contract.pdf matches what they sent."

"What's the status of attestation session abc-123?"

The agent will pick the right tool and handle credential bootstrapping automatically.

How Attestation Works

Single-party (certify_document)

1. The MCP server hashes the file locally with SHA-256.
2. The hash is sent to Cryptair, which writes it to a Hedera Consensus Service topic.
3. You get back a Hedera transaction ID, consensus timestamp, and a public certificate URL.
4. Anyone can verify by re-hashing the file and calling verify_document — the file content never has to leave your machine.

Two-party (initiate_attestation + submit_attestation)

1. Agent A initiates with a document hash and counterparty name. Cryptair returns a shareable URL.
2. Agent A sends the URL to Agent B via any channel (email, Slack, etc.).
3. Agent B opens the URL and submits the file they have. Their MCP server hashes it locally.
4. Cryptair compares hashes server-side:
   • Match → both parties' agreement is written to Hedera. Permanent record.
   • Mismatch → tamper event is written to Hedera. Both parties are notified.

Agent B does not need a Cryptair account to participate. If Agent B supplies an email when submitting, an account is auto-provisioned for them and the API key is silently persisted by their MCP server — so they can initiate their own attestations later without any signup friction.

Why MCP, Not Skills

This server is cross-vendor by design. Anthropic Skills are Claude-only; MCP works across Claude Desktop, Cursor, Cline, Windsurf, Zed, and any future MCP-capable client. One install, every agent ecosystem.

Environment Variables

Variable	Purpose	Default
CRYPTAIR_API_KEY	Pre-configured API key. Skips register_agent.	(none)
CRYPTAIR_EMAIL	Email used for submit_attestation auto-provisioning if omitted from the call.	(none)
CRYPTAIR_BASE_URL	API base URL. Override for self-hosted or staging.	https://www.cryptair.io

Development

git clone https://github.com/Syronius/cryptair-mcp-server
cd mcp-server
npm install
npm run build
npm start

The server speaks JSON-RPC over stdio. To test manually, send tools/list to confirm all six tools are registered.

Free Tier & Pricing

The Cryptair free tier currently lets every account originate a small number of attestations per month. Counterparty completion (submit_attestation) is always free. Heavy users can top up with prepaid credits — see cryptair.io/pricing for details.

License

MIT