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Tamper-evident attestation tools for AI agents — on-chain receipts on Hedera Hashgraph mainnet.
Tamper-evident attestation tools for AI agents — on-chain receipts on Hedera Hashgraph mainnet.
Cryptair MCP server is well-designed with proper authentication, secure credential handling, and clean code structure. The server appropriately uses API keys stored locally, validates all inputs with Zod schemas, and makes only expected network calls to the Cryptair API. Permissions align well with its stated purpose of cryptographic attestation. Minor observations include broad error handling and lack of request timeout configuration, but these are low-severity quality issues that do not materially impact security. Supply chain analysis found 2 known vulnerabilities in dependencies (0 critical, 2 high severity). Package verification found 1 issue.
6 files analyzed · 6 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
This plugin requests these system permissions. Most are normal for its category.
Set these up before or after installing:
Environment variable: CRYPTAIR_API_KEY
Environment variable: CRYPTAIR_EMAIL
Environment variable: CRYPTAIR_BASE_URL
Add this to your MCP configuration file:
{
"mcpServers": {
"io-github-syronius-cryptair-mcp-server": {
"env": {
"CRYPTAIR_EMAIL": "your-cryptair-email-here",
"CRYPTAIR_API_KEY": "your-cryptair-api-key-here",
"CRYPTAIR_BASE_URL": "your-cryptair-base-url-here"
},
"args": [
"-y",
"@cryptair/mcp-server"
],
"command": "npx"
}
}
}From the project's GitHub README.
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.
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." |
npm install -g @cryptair/mcp-server
Or run directly via npx (no install needed):
npx -y @cryptair/mcp-server
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"]
}
}
}
Edit ~/.cursor/mcp.json:
{
"mcpServers": {
"cryptair": {
"command": "npx",
"args": ["-y", "@cryptair/mcp-server"]
}
}
}
All MCP-capable clients use the same config shape. Point them at npx -y @cryptair/mcp-server.
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.
After installing, try prompts like:
"Certify the contents of
~/Documents/proposal-v3.pdfso we have a timestamped receipt."
"Send
~/Documents/contract.pdfto 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.pdfmatches what they sent."
"What's the status of attestation session
abc-123?"
The agent will pick the right tool and handle credential bootstrapping automatically.
Single-party (certify_document)
verify_document — the file content never has to leave your machine.Two-party (initiate_attestation + submit_attestation)
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.
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.
| 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 |
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.
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.
MIT
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