Agent Identity

A Ledger makes an agent real.

A minimal, serious demonstration of one idea: an AI agent's identity must be anchored in hardware. Software credentials can be copied, so an agent that can only present software has no identity it can actually prove. Only a hardware signature, anchored in the Secure Element and confirmed by a human on the device's trusted display, gives an agent a real, unforgeable identity.

One central line-art fingerprint is the whole demo. It starts hollow (a software credential proves nothing) and becomes full and green only when the agent proves its identity by signing a short message on a Ledger device, with a human approving and the signature verified to recover to the device address.

Agents propose, humans sign, hardware enforces.

This illustrates the Agent Identity pillar of Ledger's 2026 AI roadmap, built on the Ledger Agent Stack.

What it shows

• Use software credential — the fingerprint stays a faint outline, with a duplicate peeling away. A copyable token is not an identity; anyone could present the same one. (An illustrative animation, not a live operation.)
• Prove with Ledger — the agent signs I am agent-7f3a. Identity challenge: 0x…. (EIP-191 personal_sign) on the Ledger Ethereum app. The message text is shown on the device (clear signing), the human approves, and the signature is verified to recover to the device address. The fingerprint fills green. This is the "a Ledger makes an agent real" moment.

Built on the Ledger Agent Stack

This project uses the foundational layer of the Ledger Agent Stack and follows its standards. Concretely:

Agent Stack component	How this project uses it
Device Management Kit (@ledgerhq/device-management-kit)	All device interaction: session, device-state gate, app management, the signing device action.
Ethereum Signer Kit (@ledgerhq/device-signer-kit-ethereum)	SignerEthBuilder(...).signMessage(path, message) for EIP-191 personal-message signing.
Speculos transport (@ledgerhq/device-transport-kit-speculos)	Reaches the emulated Ledger over HTTP in LIVE mode.
DMK Skills (ledgerhq/agent-skills)	Installed into .agents/skills/; the server bridge implements the official DMK Signing Flow gate-by-gate.

The signing bridge in src/lib/ledger/bridge.ts follows the DMK Skills "DMK Signing Flow" step by step:

1. SDK init — one DMK instance per process.
2. Device session — discover and connect (the listenToAvailableDevices pattern prescribed for Node contexts).
3. Device-state gate — check getDeviceSessionState; a locked or disconnected device is escalated, never worked around.
4. App management — ensure the Ethereum app is the open app.
5. Operation — signMessage, surfacing the required user interaction and enforcing a 60-second human-confirmation timeout.

Standards we follow from the Agent Stack docs:

• The device screen is the only trusted display. The signature cannot be produced without the human physically approving the message on the device.
• Clear signing, not blind signing. The identity message is plain human-readable text, so the Ethereum app displays exactly what is signed. Blind signing is not required.
• The agent never holds keys. It only proposes the message; the key lives in the Secure Element.
• User rejection is a distinct outcome, not an error; errors are classified per the DMK Skills table.
• No stub, no mock, no fabrication. If no device is reachable the app shows DEMO mode and refuses to fake a signature, screen, or verification.

What this project does not use, and why

The Agent Stack also includes the Ledger Wallet CLI and the Enterprise Multisig CLI. Those are USB tools for moving value and for enterprise quorum flows. This demo is about identity (signing a challenge), so they are out of scope here; bolting them on would be artificial.

Modes

• DEMO — no emulator. The page and software animation work; the Ledger button is disabled. Nothing is ever fabricated. This is how it runs on Render.
• LIVE — a Speculos emulator is reachable; a real signing round-trip happens and the fingerprint fills green only on real success.

See docs/RUN.md for exact DEMO and LIVE steps.

Honest limitations and the path to real hardware

This is a faithful emulator / testnet demonstration. It is not wired for a real Ledger as-is:

• The only transport configured is Speculos. Signing on a real device needs a real transport — @ledgerhq/device-transport-kit-web-hid (browser) or a Node-HID transport.
• Signing here runs server-side against the emulator. A real Ledger is plugged into the user's machine, so a production build must sign client-side (e.g. browser WebHID next to the device), not on the server.
• Genuine Check (device authenticity attestation) is the Agent Stack's real-hardware authenticity gate. It requires a live connection to Ledger's backend and a genuine device, so it is not exercised against Speculos.

Stack

Next.js + TypeScript. Server-side-only signing via the Ledger Device Management Kit and Ethereum Signer Kit (with a direct-APDU fallback to Speculos for robustness), and ethers for signature verification.

References

• Ledger Agent Stack overview — https://developers.ledger.com/docs/ai-tools/overview
• DMK Skills — https://developers.ledger.com/docs/ai-tools/ledger-dmk-skills
• Agent skills repo — https://github.com/LedgerHQ/agent-skills
• Ethereum Signer Kit — https://developers.ledger.com/docs/device-interaction/references/signers/eth
• Speculos — https://github.com/LedgerHQ/speculos

Disclaimer

Independent demonstration. Not an official Ledger product and not affiliated with or endorsed by Ledger. Emulator and testnet only. The software-credential state is an illustrative animation of a known limitation, not a live cryptographic operation.