ZK ID Presentation

This demonstration allows you to present an identity attribute from your digital ID in Google Wallet using a Longfellow zero-knowledge (ZK) proof. This method is the most privacy-friendly way to share your identity information online.

✦ How does this work?

Google Wallet lets you manage a digital ID on your phone. Sometimes you need to prove something about yourself---like that you're over 18---but you shouldn't have to hand over your full name, address, and birthday just to do that. Longfellow is a zero-knowledge protocol that lets you prove specific facts about your identity without revealing anything else.

🪪 Your ID
Digital credential
Your phone holds a cryptographically signed digital ID (mDOC)
→
🔐 ZK Proof
Prove, don't reveal
Longfellow generates a proof that you meet a requirement — without exposing your data
→
🛡️ Verified
Verifier is convinced
The verifier can confirm the proof is valid, but learns nothing else about you

The privacy guarantee: the verifier learns only what you choose to share (e.g., "age ≥ 18") and nothing more: not your name, not your birthday, not your address. This is possible by the mathematical properties of zero-knowledge.

Without zero-knowledge protocols, schemes like mdoc and SD-JWT have privacy flaws that inadvertently allow relying parties or issuers to track your activity.

Read the paper Documentation IETF Draft