zkLogin

You can find the slides in this link.

• Introduction: Web3’s Onboarding Problem
  • Web3 adoption is limited due to complex onboarding processes, such as managing mnemonics and private keys.
  • There are around 100 million active crypto wallets compared to billions of Web2 accounts.
  • The key to mass adoption is simplifying accessibility, making Web3 onboarding as easy as signing in with Google or Facebook.
• zkLogin: The Solution
  • Combines OAuth with Zero-Knowledge Proofs (ZKPs) for:
    • Non-custodial access.
    • User-friendly authentication.
    • Privacy-preserving identity management.
  • Uses OpenID Connect (OAuth 2.0 extension) and JWT (JSON Web Tokens) as alternatives to private keys.
• Technical Details
  • JWT Structure:
    • aud: Wallet ID
    • sub: User ID
    • Includes a nonce with an ephemeral public key and expiration.
  • Circuit implemented in Circom with ~1M R1CS constraints.
  • Key Operations:
    • SHA-2 (66%)
    • RSA signature verification (14%)
    • JSON parsing, Poseidon hashing, Base64 decoding (20%)
  • Prover based on RapidSNARK for efficient proof generation.
• Challenges and Solutions
  • Challenge 1: Authorizing transactions with JWTs.
    • Solution: Inject a fresh public key into the JWT for transaction-specific authorization.
  • Challenge 2: Identifying users without linking identities.
    • Solution: Add a persistent randomizer (salt) to ensure unlinkability across sessions.
  • Challenge 3: Hiding the JWT from third parties.
    • Solution: Use SNARKs to prove JWT validity without revealing its contents.
  • Challenge 4: Achieving proof generation and round-trip time (RTT) under 3 seconds.
    • Solution: Optimize the circuit and delegate proving to a ZKP service for faster processing.
• Benefits of zkLogin
  • Embedded wallets for seamless integration into mobile apps and websites without pop-ups.
  • Supports 2FA using multiple OAuth providers (e.g., Google, Facebook, Apple).
  • ID-based wallets that can be linked to email or phone numbers, offering partial or full identity disclosure.
  • Efficient and cost-effective, with gas costs comparable to standard signature verification.
• Conclusion: zkLogin provides a scalable, privacy-preserving, and user-friendly solution for onboarding the next billion users to Web3.