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Use Cases & Examples

TACEO:OPRF solves critical privacy problems in Web3 and digital identity. Here are the key use cases where threshold OPRFs provide essential security guarantees.

Nullifiers for Digital Identity​

The Problem ZK identity systems rely on a single secret key. If it leaks, your entire history is exposed. Here's how threshold OPRFs solve this.

Current Vulnerability​

Traditional ZK identity systems like face a fundamental weakness:

Traditional: nullifier = OPRF(user_secret, action_id)

If your secret leaks:

  • Attacker can compute ALL your past nullifiers
  • Attacker can trace your complete transaction history
  • Your entire identity becomes linkable
  • No way to revoke or rotate compromised identity

TACEO:OPRF Solution​

Enhanced: nullifier = OPRF(user_secret, action_id, [k])

With threshold OPRF:

  • Attacker needs BOTH your secret AND break MPC threshold
  • Past nullifiers remain private even if secret leaks
  • Identity history cannot be reconstructed from single compromise
  • Multiple independent parties must be compromised

Private Revenue Sharing for DeFi​

The Problem DeFi protocols need to pay referral fees and track user activity, but current methods surveillance all transactions and wallets, destroying financial privacy.

Current Surveillance Model​

  • Referral tracking requires linking wallets to referrers
  • Fee distribution exposes user trading patterns
  • On-chain analysis reveals complete transaction history

TACEO:OPRF Solution​

Private Referral Tracking

referral_id = OPRF(user_wallet + referrer_code, protocol_id, [k])

Privacy-Preserving Fee Distribution

  1. User generates private referral identifier via OPRF
  2. Protocol pays fees to identifier without knowing wallet
  3. Referrer can claim fees using OPRF output
  4. No link between user wallet and referrer exposed

Benefits​

For Users:

  • Private trading without referral surveillance
  • Protection from MEV and front-running
  • Cannot be profiled by trading patterns
  • Referral participation without privacy loss

For Protocols:

  • Maintain referral incentive programs
  • Distribute fees fairly and transparently
  • Attract privacy-conscious users
  • Comply with emerging privacy regulations

For Referrers:

  • Earn referral fees without user surveillance
  • Build privacy-respecting referral networks
  • Cannot be gamed by fake referrals
  • Preserve user trust and loyalty

Implementation Example​

# User generates private referral ID
taceo-oprf-testnet-client \
    --input "0x742d35Cc6639C85a6d3C28f06b6DB03f2134d7F6:REFERRER123" \
    --authorization defi-protocol

Private Wallet Recovery​

The Problem Seed phrases are a UX disaster. Custodial backup defeats the point. TACEO:OPRF enables wallet recovery where no one, not even the recovery service, ever sees your keys.

Current Recovery Solutions Fall Short​

Seed Phrases

  • Difficult to remember and store securely
  • Single point of failure
  • No recovery if lost or destroyed
  • Vulnerable to theft and duplication

Custodial Solutions

  • Defeats self-custody purpose
  • Provider can access your funds
  • Single point of failure and censorship
  • Regulatory and trust risks

Social Recovery

  • Friends/family become attack targets
  • Social engineering vulnerabilities
  • Privacy loss (guardians know your identity)
  • Coordination challenges for recovery

TACEO:OPRF Private Recovery​

How It Works

  1. Setup: Derive recovery key using OPRF with personal information
  2. Storage: Recovery key posted publicly (encrypted/blinded)
  3. Recovery: Prove identity to OPRF network via multiple factors
  4. Restoration: Regenerate wallet keys without anyone else seeing them
Original Setup:
wallet_seed = OPRF(biometric + email + phone + additional_factors)

Recovery Process:  
1. Prove identity factors to OPRF network
2. OPRF nodes verify proofs independently  
3. User reconstructs wallet_seed from OPRF output
4. Restore wallet without revealing seed to anyone

Key Properties​

True Privacy

  • Recovery service never sees your wallet keys
  • Personal data never fully reconstructed by any single party
  • MPC threshold provides security guarantees

Better UX

  • No seed phrases to manage
  • Recover using familiar identity factors
  • Works across devices and platforms
  • Gradual recovery factor updates possible

Practical Security

  • Multiple independent verification sources
  • Resistant to social engineering
  • No single point of compromise
  • Auditability without privacy loss

Authorization Module Design​

Multi-Factor Identity Proof

  • Biometric verification (FaceID, fingerprint)
  • Email + phone number verification
  • Knowledge-based questions
  • Time-delayed verification for security

Implementation Example

# Recovery initialization
taceo-oprf-testnet-client \
    --authorization wallet-recovery \
    --biometric-proof face_hash.proof \
    --email-verification email.proof \
    --phone-verification sms.proof

Getting Started​

Choose Your Use Case​

Identity Systems: Enhance existing ZK identity with nullifier protection

DeFi Protocols: Implement private referral tracking

Wallet Recovery: Build privacy-preserving recovery systems

  • Check Local Setup for development
  • Contact us for production deployment planning

Ready to Build?​

Each use case requires different authorization modules and integration approaches. Start with our Quickstart Guide to experiment, then move to local development for custom implementation.

Need help choosing? Contact us to discuss your specific requirements.