Zelf Proofs vs Others
In the last decade, many ZK-proof solutions have been born with applications in the blockchain industry. Some developers may ask, what's the difference between Zelf Proof and the conventional open-source ZK solutions? Here we present a breakdown for each technology, pointing out their differences, applications, and limits.
Breakdown
Zelf Proof (ZK- Face Proofs™)
Definition Non-interactive, Highly scalable, small proof size, trusted setup through licensing mechanism.
ZelfProof (ZK- Face Proofs™) technology does not rely on conventional zero-knowledge proofs (ZKPs). Yet, it achieves the same objective: verifying the authenticity of a face without revealing any biometric information. By generating a unique ZelfQR, ZelfProof enables a verifier to confirm the face’s authenticity, upon presentation of the correct face. However, much like in ZKP systems, the verifier gains no additional information beyond the validity of the proof - the ZelfQR does not disclose the individual's nor can it be linked. This ensures privacy-preserving and secure identity verification without the need to expose or store biometric data.
Trusted Setup
Trusted setup through a licensing mechanism
Interactivity
Non-interactive, can be verified offline
Proof Size
~ 2- 3kb and 60 kb in QR format
Verification Time
Fast, runs on mobile as well
Scalability
Highly scalable as it can run on the mobile directly without any server computation
Security Assumptions
ZelfQRs are based on Elliptic Curve cryptography. Face Certificates will soon be quantum-safe.
Post-Quantum Security
Face Certificates PQC version are quantum-safe.
Complexity
Simple SDK
Transparency
Trusted setup through a licensing mechanism (not fully transparent).
Use Cases
Verification of functional eID attributes (eKYC) Proof of presence and unique humanness Face-based transaction authentication Face-based signup Face-based login Face-based document/file/disk encryption Face-based document/file signing National IDs/eID with Offline/Online Verification Wallet Security
Suitability for Blockchain
ZelfQR can be integrated into an identity blockchain, such as HyperLedger Indy, via the ZelfEncrypt Distributed Ledger Technology (DLT) protocol. This allows for secure, privacy-preserving identity verification on the blockchain without exposing or storing sensitive biometric data.
zk Proof
A general class of zero-knowledge proofs where one party proves the validity of a statement without revealing information.
Trusted Setup
It depends on the specific protocol, typically interactive.
Interactivity
Often interactive (multiple rounds of communication between prover and verifier).
Proof Size
It can be large depending on the complexity of the proof.
Verification Time
It can be slow and depends on the size of the proof and computation.
Scalability
Limited, especially for large computations.
Security Assumptions
Varies, are often based on standard cryptographic assumptions.
Post-Quantum Security
Depends on the cryptographic primitives used (most are not quantum-safe).
Complexity
Generally simple, but requires multiple rounds of interaction.
Transparency
Varies based on the protocol.
Use Cases
Privacy-preserving authentication, data sharing, etc.
Suitability for Blockchain
Limited; typically not used directly in blockchains due to larger proof sizes and interactivity.
zk SNARK
Succinct, non-interactive zero-knowledge proofs with small proof sizes and fast verification.
Trusted Setup
Yes (requires trusted setup).
Interactivity
Non-interactive (once the proof is generated, no further interaction is needed).
Proof Size
Small (a few hundred bytes).
Verification Time
Very fast verification.
Scalability
Less scalable for very large computations.
Security Assumptions
Based on elliptic curve cryptography (ECDLP), not quantum-safe.
Post-Quantum Security
No (vulnerable to quantum attacks due to reliance on elliptic curve cryptography).
Complexity
More complex due to elliptic curve math and trusted setup.
Transparency
Requires trusted setup (not fully transparent).
Use Cases
Privacy-focused systems like Zcash, and identity proofs.
Suitability for Blockchain
Widely used for privacy in blockchain applications (e.g., Zcash).
zk STARK
Scalable, transparent zero-knowledge proofs designed for large computations, with no trusted setup.
Trusted Setup
No (transparent, no trusted setup).
Interactivity
Non-interactive (like ZK-SNARKs).
Proof Size
Large (kilobytes to megabytes).
Verification Time
Fast verification, but slightly slower than SNARKs for small proofs.
Scalability
Highly scalable, handles large computations efficiently.
Security Assumptions
Based on hash functions (quantum-safe).
Post-Quantum Security
Yes (resistant to quantum attacks).
Complexity
Simpler than SNARKs, no setup needed, uses basic hash functions.
Transparency
Fully transparent (no trusted setup required).
Use Cases
Blockchain scaling, large-scale computations (e.g., StarkWare).
Suitability for Blockchain
Best suited for blockchain scaling and high throughput DApps (e.g., layer-2 solutions).
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