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mukul975
59 lines
2.5 KiB
Markdown
59 lines
2.5 KiB
Markdown
---
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name: implementing-zero-knowledge-proof-for-authentication
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description: Zero-Knowledge Proofs (ZKPs) allow a prover to demonstrate knowledge of a secret (such as a password or private key) without revealing the secret itself. This skill implements the Schnorr identificati
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domain: cybersecurity
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subdomain: cryptography
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tags: [cryptography, zero-knowledge-proof, authentication, privacy, zkp]
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version: "1.0"
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author: mahipal
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license: MIT
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---
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# Implementing Zero-Knowledge Proof for Authentication
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## Overview
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Zero-Knowledge Proofs (ZKPs) allow a prover to demonstrate knowledge of a secret (such as a password or private key) without revealing the secret itself. This skill implements the Schnorr identification protocol and a simplified ZKPP (Zero-Knowledge Password Proof) using the discrete logarithm problem, enabling authentication where the server never learns the user's password.
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## Objectives
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- Implement Schnorr's identification protocol for ZKP authentication
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- Build a non-interactive ZKP using Fiat-Shamir heuristic
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- Implement zero-knowledge password proof (ZKPP)
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- Demonstrate completeness, soundness, and zero-knowledge properties
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- Compare ZKP authentication with traditional password verification
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## Key Concepts
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### ZKP Properties
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| Property | Description |
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|----------|------------|
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| Completeness | Honest prover always convinces honest verifier |
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| Soundness | Dishonest prover cannot convince verifier (except negligible probability) |
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| Zero-Knowledge | Verifier learns nothing beyond the statement's truth |
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### Schnorr Protocol
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1. **Setup**: Public generator g, prime p, q (order of g)
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2. **Registration**: Prover computes y = g^x mod p (public key from secret x)
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3. **Commitment**: Prover sends t = g^r mod p (random r)
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4. **Challenge**: Verifier sends random c
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5. **Response**: Prover sends s = r + c*x mod q
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6. **Verify**: Check g^s == t * y^c mod p
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## Security Considerations
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- Use cryptographically secure random number generators
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- Challenge must be unpredictable (from verifier's perspective)
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- For non-interactive proofs, use Fiat-Shamir with collision-resistant hash
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- ZKP alone does not provide forward secrecy; combine with TLS
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## Validation Criteria
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- [ ] Honest prover always verifies successfully (completeness)
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- [ ] Random response without secret does not verify (soundness)
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- [ ] Server never receives the secret value
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- [ ] Non-interactive proof is verifiable offline
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- [ ] Multiple authentications produce different transcripts
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- [ ] Protocol resists replay attacks
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