Zero-Knowledge Proof for Authentication
FreeSecurely authenticate without revealing secrets.
Free · Opens the source repo
What Zero-Knowledge Proof for Authentication does
This skill provides an implementation of Zero-Knowledge Proofs (ZKPs) specifically tailored for authentication purposes. By utilizing the Schnorr identification protocol and a simplified Zero-Knowledge Password Proof (ZKPP), it allows a prover to authenticate their identity without disclosing their secret, such as a password, to the server. This is particularly valuable in scenarios where privacy and security are paramount, as it ensures that sensitive information is never exposed during the authentication process.
The implementation is grounded in cryptographic principles, leveraging the discrete logarithm problem to establish a secure method for verification. Users can expect to implement a non-interactive ZKP using the Fiat-Shamir heuristic, which enhances the efficiency of the proof while maintaining its security properties. The skill also emphasizes the importance of security considerations, such as using cryptographically secure random number generators and ensuring that challenges are unpredictable, to fortify the authentication process against potential attacks.
This skill is ideal for developers and security architects looking to enhance their systems with robust authentication mechanisms that comply with privacy standards. It is particularly useful when designing systems that require password-less authentication or when there is a need to verify user credentials without storing sensitive information. By integrating this skill into your security architecture, you can significantly improve your system's resilience against unauthorized access and credential theft.
Overall, this skill not only facilitates the implementation of advanced authentication techniques but also serves as an educational resource for understanding the underlying cryptographic concepts and protocols. It is a practical tool for those committed to building secure applications and systems that prioritize user privacy.
When to use it
Use this skill when implementing password-less authentication or when needing to verify user credentials without revealing secrets.
When not to use it
This skill may not be suitable for applications that do not require high levels of security or where traditional password-based methods are adequate.
What you can build with it
Implementing Password-less Authentication
Use this skill to create systems that allow users to authenticate without passwords, enhancing security and user experience.
Conducting Security Assessments
Leverage this skill during security assessments to evaluate the effectiveness of authentication mechanisms without exposing sensitive data.
Building Secure Applications
Integrate this skill into application development to ensure that user credentials are verified securely, without risk of exposure.
How to install Zero-Knowledge Proof for Authentication
View source1. Install with the skills CLI
npx skills add mukul975/anthropic-cybersecurity-skills/implementing-zero-knowledge-proof-for-authentication --agent claude-code2. Or install it manually
Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.
Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs
Inside SKILL.md
Written by mukul975Implementing Zero-Knowledge Proof for Authentication
Overview
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.
When to Use
- When deploying or configuring implementing zero knowledge proof for authentication capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Prerequisites
- Familiarity with cryptography concepts and tools
- Access to a test or lab environment for safe execution
- Python 3.8+ with required dependencies installed
- Appropriate authorization for any testing activities
Objectives
- Implement Schnorr's identification protocol for ZKP authentication
- Build a non-interactive ZKP using Fiat-Shamir heuristic
- Implement zero-knowledge password proof (ZKPP)
- Demonstrate completeness, soundness, and zero-knowledge properties
- Compare ZKP authentication with traditional password verification
Key Concepts
ZKP Properties
| Property | Description |
|---|---|
| Completeness | Honest prover always convinces honest verifier |
| Soundness | Dishonest prover cannot convince verifier (except negligible probability) |
| Zero-Knowledge | Verifier learns nothing beyond the statement's truth |
Schnorr Protocol
- Setup: Public generator g, prime p, q (order of g)
- Registration: Prover computes y = g^x mod p (public key from secret x)
- Commitment: Prover sends t = g^r mod p (random r)
- Challenge: Verifier sends random c
- Response: Prover sends s = r + c*x mod q
- Verify: Check g^s == t * y^c mod p
Security Considerations
- Use cryptographically secure random number generators
- Challenge must be unpredictable (from verifier's perspective)
- For non-interactive proofs, use Fiat-Shamir with collision-resistant hash
- ZKP alone does not provide forward secrecy; combine with TLS
Validation Criteria
- Honest prover always verifies successfully (completeness)
- Random response without secret does not verify (soundness)
- Server never receives the secret value
- Non-interactive proof is verifiable offline
- Multiple authentications produce different transcripts
- Protocol resists replay attacks
Frequently asked questions about Zero-Knowledge Proof for Authentication
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