Design and Implement Circom Circuits for Vaccination Status Proof

[grantfox-oss]

Description: Implement production-ready Circom circuits that enable users to generate zero-knowledge proofs of their vaccination status without revealing any personal health information. This task focuses solely on circuit design, implementation, and testing.

Requirements:

Circuit Design:
Design a main circuit VaccinationProof.circom that proves:
User has a valid vaccination credential
Vaccination date is within a specified time window
Vaccine type matches the required type
Booster shot requirements are met (if applicable)
Implement sub-circuits for:
Merkle tree membership proof (credential exists in registry)
Date range verification
Vaccine type matching
Nullifier generation (to prevent proof replay)
Circuit Implementation:
Use Circom 2.0+ syntax
Optimize for constraint count (< 500k constraints)
Implement custom templates for common operations
Add comprehensive comments for circuit logic
Ensure circuits are deterministic and reproducible
Testing:
Write Circom test cases for all circuit components
Test with edge cases (invalid dates, wrong vaccine types, missing boosters)
Measure proving time and constraint count
Verify proof generation and verification locally
Achieve >95% test coverage
Documentation:
Document circuit architecture and signal flow
Create input/output specification
Explain security assumptions and guarantees
Provide usage examples with sample inputs
Technical Constraints:

Maximum circuit size: 500k constraints
Proving time: < 30s on consumer hardware
Proof size: < 2KB
Must use Circom 2.0+ compatible libraries
Acceptance Criteria:

Main circuit VaccinationProof.circom implemented and compiles successfully
All sub-circuits implemented and tested
Circuit constraint count < 500k
Proving time < 30s on average hardware
Test suite with >95% coverage
Documentation complete (architecture, inputs/outputs, usage)
Sample proof generation and verification working
Security review checklist completed
Priority: High Difficulty: Hard Estimated Effort: 2-3 weeks

Dependencies:

Circom compiler installed
Circomlib available for common templates
Basic understanding of zk-SNARKs
Resources:

Circom documentation: https://docs.circom.io/
Circomlib: https://github.com/iden3/circomlib
Existing zk/README.md in project

[clintjeff2]

Hello, I have 6 years of experience working on tasks like this and handling similar challenges across backend, frontend, and smart-contract development. I have carefully read and fully understood the task requirements, and I am confident I can deliver a clean, efficient, and well-tested solution promptly. I always ensure high-quality implementation, maintainability, and adherence to best practices.

Pull request in 5 hours.

[angelraph]

I'd love to contribute to this issue.

My background is in blockchain development, smart contracts, and open-source software, with a growing focus on zero-knowledge technologies and privacy-preserving systems. I've worked on projects involving cryptographic verification, decentralized applications, and secure data workflows, and I'm particularly interested in how ZK proofs can enable selective disclosure of sensitive information.

This issue is especially interesting because it combines real-world identity verification with privacy. My approach would be to carefully design the Circom circuits to prove vaccination status while minimizing unnecessary data exposure, ensuring the circuits are efficient, well-documented, and easy to integrate with the broader ValidFi architecture. I would also prioritize comprehensive testing and clear documentation to make future maintenance and audits easier.

Beyond delivering the implementation, I'm excited about contributing to a project that demonstrates practical applications of zero-knowledge proofs in healthcare and identity verification. I look forward to collaborating with the team and helping build a secure and user-friendly solution.