---
id: task-029
title: zkGPS Protocol Design
status: To Do
assignee: []
created_date: '2025-12-04 21:12'
labels:
  - feature
  - privacy
  - cryptography
  - research
dependencies: []
priority: medium
---

## Description

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Design and implement a zero-knowledge proof system for privacy-preserving location sharing. Enables users to prove location claims without revealing exact coordinates.

Key capabilities:
- Proximity proofs: Prove "I am within X distance of Y" without revealing exact location
- Region membership: Prove "I am in Central Park" without revealing which part
- Temporal proofs: Prove "I was in region R between T1 and T2"
- Group rendezvous: N people prove they are all nearby without revealing locations to each other

Technical approaches to evaluate:
- ZK-SNARKs (Groth16, PLONK) for succinct proofs
- Bulletproofs for range proofs on coordinates
- Geohash commitments for variable precision
- Homomorphic encryption for distance calculations
- Ring signatures for group privacy

Integration with canvas:
- Share location with configurable precision per trust circle
- Verify location claims from network participants
- Display verified presence without exact coordinates
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## Acceptance Criteria
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- [ ] #1 Protocol specification document complete
- [ ] #2 Proof-of-concept proximity proof working
- [ ] #3 Geohash commitment scheme implemented
- [ ] #4 Trust circle precision configuration UI
- [ ] #5 Integration with canvas presence system
- [ ] #6 Performance benchmarks acceptable for real-time use
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