DIMY Contact Tracing Protocol Simulator

A course project that translates privacy-preserving protocol concepts into a runnable network simulator.

Problem / goal

The project needed to demonstrate how ephemeral identifiers, secret sharing, and Bloom filters could work together while exposing privacy assumptions to a passive attacker model.

My role

Contributed mainly to frontend protocol logic, UDP communication, Shamir reconstruction, and Bloom-filter lifecycle.

What I personally contributed

• Implemented rotating ephemeral identifiers, UDP broadcast behavior, TCP request-response flows, and Bloom-filter encounter storage.
• Coordinated threading, locks, background loops, and interactive commands for node, server, and attacker workflows.
• Modelled passive attacker observation points to make privacy assumptions easier to inspect.

Technical approach

• Implemented rotating ephemeral identifiers, Shamir Secret Sharing, Bloom filter encounter storage, UDP broadcasting, and TCP request-response communication.
• Used threading, locks, and background loops to coordinate node behavior, upload/query operations, and interactive commands.
• Modelled a passive attacker that collects protocol broadcasts for privacy testing.

Key features

• Frontend nodes that broadcast and receive temporary identifiers.
• Backend TCP server for upload and query workflows.
• Bloom-filter lifecycle for encounter data.
• Passive attacker model for protocol assumption testing.

Impact / results

• Delivered a runnable simulator that demonstrates core protocol workflows and attacker observation points.
• Made privacy and networking behavior easier to inspect through interactive commands and structured JSON messages.

What I learned

• Concurrency and protocol state must be designed together when simulations depend on timing and background behavior.
• A passive attacker model is useful for making security assumptions concrete rather than abstract.