Loopix Deep Dive
The Nym mixnet implements the Loopix anonymous communication protocol. This page covers the protocol details relevant to BlindHop.
Stratified Cascade Topology
Nym organizes mix nodes into layers forming a cascade:
The client randomly selects one node per layer, constructing a path like G1 → M2 → N1 → O3 → H2.
Poisson Mixing
At each hop, mix nodes apply a Poisson delay:
- Packets are reordered (prevents timing correlation)
- The delay distribution is memoryless (observing one delay gives no information about future delays)
- Combined with cover traffic, this makes traffic analysis infeasible
Security Properties
| Property | Guarantee |
|---|---|
| Sender anonymity | No entity knows both sender IP and message content |
| Receiver anonymity | Exit service knows content but not sender |
| Unlinkability | Cannot link input/output packets at any hop |
| Unobservability | Real traffic is indistinguishable from cover traffic |
BlindHop's Use of Loopix
BlindHop relies entirely on Nym's Loopix implementation. The nym-sdk manages:
- Cover traffic generation and rate control
- Mix node selection and route construction
- Sphinx packet creation and SURB management
- Gateway connection and message delivery
BlindHop adds the application layer on top: JSON-RPC message wrapping, privacy mode switching, and Substrate-specific exit service logic.