Loopix Cover Traffic
In Full privacy mode, the Nym client generates cover traffic using the Loopix protocol. This is a key advantage over simple onion routing (like Tor).
What Is Cover Traffic?
Cover traffic consists of dummy packets that are cryptographically indistinguishable from real traffic. They serve to:
- Hide activity patterns: An observer cannot tell when a user is actually sending real data
- Prevent traffic analysis: Constant packet flow masks bursts of real activity
- Provide sender anonymity: Even if all mix nodes are compromised, the observer cannot distinguish real from cover packets
Loopix Protocol
Nym implements the Loopix anonymous communication system:
Packet Types
| Type | Path | Purpose |
|---|---|---|
| Real packets | Sender → Mix nodes → Recipient | Carry actual data |
| Loop cover | Sender → Mix nodes → Sender | Verify mixnet is working |
| Drop cover | Sender → Mix nodes → (discarded) | Add noise to traffic flow |
Timing Distribution
All packets (real and cover) are sent according to a Poisson distribution:
- Packet intervals are memoryless (no timing patterns)
- Rate parameter λ controls bandwidth usage
- Real packets are inserted into the cover traffic stream
BlindHop Privacy Modes
| Mode | Cover Traffic | Effect |
|---|---|---|
| None | ❌ | Direct connection, no privacy |
| Fast | ❌ | IP hidden but timing visible |
| Full | ✅ | IP hidden + timing hidden + traffic analysis resistant |
Why This Matters
Without cover traffic (e.g., Tor, VPNs), an observer can determine:
- When you're active (by watching packet timing)
- How much data you're sending (by counting packets)
- Correlation between your sends and blockchain events
With Loopix cover traffic, your traffic is indistinguishable from background noise.