Rook: Using Video Games as a Low-Bandwidth Censorship Resistant Communication Platform

Rook constructs per-field symbol tables by observing 600 packets (~60 seconds) of real gameplay at session start, then restricts substituted values to only those previously observed with frequency within two orders of magnitude of the median. This ensures altered packets never contain field values that are absent or anomalously rare in legitimate traffic, defeating value-anomaly and out-of-range DPI filters.

§2.6 defense dpirandom-payload-detect generic

Rook achieves 34 bits/second client-to-server and 26 bits/second server-to-client within Team Fortress 2, sufficient for OTR-encrypted real-time chat. Rook use did not trigger Valve Anti-Cheat warnings and did not noticeably degrade gameplay for co-located legitimate players.

§4.1 defense dpitraffic-shape generic

Kolmogorov-Smirnov two-sample tests on packet-size distributions and inter-packet timing show that standard Rook (altering ~1-in-10 packets) is statistically indistinguishable from normal TF2 gameplay across 20 samples each. High-bandwidth Rook (1-in-2 packets) shows a slightly higher average bandwidth but remains difficult to distinguish on traffic-shape metrics.

§4.3 Traffic Shape Analysis evaluation traffic-shapedpi generic

Because Rook runs the actual game client and server rather than mimicking them, active anti-mimicry probes receive identical responses to a normal game instance. Systems based on protocol mimicry are vulnerable to probes that expose non-conforming behavior, but Rook eliminates this attack surface entirely.

§4.2 Anti-Mimicry defense active-probingdpi generic

Game-specific trigram analysis of mutable fields distinguishes high-bandwidth Rook (1-in-2 substitution rate) in server-side packet counts, showing clearly reduced distinct-trigram counts versus baseline. Standard Rook (1-in-10) produces only a few outliers and is not reliably distinguishable; any detector would face a high false-negative or false-positive rate against normal-rate Rook.

§4.3 Game-Specific n-gram Analysis evaluation dpiml-classifier generic