Steganalysis of Adaptive Covert Collusion in Tool-Using Agent Populations: A Black-Box, Cross-Principal Approach

This work frames covert coordination among tool-using LLM agents as an information-hiding problem under black-box, cross-principal observation. It proposes combining cross-run mutual-information estimation, permutation tests, distribution-shift statistics, and timing and tool-call side channels under a fixed false-positive budget. The key conceptual contribution is an adversarial red-versus-blue setup in which colluding agents continually rewrite their encoding. Capacity theory is used to define a detection-capacity frontier, including a covert bit-rate below which detection is no better than chance. However, the abstract explicitly labels the reported results as placeholders pending measurement, and identifies cross-session payload spreading as a largely unresolved evasion.