[2604.04757] Undetectable Conversations Between AI Agents via Pseudorandom Noise-Resilient Key Exchange

Computer Science > Cryptography and Security arXiv:2604.04757 (cs) [Submitted on 6 Apr 2026] Title:Undetectable Conversations Between AI Agents via Pseudorandom Noise-Resilient Key Exchange Authors:Vinod Vaikuntanathan, Or Zamir View a PDF of the paper titled Undetectable Conversations Between AI Agents via Pseudorandom Noise-Resilient Key Exchange, by Vinod Vaikuntanathan and 1 other authors View PDF HTML (experimental) Abstract:AI agents are increasingly deployed to interact with other agents on behalf of users and organizations. We ask whether two such agents, operated by different entities, can carry out a parallel secret conversation while still producing a transcript that is computationally indistinguishable from an honest interaction, even to a strong passive auditor that knows the full model descriptions, the protocol, and the agents' private contexts. Building on recent work on watermarking and steganography for LLMs, we first show that if the parties possess an interaction-unique secret key, they can facilitate an optimal-rate covert conversation: the hidden conversation can exploit essentially all of the entropy present in the honest message distributions. Our main contributions concern extending this to the keyless setting, where the agents begin with no shared secret. We show that covert key exchange, and hence covert conversation, is possible even when each model has an arbitrary private context, and their messages are short and fully adaptive, assuming only ...