Under the DARPA Resilient Anonymous Communication for Everyone (RACE) program, Stealth is developing a novel communication-channel-agnostic anonymous message routing control-plane system, called CARMA: Covert Anonymous Reliable Messaging Application. At a high level, CARMA provides a platform for an ecosystem of servers that enable clients (or “users”) to communicate with each other anonymously in the presence of malicious and/or corrupted actors that attempt to de-anonymize or otherwise actively disrupt the communication.
Stealth’s novel cryptographic core and novel optimized topology design of participating servers and clients in a dynamic environment combine to provide unique and scalable system-control and anonymization capabilities:
- Secure Configuration and Evolution: New clients can join by downloading the current version of the CARMA application with an existing client’s valid invitation, and clients can be promoted to act as servers in a manner that is controlled by the CARMA system so as to ensure a sustainable majority of honest servers among the control plane. The decentralized role and connection (edges) sampling module maximizes the messaging platform’s survival over multiple epochs, even under severe cyberattacks that shut down or even fully compromise a fraction of participating servers.
- Secure Discovery: New users can discover other clients’ salient information, such as their public keys and authentication information, with maximum security protecting their phonebook retrieval activities and sensitive information.
- Cryptographic Mixing: Our core cryptographic mixing module, based on secure multiparty computation (MPC), provides strong anonymity with meta-data protection – even when a subset of participating servers are fully compromised, allowing the adversary to inspect and analyze all packets.
Most importantly, the CARMA system is designed to be agnostic with respect to the channels over which servers communicate, enabling seamless integration with many types of anonymous, detection-evading, or steganographic channels to realize communications between servers and clients.
See also the page for our Kestrel solution, which is a technology developed under the CARMA project which enables covert communication in adversarial settings that is safe, reliable, and undetectable.
This work was supported by the United States Air Force and DARPA under contract number FA8750-19-C-0031, Distribution Statement A: “Approved for Public Release, Distribution Unlimited. If you have any questions, please contact the Public Release Center”. The views, opinions and/or findings expressed are those of the author and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.
