The 4th edition of the “I have a project” award of the Institute of Physical and Information Technologies “Leonardo Torres Quevedo” (ITEFI) for the best final degree or master’s thesis granted the first prize to David Balbas, PhD Student at the Institute IMDEA Software, at the CSIC’s Serrano Street headquarters on May 12th.
Balbas’ project, entitled “Secure Administrators for Group Messaging Protocols”, studies group messaging from a security point of view, and in particular, asynchronous group key exchange protocols. Group instant messaging protocols, such as WhatsApp or Signal Messenger, must preserve the confidentiality and authenticity of sent messages.
David’s main contribution is the formalization of the administration of a messaging group, which is the usual scenario in which there is a restricted group of users, (the administrators) with the ability to add and remove members. For this purpose, the cryptographic primitive “administrated continuous group key agreement” (A-CGKA) is introduced, along with a definition of correctness and a discussion of security models. Finally, it presents two practical modular constructions of A-CGKA using digital signatures.
In the paper, he proposes a formalism and cryptographic protocols that allow managing messaging groups with strong security guarantees. All this represents an advance in security, protecting against certain attacks, and can be applied to protocols such as those used in the world’s largest instant messaging applications, which are used by billions of people every day.
