• New Techniques for Public Key Encryption with Sender Recovery

      Godi, Murali; Viswanathan, Roopa; Adviser; Novillo, Jorge; Reviewer; Chiang, Chen-Fu; Reviewer (2016-12-15)
      In this paper, we consider a situation where a sender transmits a ciphertext to a receiver using a public-key encryption scheme, and at a later point of time, wants to retrieve the plaintext, without having to request the receiver’s help in decrypting the ciphertext, and without having to store a set of plaintext/ciphertext pairs for every receiver the sender interacts with. This problem, known as public key encryption with sender recovery has intuitive solutions based on KEM/DEM schemes. We propose a KEM/DEM-based solution that is CCA-secure, and only requires the receiver to be equipped with a public/secret key pair (the sender needs only a symmetric recovery key), and has much simplified proofs compared to prior work in this area. We prove our protocols secure in the single receiver and multi-receiver setting. To achieve our goals, we use an analysis technique called plaintext randomization that results in greatly simplified and intuitive proofs for protocols that use a PKE internally as a component and compose the PKE with other primitives. We instantiate our protocol for public key encryption with sender recovery with the well-known KEM/DEM scheme due to Cramer and Shoup.
    • Swarm Intelligence in the Multi Agent System Environment

      Bollam, Sravani; Sengupta, Saumendra; Adviser; Chiang, Chen-Fu; Reviewer; Rezk, Mohamed; Reviewer (2016-12-20)
      This thesis is focused on the use of naturally occurring concept of “swarm intelligence” to multiagentcsystems, namely the relatively new system-theoretic framework known as Swarm Intelligence Systems (SIS). In this work, outlined is the general framework of an interacting agents behaving as a swarm group on a mission to deliver a service such as transporting a set of goods from a given starting point to a destination. As an example, one could think of a team of drones, for instance, providing a delivery service in a milieu where normal transportation mode may be prohibitively expensive. The entire logistic, in detail as a commercial project, is too involved for our thesis focus; instead, some of the structural interaction issues with a group are outlined and discussed here to articulate the behavior of multi-agent based swarm as a group necessary to function as a distributed entity somewhat different from the standard swarm models found in literature.