Consider the problem of securely identifying$\tau$-heavy hitters, where given a set of client inputs, the goal is to identify those inputs which are held by at least$\tau$clients in a privacy-preserving manner. Towards this, we design a novel system$\mathsf {Vogue}$, whose key highlight in comparison to prior works, is that it ensures complete privacy and does not leak any information other than the heavy hitters. In doing so,$\mathsf {Vogue}$aims to achieve as efficient a solution as possible. To showcase these efficiency improvements, we benchmark our solution and observe that it requires around 14 minutes to compute the heavy hitters for$\tau$= 100 on 256-bit inputs when considering 400 K clients. This is in contrast to the state of the art solution that requires over an hour for the same. In addition to the static input setting described above,$\mathsf {Vogue}$also accounts for streaming inputs and provides a protocol that outperforms the state-of-the-art therein. The efficiency improvements witnessed while computing heavy hitters in both, the static and streaming input settings, are attributed to our new secure stable compaction protocol, whose round complexity is independent of the size of the input array to be compacted.

Secure shuffle is an important primitive that finds use in several applications such as secure electronic voting, oblivious RAMs, secure sorting, to name a few. For time-sensitive shuffle-based applications that demand a fast response time, it is essential to design a fast and efficient shuffle protocol. In this work, we design secure and fast shuffle protocols relying on the techniques of secure multiparty computation. We make several design choices that aid in achieving highly efficient protocols. Specifically, we consider malicious 3-party computation setting with an honest majority and design robust ring-based protocols. Our shuffle protocols provide a fast online (i.e., input-dependent) phase compared to the state-of-the-art for the considered setting. To showcase the efficiency improvements brought in by our shuffle protocols, we consider two distinct applications of anonymous broadcast and secure graph computation via the GraphSC paradigm. In both cases, multiple shuffle invocations are required. Hence, going beyond standalone shuffle invocation, we identify two distinct scenarios of multiple invocations and provide customised protocols for the same. Further, we showcase that our customized protocols not only provide a fast response time, but also provide improved overall run time for multiple shuffle invocations. With respect to the applications, we not only improve in terms of efficiency, but also work towards providing improved security guarantees, thereby outperforming the respective state-of-the-art works. We benchmark our shuffle protocols and the considered applications to analyze the efficiency improvements with respect to various parameters.

Consider a set of N clients, each of which holds a private input string. An input string that is held by at least τ clients is defined as a τ-heavy hitter. In various application scenarios, data-aggregation servers are interested in learning τ-heavy hitters. To ensure that the servers do not learn anything about client input in the process, the problem of identifying heavy hitters privately is gaining popularity. Towards this, we design a novel system called Vogue, which provides improved efficiency as well as security guarantees over the state-of-the-art system of Poplar. Concretely, Vogue provides up to 27x efficiency improvement over Poplar when considering 400,000 clients who hold 256-bit input strings. Moreover, Vogue overcomes intermediate information leakages present in Poplar and guarantees full security in the presence of a malicious adversary. In the process of designing Vogue, we also design secure and efficient protocols for stable compaction and shuffle, each of which improves over its respective state-of-the-art.

Gene Expression Programming, a popular evolutionary paradigm, has acquired great attention from researchers in the domain of mathematical modeling. In view of its insufficiencies arising due to premature convergence, this paper presents an Augmented Gene Expression Programming (AGEP) algorithm. Improvements suggested over classical GEP mechanism are (1) Opposition Based Learning to initialize the population of individuals to speed up convergence, (2) A diversifying clonal selection algorithm to eliminate bias towards fitter individuals, and (3) A population upliftment step to counter stagnancy over generations. A set of experiments related to function finding was conducted using AGEP and the results show a prominent improvement by AGEP over its classical counterpart, GEP and an improved version from authoritative literature (Niche technology of Outbreeding Fusion-OFN-GEP). The results have been used to reason that AGEP gives more accurate solutions at a better convergence rate.