Sriramkrishnan Srinivasan

Versatile Pret a Voter: Handling Multiple Election Methods with a Unified Interface

A number of end-to-end verifiable voting schemes have been introduced recently. These schemes aim to allow voters to verify that their votes have contributed in the way they intended to the tally and in addition allow anyone to verify that the tally has been generated correctly. These goals must be achieved while maintaining voter privacy and providing receipt-freeness. However, most of these end-to-end voting schemes are only designed to handle a single election method and the voter interface varies greatly between different schemes. In this paper, we introduce a scheme which handles many of the popular election methods that are currently used around the world. Our scheme not only ensures privacy, receipt-freeness and end-to-end verifiability, but also keeps the voter interface simple and consistent between various election methods.

Identity based encryption: Progress and challenges

Identity based cryptography is currently among the most active areas of research in cryptography. In this article we discuss identity based encryption (IBE) which has the potential for widespread real world adoption and has in fact already been deployed commercially. We will discuss the many advantages and disadvantages of IBE and briefly introduce various schemes that have been proposed in the literature. We discuss the real world impact of IBE and highlight some issues which we think will become more pertinent as IBE and related technologies become more well known and widely deployed.

Countering Ballot Stuffing and Incorporating Eligibility Verifiability in Helios

Helios is a web-based end-to-end verifiable electronic voting system which has been said to be suitable for low-coercion environments. Although many Internet voting schemes have been proposed in the literature, Helios stands out for its real world relevance. It has been used in a number of elections in university campuses around the world and it has also been used recently by the IACR to elect its board members. It was noted that a dishonest server in Helios can stuff ballots and this seems to limit the claims of end-to-end verifiability of the system. In this work, we investigate how the issue of ballot stuffing can be addressed with minimum change to the current vote casting experience in Helios and we argue formally about the security of our techniques. Our ideas are intuitive and general enough to be applied in the context of other Internet voting scheme and they also address recent attacks exploiting the malleability of ballots in Helios.

Solving the Discrete Logarithm Problem for Packing Candidate Preferences

Ranked elections are used in many places across the world, and a number of end-to-end verifiable voting systems have been proposed to handle these elections recently. One example is the vVote system designed for the Victorian State Election, Australia. In this system, many voters will give a full ranking of up to 38 candidates. The easiest way to do this is to ask each voter to reorder ciphertexts representing the different candidates, so that the ciphertext ordering represents the candidate ranking. But this requires sending 38 ciphertexts per voter through the mixnets, which will take a long time. In this paper, we explore how to “pack” multiple candidate preferences into a single ciphertext, so that these preferences can be represented in the least number of ciphertexts possible, while maintaining efficient decryption. Both the packing and the unpacking procedure are performed publicly: we still provide 38 ciphertexts, but they are combined appropriately before they enter the mixnets, and after decryption, a meet-in-the-middle algorithm can be used to recover the full candidate preferences despite the discrete logarithm problem.