The PhD student seminars are intended to be informal and relaxed without the "polish" of the official seminars. The seminars can discuss for example recent results (your own or from an article) or survey some interesting topic. The intended audience is primarily PhD students, but everyone is welcome. Contact Stephan Gocht if you want to give a seminar or receive email announcements about upcoming seminars.
More information about practical details are available in Swedish. There is also a page with previous seminars.
See also the page with the TCS groups official seminars.
04 Dec 2018 at 14:15 in 4523
(30% seminar) Dynamic Algebraic Algorithms
(Jan van den Brand, KTH)
One research topic of my group is dynamic algorithms (data-structures). I focus on dynamic algebraic algorithms, which maintain some algebraic property when the input matrix changes. For example we try to efficiently re-compute the solution of a linear system, when one or more constraints of the system are changed. These algebraic techniques can be used to obtain fast data-structures for other graph-theoretic problems such as transitive closure or bipartite matching. In this talk, I will give an overview of my results of the past 1.5 years.
29 Oct 2018 at 13:15 in 4523
Parallelized Side-Channel Attack Resisted Scalar Multiplication Using q-Based Addition-Subtraction k-chains
This paper presents parallel scalar multiplication techniques for elliptic curve cryptography using q-based addition-subtraction k-chain which can also effectively resist side-channel attack. Many techniques have been discussed to improve scalar multiplication, for example, double-and-add, NAF, w-NAF, addition chain, and addition-subtraction chain. However, these techniques cannot resist side-channel attack. Montgomery ladder, random w-NAF, and uniform operation techniques are also widely used to prevent side-channel attack, but their operations are not efficient enough comparing to those with no side-channel attack prevention. We have found a new way to use k-chain for this purpose. In this paper, we extend the definition of k-chain to q-based addition-subtraction k-chain and modify an algorithm proposed by Jarvinen et al. to generate the q-based addition-subtraction k-chain. We show the upper and lower bounds of its length which lead to the computation time using the new chain techniques. The chain techniques are used to reduce the cost of scalar multiplication in parallel ways. Comparing to w-NAF, which is faster than double-and-add and Montgomery ladder technique, the maximum computation time of our q-based addition-subtraction k-chain techniques can have up to 25.92% less addition costs using only 3 parallel computing cores. We also discuss on the optimization for multiple operand point addition using hybrid-double multiplier which is proposed by Azarderakhsh and Reyhani-Masoleh. The proposed parallel chain techniques can also tolerate side-channel attack efficiently.