Keyed Sum of Permutations: a simpler RP-based PRF

Idealized constructions in cryptography prove the security of a primitive based on the security of another primitive. The challenge of building a pseudorandom function (PRF) from a random permutation (RP) has only been recently tackled by Chen, Lambooij and Mennink [CRYPTO 2019] who proposed Sum of Even-Mansour (SoEM) with a provable beyond-birthday-bound security. In this work, we revisit the challenge of building a PRF from an RP. On the one hand, we describe Keyed Sum of Permutations (KSoP) that achieves the same provable security as SoEM while being strictly simpler since it avoids a key addition but still requires two independent keys and permutations. On the other hand, we show that it is impossible to further simplify the scheme by deriving the two keys with a simple linear key schedule as it allows a non-trivial birthday-bound key recovery attack. The birthday-bound attack is mostly information-theoretic, but it can be optimized to run faster than a brute-force attack

A Discrete Logarithm-based Approach to Compute Low-Weight Multiples of Binary Polynomials

Being able to compute efficiently a low-weight multiple of a given binary polynomial is often a key ingredient of correlation attacks to LFSR-based stream ciphers. The best known general purpose algorithm is based on the generalized birthday problem. We describe an alternative approach which is based on discrete logarithms and has much lower memory complexity requirements with a comparable time complexity.Comment: 12 page

A New Algorithm for Solving Ring-LPN with a Reducible Polynomial

The LPN (Learning Parity with Noise) problem has recently proved to be of great importance in cryptology. A special and very useful case is the RING-LPN problem, which typically provides improved efficiency in the constructed cryptographic primitive. We present a new algorithm for solving the RING-LPN problem in the case when the polynomial used is reducible. It greatly outperforms previous algorithms for solving this problem. Using the algorithm, we can break the Lapin authentication protocol for the proposed instance using a reducible polynomial, in about 2^70 bit operations

The Tragedy of a Cambridge Feminist

Overview: Stephen Frug sits down at his computer desk on April 4th, 2011. His wife, Sarah, is in the kitchen trying to feed their three year old son and for once, all is quiet. He picks up his glasses and slides them on his face, then continues to log onto his online blog. He had started writing the blog in 2005 when he was still a 34 year old graduate student in the history department of Cornell University. Since then, he’d gotten his Ph.D. and started teaching history at Hobart and William Smith in Geneva, New York, an hour\u27s drive away from his home in Ithaca. Stephen reminisces as he clicks through some of his older blog posts. He smiles as he scrolls past the post about his son’s birthday and another about the frustrations he had while trying to write his graphic novel. A few minutes later, he finds himself staring at a new, blank entry. He had, after all, logged onto this blog for a particular reason. Taking a big sigh, he finally begins to write. “Twenty years ago today my mother, Mary Joe Frug, was murdered about a block from our house in Cambridge, Massachusetts. It was early evening; she was out for a walk. No one was ever caught or charged; we have no idea, to this day, who killed her. It was less than a month after my twentieth birthday.” Author\u27s Reflection: My name is Ellen Lapointe and I am currently a nursing major at St. John Fisher College. As my classes progress I am realizing that I love nursing and cannot wait to work in a hospital one day, but I also have a true passion for writing. Writing this paper, at least to me, was much different than any other paper I’ve written previously. Having a whole class centered on one final paper really made me very conscious about research as well as the editing process. It was also a different experience because I was writing about something that I was truly interested in, and I felt like a detective as I pried deeper into the lives of the victim and all of the people involved in the case. At first I stumbled upon some road blocks that put a temporary halt to my writing. As I tried to look up more information surrounding this 1991 murder mystery, I was having trouble finding information. With the help of the librarians, my professor, and some of my peers, I was able to find more clues that helped me write my paper. Although I put a lot of time and energy into writing and editing this paper, I now look back on it and I am genuinely proud of the effort I made, even if it’s not perfect

216 Jewish Hospital of St. Louis

https://digitalcommons.wustl.edu/bjc_216/1179/thumbnail.jp