# Technical Program

## Paper Detail

 Paper ID P.2.3 Paper Title An Information-Theoretic Proof of the Streaming Switching Lemma for Symmetric Encryption Authors Ido Shahaf, Or Ordentlich, Gil Segev, Hebrew University of Jerusalem, Israel Session P.2: Cryptography Presentation Lecture Track Cryptography, Security and Privacy Manuscript Click here to download the manuscript Virtual Presentation Click here to watch in the Virtual Symposium Abstract Motivated by a fundamental paradigm in cryptography, we consider a recent variant of the classic problem of bounding the distinguishing advantage between a random function and a random permutation. Specifically, we consider the problem of deciding whether a sequence of $q$ values was sampled uniformly with or without replacement from $[N]$, where the decision is made by a streaming algorithm restricted to using at most $s$ bits of internal memory. In this work, the distinguishing advantage of such an algorithm is measured by the KL divergence between the distributions of its output as induced under the two cases. We show that for any $s=\Omega(\log N)$ the distinguishing advantage is upper bounded by $O(q \cdot s / N)$, and even by $O(q \cdot s / N \log N)$ when $q \leq N^{1 - \epsilon}$ for any constant $\epsilon > 0$ where it is nearly tight with respect to the KL divergence.