"Make sure DSA signing exponentiations really are constant-time"

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Journal Title
Journal ISSN
Volume Title
Conference article in proceedings
Date
2016-10-24
Major/Subject
Mcode
Degree programme
Language
en
Pages
12
1639-1650
Series
CCS 2016 - Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security, Volume 24-28-October-2016
Abstract
TLS and SSH are two of the most commonly used protocols for securing Internet traffic. Many of the implementations of these protocols rely on the cryptographic primitives provided in the OpenSSL library. In this work we disclose a vulnerability in OpenSSL, affecting all versions and forks (e.g. LibreSSL and BoringSSL) since roughly October 2005, which renders the implementation of the DSA signature scheme vulnerable to cache-based side-channel attacks. Exploiting the software defect, we demonstrate the first published cache-based key-recovery attack on these protocols: 260 SSH-2 handshakes to extract a 1024/160-bit DSA host key from an OpenSSH server, and 580 TLS 1.2 handshakes to extract a 2048/256-bit DSA key from an stunnel server.
Description
Keywords
Applied cryptography, Cache-timing attacks, CVE-2016-2178, Digital signatures, DSA, OpenSSL, Side-channel analysis, Timing attacks
Other note
Citation
García , C P , Brumley , B B & Yarom , Y 2016 , "Make sure DSA signing exponentiations really are constant-time" . in CCS 2016 - Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security . vol. 24-28-October-2016 , ACM , pp. 1639-1650 , ACM Conference on Computer and Communications Security , Vienna , Austria , 24/10/2016 . https://doi.org/10.1145/2976749.2978420