WE2.R1.3

A Key-recovery Attack on the LCMQ Authentication Protocol

Vu Nguyen, Thomas Johansson, Qian Guo, Lund University, Sweden

Session:
Code Based Cryptography

Track:
1: Algebraic Aspects of Coding Theory

Location:
Ballroom II & III

Presentation Time:
Wed, 10 Jul, 12:10 - 12:30

Session Chair:
Violetta Weger, Technical university Munich
Abstract
We present a simple key-recovery attack on the LCMQ Authentication Protocol, an RFID authentication protocol proposed by Li, Gong, and Qin in 2013. We show that a successful attack is performed by solving a \textit{Learning Parity with Noise} instance in a not-too-large dimension. For the proposed LCMQ parameters, the attack requires only a few invocations with the tag under attack. When there is no restriction on the number of invocations, state-of-the-art LPN solvers recover the keys with complexity below $2^{51}$ and $2^{86}$, when attacking LCMQ parameters for security levels $80$-bit and $128$-bit, respectively. To the best of our knowledge, this is the first attack on LCMQ with complexity below exhaustive key search.
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