Improved Brute-Force Search Strategies for Single-Trace and Few-Traces Template Attacks on the DES Round Keys

Mathias Wagner; Stefan Heyse

Paper 2018/937

Improved Brute-Force Search Strategies for Single-Trace and Few-Traces Template Attacks on the DES Round Keys

Mathias Wagner and Stefan Heyse

Abstract

We present an improved search strategy for a template attack on the secret DES key of a widely-used smart card, which is based on a Common-Criteria certified chip. We use the logarithm of the probability function as returned by the template attack itself, averaged over all 28 template positions along the rings representing the C and D Registers of the DES key schedule, as the sorting criteria for the key candidates. For weak keys - which in this attack model have a minimal rest entropy of only two bits - we find that on average only 37.75 bits need to be recovered by brute force when using only a single trace in the Exploitation Phase. This effort goes down to just a few bits for a single DES key when using only a few traces in Exploitation Phase.

Metadata

Available format(s): PDF
Category: Implementation
Publication info: Preprint. MINOR revision.
Keywords: DES TDES Template Attack Side-channel Attack Smart Card SCA block cipher key enumeration brute-force attack
Contact author(s): mathias wagner @ nxp com
History: 2018-10-05: received
Short URL: https://ia.cr/2018/937
License: CC BY

BibTeX

@misc{cryptoeprint:2018/937,
      author = {Mathias Wagner and Stefan Heyse},
      title = {Improved Brute-Force Search Strategies for Single-Trace and Few-Traces Template Attacks on the {DES} Round Keys},
      howpublished = {Cryptology {ePrint} Archive, Paper 2018/937},
      year = {2018},
      url = {https://eprint.iacr.org/2018/937}
}