International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Cryptanalysis of White-Box DES Implementations with Arbitrary External Encodings

Brecht Wyseur
Wil Michiels
Paul Gorissen
Bart Preneel
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Abstract: At DRM 2002, Chow et al. presented a method for implementing the DES block cipher such that it becomes hard to extract the embedded secret key in a white-box attack context. In such a context, an attacker has full access to the implementation and its execution environment. In order to provide an extra level of security, an implementation shielded with external encodings was introduced by Chow et al. and improved by Link and Neumann. In this paper, we present an algorithm to extract the secret key from such white-box DES implementations. The cryptanalysis is a differential attack on obfuscated rounds, and works regardless of the shielding external encodings that are applied. The cryptanalysis has a average time complexity of $2^{14}$ and a negligible space complexity.
  title={Cryptanalysis of White-Box DES Implementations with Arbitrary External Encodings},
  booktitle={IACR Eprint archive},
  keywords={White-Box Cryptography / Obfuscation / DES / Data Encryption Standard / Cryptanalysis},
  note={Selected Areas in Cryptography 2007 (SAC'07) 13770 received 22 Mar 2007, last revised 14 Sep 2007},
  author={Brecht Wyseur and Wil Michiels and Paul Gorissen and Bart Preneel},