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cosec >students >Teaching >Summer 2012 

DESL+: An improved lightweight variant of the data encryption standard

Daniel Loebenberger (b-it cosec)

Thursday 10 May 2012, 15.00, b-it 1.25 (cosec meeting room)

DESL is a lightweight variant of the data encryption standard (DES) that uses just a single S-box instead of eight different ones, while keeping the rest of the algorithm identical to DES. To ensure that the simplification does not impose new security risks, one has to carefully select this single S-box and show that the simplified algorithm is still resistant against known attacks, like differential and linear cryptanalysis.

In this talk we discuss in detail the development of the cryptographically relevant properties of S-boxes used in DES-like ciphers. Stronger requirements on S-boxes greatly simplify the security analysis. In the past these properties have never been used since one did not find examples fulfilling them. We present solutions and explain how we found them in a search tree with roughly 10^14 nodes.

Afterwards, we analyze thoroughly the cryptographic properties of the resulting algorithm revealing some hidden complications which may possibly lead to better attacks against DES or DESL.

This is joint work with Michael Nüsken.

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