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Weak keys of reduced-round PRESENT for linear cryptanalysis. (English) Zbl 1267.94088
Jacobson, Michael J. jun. (ed.) et al., Selected areas in cryptography. 16th annual international workshop, SAC 2009, Calgary, Alberta, Canada, August 13–14, 2009. Revised selected papers. Berlin: Springer (ISBN 978-3-642-05443-3/pbk). Lecture Notes in Computer Science 5867, 249-265 (2009).
Summary: The block cipher PRESENT designed as an ultra-light weight cipher has a 31-round SPN structure in which the S-box layer has 16-parallel 4-bit S-boxes and the diffusion layer is a bit permutation. The designers claimed that the maximum linear characteristic deviation is not more than $$2^{ - 43}$$ for 28 rounds and concluded that PRESENT is not vulnerable to linear cryptanalysis. But we have found that 32% of PRESENT keys are weak for linear cryptanalysis, and the linear deviation can be much larger than the linear characteristic value by the multi-path effect. And we discovered a 28-round path with a linear deviation of $$2^{ - 39.3}$$ for the weak keys. Furthermore, we found that linear cryptanalysis can be used to attack up to 24 rounds of PRESENT for the weak keys.
For the entire collection see [Zbl 1177.94012].

##### MSC:
 94A60 Cryptography
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