Mohamed Ahmed Abdelraheem

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At CHES 2010, the new block cipher PRINTcipher was presented as a lightweight encryption solution for printable circuits [15]. The best attack to date is a differential attack [1] that breaks less than half of the rounds. In this paper, we will present a new attack called invariant subspace attack that breaks the full cipher for a significant fraction of(More)
At CHES 2010, the new block cipher PRINTcipher was presented. In addition to using an xor round key as is common practice for round-based block ciphers, PRINTcipher also uses key-dependent permutations. While this seems to make differential cryptanalysis difficult due to the unknown bit permutations, we show in this paper that this is not the case. We(More)
ARMADILLO2 is the recommended variant of a multi-purpose cryptographic primitive dedicated to hardware which has been proposed by Badel et al. in [1]. In this paper, we describe a meet-in-the-middle technique relying on the parallel matching algorithm that allows us to invert the ARMADILLO2 function. This makes it possible to perform a key recovery attack(More)
In this paper we analyse two variants of SIMON family of lightweight block ciphers against linear cryptanalysis and present the best linear cryptanalytic results on these variants of reduced-round SIMON to date. We propose a time-memory trade-off method that finds differential/linear trails for any permutation allowing low Hamming weight differential/linear(More)
Polynomial hashing as an instantiation of universal hashing is a widely employed method for the construction of MACs and authenticated encryption (AE) schemes, the ubiquitous GCM being a prominent example. It is also used in recent AE proposals within the CAESAR competition which aim at providing nonce misuse resistance, such as POET. The algebraic(More)
Despite the fact that we evidently have very good block ciphers at hand today, some fundamental questions on their security are still unsolved. One such fundamental problem is to precisely assess the security of a given block cipher with respect to linear cryptanalysis. In by far most of the cases we have to make (clearly wrong) assumptions, e.g., assume(More)
We evaluate the security of the recently proposed authenticated encryption scheme POET with regard to weak keys when its universal hash functions are instantiated with finite field multiplications. We give explicit constructions for weak key classes not covered by POET's weak key testing strategy, and demonstrate how to leverage them to obtain universal(More)