Santanu Sarkar

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RC4 has been the most popular stream cipher in the history of symmetric key cryptography. Its internal state contains a permutation over all possible bytes from 0 to 255, and it attempts to generate a pseudo-random sequence of bytes (called keystream) by extracting elements of this permutation. Over the last twenty years, numerous cryptanalytic results on(More)
The series of published works, related to Differential Fault Attack (DFA) against the Grain family, require (i) quite a large number (hundreds) of faults (around n lnn, where n = 80 for Grain v1 and n = 128 for Grain-128, Grain-128a) and also (ii) several assumptions on location and timing of the fault injected. In this paper we present a significantly(More)
Design of secure light-weight stream ciphers is an important area in cryptographic hardware & embedded systems and a very recent design by Armknecht and Mikhalev (FSE 2015) has received serious attention that uses shorter internal state and still claims to resist the time-memory-data-tradeoff (TMDTO) attacks. An instantiation of this design paradigm is the(More)
In this paper we study a differential fault attack against the Grain family of stream ciphers. The attack works due to certain properties of the Boolean functions and corresponding choices of the taps from the LFSR. The existing works, by Berzati et al. (2009) and Karmakar et al. (2011), are applicable only on Grain-128 exploiting certain properties of the(More)
In PKC 2009, May and Ritzenhofen presented interesting problems related to factoring large integers with some implicit hints. One of the problems is as follows. Consider N1 = p1q1 and N2 = p2q2, where p1, p2, q1, q2 are large primes. The primes p1, p2 are of same bit-size with the constraint that certain amount of Least Significant Bits (LSBs) of p1, p2 are(More)