Blind side channel analysis on the Elephant LFSR Extended version
Résumé
The National Institute of Standards and Technology (NIST) started a competition for lightweight cryptography candidates for authenticated encryption. Elephant is one of the ten finalists. Many physical attacks exist on the different traditional cryptographic algorithms. New standard are a new targets for this domain. In this paper, an improvement of the first theoretical blind side channel attack against the authenticated encryption algorithm Elephant is presented. More precisely, we are targeting the LFSR-based counter used internally. LFSRs are classic functions used in symmetric cryptography. In the case of Elephant, retrieving the initial state of the LFSR is equivalent to recovering the encryption key. This paper is an extension of a previous version. So an optimization of our previous theoretical attack is given. In the previous version, in only half of the cases, the attack succeeds in less than two days. In this extended paper, with optimization, the attack succeeds in three quarters of the cases.
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