Cryptanalysis of Elisabeth-4

ePrint Report: Cryptanalysis of Elisabeth-4

Henri Gilbert, Rachelle Heim Boissier, Jérémy Jean, Jean-René Reinhard

Elisabeth-4 is a stream cipher tailored for usage in hybrid homomorphic encryption applications that has been introduced by Cosseron et al. at ASIACRYPT 2022. In this paper, we present several variants of a key-recovery attack on the full Elisabeth-4 that break the 128-bit security claim of that cipher. Our most optimized attack is a chosen-IV attack with a time complexity of $2^{88}$ elementary operations, a memory …

applications asiacrypt attack cipher cryptanalysis encryption eprint report gilbert heim homomorphic encryption hybrid key recovery report stream stream cipher