International Association for Cryptologic Research (IACR)
Abstract
Differential attack is a basic cryptanalysis method for block ciphers that exploits the high probability relations between the input and output differences. The existing work in quantum differential cryptanalysis of block ciphers focuses on resource estimation to recover the last round subkeys on the basis of existing relations constructed on classical computers. To find such relations using quantum computer, we propose a method to search the high probability differential and impossible differential characteristics using quantum computer. The method explores all possible input and output difference pairs simultaneously using superposition of qubits. The proposed method is used to design the quantum circuit to search the differential characteristics for a toy cipher smallGIFT. The branch-and-bound based method is used to validate differential and impossible differential characteristics obtained using proposed method
