• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.4
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• pp.591-599
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• 2023

Due to the recent attack by Castryck-Decru, the private key of SIDH can be recovered in polynomial time so several methods have been proposed to prevent the attack. Among them, M-SIDH proposed by Fouotsa et al, counteracts the attack by masking the torsion point information during the key exchange. In this paper, we implement M-SIDH and evaluate its performance. To the best of our knowledge, this is the first implementation of M-SIDH in C language. Toward that end, we propose a method to select parameters for M-SIDH instantiation and propose a 1024-bit prime for implementation. We implemented the square-root Velu formula over the extension field for further optimization. As a result, 1129 ms is required for a key exchange in the case of MSIDH-1024, providing the classic 64-bit security level.