• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1089-1097
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• 2016

It is well-known that, if additional information other than a plaintext-ciphertext pair is available, breaking the RSA cryptosystem may be much easier than factorizing the RSA modulus. For example, Coppersmith showed that, given the 1/2 fraction of the least or most significant bits of one of two RSA primes, the RSA modulus can be factorized in a polynomial time. More recently, Henecka et. al showed that the RSA private key of the form (p, q, d, $d_p$, $d_q$) can efficiently be recovered whenever the bits of the private key are erroneous with error rate less than 23.7%. It is notable that their algorithm is based on counting the matching bits between the candidate key bit string and the given decayed RSA private key bit string. And, extending the algorithm, this paper proposes a new RSA private key recovery algorithm using a generalized probabilistic measure for measuring the consistency between the candidate key bits and the given decayed RSA private key bits.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.73-83
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• 2018

There has been increasing interest from NIST and other companies in studying post-quantum cryptography in order to resist against quantum computers. Multivariate polynomial based, code based, lattice based, hash based digital signature, and isogeny based cryptosystems are one of the main categories in post quantum cryptography. Among these categories, isogeny based cryptosystem is known to have shortest key length. In this paper, we implemented Supersingular Isogeny Diffie-Hellman (SIDH) protocol efficiently on low-end mobile device. Considering the device's specification, we select supersingular curve on 523 bit prime field, and generate efficient isogeny computation tree. Our implementation of SIDH module is targeted for 32bit environment.