One family of candidates to build a post-quantum cryptosystem upon relies on euclidean lattices. In order to make such cryptosystems more efficient, one can consider special lattices with an additional algebraic structure such as ideal lattices. Ideal lattices can be seen as ideals in a number field. However recent progress in both quantum and classical computing showed that such cryptosystems can be cryptanalysed efficiently over some number fields. It is therefore important to study the security of such cryptosystems for other number fields in order to have a better understanding of the complexity of the underlying mathematical problems. We study in this paper the case of multicubic fields.

Cryptography RSA cryptosystem Power analysis Montgomery multiplication in RNS 2 Randomized modular exponentiation in RNS Randomized Montgomery multiplication Proposed approach Level of randomization 3 Conclusion 2 / 19 Outline 1 Cryptography RSA cryptosystem Power analysis Montgomery multiplication in RNS 2 Randomized modular exponentiation in RNS Randomized Montgomery multiplication Proposed approach Level of randomization 3 Conclusion 3 / 19 RSA encryption (Rivest, Shamir and Adleman) Bob chooses p and q two large prime numbers and computes N = pq. He generates E and D two integers such that ED = 1 (mod (p − 1)(q − 1)).

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