## Cryptology ePrint Archive: Report 2021/385

Solving the problem of Blockwise Isomorphism of Polynomials with Circulant matrices

Yasufumi Hashimoto

Abstract: The problem of Blockwise Isomorphism of Polynomials was introduced by Santoso at PQCrypto 2020 as a generalization of the problem of Isomorphism of Polynomials. In the present paper, we describe how to solve this problem with circulant matrices, used in Santoso's Diffie-Hellman type encryption scheme.

Category / Keywords: public-key cryptography / Isomorphism of Polynomials, Blockwise Isomorphism of Polynomials, circulant matrix