Journal on Communications ›› 2015, Vol. 36 ›› Issue (6): 60-65.doi: 10.11959/j.issn.1000-436x.2015182

• Academic paper • Previous Articles     Next Articles

Cryptanalysis of novel extended multivariate public key cryptosystem

Xu-yun NIE1,2,Bo LIU1,Gang LU3,Ting ZHONG1   

  1. 1 School of Information and Software Engineering,University of Electronic Science and Technology of China,Chengdu 611731,China
    2 State Key Laboratory of Information Security,Institute of Information Engineering,Chinese Academy of Sciences,Beijing 100093,China
    3 School of Computer Science and Engineering,University of Electronic Science and Technology of China,Chengdu 611731,China
  • Online:2015-06-25 Published:2017-05-11
  • Supported by:
    The National Natural Basic Research Program of China;The National Natural Science Foundation of China;The National Natural Science Foundation of China

Abstract:

The novel extended multivariate public key cryptosystem is a new security enhancement method on multivariate public key cryptosystems,which is proposed by Qiao,et al.A nonlinear invertible transformation was used,named“tame transformation”,on the original multivariate public key cryptosystem to hide its weakness such as linearization equation.However,it is found that if there are many linearization equations satisfied by the original MPKC,there would be many quadratization equations (QE) satisfied by the improved scheme.Given a public key,after finding all QE,a valid cipheretext can be substituted into the QE to derive a set of quadratic equations on the plaintext variable.This exactly reduce the degree of the system wanted to solve.Then the corresponding plaintext can be recovered for a given valid ciphertext combining with Groebner basis method.

Key words: multivariate public key cryptosystems, quadratic equations, linear equations, tame transformation, algebraic attack

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