Cryptology ePrint Archive: Report 2009/542

Analysis of Intermediate Field Systems

Olivier Billet and Jacques Patarin and Yannick Seurin

Abstract: We study a new generic trapdoor for public key multivariate cryptosystems, called IFS for Intermediate Field Systems, which can be seen as dual to HFE. This new trapdoor relies on the possibility to invert a system of quadratic multivariate equations with few (logarithmic with respect to the security parameter) unknowns on an intermediate field thanks to Groebner bases algorithms. We provide a comprehensive study of the security of this trapdoor and show that it is equivalent to the security provided by HFE. Therefore, while insecure in its basic form, this trapdoor may reveal quite attractive when used with, e.g., the minus modifier.

Category / Keywords: public-key cryptography /

Date: received 5 Nov 2009

Contact author: yannick seurin at m4x org

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Version: 20091108:042928 (All versions of this report)

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