Solving generalized small inverse problems

  • Authors:
  • Noboru Kunihiro

  • Affiliations:
  • The University of Tokyo, Japan

  • Venue:
  • ACISP'10 Proceedings of the 15th Australasian conference on Information security and privacy
  • Year:
  • 2010

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Abstract

We introduce a "generalized small inverse problem (GSIP)" and present an algorithm for solving this problem. GSIP is formulated as finding small solutions of f(x0, x1, . . . , xn) = x0h(x1, . . . , xn) + C = 0(mod M) for an n-variate polynomial h, non-zero integers C and M. Our algorithm is based on lattice-based Coppersmith technique. We provide a strategy for construction of a lattice basis for solving f = 0, which are systematically transformed from a lattice basis for solving h = 0. Then, we derive an upper bound such that the target problem can be solved in polynomial time in log M in an explicit form. Since GSIPs include some RSA-related problems, our algorithm is applicable to them. For example, the small key attacks by Boneh and Durfee are refound automatically.