Complexity of Decoding Positive-Rate Reed-Solomon Codes

  • Authors:
  • Qi Cheng;Daqing Wan

  • Affiliations:
  • School of Computer Science, The University of Oklahoma, Norman, OK73019;Department of Mathematics, University of California, Irvine CA 92697-3875

  • Venue:
  • ICALP '08 Proceedings of the 35th international colloquium on Automata, Languages and Programming, Part I
  • Year:
  • 2008

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Abstract

The complexity of maximum likelihood decoding of theReed-Solomon codes [q - 1,k]q is a well known open problem. Theonly known result [4] in this direction states that it is at leastas hard as the discrete logarithm in some cases where theinformation rate unfortunately goes to zero. In this paper, weremove the rate restriction and prove that the same complexityresult holds for any positive information rate. In particular, thisresolves an open problem left in [4], and rules out the possibilityof a polynomial time algorithm for maximum likelihood decodingproblem of Reed-Solomon codes of any rate under a well knowncryptographical hardness assumption. As a side result, we give anexplicit construction of Hamming balls of radius bounded away fromthe minimum distance, which contain exponentially many codewordsfor Reed-Solomon code of any positive rate less than one. Theprevious constructions in [2][7] only apply to Reed-Solomon codesof diminishing rates. We also give an explicit construction ofHamming balls of relative radius less than 1 which containsubexponentially many codewords for Reed-Solomon code of rateapproaching one.