Optimizing Information Set Decoding Algorithms to Attack Cyclosymmetric MDPC Codes

  • Ray Perlner
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 8772)


Recently, several promising approaches have been proposed to reduce keysizes for code based cryptography using structured, but non-algebraic codes, such as quasi-cyclic (QC) Moderate Density Parity Check (MDPC) codes. Biasi et al. propose further reducing the keysizes of code-based schemes using cyclosymmetric (CS) codes. While Biasi et al. analyze the complexity of attacking their scheme using standard information-set-decoding algorithms, the research presented here shows that information set decoding algorithms can be improved, by choosing the columns of the information set in a way that takes advantage of the added symmetry. The result is an attack that significantly reduces the security of the proposed CS-MDPC schemes to the point that they no longer offer an advantage in keysize over QC-MDPC schemes of the same security level. QC-MDPC schemes are not affected by this paper’s result.


information set decoding code-based cryptography moderate density parity check (MDPC) codes cyclosymmetric 


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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Ray Perlner
    • 1
  1. 1.National Institute of Standards and TechnologyGaithersburgUSA

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