Damaged BZip Files Are Difficult to Repair

  • Christian Hundt
  • Ulf Ochsenfahrt
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5092)


bzip is a program written by Julian Seward that is often used under Unix to compress single files. It splits the file into blocks which are compressed individually using a combination of the Burrows-Wheeler-Transformation, the Move-To-Front algorithm, Huffman and Runlength encoding. The author himself stated that compressed blocks that are damaged, i.e., part of which are lost, are essentially non-recoverable. This paper gives a formal proof that this is indeed true: focusing on the Burrows-Wheeler-Transformation, the problem of completing a transformed string, such that the decoded string obeys certain file format restrictions, is NP-hard.


Bipartite Graph Hamiltonian Cycle Original Graph Outgoing Edge Input String 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Christian Hundt
    • 1
  • Ulf Ochsenfahrt
    • 1
  1. 1.Fakultät für Informatik und ElektrotechnikUniversität RostockGermany

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