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Breaking DVB-CSA

  • Erik Tews
  • Julian Wälde
  • Michael Weiner
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7242)

Abstract

Digital Video Broadcasting (DVB) is a set of standards for digital television. DVB supports the encryption of a transmission using the Common Scrambling Algorithm (DVB-CSA). This is commonly used for PayTV or for other conditional access scenarios. While DVB-CSA support 64 bit keys, many stations use only 48 bits of entropy for the key and 16 bits are used as a checksum. In this paper, we outline a time-memory-tradeoff attack against DVB-CSA, using 48 bit keys. The attack can be used to decrypt major parts a DVB-CSA encrypted transmission online with a few seconds delay at very moderate costs. We first propose a method to identify plaintexts in an encrypted transmission and then use a precomputed rainbow table to recover the corresponding keys. The attack can be executed on a standard PC, and the precomputations can be accelerated using GPUs. We also propose countermeasures that prevent the attack and can be deployed without having to alter the receiver hardware.

Keywords

Smart Card Lookup Table Block Cipher Stream Cipher Round Function 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Erik Tews
    • 1
  • Julian Wälde
    • 1
  • Michael Weiner
    • 2
  1. 1.Fachbereich InformatikTechnische Universität DarmstadtDarmstadtGermany
  2. 2.Technische Universität MünchenGermany

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