Yet Another Attack on Vest

  • Pascal Delaunay
  • Antoine Joux
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5023)


We present a new side-channel attack against VEST, a set of four stream ciphers which reached the second phase of the eSTREAM project (the European stream cipher project). The proposed attacks target the counter part of the ciphers, composed of 16 short-length non-linear feedback shift registers (NLFSR) independently updated. Our aim is to retrieve the whole initial state of the counter (163 to 173 bits) which is a part of the keyed state. The first attack is directly adapted from previous works on differential side-channel attacks. The second attack is brand new. It involves a unique measurement thus it can be seen as a simple side-channel attack. However, it requires some signal processing so we call it Refined Simple Power Analysis. As we expect full recovery of the initial state with minimal complexity, one should carefully consider implementing any VEST cipher in an embedded device.


Side Channel Attacks VEST Stream Ciphers Fourier Transform 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Pascal Delaunay
    • 1
    • 2
  • Antoine Joux
    • 2
    • 3
  1. 1.THALES Land and Joint SystemColombesFrance
  2. 2.Université de Versailles Saint-Quentin-en-YvelinesVersailles CedexFrance
  3. 3.DGA 

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