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Cryptography II

Liliya Andreicheva (lna5520@rit.edu)

BLUE MIDNIGHT WISH

Abstract:

Blue Midnight Wish (BMW) by Danilo Gligoroski, Vlastimil Klima, Svein Johan Knapskog, Mohamed El-Hadedy, Jorn Amundsen,Stig Frode Mjolsnes is one of the candidate hash-functions for the second round of NIST competition for new cryptographic standard SHA-3. It has been designed to be much more efficient than SHA-2, while in the same time offering same or better security. In this paper I am going to make the overview of BMW and look at the possible attacks which have been already presented.

The version of BMW which is now in the second round of the NIST competition is a tweaked version. The original one was optimized to prevent the possibility of the attacks described by Soren S. Thomsen. In his paper [3] he showed how to find collisions, preimages and second preimages in the compression function used in BMW. Despite this the complexities of these attacks applied to the length of output of the hash function are still giving infeasible time like from 2^81 up to 2^384 for different versions of BMW. But all that made the authors submit the improved version of the design of the hash function.

After the tweaked version was presented the possible attacks are still being developed. J. P. Aumasson presented a rotational analysis of the hash function and managed to find some weaknesses in compression function of BMW. Further work in papers [2] and [4] is done in the area of developing the mechanism of these rotational attacks applied to improved versions of BMW. But the area is still not fully investigated.


Overview:
  • Introduction
  • Description of BMW
  • Attacks by S.Thomsen
  • Rotational analysis
  • Conclusion

Deliverables:
Paper [pdf]
Presentation [pdf] [ppt]

References:

[1] Soren S. Thomsen - Pseudo-cryptanalysis of Blue Midnight Wish. Available online, 2009
[2] Jian Guo, Soen S. Thomsen - Distinguishers for the Compression Function of Blue Midnight Wish with Probability 1. Available online, 2010
[3] Soren S. Thomsen - Pseudo-cryptanalysis of the Original Blue Midnight Wish. In S.Hong and T.Iwata, editors, Fast Software Encryption, LNCS, Seoul, South Korea, 2010. To appear
[4] Ivica Nikolic, Josef Pieprzyk, Przemyslaw Sokolowski, Ron Steinfeld - Rotational Cryptanalysis of (Modified) Versions of BMW and SIMD. Available online, 2010 Soren S. Thomsen - A near-collision attack on the Blue Midnight Wish compression function. Version 2.0, available online, 2008

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