Abstract
We consider a range of attacks on reduced-round variants of the block cipher Skipjack. In particular we concentrate on the role of truncated differentials and consider what insight they give us into the design and long-term security of Skipjack. An attack on the full 32 rounds of Skipjack remains elusive. However we give attacks on the first 16 rounds of Skipjack that can efficiently recover the key with about 217 chosen plaintexts and an attack on the middle sixteen rounds of Skipjack which recovers the secret key using only two chosen plaintexts. Several high-probability truncated differentials are presented the existence of which might best be described as surprising. Most notably, we show that the techniques used by Biham et al. can be presented in terms of truncated differentials and that there exists a 24-round truncated differential that holds with probability one.
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E. Biham, A. Biryukov, O. Dunkelmann, E. Richardson, A. Shamir. Initial Observations on the Skipjack Encryption Algorithm. June 25, 1998. Available at http://www.cs.technion.ac.il/~biham/Reports/SkipJack/.
E. Biham, A. Biryukov, O. Dunkelmann, E. Richardson, and A. Shamir. Cryptanalysis of Skipjack-3XOR in 220 time and using 29 chosen plaintexts. July 2, 1998. Available at http://www.cs.technion.ac.il/~biham/Reports/SkipJack/.
E. Biham, A. Biryukov, O. Dunkelmann, E. Richardson, and A. Shamir. Cryptanalysis of Skipjack-4XOR. June 30, 1998. Available at http://www.cs.technion.ac.il/~biham/Reports/SkipJack/.
E. Biham, A. Biryukov, and A. Shamir. Initial Observations on Skipjack: Cryptanalysis of Skipjack-3XOR. SAC’98. Available at http://www.cs.technion.ac.il/~biham/Reports/SkipJack/.
E. Biham, A. Biryukov, and A. Shamir. Cryptanalysis of Skipjack reduced to 31 rounds using impossible differentials. In J. Stern, editor, Advances in Cryptology-Eurocrypt’ 99, volume 1592 of Lecture Notes in Computer Science, pages 12–23, 1999. Springer Verlag. Also available at http://www.cs.technion.ac.il/~biham/Reports/SkipJack.
E. Biham and A. Shamir. Differential Cryptanalysis of the Data Encryption Standard. Springer-Verlag, New York, 1993.
L.R. Knudsen. Applications of higher order differentials and partial differentials. In B. Preneel, editor, Fast Software Encryption, volume 1008 of Lecture Notes in Computer Science, pages 196–211, 1995. Springer Verlag.
L.R. Knudsen, V. Rijmen, R.L. Rivest, and M.J.B. Robshaw. On the design and security of RC2. In S. Vaudenay, editor, Fast Software Encryption, volume 1372 of Lecture Notes in Computer Science, pages 206–219, 1998. Springer Verlag.
E.F. Brickell, D.E. Denning, S.T. Kent, D.P. Maher, and W. Tuchman. Skipjack Review Interim Report. July 28, 1993.
M. Matsui. Linear cryptanalysis method for DES cipher. In T. Helleseth, editor, Advances in Cryptology-Eurocrypt’ 93, volume 765 of Lecture Notes in Computer Science, pages 386–397, 1993. Springer Verlag.
B. Schneier and D. Banisar. The Electronic Privacy Papers. John Wiley & Sons, 1997.
W. Diffe and S. Landau. Privacy on the Line. MIT Press, 1998.
National Institute of Standards and Technology (NIST). FIPS Publication 186: Digital Signature Standard (DSS). May 1994.
National Institute of Standards and Technology (NIST). FIPS Publication 180-1: Secure Hash Standard (SHS). May 1994.
National Security Agency. Skipjack and KEA algorithm specifications. May 1998. Available at http://csrc.ncsl.nist.gov/encryption/skipjack-1.pdf.
National Security Agency. NSA Releases Fortezza Algorithms, Press Release, June 24, 1998. Available at http://csrc.ncsl.nist.gov/encryption/nsa-press.pdf.
D. Wagner. The boomerang attack. In L. Knudsen, editor, Fast Software Encryption, volume 1636 of Lecture Notes in Computer Science, pages 156–170, 1999. Springer Verlag.
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Knudsen, L.R., Robshaw, M.J.B., Wagner, D. (1999). Truncated Differentials and Skipjack. In: Wiener, M. (eds) Advances in Cryptology — CRYPTO’ 99. CRYPTO 1999. Lecture Notes in Computer Science, vol 1666. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-48405-1_11
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DOI: https://doi.org/10.1007/3-540-48405-1_11
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