Abstract
The hash function Skein is the submission of Ferguson et al. to the NIST Hash Competition, and is arguably a serious candidate for selection as SHA-3. This paper presents the first third-party analysis of Skein, with an extensive study of its main component: the block cipher Threefish. We notably investigate near collisions, distinguishers, impossible differentials, key recovery using related-key differential and boomerang attacks. In particular, we present near collisions on up to 17 rounds, an impossible differential on 21 rounds, a related-key boomerang distinguisher on 34 rounds, a known-related-key boomerang distinguisher on 35 rounds, and key recovery attacks on up to 32 rounds, out of 72 in total for Threefish-512. None of our attacks directly extends to the full Skein hash. However, the pseudorandomness of Threefish is required to validate the security proofs on Skein, and our results conclude that at least 36 rounds of Threefish seem required for optimal security guarantees.
Chapter PDF
Similar content being viewed by others
Keywords
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.
References
Wang, X., Yu, H.: How to Break MD5 and Other Hash Functions. In: Cramer, R. (ed.) EUROCRYPT 2005. LNCS, vol. 3494, pp. 19–35. Springer, Heidelberg (2005)
Wang, X., Yin, Y.L., Yu, H.: Finding Collisions in the Full SHA-1. In: Shoup, V. (ed.) CRYPTO 2005. LNCS, vol. 3621, pp. 17–36. Springer, Heidelberg (2005)
Cannière, C.D., Rechberger, C.: Finding SHA-1 Characteristics: General Results and Applications. In: Lai, X., Chen, K. (eds.) ASIACRYPT 2006. LNCS, vol. 4284, pp. 1–20. Springer, Heidelberg (2006)
Stevens, M., Lenstra, A.K., de Weger, B.: Chosen-Prefix Collisions for MD5 and Colliding X.509 Certificates for Different Identities. In: Naor, M. (ed.) EUROCRYPT 2007. LNCS, vol. 4515, pp. 1–22. Springer, Heidelberg (2007)
NIST: FIPS 180-2 Secure Hash Standard (2002)
NIST: Cryptographic Hash Competition, http://www.nist.gov/hash-competition
Ferguson, N., Lucks, S., Schneier, B., Whiting, D., Bellare, M., Kohno, T., Callas, J., Walker, J.: The Skein Hash Function Family. Submission to NIST (2008)
Bellare, M., Kohno, T., Lucks, S., Ferguson, N., Schneier, B., Whiting, D., Callas, J., Walker, J.: Provable Security Support for the Skein Hash Family, http://www.skein-hash.info/sites/default/files/skein-proofs.pdf (Draft) (February 18, 2009)
Aumasson, J.P., Çalık, Ç., Meier, W., Özen, O., Phan, R.C.W., Varici, K.: Improved Cryptanalysis of Skein. In: Cryptology ePrint Archive (2009)
Biham, E., Chen, R.: Near-Collisions of SHA-0. In: Franklin, M.K. (ed.) CRYPTO 2004. LNCS, vol. 3152, pp. 290–305. Springer, Heidelberg (2004)
NIST: SP 800-22, A Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications (2001)
Biham, E., Biryukov, A., Shamir, A.: Miss in the Middle Attacks on IDEA and Khufu. In: Knudsen, L.R. (ed.) FSE 1999. LNCS, vol. 1636, pp. 124–138. Springer, Heidelberg (1999)
Knudsen, L.R.: DEAL - a 128-bit Block Cipher. Technical Report 151, University of Bergen (1998); submitted as an AES candidate
Jakimoski, G., Desmedt, Y.: Related-Key Differential Cryptanalysis of 192-bit Key AES Variants. In: Matsui, M., Zuccherato, R.J. (eds.) SAC 2003. LNCS, vol. 3006, pp. 208–221. Springer, Heidelberg (2004)
Biham, E., Dunkelman, O., Keller, N.: Related-Key Impossible Differential Attacks on 8-Round AES-192. In: Pointcheval, D. (ed.) CT-RSA 2006. LNCS, vol. 3860, pp. 21–33. Springer, Heidelberg (2006)
Aumasson, J.P., Fischer, S., Khazaei, S., Meier, W., Rechberger, C.: New Features of Latin Dances: Analysis of Salsa, ChaCha, and Rumba. In: Nyberg, K. (ed.) FSE 2008. LNCS, vol. 5086, pp. 470–488. Springer, Heidelberg (2008)
Wagner, D.: The Boomerang Attack. In: Knudsen, L.R. (ed.) FSE 1999. LNCS, vol. 1636, pp. 156–170. Springer, Heidelberg (1999)
Biham, E., Dunkelman, O., Keller, N.: Related-Key Boomerang and Rectangle Attacks. In: Cramer, R. (ed.) EUROCRYPT 2005. LNCS, vol. 3494, pp. 507–525. Springer, Heidelberg (2005)
Biham, E., Dunkelman, O., Keller, N.: New Combined Attacks on Block Ciphers. In: Gilbert, H., Handschuh, H. (eds.) FSE 2005. LNCS, vol. 3557, pp. 126–144. Springer, Heidelberg (2005)
Dunkelman, O.: Techniques for Cryptanalysis of Block Ciphers. PhD thesis, Technion, Israel (February 2006)
Lipmaa, H., Moriai, S.: Efficient Algorithms for Computing Differential Properties of Addition. In: Matsui, M. (ed.) FSE 2001. LNCS, vol. 2355, pp. 336–350. Springer, Heidelberg (2002)
Lipmaa, H., Wallén, J., Dumas, P.: On the Additive Differential Probability of Exclusive-Or. In: Roy, B., Meier, W. (eds.) FSE 2004. LNCS, vol. 3017, pp. 317–331. Springer, Heidelberg (2004)
Knudsen, L.R., Rijmen, V.: Known-Key Distinguishers for Some Block Ciphers. In: Kurosawa, K. (ed.) ASIACRYPT 2007. LNCS, vol. 4833, pp. 315–324. Springer, Heidelberg (2007)
Mendel, F., Rechberger, C., Schläffer, M., Thomsen, S.S.: The Rebound Attack: Cryptanalysis of Reduced Whirlpool and Grøstl. In: Dunkelman, O. (ed.) FSE 2009. LNCS, vol. 5665, pp. 260–276. Springer, Heidelberg (2009)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2009 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Aumasson, JP., Çalık, Ç., Meier, W., Özen, O., Phan, R.C.W., Varıcı, K. (2009). Improved Cryptanalysis of Skein. In: Matsui, M. (eds) Advances in Cryptology – ASIACRYPT 2009. ASIACRYPT 2009. Lecture Notes in Computer Science, vol 5912. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-10366-7_32
Download citation
DOI: https://doi.org/10.1007/978-3-642-10366-7_32
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-10365-0
Online ISBN: 978-3-642-10366-7
eBook Packages: Computer ScienceComputer Science (R0)