Skein

1 The algorithm

• Author(s): Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas, Jesse Walker
• Website: http://www.schneier.com/skein.html; http://skein-hash.info/
• NIST submission package:
  • round 1: SkeinUpdate.zip (old version: Skein.zip)
  • round 2: Skein_Round2.zip

Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas, Jesse Walker - The Skein Hash Function Family

,2009

http://www.skein-hash.info/sites/default/files/skein1.2.pdf
Bibtex

Author : Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas, Jesse Walker
Title : The Skein Hash Function Family
In : -
Address :
Date : 2009

Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas, Jesse Walker - The Skein Hash Function Family

,2008

http://www.skein-hash.info/sites/default/files/skein.pdf
Bibtex

Author : Niels Ferguson, Stefan Lucks, Bruce Schneier, Doug Whiting, Mihir Bellare, Tadayoshi Kohno, Jon Callas, Jesse Walker
Title : The Skein Hash Function Family
In : -
Address :
Date : 2008

2 Cryptanalysis

We distinguish between two cases: results on the complete hash function, and results on underlying building blocks.

A description of the tables is given here.

Recommended security parameter: 72 rounds

2.1 Hash function

Here we list results on the hash function according to the NIST requirements. The only allowed modification is to change the security parameter.

Type of Analysis	Hash Size (n)	Parameters	Compression Function Calls	Memory Requirements	Reference

2.2 Building blocks

Here we list results on underlying building blocks, and the hash function modified by other means than the security parameter.

Note that these results assume more direct control or access over some internal variables (aka. free-start, pseudo, compression function, block cipher, or permutation attacks).

Type of Analysis	Hash Function Part	Hash Size (n)	Parameters/Variants	Compression Function Calls	Memory Requirements	Reference
near collision	compression function	512	17 rounds (Round 1)	224	-	Aumasson,Calik,Meier,Ozen,Phan,Varici
distinguisher	block cipher	512	35 rounds (Round 1)	2478	-	Aumasson,Calik,Meier,Ozen,Phan,Varici
impossible differential	block cipher	512	21 rounds (Round 1)	-	-	Aumasson,Calik,Meier,Ozen,Phan,Varici
key recovery	block cipher	512	32 rounds (Round 1)	2312	-	Aumasson,Calik,Meier,Ozen,Phan,Varici
key recovery	block cipher	512	32 rounds (Round 1)	2226 (2222)	212	Chen,Jia
key recovery	block cipher	512	33 rounds (Round 1)	2352.17 (2355.5)	-	Chen,Jia
key recovery	block cipher	256	39 rounds	2254.1	-	Khovratovich,Nikolic
key recovery	block cipher	512	42 rounds	2507	-	Khovratovich,Nikolic

Jean-Philippe Aumasson, Cagdas Calik, Willi Meier, Onur Ozen, Raphael C.-W. Phan, Kerem Varici - Improved Cryptanalysis of Skein

,2009

http://eprint.iacr.org/2009/438.pdf
Bibtex

Author : Jean-Philippe Aumasson, Cagdas Calik, Willi Meier, Onur Ozen, Raphael C.-W. Phan, Kerem Varici
Title : Improved Cryptanalysis of Skein
In : -
Address :
Date : 2009

Jiazhe Chen, Keting Jia - Improved Related-key Boomerang Attacks on Round-Reduced Threefish-512

,2009

http://eprint.iacr.org/2009/526.pdf
Bibtex

Author : Jiazhe Chen, Keting Jia
Title : Improved Related-key Boomerang Attacks on Round-Reduced Threefish-512
In : -
Address :
Date : 2009

Dmitry Khovratovich, Ivica Nikolic - Rotational Cryptanalysis of ARX

,2010

http://cryptolux.org/mediawiki/uploads/5/5b/Rotational_Cryptanalysis_of_Skein.pdf
Bibtex

Author : Dmitry Khovratovich, Ivica Nikolic
Title : Rotational Cryptanalysis of ARX
In : -
Address :
Date : 2010

2.3 Archive

Jean-Philippe Aumasson, Willi Meier, Raphael Phan - Improved analyis of Threefish

,2009

http://131002.net/data/talks/threefish_rump.pdf
Bibtex

Author : Jean-Philippe Aumasson, Willi Meier, Raphael Phan
Title : Improved analyis of Threefish
In : -
Address :
Date : 2009