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
observations	block cipher	all	-	-	-	McKay,Vora
observations	compression function	all	-	-	-	Kaminsky
key recovery	block cipher	256	39 rounds	2^254.1	-	Khovratovich,Nikolic
key recovery	block cipher	512	42 rounds	2⁵⁰⁷	-	Khovratovich,Nikolic
key recovery	block cipher	512	32 rounds (Round 1)	2²²⁶ (2²²²)	2¹²	Chen,Jia
key recovery	block cipher	512	33 rounds (Round 1)	2^352.17 (2^355.5)	-	Chen,Jia
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