The Skein Hash Function Family

Romeo Costanza writes:

From: Romeo Costanzo
Subject: R: Skein code release
Date: July 21, 2011 7:08:31 AM PDT
To: Jon Callas

Hi Jon,

in the attached file you'll find the following:
1. mlskntst.asm is the test driver
2. mlsknalg.asm contains the implementation of skein-512-512 and skein-mac
3. mlskndef.inc contains few definitions and macros
Please put it in your site; the code is free for non-commercial and commercial
use.

The target is the Microchip's MCU PIC18F45K20; target IDE: "MPLAB IDE v 8.73".

The SPARKSkein 2011 release has been updated to meet version 1.3 of the Skein specification. All analyses and proofs have also been regenerated using the recently-released GPL 2011 edition of the SPARK toolset.

The updated release is available here.

We would also like to see other implementations, as well.

Date: Tue, 28 Jun 2011 09:22:32 -0500
From: HГҐkon Hitland
Subject: Skein implementation for ARM

Hi,

I recently tried to find information on the performance of Skein on ARM platforms, but I could not find any implementation of Skein that were optimised for the ARM architecture.

I have therefore created an implementation of the Skein block function that uses the 128-bit SIMD operations that are available on high-performance ARM processors, like the ones used in smart phones.

On a Cortex-A8 processor I get 15.5 cycles per byte for Skein-512, and around 20.3 cpb for Skein-256 and Skein-1024.

The code is available at https://github.com/unbounded/skein-arm

I would like to know if the Skein team are aware of any comparable implementations.

Best regards,
HГҐkon Hitland

One of the major features of Skein is that it has a hashing mode that is a one-pass MAC. Normally, HMACs are used with hash functions, but generating an HMAC requires two hashes. In protocols that send a lot of short messages (like VOIP and other media services), a one-pass MAC effectively halves the amount of computes needed. Werner writes of his work:

Date: Wed, 29 Dec 2010 10:56:17 -0600
To: Bruce Schneier
From: Werner Dittmann
Subject: Skein and Threefish - yet another contribution

Dear Bruce, dear Skein team,

Jörg Walter has updated his fhreefish implementation of Skein to the 1.3 spec.

The URL is the same, http://www.syntax-k.de/projekte/fhreefish/.

From: "Burr, William E."
Date: December 9, 2010 2:24:30 PM PST
To: Multiple recipients of list
Subject: The SHA-3 Finalists
Reply-To: hash-forum@nist.gov

NIST has selected five SHA-3 candidate algorithms to advance to the third (and final) round:
g BLAKE
g GrЁstl
g JH
g Keccak
g Skein

AN EFFICIENT PARALLEL ALGORITHM FOR SKEIN HASH FUNCTIONS
K. Atighehchi and A. Enache and T. Muntean and G. Risterucci

Altran Praxis and AdaCore have released SPARKSkein - a new reference implementation of Skein-512 written and verified using the SPARK language and toolset. In particular, this release includes a complete proof of type-safety for the implementation, test cases for structural coverage, performance, and the reference test vectors from the Skein specification.

Download is available from the downloads page or here directly.

Hagen F¬rstenau has updated his pyskein implementation of Skein in Python. The new implementation includes the one-pass MAC generation, nonce and personalization inputs, and the Skein-PRNG. All the extra features are done for all three state sizes, Skein-256, Skein-512, and Skein-1024.

The package is available at http://packages.python.org/pyskein/.