Below is a list of Skein files included on the NIST submission CD, along
with a very brief description of each file. In both the reference and
optimized directories, all C files should be compiled to generate a
SHA3 NIST API "library" for Skein.
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The following files are identical and common between the reference and optimized
versions of the code:
File Name Description
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brg_endian.h Brian Gladman's header file to auto-detect CPU endianness
(with a few extensions for handling various platforms/compilers)
brg_types.h Brian Gladman's header file to auto-detect integer types
(with a few extensions for handling various platforms/compilers)
SHA3api_ref.h API definitions for SHA3 API, implemented in SHA3api_ref.c
SHA3api_ref.c "Wrapper" code that implements the NIST SHA3 API on top of the
Skein API.
skein_debug.h Header for with routines used internally by Skein routines for
generating debug i/o (e.g., round-by-round intermediate values)
If SKEIN_DEBUG is not defined at compile time, these interface
declarations instead become "dummy" macros so that there is
no performance impact.
skein_debug.c Debug i/o routines called by Skein functions.
skein.h Function prototypes, data structures, and constant definitions
for Skein. The Skein API is more general than the NIST API
(e.g., MAC functions).
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The following files are different for the reference and optimized versions
of the code. Note that the source files in Optimized_32bit and Optimized_64bit
directories are identical.
File Name Description
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skein_port.h Definitions that might need to be changed to port Skein to
a different CPU platform (e.g., big-endian). The Skein code
should run on most CPU platforms, but the macros/functions here
may be helpful in making the code run more efficiently
skein.c The main Skein interface functions: Init, Update, and Final, for
all three Skein block sizes. Additionally, the InitExt() function
allows for MAC and other extended functionality.
skein_block.c The Skein block processing function, based on the Threefish block
cipher. This module contains the most performance-sensitive code
and can be replaced by the assembly modules for slight speedups
on some platforms. The functions here are only for internal use
inside "skein.c" and are not intended for external APIs.
skein_iv.h Initial values for various Skein hash functions. Note that these
values are NOT "magic constants", as they are computed using
the initial Skein "configuration" block. These values are used
only by the optimized code, in order to speed up the hash
computations.
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The following files are included in the Additional_Implementations directory:
File Name Description
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skein_test.c The Skein test module, used to measure performance and generate
KAT vectors for testing. This module should be compiled together
with the Skein source files (i.e., from the Reference or the
Optimized directories) to generate an executable, skein_test.exe.
This program is used internally to test/validate/compare different
implementations (e.g., Reference, Optimized, Assembly).
skein_block_x64.asm This is the 64-bit assembly language version of skein_block.c.
It may be used to replace that file in the Optimized_64bit
directory to improve performance on 64-bit Intel/AMD systems.
It should be assembled with ml64.exe.
skein_block_x86.asm This is the 32-bit assembly language version of skein_block.c.
It may be used to replace that file in the Optimized_32bit
directory to improve performance on 32-bit Intel/AMD systems.
It should be assembled with ml.exe.
skein_rot_search.c This is the program that searches for the Threefish rotation
constants. It has many different command-line switches, but by
default it generates the constants used in the Skein paper.
This file is a stand-alone C file. To run it, simply re-direct
the output to a test file: "skein_rot_search > srs_log.txt".
Note that it takes nearly 3 DAYS on a Core 2 Duo to complete
program execution in this case. Alternately, to generate individual
files, run the following command lines:
skein_rot_search -b256 > srs_256.txt
skein_rot_search -b512 > srs_512.txt
skein_rot_search -b1024 > srs_1024.txt
srs_256.txt These three files contain the results of running skein_rot_search.exe
srs_512.txt for the three different Skein block sizes. They are rather large.
srs_1024.txt At the end of each file, the "finalists" are re-graded with different
number of random samples.
Atmel_AVR.c This file was used to compile on the Atmel AVR 8-bit CPU.
It includes the optimized versions of skein.c and skein_block.c
with compile-time settings to only implement one at time.
This was compiled with the free AVR tool set from Atmel
and simulated to give the 8-bit C performance numbers.
skein_8bit_estimates.xls
This file is a spreadsheet used to generate the estimates for
code size and speed of assembly versions of Skein on the Atmel
8-bit CPU family. Note that this is MUCH faster than the C
versions, since it uses static variables, with optimized loading
and rotations. No attempt is made here to minimize code size by
sharing code using calls, although the code size could be shrunk
significantly using calls, at some cost in performance.
skein_perf_core2.txt
This file contains code size and performance data running on
an Intel Core 2 Duo CPU under Windows Vista 64-bit, using the
Microsoft and other compilers and assemblers. It includes
results for both 32-bit and 64-bit code.
skein_MSC_v9_perf.txt
This file contains a subset of the skein_perf_core2.txt file,
including only results from the MSVC 2008 compiler, with message
sizes that are powers of 10.
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The following files are included in the KAT_MCT directory, in addition to the
KAT/MCT files required by NIST:
genKAT.c NIST-supplied source file for generating KAT_MCT vectors.
This module should be compiled together with the Skein source
files (i.e., from the Reference or the Optimized directories)
to generate an executable genKAT.exe, which can generate the
KAT_MCT vectors.
[FWIW, compiling this source file under gcc gives several nasty compiler warnings!]
skein_golden_kat.txt
The "golden" KAT file generated using "skein_test.exe -k". This
file tries to cover various block sizes, message sizes, and output
sizes, as well as MAC modes. It is used for testing compliance of
a Skein implementation, using skein_test.c
skein_golden_kat_internals.txt
The KAT file generated using "skein_test.exe -k -dc". It covers
the same test as "skein_golden_kat.txt" , but also prints out
intermediate (round-by-round) values. The file is very large, but
it is quite useful in debugging when porting Skein to a new
CPU platform and/or programming language.
skein_golden_kat_short.txt
This is a shorter version (subset) of skein_golden_kat.txt
skein_golden_kat_short_internals.txt
This is a shorter version (subset) of skein_golden_kat_internals.txt
