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Author Contact Information:

   Robert G. Brown	
   Duke University Dept. of Physics, Box 90305
   Durham, N.C. 27708-0305
   Phone: 1-919-660-2567  
   Fax: 919-660-2525  
   Email: rgb@phy.duke.edu
   URL: http://www.phy.duke.edu/~rgb

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               Notes About the Tests in Dieharder

Dieharder is original code written by and Copyright Robert G. Brown
(with different code modules written over the period 2003-present).  The
tests included (or expected to be included in the future) in dieharder,
are, however, derived from descriptions from several places.

  * Diehard, a famous suite of random number tests written over many
years by George Marsaglia.  The original Diehard sources (written in
Fortran) are (of course) Copyright George Marsaglia according to the
Berne convention, where authors retain copyright with or without a
notice in any original work.  The original Diehard code written by
Marsaglia did not include a copyright notice or an explicit license in
or with the sources that have been made publically available on the web
for many years.  When contacted, Dr. Marsaglia has indicated his wish to
restrict commercial usage of his code and permit only academic/research
related use.  For this reason the the algorithms are fully
re-implemented, in original code, in dieharder to keep authorship and
GPL licensing issues clear.  However, all diehard-equivalent tests are
clearly labelled as such and academically attributed to Dr. Marsaglia.

  * The National Institute of Standards and Technology (NIST)
Statistical Test Suite (STS) as described in publication SP800-22b.
Although this test suite was developed with government support and is
explicitly in the public domain, and is available in C source.  There is
some overlap between STS and Diehard -- for example, both have binary
matrix rank tests -- but the STS focusses primarily on bitlevel
randomness and the suitability of a random number generator for use in
cryptographic applications.  The tests described in SP800-22b that are
implemented in dieharder are completely rewritten in original C by
Robert G. Brown to keep copyright and GPL issues clear.  All STS-derived
tests are clearly labelled as such and are academically attributed to
the various authors of the suite (Andrew Rukhin, Juan Soto, James
Nechvatal, Miles Smid, Elaine Barker, Stefan Leigh, Mark Levenson, Mark
Vangel, David Banks, Alan Heckert, James Dray, San Vo).

  * Original tests or timing operations inserted by Robert G. Brown.
Almost any distribution that can be computed on the basis of a source of
random numbers with a derived statistic with known or reliably
measurable statistical properties can serve as a test of random numbers
using the general approach implemented in Diehard, the STS, Dieharder,
and elsewhere.

  * Tests described in Knuth's The Art of Computer Programming.

  * User-contributed tests.

  * Tests described elsewhere in the literature.

In all cases some effort has been made to correctly attribute the
originator of a test algorithm, and if there are any errors in this
regard they will be happily corrected once they are brought to the
attention of the author.

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                         To Build Dieharder

Dieharder can be built from source in most cases by simply typing "make"
on the command line while in the source directory.  However, it does
require certain resources to build, notably the Gnu Scientific Library
in a revision no earlier than 1.4 (and ideally greater than 1.6).  It
has been tested primarily on gcc/linux-based systems, but should port
well to any unixoid environment with at most some minor hacking of the
include files or systems calls used.

If one is using an RPM-based linux, the easiest way to simply build and
install the library is to either take a chance on installing a binary
rpm, preferrably one that was built on a system with the same general
distribution and environment, or rebuilding the source RPM.  However,
RPM based installations are actually less desireable with a tool such as
diehard than source builds, since part of its appeal is the availability
of its source and the ease with which new tests or generators can be
directly implemented.  

Dieharder is an open source project for a reason -- it simply is not
possible to trust a test suite of this sort without access to the source
because even a subtle error in the sources or data used to perform a
test will cause the test to return incorrect answers, conceivably to the
detriment of all concerned.  With the source readily available, any user
is free to examine or modify the source for any test and determine
whether or not the test is working and participate in the critical
process whereby academia arrives at a consensus truth.

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                 Licensing and Revision Control

Dieharder is (as noted) Copyright Robert G. Brown, 2003-2006.  It has
been kept under revision control (first CVS, more recently Subversion)
since the inception of the process in 2003 and all incremental changes
to the code as it was developed are carefully documented.

Dieharder was deliberately developed to by a GPL project, since
alternative random number test suites were either incomplete with regard
to the span of test possibilities of interest to the author, restricted
or unclear about their licensing restrictions, or both.  In addition, by
integrating from the beginning with the Gnu Scientific Library (which is
a full GPL project with the viral version of the license) it becomes
itself a GPL project in any event.

It is strongly suggested that prospective users of this test read the
terms of the license included with this source distribution in the file
COPYING.  In summary, permission is granted to freely use and modify the
sources and distribute the result or any binary objects derived
therefrom as long as the terms of the GPL are abided by.  These terms
require the preservation of all copyright and license information in the
sources and that the source of any and all revisions to the original
dieharder code be made available upon request to any receivers of a
dieharder binary, among other things.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

If any user of the dieharder program should revise the program in a way
that is likely to be of use to others, they are encouraged to at least
offer to contribute the revision back to the project (subject to the
"editorial" approval of the primary author).  Contact Robert G. Brown to
arrange for such a contribution.

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