Grøstl hash function for PHP 
Version 0.1

Grøstl is a new cryptographic hash function designed in response to the
Cryptographic Hash Algorithm Competition announced by NIST. Grøstl is one of
the five finalists in the competition and it is a tweaked version of its
predecessor called Grøstl-0, the original submission to the competition. 

The author of this extension was in no way involved in the development of the
Grøstl hash function. The hash source code was taken directly from NIST
submission package with a few minor variable name changes so that it would play
nice with PHP.

See the CREDITS section for more details.

= INSTALLATION =

You'll need to have the PHP 5 development package and a working build
environment to compile this module.

To compile and install:

   phpize
   ./configure --enable-groestl
   make
   sudo make install

Then add the following to your php.ini file:

   extension=groestl.so

= USAGE =

Function Description:
   
   string groestl_hash(string $string [, int bit_length = 512])

Example:

   // Build a base-64 encoded hash
   $hash = base64_encode(groestl_hash('Hello, world.'));

= CREDITS =

The Grøstl team: Søren Steffen Thomsen, Martin Schläffer, Christian Rechberger,
Florian Mendel, Krystian Matusiewicz, Lars R. Knudsen, Praveen Gauravaram

PHP extension written by Bryan C. Geraghty <[email protected]>

For more details, see: 

   https://www.groestl.info/
   https://csrc.nist.gov/groups/ST/hash/sha-3/Round3/submissions_rnd3.html

= LICENSE =

The SHA-3 Submission Requirements states:

   "Each submitted algorithm must be available worldwide on a royalty free
   basis during the period of the hash function competition."

If the algorithm is selected as the winner of the competition, the following
applies: 

   "an irrevocable nonexclusive royalty-free license to practice the referenced
   algorithm, reference implementation or the optimized implementations"

If the algorithm is not selected as the winner, the license will be determined
by the team.