Digest::SHA version 4.0.0
=========================

The Digest::SHA module provides a Perl interface to all varieties
of the Secure Hash Algorithm, namely, SHA-1, SHA-256, SHA-384, and
SHA-512.  Fuctions are also included to compute keyed-hashes using
the HMAC algorithm.

The inteface conforms to all requirements, styles, and conventions
specified in the CPAN Digest:: module, including the option to
calculate digests for messages that aren't aligned on byte boundaries.
Also provided are methods to save and subsequently retrieve
intermediate SHA states to and from persistent storage.

The underlying C code is designed to be portable, and requires no
special libraries beyond those found with typical compilers.
However, if your compiler doesn't recognize the "long long" type,
the functions associated with the SHA-384 and SHA-512 transforms
will return null values.

As of Version 4.0.0, the Digest::SHA module is beginning the process
of deprecating the old "shaopen()/shawrite()/shaclose()" interface
in favor of the more streamlined OO style.  The old functions are
still available, and can be conveniently accessed by inserting

	use Digest::SHA ':legacy';

in your code.  However, continued use of these functions is discouraged.

The tests subdirectory (t/*.t) contains an extensive set of SHA
vectors compiled from various sources.  Of particular interest are
the NIST vectors, which examine a large variety of bit-strings and
byte-strings (see the "t/nist/COPYRIGHT" file for details).  Also
useful are the bit-vectors supplied by Jim Gillogly and Francois
Grieu, which check the behavior of implementations for input strings
that exceed 2^32 bits in length.

INSTALLATION

To install this module type the following:

   perl Makefile.PL
   make
   make test
   make install

DEPENDENCIES

   None.

COPYRIGHT AND LICENCE

Copyright (C) 2003 Mark Shelor

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
