Digest::SHA version 4.0.2
=========================

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.

The  24th  test  vector,  courtesy of David Ireland,  tests  how  well
SHA-256  is implemented for a message containing 2^29 byte repetitions
of  the  ASCII character, 'a'. Please read  t/ireland/ireland.txt  for
details.  Since  this test takes a very long time, it is disabled,  by
default.  To  use  it,  just rename  the  file  "t/24-ireland.tmp"  to
"t/24-ireland.t".

INSTALLATION

To install this module type the following:

    perl Makefile.PL
    make
    make test
    make install

DEPENDENCIES

Digest::base

COPYRIGHT AND LICENSE

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.