NAME
    Authen::Captcha - Perl extension for creating captcha's to verify the
    human element in transactions.

SYNOPSIS
      use Authen::Captcha;

      # create a new object
      my $captcha = Authen::Captcha->new();

      # set the data_folder. contains flatfile db to maintain state
      $captcha->data_folder('/some/folder');

      # set directory to hold publicly accessable images
      $captcha->output_folder('/some/http/folder');

      # Alternitively, any of the methods to set variables may also be
      # used directly in the constructor

      my $captcha = Authen::Captcha->new(
        data_folder => '/some/folder',
        output_folder => '/some/http/folder',
        );

      # create a captcha. Image filename is "$md5sum.png"
      my $md5sum = $captcha->generate_code($number_of_characters);

      # check for a valid submitted captcha
      #   $code is the submitted letter combination guess from the user
      #   $md5sum is the submitted md5sum from the user (that we gave them)
      my $results = $captcha->check_code($code,$md5sum);
      # $results will be one of:
      #          1 : Passed
      #          0 : Code not checked (file error)
      #         -1 : Failed: code expired
      #         -2 : Failed: invalid code (not in database)
      #         -3 : Failed: invalid code (code does not match crypt)
      ##############

ABSTRACT
    Authen::Captcha provides an object oriented interface to captcha file
    creations. Captcha stands for Completely Automated Public Turning test
    to tell Computers and Humans Apart. A Captcha is a program that can
    generate and grade tests that:

        - most humans can pass.
        - current computer programs can't pass

    The most common form is an image file containing distorted text, which
    humans are adept at reading, and computers (generally) do a poor job.
    This module currently implements that method. We plan to add other
    methods, such as distorted sound files, and plain text riddles.

REQUIRES
        GD          (see http://search.cpan.org/~lds/GD-2.11/)
        Digest::MD5 (standard perl module)

    In most common situations, you'll also want to have:

     A web server (untested on windows, but it should work)
     cgi-bin or mod-perl access
     Perl: Perl 5.00503 or later must be installed on the web server.
     GD.pm (with PNG support)

INSTALLATION
    Download the zipped tar file from:

        http://search.cpan.org/search?dist=Authen-Captcha

    Unzip the module as follows or use winzip:

        tar -zxvf Authen-Captcha-1.xxx.tar.gz

    The module can be installed using the standard Perl procedure:

        perl Makefile.PL
        make
        make test
        make install    # you need to be root

    Windows users without a working "make" can get nmake from:

        ftp://ftp.microsoft.com/Softlib/MSLFILES/nmake15.exe

METHODS
  MAIN METHODS

    "$captcha = Authen::Captcha->new();"
        This creates a new Captcha object. Optionally, you can pass in a
        hash with configuration information. See the method descriptions for
        more detail on what they mean.

             data_folder => '/some/folder', # required
             output_folder => '/some/http/folder', # required
             expire => 300, # optional. default 300
             width =>  25, # optional. default 25
             height => 35, # optional. default 35
             images_folder => '/some/folder', # optional. default to lib dir
             debug => 0, # optional. default 0

    "$md5sum = $captcha->generate_code( $number_of_characters );"
        Creates a captcha. Image filename is "$md5sum.png"

        It can also be called in array context to retrieve the string of
        characters used to generate the captcha (the string the user is
        expected to respond with). This is useful for debugging. ex.

        "($md5sum,$chars) = $captcha->generate_code( $number_of_characters
        );"

    "$results = $captcha->check_code($code,$md5sum);"
        check for a valid submitted captcha $code is the submitted letter
        combination guess from the user $md5sum is the submitted md5sum from
        the user (that we gave them) $results will be one of:

            1 : Passed
            0 : Code not checked (file error)
           -1 : Failed: code expired
           -2 : Failed: invalid code (not in database)
           -3 : Failed: invalid code (code does not match crypt)

  ACCESSOR METHODS

    "$captcha->data_folder( '/some/folder' );"
        Required. Sets the directory to hold the flatfile database that will
        be used to store the current non-expired valid captcha md5sum's.
        Must be writable by the process running the script (usually the web
        server user, which is usually either "apache" or "http"), but should
        not be accessable to the end user.

    "$captcha->output_folder( '/some/folder' );"
        Required. Sets the directory to hold the generated Captcha image
        files. This is usually a web accessable directory so that the user
        can view the images in here, but it doesn't have to be web
        accessable (you could be attaching the images to an e-mail for some
        verification, or some other Captcha implementation). Must be
        writable by the process running the script (usually the web server
        user, which is usually either "apache" or "http").

    "$captcha->images_folder( '/some/folder' );"
        Optional, and may greatly affect the results... use with caution.
        Allows you to override the default character graphic png's and
        backgrounds with your own set of graphics. These are used in the
        generation of the final captcha image file. The defaults are held
        in: [lib install dir]/Authen/Captcha/images

    "$captcha->expire( 300 );"
        Optional. Sets the number of seconds this captcha will remain valid.
        This means that the created captcha's will not remain valid forever,
        just as long as you want them to be active. Set to an appropriate
        value for your application. Defaults to 300.

    "$captcha->width( 25 );"
        Optional. Number of pixels high for the character graphics. Defaults
        to 25.

    "$captcha->height( 35 );"
        Optional. Number of pixels wide for the character graphics. Defaults
        to 35.

    "$captcha->debug( [0|1|2] );"
        Optional. Sets the debugging bit. 1 turns it on, 0 turns it off. 2
        will print out verbose messages to STDERR.

TODO
    sound file captcha: Incorporating distorted sound file creation.

SEE ALSO
    The Captcha project: http://www.captcha.net/

    The origonal perl script this came from:
    http://www.firstproductions.com/cgi/

AUTHORS
    Seth T. Jackson, <sjackson@purifieddata.net>

    Josh I. Miller, <jmiller@purifieddata.net>

    First Productions, Inc. created the cgi-script distributed under the GPL
    which was used as the basis for this module. Much work has gone into
    making this more robust, and suitable for other applications, but much
    of the origonal code remains.

COPYRIGHT AND LICENSE
    Copyright 2003, First Productions, Inc. (FIRSTPRODUCTIONS HUMAN TEST
    1.0)

    Copyright 2003 by Seth Jackson

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
    Free Software Foundation; either version 2 of the License, or (at your
    option) any later version. (see license.txt).

    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.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA