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

  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)
  ##############

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.

    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)

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

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
   keep_failures => 0, # optional, defaults to 0(false)
   debug => 0, # optional. default 0

    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)

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. 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). 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 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. Optional. Number of pixels high for the character graphics. Defaults to 25. Optional. Number of pixels wide for the character graphics. Defaults to 35. Optional. Defaults to zero. This option controls whether or not the captcha will remain valid after a failed attempt. By default, we only allow one attempt to solve it. This greatly reduces the possibility that a bot could brute force a correct answer. Change it at your own risk. Optional. Sets the debugging bit. 1 turns it on, 0 turns it off. 2 will print out verbose messages to STDERR.

sound file captcha: Incorporating distorted sound file creation.

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

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

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 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