phpman > perldoc > Authen::Captcha(3pm)

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 accessible 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 "$token.png"
      my $token = $captcha->generate_code($number_of_characters);

      # check for a valid submitted captcha
      #   $code is the submitted letter combination guess from the user
      #   $token is the submitted token from the user (that we gave them)
      my $results = $captcha->check_code($code,$token);
      # $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 token)
      ##############

WARNING
    The captcha produced by this module is rather weak compared to other modules available. You are
    advised to update to GD::SecurityImage, which provides API-compatible interface in
    GD::SecurityImage::AC module.

ABSTRACT
    Authen::Captcha provides an object oriented interface to captcha file creations. Captcha stands
    for Completely Automated Public Turing 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
             keep_failures => 0, # optional, defaults to 0(false)
             debug => 0, # optional. default 0

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

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

    "$results = $captcha->check_code($code,$token);"
        check for a valid submitted captcha

        $code is the submitted letter combination guess from the user

        $token is the submitted token from the user (that we gave them)

        If the $code and $token are correct, the image file and database entry will be removed.

        If the $token matches one in the database, and "keep_failures" is false (the default), the
        image file and database entry will be removed to avoid repeated attempts on the same
        captcha.

        $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 token)

  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 tokens. 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
        accessible 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 accessible directory so that the user can view the images in here, but it doesn't have
        to be web accessible (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->keep_failures( [0|1] );"
        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.

    "$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 AT purifieddata.net>

    Josh I. Miller, <jmiller AT 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.

    Fixes were reported and contributed by various people, see Changes file for a complete list.

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

    Copyright 2003 by Seth Jackson

    Copyright 2012 by Paolo Rossi, Lubomir Rintel, Chris Dunlop, Gert Schepens and Ernesto
    Hernández-Novich

    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