Authen::Captcha(3pm) - phpMan

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Captcha(3pm)                   User Contributed Perl Documentation                   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
       Hernandez-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

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