NAME

Captcha::reCAPTCHA - A Perl implementation of the reCAPTCHA API

VERSION

This document describes Captcha::reCAPTCHA

SYNOPSIS

use Captcha::reCAPTCHA;

my $c = Captcha::reCAPTCHA->new;

# Output form
print $c->get_html( 'your public key here' );

# Verify submission
my $result = $c->check_answer(
    'your private key here', $ENV{'REMOTE_ADDR'},
    $challenge, $response
);

if ( $result->{is_valid} ) {
    print "Yes!";
}
else {
    # Error
    $error = $result->{error};
}

For complete examples see the /examples subdirectory

DESCRIPTION

reCAPTCHA is a hybrid mechanical turk and captcha that allows visitors who complete the captcha to assist in the digitization of books.

From http://recaptcha.net/learnmore.html:

reCAPTCHA improves the process of digitizing books by sending words that
cannot be read by computers to the Web in the form of CAPTCHAs for
humans to decipher. More specifically, each word that cannot be read
correctly by OCR is placed on an image and used as a CAPTCHA. This is
possible because most OCR programs alert you when a word cannot be read
correctly.

This Perl implementation is modelled on the PHP interface that can be found here:

http://recaptcha.net/plugins/php/

To use reCAPTCHA you need to register your site here:

https://www.google.com/recaptcha/admin/create

INTERFACE

new

Create a new Captcha::reCAPTCHA.

get_html( $pubkey, $error, $use_ssl, $options )

Generates HTML to display the captcha.

print $captcha->get_html( $PUB, $err );

$pubkey

Your reCAPTCHA public key, from the API Signup Page

$error

Optional. If set this should be either a string containing a reCAPTCHA status code or a result hash as returned by check_answer.

$use_ssl

Optional. Should the SSL-based API be used? If you are displaying a page to the user over SSL, be sure to set this to true so an error dialog doesn't come up in the user's browser.

$options

Optional. A reference to a hash of options for the captcha. See get_options_setter for more details.

Returns a string containing the HTML that should be used to display the captcha.

get_options_setter( $options )

You can optionally customize the look of the reCAPTCHA widget with some JavaScript settings. get_options_setter returns a block of Javascript wrapped in <script> .. </script> tags that will set the options to be used by the widget.

$options is a reference to a hash that may contain the following keys:

theme

Defines which theme to use for reCAPTCHA. Possible values are 'red', 'white' or 'blackglass'. The default is 'red'.

tabindex

Sets a tabindex for the reCAPTCHA text box. If other elements in the form use a tabindex, this should be set so that navigation is easier for the user. Default: 0.

check_answer

After the user has filled out the HTML form, including their answer for the CAPTCHA, use check_answer to check their answer when they submit the form. The user's answer will be in two form fields, recaptcha_challenge_field and recaptcha_response_field. The reCAPTCHA library will make an HTTP request to the reCAPTCHA server and verify the user's answer.

$privkey

Your reCAPTCHA private key, from the API Signup Page.

$remoteip

The user's IP address, in the format 192.168.0.1.

$challenge

The value of the form field recaptcha_challenge_field

$response

The value of the form field recaptcha_response_field.

Returns a reference to a hash containing two fields: is_valid and error.

my $result = $c->check_answer(
    'your private key here', $ENV{'REMOTE_ADDR'},
    $challenge, $response
);

if ( $result->{is_valid} ) {
    print "Yes!";
}
else {
    # Error
    $error = $result->{error};
}

See the /examples subdirectory for examples of how to call check_answer.

Note: this method will make an HTTP request to Google to verify the user input. If this request must be routed via a proxy in your environment, use the standard environment variable to specify the proxy address, e.g.:

$ENV{http_proxy} = 'http://myproxy:3128';

CONFIGURATION AND ENVIRONMENT

Captcha::reCAPTCHA requires no configuration files or environment variables.

To use reCAPTCHA sign up for a key pair here:

https://www.google.com/recaptcha/admin/create

DEPENDENCIES

LWP::UserAgent, HTML::Tiny

INCOMPATIBILITIES

None reported .

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to bug-captcha-recaptcha@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

Andy Armstrong <andy@hexten.net>

LICENCE AND COPYRIGHT

Copyright (c) 2007, Andy Armstrong <andy@hexten.net>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.