NAME Catalyst::Plugin::HashedCookies - Tamper-resistant HTTP Cookies VERSION This document refers to version 1.05 of Catalyst::Plugin::HashedCookies SYNOPSIS use Catalyst qw/HashedCookies/; MyApp->config->{hashedcookies} = { key => $secret_key, algorithm => 'SHA1', # optional required => 1, # optional }; MyApp->setup; # later, in another part of MyApp... print "this cookie tastes good!\n" if $c->request->valid_cookie('my_cookie_name'); DESCRIPTION Overview When HTTP cookies are used to store a user's state or identity it's important that your application is able to distinguish legitimate cookies from those that have been edited or created by a malicious user. This module allows you to determine whether a cookie presented by a client was created in its current state by your own application. Implementation HashedCookies adds a keyed cryptographic hash to each cookie that your application creates, and checks every client-provided cookie for a valid hash. This is done in a transparent way such that you do not need to change any application code that handles cookies when using this plugin. A cookie that fails to contain a valid hash will still be available to your application through "$c->request->cookie()". Two additional methods within the Catalyst request object allow you to check the status (in other words, the vailidity) of your cookies. METHODS Catalyst Request Object Methods "$c->request->valid_cookie($cookie_name)" If a cookie was successfully authenticated then this method will return True, otherwise it will return False. "$c->request->invalid_cookie($cookie_name)" If a cookie failed its authentication, then this method will return True, otherwise it will return False. Please read the "CONFIGURATION" section below to understand what 'failed authentication' really means. CONFIGURATION key MyApp->config->{hashedcookies}->{key} = $secret_key; This parameter is required, and sets the secret key that is used to generate a message authentication hash. Clearly, for a returned cookie to be authenticated the same key must be used both when setting the cookie and retrieving it. algorithm MyApp->config->{hashedcookies}->{algorithm} = 'SHA1'; # or MyApp->config->{hashedcookies}->{algorithm} = 'MD5'; This parameter is optional, and will default to "SHA1" if not set. It instructs the module to use the given message digest algorithm. required MyApp->config->{hashedcookies}->{required} = 0; # or MyApp->config->{hashedcookies}->{required} = 1; This parameter is optional, and will default to 1 if not set. If a cookie is read from the client but does not contain a HashedCookies hash (i.e. this module was not running when the cookie was set), then this parameter controls whether the cookie is ignored. Setting this parameter to True means that a cookie without a hash is treated as if it did have a hash, and therefore the authentication will fail. Setting this parameter to False means that the cookie will be ignored. When a cookie is ignored, neither "$c->request->valid_cookie()" nor "$c->request->invalid_cookie()" will return True, but you can of course still access the cookie through "$c->request->cookie()". DIAGNOSTICS 'Request for unknown digest algorithm to ...' You have attempted to configure this module with an unrecognized message digest algorithm. Please see the "CONFIGURATION" section for the valid algorithms. '"key" is a required configuration parameter to ...' You have forgotten to set the secret key that is used to generate a message authentication hash. See the "SYNOPSIS" or "CONFIGURATION" section for examples of how to set this parameter. 'Attempted use of restricted ("_hashedcookies_*") value in cookie' This module adds values to your cookie, and to avoid clashes with your own values they are named in a special way. If you try to set a cookie with values matching this special name format, your Catalyst Engine's default error handler will be triggered, and the response status code will be set to "500". You cannot trap such errors because they are raised after all the application code has run, but you will see the above error in your log file, and your Application will certainly halt so that Catalyst can display its error page. 'Please make a Request subclass for your application which isa Catalyst::Request::HashedCookies' In order to properly hook into Catalyst, you need a Class for the Catalyst Request object which isa "Catalyst::Request::HashedCookies". This error is thrown not if you are using "Catalyst::Request" as the Class (this is detected and worked around), but instead some 3rd party Class. It can happen, apparently, to "Catalyst::Action::REST" users. Please check the Catalyst wiki for some examples on how to fix your application. DEPENDENCIES Other than the natural dependencies of Catalyst and the contents of the standard Perl distribution, you will need the following: * Digest::HMAC BUGS Please report any bugs or feature requests to "bug-catalyst-plugin-hashedcookies@rt.cpan.org", or through the web interface at . I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. SEE ALSO Catalyst, Digest::HMAC_SHA1, Digest::HMAC_MD5 AUTHOR Oliver Gorwits "" ACKNOWLEDGEMENTS All the helpful people in #catalyst. COPYRIGHT & LICENSE Copyright (c) The University of Oxford 2008. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.