Catalyst::Plugin::Authentication::Credential::CHAP - Authenticate a user using a CHAP login system.


    use Catalyst qw/

    __PACKAGE__->config->{authentication}->{chap} = {
        hash_algorithm => 'SHA-1',

    sub begin : Private {
        my ($self, $c) = @_;
        $c->chap_init; # Generate a Challenge string and stores it in the session.
        $c->stash("challenge_string", $c->get_challenge_string);

    package MyApp::Controller::Auth;

    # *** NOTE ***
    # if you place an action named 'login' in your application's root (as
    # opposed to inside a controller) the following snippet will recurse,
    # giving you lots of grief.
    # never name actions in the root controller after plugin methods - use
    # controllers and : Global instead.

    sub login : Local {
        my ( $self, $c ) = @_;

        $c->login( $c->req->param('username'), $c->req->param('password') );

    # Template.html
    <form name="MyForm">
    <input type="password" name="form_password" onclick="sendPassword();"/>
    <input type="hidden" name="password" value="" />
    <input type="hidden" name="challenge" value="[% challenge_string %]" />

    # Javascript (Client side)
    function sendPassword() {
        var password = document.forms['MyForm'].form_password.value
                       + document.forms['MyForm'].challenge.value;
        document.forms['MyForm'].password.value = encode_sha1(password);
        document.forms['MyForm'].form_password.value = '';
        document.forms['MyForm'].challenge.value = '';


This credential checker inherits from Catalyst::Plugin::Authentication::Credential::Password. It generates a challenge string that the user agent must concatenate to the password before encoding it with a hash algorithm. When logging in, this plugin will compare the sent password to the one stored, encoded with the same challenge string saved in the session data. It is meant to allow you to securely send passwords over a clear HTTP connection.

clear text password

If the user has a clear text password it will be compared directly. You just have to concatenate the challenge string to the password and encode it with any of the hash methods supported by the Digest module.

hashed password

If the stored password is hashed, you will have to encode it in your client BEFORE concatenating the challenge string to it, and then encode the whole string again before sending it to the server.

crypted password

UNIX crypt hashed password are not supported. You must store your passwords either in clear or hashed.


You must use Sessions.



The length of the challenge string. Default is 40.


The hash method used to encode the password+challenge string, client-side. It can be any method supported by the Digest module, as long as you have a way to use the same on the client. Default is MD5. More information and javascript functions can be found at


login $username, $password

Inherited from Catalyst::Plugin::Authentication::Credential::Password.

Try to log a user in.

$username can be a string (e.g. retrieved from a form) or an object. If the object is a Catalyst::Plugin::Authentication::User it will be used as is. Otherwise $c->get_user is used to retrieve it.

$password is a hash of the password and the challenge string, encoded client side.

If $username or $password are not provided, the query parameters login, user, username and password, passwd, pass will be tried instead.

chap_init $force

Generates a challenge string for the current session. You can put it in your root's begin/end actions if needed, the challenge string won't change until the session ends or you call this method with $force set to 1.


Returns the current challenge string.



After the user is logged in, the user object for the current logged in user can be retrieved from the context using the $c->user method.

The current user can be logged out again by calling the $c->logout method.


See Catalyst::Plugin::Authentication::Credential::Password.


Catalyst::Plugin::Authentication, Catalyst::Plugin::Authentication::Credential::Password, Catalyst::Plugin::Session.


    Renaud Drousies.