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lib/Authen/SCRAM/Server.pm  view on Meta::CPAN

use 5.008;
use strict;
use warnings;

package Authen::SCRAM::Server;
# ABSTRACT: RFC 5802 SCRAM Server

our $VERSION = '0.011';

use Moo 1.001000;

use Authen::SASL::SASLprep qw/saslprep/;
use Carp qw/croak/;
use Crypt::URandom qw/urandom/;
use Encode qw/encode_utf8/;
use MIME::Base64 qw/decode_base64/;
use PBKDF2::Tiny 0.003 qw/derive digest_fcn hmac/;
use Types::Standard qw/Str Num CodeRef Bool/;

use namespace::clean;

with 'Authen::SCRAM::Role::Common';

#--------------------------------------------------------------------------#
# public attributes
#--------------------------------------------------------------------------#

#pod =attr credential_cb (required)
#pod
#pod This attribute must contain a code reference that takes a username (as a
#pod character string normalized by SASLprep) and returns the four user-credential
#pod parameters required by SCRAM: C<salt>, C<StoredKey>, C<ServerKey>, and
#pod C<iteration count>.  The C<salt>, C<StoredKey> and C<ServerKey> must be
#pod provided as octets (i.e. B<NOT> base64 encoded).
#pod
#pod If the username is unknown, it should return an empty list.
#pod
#pod     ($salt, $stored_key, $server_key, $iterations) =
#pod         $server->credential_cb->( $username );
#pod
#pod See L<RFC 5802: SCRAM Algorithm Overview|http://tools.ietf.org/html/rfc5802#section-3>
#pod for details.
#pod
#pod =cut

has credential_cb => (
    is       => 'ro',
    isa      => CodeRef,
    required => 1,
);

#pod =attr auth_proxy_cb
#pod
#pod If provided, this attribute must contain a code reference that takes an
#pod B<authentication> username and a B<authorization> username (both as character
#pod strings), and return a true value if the authentication username is permitted
#pod to act as the authorization username:
#pod
#pod     $bool = $server->auth_proxy_cb->(
#pod         $authentication_user, $authorization_user
#pod     );
#pod
#pod It will only be all called if the authentication username has successfully
#pod authenticated.  Both usernames will have been normalized via C<SASLprep> with
#pod any transport encoding removed before being passed to this function.
#pod
#pod =cut

has auth_proxy_cb => (
    is      => 'ro',
    isa     => CodeRef,
    default => sub {
        return sub { 1 }
    },
);

#--------------------------------------------------------------------------#
# provided by Authen::SCRAM::Role::Common
#--------------------------------------------------------------------------#

with 'Authen::SCRAM::Role::Common';

#pod =attr digest
#pod
#pod Name of a digest function available via L<PBKDF2::Tiny>.  Valid values are
#pod SHA-1, SHA-224, SHA-256, SHA-384, or SHA-512.  Defaults to SHA-1.
#pod
#pod =attr nonce_size
#pod
#pod Size of the client-generated nonce, in bits.  Defaults to 192.
#pod The server-nonce will be appended, so the final nonce size will
#pod be substantially larger.
#pod
#pod =attr skip_saslprep
#pod
#pod A boolean that defaults to false.  If set to true, usernames and passwords will
#pod not be normalized through SASLprep.  This is a deviation from the RFC5802 spec
#pod and is not recommended.

lib/Authen/SCRAM/Server.pm  view on Meta::CPAN

=encoding UTF-8

=head1 NAME

Authen::SCRAM::Server - RFC 5802 SCRAM Server

=head1 VERSION

version 0.011

=head1 SYNOPSIS

    use Authen::SCRAM::Server;
    use Try::Tiny;

    $server = Authen::SCRAM::Server->new(
        credential_cb => \&get_credentials,
    );

    $username = try {
        # get client-first-message

        $server_first = $server->first_msg( $client_first );

        # send to client and get client-final-message

        $server_final = $server->final_msg( $client_final );

        # send to client

        return $server->authorization_id; # returns valid username
    }
    catch {
        die "Authentication failed!"
    };

=head1 DESCRIPTION

This module implements the server-side SCRAM algorithm.

=head1 NAME

Authen::SCRAM::Server - RFC 5802 SCRAM Server

=head1 VERSION

version 0.011

=head1 ATTRIBUTES

=head2 credential_cb (required)

This attribute must contain a code reference that takes a username (as a
character string normalized by SASLprep) and returns the four user-credential
parameters required by SCRAM: C<salt>, C<StoredKey>, C<ServerKey>, and
C<iteration count>.  The C<salt>, C<StoredKey> and C<ServerKey> must be
provided as octets (i.e. B<NOT> base64 encoded).

If the username is unknown, it should return an empty list.

    ($salt, $stored_key, $server_key, $iterations) =
        $server->credential_cb->( $username );

See L<RFC 5802: SCRAM Algorithm Overview|http://tools.ietf.org/html/rfc5802#section-3>
for details.

=head2 auth_proxy_cb

If provided, this attribute must contain a code reference that takes an
B<authentication> username and a B<authorization> username (both as character
strings), and return a true value if the authentication username is permitted
to act as the authorization username:

    $bool = $server->auth_proxy_cb->(
        $authentication_user, $authorization_user
    );

It will only be all called if the authentication username has successfully
authenticated.  Both usernames will have been normalized via C<SASLprep> with
any transport encoding removed before being passed to this function.

=head2 digest

Name of a digest function available via L<PBKDF2::Tiny>.  Valid values are
SHA-1, SHA-224, SHA-256, SHA-384, or SHA-512.  Defaults to SHA-1.

=head2 nonce_size

Size of the client-generated nonce, in bits.  Defaults to 192.
The server-nonce will be appended, so the final nonce size will
be substantially larger.

=head2 skip_saslprep

A boolean that defaults to false.  If set to true, usernames and passwords will
not be normalized through SASLprep.  This is a deviation from the RFC5802 spec
and is not recommended.

=head1 METHODS

=head2 first_msg

    $server_first_msg = $server->first_msg( $client_first_msg );

This takes the C<client-first-message> received from the client and returns the
C<server-first-message> string to be sent to the client to continue a SCRAM
session.  Calling this again will reset the internal state and initiate a new
session.  This will throw an exception should an error occur.

=head2 final_msg

    $server_final_msg = $server->final_msg( $client_final_msg );

This takes the C<client-final-message> received from the client and returns the
C<server-final-message> string containing the verification signature to be sent
to the client.

If an authorization identity was provided by the client, it will confirm that
the authenticating username is authorized to act as the authorization id using
the L</auth_proxy_cb> attribute.