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

use 5.008;
use strict;
use warnings;

package Authen::SCRAM::Client;
# ABSTRACT: RFC 5802 SCRAM client

our $VERSION = '0.011';

use Moo 1.001000;

use Carp qw/croak/;
use Encode qw/encode_utf8/;
use MIME::Base64 qw/decode_base64/;
use PBKDF2::Tiny 0.003 qw/derive/;
use Try::Tiny;
use Types::Standard qw/Str Num/;

use namespace::clean;

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

#pod =attr username (required)
#pod
#pod Authentication identity.  This will be normalized with the SASLprep algorithm
#pod before being transmitted to the server.
#pod
#pod =cut

has username => (
    is       => 'ro',
    isa      => Str,
    required => 1,
);

#pod =attr password (required)
#pod
#pod Authentication password.  This will be normalized with the SASLprep algorithm
#pod before being transmitted to the server.
#pod
#pod =cut

has password => (
    is       => 'ro',
    isa      => Str,
    required => 1,
);

#pod =attr authorization_id
#pod
#pod If the authentication identity (C<username>) will act as a different,
#pod authorization identity, this attribute provides the authorization identity.  It
#pod is optional.  If not provided, the authentication identity is considered by the
#pod server to be the same as the authorization identity.
#pod
#pod =cut

has authorization_id => (
    is      => 'ro',
    isa     => Str,
    default => '',
);

#pod =attr minimum_iteration_count
#pod
#pod If the server requests an iteration count less than this value, the client
#pod throws an error.  This protects against downgrade attacks.  The default is
#pod 4096, consistent with recommendations in the RFC.
#pod
#pod =cut

has minimum_iteration_count => (
    is      => 'ro',
    isa     => Num,

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

    return 1;
}

#pod =method computed_keys
#pod
#pod This method returns the opaque keys used in the SCRAM protocol.  It returns
#pod the 'stored key', the 'client key' and the 'server key'.  The server must
#pod have a copy of the stored key and server key for a given user in order to
#pod authenticate.
#pod
#pod This method caches the computed values -- it generates them fresh only if
#pod the supplied salt and iteration count don't match the cached salt and
#pod iteration count.
#pod
#pod =cut

sub computed_keys {
    my ( $self, $salt, $iters ) = @_;
    my $cache = $self->_cached_credentials;

    if ( $cache->[0] eq $salt && $cache->[1] == $iters ) {
        # return stored key, client key, server key
        return @{$cache}[ 2 .. 4 ];
    }

    my $salted_pw =
      derive( $self->digest, encode_utf8( $self->_prepped_pass ), $salt, $iters );
    my $client_key = $self->_hmac_fcn->( $salted_pw, "Client Key" );
    my $server_key = $self->_hmac_fcn->( $salted_pw, "Server Key" );
    my $stored_key = $self->_digest_fcn->($client_key);

    $self->_cached_credentials(
        [ $salt, $iters, $stored_key, $client_key, $server_key ] );

    return ( $stored_key, $client_key, $server_key );
}

1;


# vim: ts=4 sts=4 sw=4 et:

__END__

=pod

=encoding UTF-8

=head1 NAME

Authen::SCRAM::Client - RFC 5802 SCRAM client

=head1 VERSION

version 0.011

=head1 SYNOPSIS

    use Authen::SCRAM::Client;
    use Try::Tiny;

    $client = Authen::SCRAM::Client->new(
        username => 'johndoe',
        password => 'trustno1',
    );

    try {
        $client_first = $client->first_msg();

        # send to server and get server-first-message

        $client_final = $client->final_msg( $server_first );

        # send to server and get server-final-message

        $client->validate( $server_final );
    }
    catch {
        die "Authentication failed!"
    };

=head1 DESCRIPTION

This module implements the client-side SCRAM algorithm.

=head1 NAME

Authen::SCRAM::Client - RFC 5802 SCRAM client

=head1 VERSION

version 0.011

=head1 ATTRIBUTES

=head2 username (required)

Authentication identity.  This will be normalized with the SASLprep algorithm
before being transmitted to the server.

=head2 password (required)

Authentication password.  This will be normalized with the SASLprep algorithm
before being transmitted to the server.

=head2 authorization_id

If the authentication identity (C<username>) will act as a different,
authorization identity, this attribute provides the authorization identity.  It
is optional.  If not provided, the authentication identity is considered by the
server to be the same as the authorization identity.

=head2 minimum_iteration_count

If the server requests an iteration count less than this value, the client
throws an error.  This protects against downgrade attacks.  The default is
4096, consistent with recommendations in the RFC.

=head2 digest