# Copyright (c) 2004-2006 Peter Marschall <peter@adpm.de>.
# Copyright (c) 2025 Aditya Garg <gargaditya08@live.com>.
# All rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.

=head1 NAME

Authen::SASL::Perl -- Perl implementation of the SASL Authentication framework

=head1 VERSION

version 2.2000

=head1 SYNOPSIS

 use Authen::SASL qw(Perl);

 $sasl = Authen::SASL->new(
   mechanism => 'CRAM-MD5 PLAIN ANONYMOUS',
   callback => {
     user => $user,
     pass => \&fetch_password
   }
 );

=head1 DESCRIPTION

B<Authen::SASL::Perl> is the pure Perl implementation of SASL mechanisms
in the B<Authen::SASL> framework.

At the time of this writing it provides the client part implementation
for the following SASL mechanisms:

=over 4

=item ANONYMOUS

The Anonymous SASL Mechanism as defined in RFC 2245 resp. 
in IETF Draft draft-ietf-sasl-anon-03.txt from February 2004
provides a method to anonymously access internet services.

Since it does no authentication it does not need to send 
any confidential information such as passwords in plain text
over the network.


=item CRAM-MD5

The CRAM-MD5 SASL Mechanism as defined in RFC2195 resp.
in IETF Draft draft-ietf-sasl-crammd5-XX.txt
offers a simple challenge-response authentication mechanism.

Since it is a challenge-response authentication mechanism
no passwords are transferred in clear-text over the wire.

Due to the simplicity of the protocol CRAM-MD5 is susceptible
to replay and dictionary attacks, so DIGEST-MD5 should be used
in preference.


=item DIGEST-MD5

The DIGEST-MD5 SASL Mechanism as defined in RFC 2831 resp.
in IETF Draft draft-ietf-sasl-rfc2831bis-XX.txt
offers the HTTP Digest Access Authentication as SASL mechanism.

Like CRAM-MD5 it is a challenge-response authentication
method that does not send plain text passwords over the network.

Compared to CRAM-MD5, DIGEST-MD5 prevents chosen plaintext
attacks, and permits the use of third party authentication servers,
so that it is recommended to use DIGEST-MD5 instead of CRAM-MD5
when possible.


=item EXTERNAL

The EXTERNAL SASL mechanism as defined in RFC 2222
allows the use of external authentication systems as SASL mechanisms.


=item GSSAPI

The GSSAPI SASL mechanism as defined in RFC 2222 resp. IETF Draft
draft-ietf-sasl-gssapi-XX.txt allows using the Generic Security Service
Application Program Interface [GSSAPI] KERBEROS V5 as a SASL mechanism.

Although GSSAPI is a general mechanism for authentication it is almost
exclusively used for Kerberos 5.


=item LOGIN

The LOGIN SASL Mechanism as defined in IETF Draft
draft-murchison-sasl-login-XX.txt allows  the
combination of username and clear-text password to be used
in a SASL mechanism.

It does not provide a security layer and sends the credentials
in clear over the wire.
Thus this mechanism should not be used without adequate security
protection.

=item OAUTHBEARER

It is one of the methods for OAuth2.0 based authentication.
Instead of a password, an OAUTHBEARER string is passed in a
specific format, described in RFC5801 and RFC7628

It is a newer and more secure method of authentication since it
relies on tokens that have a limited lifespan.

=item PLAIN

The Plain SASL Mechanism as defined in RFC 2595 resp. IETF Draft
draft-ietf-sasl-plain-XX.txt is another SASL mechanism that allows
username and clear-text password combinations in SASL environments.

Like LOGIN it sends the credentials in clear over the network
and should not be used without sufficient security protection.

=item XOAUTH2

It is one of the methods for OAuth2.0 based authentication.
It has been developed by Google but is used by other email providers
like Outlook as well.
Instead of a password, an XOAUTH2 string is passed in a
specific format. It is documented by Google on:
https://developers.google.com/workspace/gmail/imap/xoauth2-protocol

It is a newer and more secure method of authentication since it
relies on tokens that have a limited lifespan.

=back

As for server support, only I<PLAIN>, I<LOGIN> and I<DIGEST-MD5> are supported
at the time of this writing.

C<server_new> OPTIONS is a hashref that is only relevant for I<DIGEST-MD5> for
now and it supports the following options:

=over 4

=item - no_integrity

=item - no_confidentiality

=back

which configures how the security layers are negotiated with the client (or
rather imposed to the client).


=head1 SEE ALSO

L<Authen::SASL>,
L<Authen::SASL::Perl::ANONYMOUS>,
L<Authen::SASL::Perl::CRAM_MD5>,
L<Authen::SASL::Perl::DIGEST_MD5>,
L<Authen::SASL::Perl::EXTERNAL>,
L<Authen::SASL::Perl::GSSAPI>,
L<Authen::SASL::Perl::LOGIN>,
L<Authen::SASL::Perl::OAUTHBEARER>,
L<Authen::SASL::Perl::PLAIN>,
L<Authen::SASL::Perl::XOAUTH2>

=head1 AUTHOR

Peter Marschall <peter@adpm.de>

=head1 CONTRIBUTORS

Aditya Garg <gargaditya08@live.com>

Robert Rothenberg

Please report any bugs, or post any suggestions, to the perl-ldap mailing list
<perl-ldap@perl.org>

=head1 COPYRIGHT

Copyright (c) 2004-2006 Peter Marschall.

Copyright (c) 2025 Aditya Garg.

All rights reserved. This document is distributed, and may be redistributed,
under the same terms as Perl itself.

=cut
