=head1 NAME

Protocol::ACME - Interface to the Let's Encrypt ACME API

=head1 VERSION

Version 0.06

=head1 SYNOPSIS

 use Protocol::ACME;

 my @names = qw( www.example.com cloud.example.com );

 my $challenges = {
                    'www.example.com'   => Protocol::ACME::Challenge::SimpleSSH->new(
                      { ssh_host => "host1", www_root => "~/www" }
                    ),
                   'cloud.example.com' => Protocol::ACME::Challenge::SimpleSSH->new(
                     { ssh_host => "home2", www_root => "/opt/local/www/htdocs" }
                   )
                 };

 eval
 {
   my $acme = Protocol::ACME->new( host               => $host,
                                   account_key        => $account_key_pem_or_der,
                                 );

   $acme->directory();

   $acme->register();

   $acme->accept_tos();

   for my $domain ( @names )
   {
     $acme->authz( $domain );

     $acme->handle_challenge( $challenges->{$domain} );

     $acme->check_challenge();
   }

   my $cert = $acme->sign( $csr_file );
 };
 if ( $@ )
 {
   die $@ if ref $@ ne "Protocol::ACME::Exception";
   print "Error occured: Status: $@->{status},
                         Detail: $@->{detail},
                         Type: $@->{type}\n";
 }
 else
 {
   # do something appropriate with the DER encoded cert
   print "Success\n";
 }

=head1 DESCRIPTION

The C<Protocol::ACME> is a class implementing an interface for the
Let's Encrypt ACME API.

NOTE: This code at this point is functional but should be considered
'alpha' quality.

The class handles the protocol details behind provisioning a Let's
Encrypt certificate.

=head1 CONSTRUCTOR METHODS

The following constructor methods are available:

=over 4

=item $acme = Protcol::ACME->new( %options )

This method constructs a new C<Protocl::ACME> object and returns it.
Key/value pair arguments may be provided to set up the initial state.
The may be passed in as a hash or a hashref. The following options
correspond to attribute methods described below. Items marked with
a * are required.

   KEY                     DEFAULT
   -----------             --------------------
   *host                   undef
   account_key             undef
   account_key_path        undef
   openssl                 undef

B<host>: The API end point to connect to.  This will generally be acme-staging.api.letsencrypt.org
or acme-v01.api.letsencrypt.org

B<account_key>: The account private key as a string. DER or PEM format. Excludes C<account_key_path>.

B<account_key_path>: The filesystem path to the account private key. Excludes C<account_key>.

B<openssl>: The path to openssl.  If this option is used a local version of the openssl binary will
be used for crypto operations rather than C<Crypt::OpenSSL::RSA>.

=back

=head2 METHODS

=over

=item load_key_from_disk( $key_path )

Load a key from disk.  Currently the key needs to be unencrypted.
Callbacks for handling password protected keys are still to come.

=item directory()

Loads the directory from the ACME host.  This call must be made first
before any other calls to the API in order the bootstrap the API
resource list.

=item register()

Call the new-reg resource and create an account associated with the
loaded account key.  If that key has already been registered this method
will gracefully and silently handle that.

=item accept_tos()

In order to use the Let's Encrypt service, the account needs to accept
the Terms of Service.  This is provided in a link header in response
to the new-reg ( or reg ) resouce call.  If the TOS have already been
accepted as indicated by the reg structure returned by the API this
call will be a noop.

=item authz( $domain )

C<authz> needs to be called for each domain ( called identifiers in
ACME speak ) in the certifcate.  This included the domain in the subject
as well as the Subject Alternate Name (SAN) fields.  Each call to
C<authz> will result in a challenge being issued from Let's Encrypt.
These challenges need to be handled individually.

=item handle_challenge( $challenge_object )

C<handle_challenge> is called for each challenge issued by C<authz>.
The challenge object must be a subclass of C<Protocol::ACME::Challenge>
which implements a 'handle' method.  This objects handle method
will be passed three arguments and is expected to fulfill the
preconditions for the chosen challenge.  The three areguments
are:

  fingerprint: the sha256 hex digest of the account key
  token: the challenge token
  url: the url returned by the challenge

Fully describing how to handle every challenge type of out of the
scope of this documentation ( at least for now ).  Two challenge
classes have been included for reference:

C<Protocol::ACME::Challenge::SimpleSSH> is initialized with the
ssh host name and the www root for the web server for the http-01
challenge.  It will ssh to the host and create the file in
the correct location for challenge fulfillment.

C<Protocol::ACME::Challenge::LocalFile> is initialized with just the
www root for the web server for the http-01 challenge.  It will
simply create the challenge file in the correct place on the local
filesystem.

C<Protocol::ACME::Challenge::Manual> is intended to be run in an
interactive manner and will stop and prompt the user with the relevant
information so they can fulfill the challenge manually.

but below is an example for handling the simpleHTTP ( http-01 )
challenge.


=item check_challenge()

Called after C<handle_challenge>.  This will poll the challenge status
resource and will return when the state changes from 'pending'.

=item $cert = sign( $csr )


Call C<sign> after the challenge for each domain ( itentifier ) has
been fulfilled.  C<$csr> is the DER encoded Certificate Signing
Request ( CSR ).  On success Let's Encrypt will return the DER encoded
signed certificate.

=item revoke( $certfile )

Call C<revoke> to revoke an already issued certificate. C<$certfile>
must point the a DER encoded form of the certificate.

=item recovery_key()

LE does not yet support recovery keys.  This method will die when
called.


=back

=head1 AUTHOR

Stephen Ludin, C<< <sludin at ludin.org> >>

=head1 BUGS

Please report any bugs or feature requests to C<bug-protocol-acme at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Protocol-ACME>.  I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.

=head1 REPOSITORY

https://github.com/sludin/Protocol-ACME


=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc Protocol::ACME


You can also look for information at:

=over 4

=item * RT: CPAN's request tracker (report bugs here)

L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Protocol-ACME>

=item * AnnoCPAN: Annotated CPAN documentation

L<http://annocpan.org/dist/Protocol-ACME>

=item * CPAN Ratings

L<http://cpanratings.perl.org/d/Protocol-ACME>

=item * Search CPAN

L<http://search.cpan.org/dist/Protocol-ACME/>

=back


=head1 ACKNOWLEDGEMENTS


=head1 LICENSE AND COPYRIGHT

Copyright 2015 Stephen Ludin.

This program is free software; you can redistribute it and/or modify it
under the terms of the the Artistic License (2.0). You may obtain a
copy of the full license at:

L<http://www.perlfoundation.org/artistic_license_2_0>

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Versions is governed by this Artistic License. By using, modifying or
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or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made
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