NAME
   GnuPG::Interface - Perl interface to GnuPG

SYNOPSIS
     # A simple example
     use IO::Handle;
     use GnuPG::Interface;

     # settting up the situation
     my $gnupg = GnuPG::Interface->new();
     $gnupg->options->hash_init( armor   => 1,
                                 homedir => '/home/foobar' );

     # Note you can set the recipients even if you aren't encrypting!
     $gnupg->options->push_recipients( '[email protected]' );
     $gnupg->options->meta_interactive( 0 );

     # how we create some handles to interact with GnuPG
     my $input   = IO::Handle->new();
     my $output  = IO::Handle->new();
     my $handles = GnuPG::Handles->new( stdin  => $input,
                                        stdout => $output );

     # Now we'll go about encrypting with the options already set
     my @plaintext = ( 'foobar' );
     my $pid = $gnupg->encrypt( handles => $handles );

     # Now we write to the input of GnuPG
     print $input @plaintext;
     close $input;

     # now we read the output
     my @ciphertext = <$output>;
     close $output;

     waitpid $pid, 0;

DESCRIPTION
   GnuPG::Interface and its associated modules are designed to provide an
   object-oriented method for interacting with GnuPG, being able to perform
   functions such as but not limited to encrypting, signing, decryption,
   verification, and key-listing parsing.

 How Data Member Accessor Methods are Created
   Each module in the GnuPG::Interface bundle relies on Moo to generate the
   get/set methods used to set the object's data members. *This is very
   important to realize.* This means that any data member which is a list
   has special methods assigned to it for pushing, popping, and clearing
   the list.

 Understanding Bidirectional Communication
   It is also imperative to realize that this package uses interprocess
   communication methods similar to those used in IPC::Open3 and
   "Bidirectional Communication with Another Process" in perlipc, and that
   users of this package need to understand how to use this method because
   this package does not abstract these methods for the user greatly. This
   package is not designed to abstract this away entirely (partly for
   security purposes), but rather to simply help create 'proper', clean
   calls to GnuPG, and to implement key-listing parsing. Please see
   "Bidirectional Communication with Another Process" in perlipc to learn
   how to deal with these methods.

   Using this package to do message processing generally invovlves creating
   a GnuPG::Interface object, creating a GnuPG::Handles object, setting
   some options in its options data member, and then calling a method which
   invokes GnuPG, such as clearsign. One then interacts with with the
   handles appropriately, as described in "Bidirectional Communication with
   Another Process" in perlipc.

OBJECT METHODS
 Initialization Methods
   new( *%initialization_args* )
       This methods creates a new object. The optional arguments are
       initialization of data members.

   hash_init( *%args* ).

 Object Methods which use a GnuPG::Handles Object
   list_public_keys( % )
   list_sigs( % )
   list_secret_keys( % )
   encrypt( % )
   encrypt_symmetrically( % )
   sign( % )
   clearsign( % )
   detach_sign( % )
   sign_and_encrypt( % )
   decrypt( % )
   verify( % )
   import_keys( % )
   export_keys( % )
   recv_keys( % )
   send_keys( % )
   search_keys( % )
       These methods each correspond directly to or are very similar to a
       GnuPG command described in gpg. Each of these methods takes a hash,
       which currently must contain a key of handles which has the value of
       a GnuPG::Handles object. Another optional key is command_args which
       should have the value of an array reference; these arguments will be
       passed to GnuPG as command arguments. These command arguments are
       used for such things as determining the keys to list in the
       export_keys method. *Please note that GnuPG command arguments are
       not the same as GnuPG options*. To understand what are options and
       what are command arguments please read "COMMANDS" in gpg and
       "OPTIONS" in gpg.

       Each of these calls returns the PID for the resulting GnuPG process.
       One can use this PID in a "waitpid" call instead of a "wait" call if
       more precise process reaping is needed.

       These methods will attach the handles specified in the handles
       object to the running GnuPG object, so that bidirectional
       communication can be established. That is, the optionally-defined
       stdin, stdout, stderr, status, logger, and passphrase handles will
       be attached to GnuPG's input, output, standard error, the handle
       created by setting status-fd, the handle created by setting
       logger-fd, and the handle created by setting passphrase-fd
       respectively. This tying of handles of similar to the process done
       in *IPC::Open3*.

       If you want the GnuPG process to read or write directly to an
       already-opened filehandle, you cannot do this via the normal
       *IPC::Open3* mechanisms. In order to accomplish this, set the
       appropriate handles data member to the already-opened filehandle,
       and then set the option direct to be true for that handle, as
       described in "options" in GnuPG::Handles. For example, to have GnuPG
       read from the file input.txt and write to output.txt, the following
       snippet may do:

         my $infile  = IO::File->new( 'input.txt' );
         my $outfile = IO::File->new( '>output.txt' );
         my $handles = GnuPG::Handles->new( stdin  => $infile,
                                            stdout => $outfile,
                                          );
         $handles->options( 'stdin'  )->{direct} = 1;
         $handles->options( 'stdout' )->{direct} = 1;

       If any handle in the handles object is not defined, GnuPG's input,
       output, and standard error will be tied to the running program's
       standard error, standard output, or standard error. If the status or
       logger handle is not defined, this channel of communication is never
       established with GnuPG, and so this information is not generated and
       does not come into play. If the passphrase data member handle of the
       handles object is not defined, but the the passphrase data member
       handle of GnuPG::Interface object is, GnuPG::Interface will handle
       passing this information into GnuPG for the user as a convience.
       Note that this will result in GnuPG::Interface storing the
       passphrase in memory, instead of having it simply 'pass-through' to
       GnuPG via a handle.

 Other Methods
   get_public_keys( @search_strings )
   get_secret_keys( @search_strings )
   get_public_keys_with_sigs( @search_strings )
       These methods create and return objects of the type GnuPG::PublicKey
       or GnuPG::SecretKey respectively. This is done by parsing the output
       of GnuPG with the option with-colons enabled. The objects created do
       or do not have signature information stored in them, depending if
       the method ends in *_sigs*; this separation of functionality is
       there because of performance hits when listing information with
       signatures.

   test_default_key_passphrase()
       This method will return a true or false value, depending on whether
       GnuPG reports a good passphrase was entered while signing a short
       message using the values of the passphrase data member, and the
       default key specified in the options data member.

   version()
       Returns the version of GnuPG that GnuPG::Interface is running.

Invoking GnuPG with a custom call
   GnuPG::Interface attempts to cover a lot of the commands of GnuPG that
   one would want to perform; however, there may be a lot more calls that
   GnuPG is and will be capable of, so a generic command interface is
   provided, "wrap_call".

   wrap_call( %args )
       Call GnuPG with a custom command. The %args hash must contain at
       least the following keys:

       commands
           The value of this key in the hash must be a reference to a a
           list of commands for GnuPG, such as "[ qw( --encrypt --sign )
           ]".

       handles
           As with most other GnuPG::Interface methods, handles must be a
           GnuPG::Handles object.

       The following keys are optional.

       command_args
           As with other GnuPG::Interface methods, the value in hash for
           this key must be a reference to a list of arguments to be passed
           to the GnuPG command, such as which keys to list in a
           key-listing.

OBJECT DATA MEMBERS
   call
       This defines the call made to invoke GnuPG. Defaults to 'gpg'; this
       should be changed if 'gpg' is not in your path, or there is a
       different name for the binary on your system.

   passphrase
       In order to lessen the burden of using handles by the user of this
       package, setting this option to one's passphrase for a secret key
       will allow the package to enter the passphrase via a handle to GnuPG
       by itself instead of leaving this to the user. See also "passphrase"
       in GnuPG::Handles.

   options
       This data member, of the type GnuPG::Options; the setting stored in
       this data member are used to determine the options used when calling
       GnuPG via *any* of the object methods described in this package. See
       GnuPG::Options for more information.

EXAMPLES
   The following setup can be done before any of the following examples:

     use IO::Handle;
     use GnuPG::Interface;

     my @original_plaintext = ( "How do you doo?" );
     my $passphrase = "Three Little Pigs";

     my $gnupg = GnuPG::Interface->new();

     $gnupg->options->hash_init( armor    => 1,
                                 recipients => [ '[email protected]',
                                                 '0xABCD1234' ],
                                 meta_interactive => 0 ,
                               );

 Encrypting
     # We'll let the standard error of GnuPG pass through
     # to our own standard error, by not creating
     # a stderr-part of the $handles object.
     my ( $input, $output ) = ( IO::Handle->new(),
                                IO::Handle->new() );

     my $handles = GnuPG::Handles->new( stdin    => $input,
                                        stdout   => $output );

     # this sets up the communication
     # Note that the recipients were specified earlier
     # in the 'options' data member of the $gnupg object.
     my $pid = $gnupg->encrypt( handles => $handles );

     # this passes in the plaintext
     print $input @original_plaintext;

     # this closes the communication channel,
     # indicating we are done
     close $input;

     my @ciphertext = <$output>;  # reading the output

     waitpid $pid, 0;  # clean up the finished GnuPG process

 Signing
     # This time we'll catch the standard error for our perusing
     my ( $input, $output, $error ) = ( IO::Handle->new(),
                                        IO::Handle->new(),
                                        IO::Handle->new(),
                                      );

     my $handles = GnuPG::Handles->new( stdin    => $input,
                                        stdout   => $output,
                                        stderr   => $error,
                                      );

     # indicate our pasphrase through the
     # convience method
     $gnupg->passphrase( $passphrase );

     # this sets up the communication
     my $pid = $gnupg->sign( handles => $handles );

     # this passes in the plaintext
     print $input @original_plaintext;

     # this closes the communication channel,
     # indicating we are done
     close $input;

     my @ciphertext   = <$output>;  # reading the output
     my @error_output = <$error>;   # reading the error

     close $output;
     close $error;

     waitpid $pid, 0;  # clean up the finished GnuPG process

 Decryption
     # This time we'll catch the standard error for our perusing
     # as well as passing in the passphrase manually
     # as well as the status information given by GnuPG
     my ( $input, $output, $error, $passphrase_fh, $status_fh )
       = ( IO::Handle->new(),
           IO::Handle->new(),
           IO::Handle->new(),
           IO::Handle->new(),
           IO::Handle->new(),
         );

     my $handles = GnuPG::Handles->new( stdin      => $input,
                                        stdout     => $output,
                                        stderr     => $error,
                                        passphrase => $passphrase_fh,
                                        status     => $status_fh,
                                      );

     # this time we'll also demonstrate decrypting
     # a file written to disk
     # Make sure you "use IO::File" if you use this module!
     my $cipher_file = IO::File->new( 'encrypted.gpg' );

     # this sets up the communication
     my $pid = $gnupg->decrypt( handles => $handles );

     # This passes in the passphrase
     print $passphrase_fh $passphrase;
     close $passphrase_fh;

     # this passes in the plaintext
     print $input $_ while <$cipher_file>;

     # this closes the communication channel,
     # indicating we are done
     close $input;
     close $cipher_file;

     my @plaintext    = <$output>;    # reading the output
     my @error_output = <$error>;     # reading the error
     my @status_info  = <$status_fh>; # read the status info

     # clean up...
     close $output;
     close $error;
     close $status_fh;

     waitpid $pid, 0;  # clean up the finished GnuPG process

 Printing Keys
     # This time we'll just let GnuPG print to our own output
     # and read from our input, because no input is needed!
     my $handles = GnuPG::Handles->new();

     my @ids = ( 'ftobin', '0xABCD1234' );

     # this time we need to specify something for
     # command_args because --list-public-keys takes
     # search ids as arguments
     my $pid = $gnupg->list_public_keys( handles      => $handles,
                                         command_args => [ @ids ] );

      waitpid $pid, 0;

 Creating GnuPG::PublicKey Objects
     my @ids = [ 'ftobin', '0xABCD1234' ];

     my @keys = $gnupg->get_public_keys( @ids );

     # no wait is required this time; it's handled internally
     # since the entire call is encapsulated

 Custom GnuPG call
     # assuming $handles is a GnuPG::Handles object
     my $pid = $gnupg->wrap_call
       ( commands     => [ qw( --list-packets ) ],
         command_args => [ qw( test/key.1.asc ) ],
         handles      => $handles,
       );

       my @out = <$handles->stdout()>;
       waitpid $pid, 0;

FAQ
   How do I get GnuPG::Interface to read/write directly from a filehandle?
       You need to set GnuPG::Handles direct option to be true for the
       filehandles in concern. See "options" in GnuPG::Handles and "Object
       Methods which use a GnuPG::Handles Object" for more information.

   Why do you make it so difficult to get GnuPG to write/read from a
   filehandle? In the shell, I can just call GnuPG with the --outfile
   option!
       There are lots of issues when trying to tell GnuPG to read/write
       directly from a file, such as if the file isn't there, or there is a
       file, and you want to write over it! What do you want to happen
       then? Having the user of this module handle these questions
       beforehand by opening up filehandles to GnuPG lets the user know
       fully what is going to happen in these circumstances, and makes the
       module less error-prone.

   When having GnuPG process a large message, sometimes it just hanges
   there.
       Your problem may be due to buffering issues; when GnuPG reads/writes
       to non-direct filehandles (those that are sent to filehandles which
       you read to from into memory, not that those access the disk),
       buffering issues can mess things up. I recommend looking into
       "options" in GnuPG::Handles.

NOTES
   This package is the successor to PGP::GPG::MessageProcessor, which I
   found to be too inextensible to carry on further. A total redesign was
   needed, and this is the resulting work.

   After any call to a GnuPG-command method of GnuPG::Interface in which
   one passes in the handles, one should all wait to clean up GnuPG from
   the process table.

BUGS
   Currently there are problems when transmitting large quantities of
   information over handles; I'm guessing this is due to buffering issues.
   This bug does not seem specific to this package; IPC::Open3 also appears
   affected.

   I don't know yet how well this modules handles parsing OpenPGP v3 keys.

SEE ALSO
   GnuPG::Options, GnuPG::Handles, GnuPG::PublicKey, GnuPG::SecretKey, gpg,
   "Bidirectional Communication with Another Process" in perlipc

LICENSE
   This module is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself.

AUTHOR
   GnuPg::Interface is currently maintained by Jesse Vincent
   <[email protected]>.

   Frank J. Tobin, [email protected] was the original author of the package.

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