In order to install this module, first run

perl Makefile.PL

If this command says that some prerequisite modules are not present,
you need to install these modules; each required one should
be available from CPAN at http://www.cpan.org/

make
make test
make install

This module depends on:

	Perl 5.005
	Class::MethodMaker 1.00	or later, available from CPAN; http://www.cpan.org/
	GnuPG			available from http://www.gnupg.org/


-----------------------------------------------------------------------

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( 'ftobin@cpan.org' );
      $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 Class::MethodMaker
    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 the IPC::Open3 manpage
    and the section on "Bidirectional Communication with Another Process" in
    the perlipc manpage, 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 the section on "Bidirectional Communication with
    Another Process" in the perlipc manpage 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 the section on "Bidirectional
    Communication with Another Process" in the perlipc manpage.

OBJECT METHODS
  Initialization Methods

    new( *%initialization_args* )
        This methods creates a new object. The optional arguments are
        initialization of data members; the initialization is done in a
        manner according to the method created as described in the section
        on "new_hash_init" in the Class::MethodMaker manpage.

    hash_init( *%args* ).
        This methods work as described in the section on "new_hash_init" in
        the Class::MethodMaker manpage.

  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( % )
        These methods each correspond directly to or are very similar to a
        GnuPG command described in the gpg manpage. 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 the section on
        "COMMANDS" in the gpg manpage and the section on "OPTIONS" in the
        gpg manpage.

        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 the "options" entry in the GnuPG::Handles manpage. 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.

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
    Note that these data members are interacted with via object methods
    created using the methods described in the section on "get_set" in the
    Class::MethodMaker manpage, or the section on "object" in the
    Class::MethodMaker manpage. Please read there for more information.

    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 the
        "passphrase" entry in the GnuPG::Handles manpage.

    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
        the GnuPG::Options manpage 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 $passphrsae = "Three Little Pigs";

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

      $gnupg->options->hash_init( armor    => 1,
                                  recipients => [ 'ftobin@uiuc.edu',
                                                  '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_fd $passphrase;
      close $passphrase_fd;

      # 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 the "options" entry in the
        GnuPG::Handles manpage and the section on "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 the
        "options" entry in the GnuPG::Handles manpage.

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
    the GnuPG::Options manpage, the GnuPG::Handles manpage, the
    GnuPG::PublicKey manpage, the GnuPG::SecretKey manpage, the gpg manpage,
    the Class::MethodMaker manpage, the section on "Bidirectional
    Communication with Another Process" in the perlipc manpage

AUTHOR
    Frank J. Tobin, ftobin@cpan.org

PACKAGE UPDATES
    Package updates may be found on http://GnuPG-Interface.sourceforge.net/
    or CPAN, http://www.cpan.org/.