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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 <$cipherfile>
# 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/.