GnuPG::Interface(3) User Contributed Perl Documentation GnuPG::Interface(3)

GnuPG::Interface(3) User Contributed Perl Documentation GnuPG::Interface(3)

NNAAMMEE
GnuPG::Interface − Perl interface to GnuPG

SSYYNNOOPPSSIISS
# 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;

DDEESSCCRRIIPPTTIIOONN
GnuPG::Interface and its associated modules are designed to provide an
object‐oriented method for interacting with GnuPG, being able to per‐
form functions such as but not limited to encrypting, signing, decryp‐
tion, verification, and key‐listing parsing.

HHooww DDaattaa MMeemmbbeerr AAcccceessssoorr MMeetthhooddss aarree CCrreeaatteedd

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.
_T_h_i_s _i_s _v_e_r_y _i_m_p_o_r_t_a_n_t _t_o _r_e_a_l_i_z_e_. This means that any data member
which is a list has special methods assigned to it for pushing, pop‐
ping, and clearing the list.

UUnnddeerrssttaannddiinngg BBiiddiirreeccttiioonnaall CCoommmmuunniiccaattiioonn

It is also imperative to realize that this package uses interprocess
communication methods similar to those used in IPC::Open3 and "Bidirec‐
tional 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 creat‐
ing a GnuPG::Interface object, creating a GnuPG::Handles object, set‐
ting some options in its ooppttiioonnss data member, and then calling a method
which invokes GnuPG, such as cclleeaarrssiiggnn. One then interacts with with
the handles appropriately, as described in "Bidirectional Communication
with Another Process" in perlipc.

OOBBJJEECCTT MMEETTHHOODDSS
IInniittiiaalliizzaattiioonn MMeetthhooddss

new( _%_i_n_i_t_i_a_l_i_z_a_t_i_o_n___a_r_g_s )
This methods creates a new object. The optional arguments are ini‐
tialization of data members; the initialization is done in a manner
according to the method created as described in "new_hash_init" in
Class::MethodMaker.

hash_init( _%_a_r_g_s ).
This methods work as described in "new_hash_init" in Class::Method‐
Maker.

OObbjjeecctt MMeetthhooddss wwhhiicchh uussee aa GGnnuuPPGG::::HHaannddlleess OObbjjeecctt

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 gpg. Each of these methods takes a
hash, which currently must contain a key of hhaannddlleess which has the
value of a GnuPG::Handles object. Another optional key is ccoomm‐‐
mmaanndd__aarrggss which should have the value of an array reference; these
arguments will be passed to GnuPG as command arguments. These com‐
mand arguments are used for such things as determining the keys to
list in the eexxppoorrtt__kkeeyyss method. _P_l_e_a_s_e _n_o_t_e _t_h_a_t _G_n_u_P_G _c_o_m_m_a_n_d
_a_r_g_u_m_e_n_t_s _a_r_e _n_o_t _t_h_e _s_a_m_e _a_s _G_n_u_P_G _o_p_t_i_o_n_s. 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 hhaannddlleess
object to the running GnuPG object, so that bidirectional communi‐
cation can be established. That is, the optionally‐defined ssttddiinn,
ssttddoouutt, ssttddeerrrr, ssttaattuuss, llooggggeerr, and ppaasssspphhrraassee handles will be
attached to GnuPG’s input, output, standard error, the handle cre‐
ated by setting ssttaattuuss‐‐ffdd, the handle created by setting llooggggeerr‐‐ffdd,
and the handle created by setting ppaasssspphhrraassee‐‐ffdd respectively. This
tying of handles of similar to the process done in _I_P_C_:_:_O_p_e_n_3.

If you want the GnuPG process to read or write directly to an
already‐opened filehandle, you cannot do this via the normal
_I_P_C_:_:_O_p_e_n_3 mechanisms. In order to accomplish this, set the appro‐
priate hhaannddlleess data member to the already‐opened filehandle, and
then set the option ddiirreecctt to be true for that handle, as described
in "options" in GnuPG::Handles. For example, to have GnuPG read
from the file _i_n_p_u_t_._t_x_t and write to _o_u_t_p_u_t_._t_x_t, 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 hhaannddlleess 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 ssttaattuuss
or llooggggeerr handle is not defined, this channel of communication is
never established with GnuPG, and so this information is not gener‐
ated and does not come into play. If the ppaasssspphhrraassee data member
handle of the hhaannddlleess object is not defined, but the the ppaasssspphhrraassee
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.

OOtthheerr MMeetthhooddss

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::Pub‐
licKey or GnuPG::SecretKey respectively. This is done by parsing
the output of GnuPG with the option wwiitthh‐‐ccoolloonnss enabled. The
objects created do or do not have signature information stored in
them, depending if the method ends in ___s_i_g_s; this separation of
functionality is there because of performance hits when listing
information with signatures.

_t_e_s_t___d_e_f_a_u_l_t___k_e_y___p_a_s_s_p_h_r_a_s_e_(_)
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 ppaasssspphhrraassee data member, and the
default key specified in the ooppttiioonnss data member.

IInnvvookkiinngg GGnnuuPPGG wwiitthh aa ccuussttoomm ccaallll
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 pro‐
vided, "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, hhaannddlleess 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.

OOBBJJEECCTT DDAATTAA MMEEMMBBEERRSS
Note that these data members are interacted with via object methods
created using the methods described in "get_set" in Class::MethodMaker,
or "object" in Class::MethodMaker. Please read there for more informa‐
tion.

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 call‐
ing GnuPG via _a_n_y of the object methods described in this package.
See GnuPG::Options for more information.

EEXXAAMMPPLLEESS
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 ),
);

EEnnccrryyppttiinngg

# 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

SSiiggnniinngg

# 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

DDeeccrryyppttiioonn

# 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

PPrriinnttiinngg KKeeyyss

# 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;

CCrreeaattiinngg GGnnuuPPGG::::PPuubblliiccKKeeyy OObbjjeeccttss

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

CCuussttoomm GGnnuuPPGG ccaallll

# 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;

FFAAQQ
How do I get GnuPG::Interface to read/write directly from a filehandle?
You need to set GnuPG::Handles ddiirreecctt 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 infor‐
mation.

Why do you make it so difficult to get GnuPG to write/read from a file‐
handle? 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 nnoonn‐‐ddiirreecctt 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.

NNOOTTEESS
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 wwaaiitt to clean up GnuPG from
the process table.

BBUUGGSS
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.

SSEEEE AALLSSOO
GnuPG::Options, GnuPG::Handles, GnuPG::PublicKey, GnuPG::SecretKey,
gpg, Class::MethodMaker, "Bidirectional Communication with Another
Process" in perlipc

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

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

perl v5.8.8 2007‐04‐24 GnuPG::Interface(3)