Raku GPGME - GNU Privacy Guard (GPG) Made Easy
From the GPGME Manual:
‘GnuPG Made Easy’ (GPGME) is a C language library that allows to
add support for cryptography to a program. It is designed to make
access to public key crypto engines like GnuPG or GpgSM easier for
applications. GPGME provides a high-level crypto API for
encryption, decryption, signing, signature verification and key
GPGME uses GnuPG and GpgSM as its backends to support OpenPGP and
the Cryptographic Message Syntax (CMS).
So essentially, this is a Raku Module interfacing with a C library
interfacing with GnuPG and GpgSM command line programs.
Understanding how this module works will benefit from an understanding
of the Gnu Privacy Guard
and GnuPG Made Easy (GPGME).
Note, this is still a work in progress, more features may or may not
be forthcoming!! Patches welcome!!
my $gpg = GPGME.new(:armor); # ASCII armor for key export
$gpg.create-key('email@example.com'); # Add key to key ring
my $joes-key = $gpg.get-key('firstname.lastname@example.org'); # Retrieve a key
put $joes-key; # Stringify key summary
put my $key = $gpg.export('email@example.com'); # Export from key ring
$gpg.import($key); # Import key
my $cipher = $gpg.encrypt('message', 'firstname.lastname@example.org');
my $plain = $gpg.decrypt($cipher);
my $signed = $gpg.sign('My message');
GPGME Object and Context
The main GPGME object holds a
context with various
settings, and can be used to perform various functions.
my $gpg = GPGME.new;
my $gpg = GPGME.new(:armor, :homedir</tmp/dir>);
See GPGME for more information.
After performing an operation, the result of the operation can be
retrieved from the context with the C method. As a
convenience, most methods from the result objects are passed through
to the result object.
For example, after a key generation operation, the
CGPGME::GenKeyResult object can be retrieved with the C
method. One of the attributes of that object is the fingerprint of
the generated key, which can be retrieved with its C method.
my $result = $gpg.result;
my $fpr = $result.fpr;
This does the same thing, passing the I from the context to the
my $fpr = $gpg.fpr;
Of course, for key generation, the result object is returned from
the I operation, so you can also just do:
my $fpr = $gpg.create-key('email@example.com').fpr;
You can additionally retrieve the result object immediately following
the appropriate operation with these methods:
These are sometimes needed when an operation performs two actions
(e.g. decrypt and verify).
These are only valid immediately following the appropriate operation,
and all results must be used or copied prior to the next operation,
when the results are no longer available.
.put for GPGME.engine-info;
See GPGME::EngineInfo for more information.
A lot of data has to be exchanged between the user and the crypto
engine, like plaintext messages, ciphertext, signatures and
information about the keys. The technical details about exchanging the
data information are completely abstracted by GPGME. The user provides
and receives the data via
GPGME::Data objects, regardless of the
communication protocol between GPGME and the crypto engine in use.
In general the API will construct the appropriate
object for you.
For input objects, you can provide one of these types:
Blob -- Actual data to use
Str -- Actual data to use
IO::Path -- Filename of file to use
IO::Handle -- File with a
native-descriptor to read from
For output objects, you can provide one of these types:
Str -- Filename of file to write to
IO::Path -- Filename to write to
IO::Handle -- File with a C to write to
When an output object is omitted, a memory buffer will be used and
GPGME::Data object is returned, you can stringify it if and
only if the data are
utf8 encoded or ascii (usually produced when
the :armor option was specified during context creation).
The object can also be treated as an
IO::Handle and read from as
An important fact to remember is that in addition to providing
mechanisms to manipulate keys, GPG also serves as a Key Store or 'Key
Ring'. Keys can generally be referred to by patterns and fingerprints
that map to actual keys stored in the key store.
GPGME Supports two different interfaces to Key Generation --
my $key = $gpg.get-key('firstname.lastname@example.org');
$gpg.set-uid-flag($key, 'email@example.com'); # Make new one primary
$gpg.revuid($key, 'firstname.lastname@example.org'); # Revoke a user ID
genkey takes a set of parameters, expressed either as a single
string, or a set of named parameters:
$gpg.genkey(:Name-Email<email@example.com>); # Key-Type defaults to 'default'
See GPG Key Generation and CSR and Certificate Creation for information on all the parameters.
List keys in the key ring by specifying a list of patterns and
optionally specifying the :secret option to retrieve secret keys.
$key = $gpg.get-key('firstname.lastname@example.org');
$key = $gpg.get-key($fpr, :secret);
.put for $gpg.keylist('email@example.com', :secret);
.put for $gpg.keylist(<alice harry bob>);
Individual attributes from the keys can be queried.
See GPGME::Key for more information.
$gpg.delete-key($key, :secret, :force);
- :secret deletes secret keys
- :force overrides a user confirmation, but is only available after
Key signatures are a unique concept of the OpenPGP protocol. They can
be used to certify the validity of a key and are used to create the
$gpg.signers('firstname.lastname@example.org'); # select signers
$gpg.keysign($key); # Default sign all user IDs
$gpg.keysign($key, 'email@example.com'); # Specify a user ID
$gpg.keysign($key, :local); # Non exportable
$gpg.keysign($key, 'firstname.lastname@example.org', expires => $DateTime);
my $gpg = GPGME.new(:armor); # Use :armor to get ASCII export
put $gpg.export('email@example.com'); # Stringify and print out
$gpg.export('firstname.lastname@example.org', :out<outputfile>); # Export to filename
$gpg.export('email@example.com', out => $*OUT); # Send to a file handle
Stores the ImportResult.
Encrypting a Plaintext
$cipher = $gpg.encrypt("my message", $key); # Encrypt for a key
$cipher = $gpg.encrypt("my message", 'firstname.lastname@example.org'); # Encrypt for a pattern
$cipher = $gpg.encrypt("my message", 'email@example.com', :sign); # Encrypt and sign
Stores the EncryptResult.
If signed as well with the :sign option,
SignResult can be examined as well.
$plain = $gpg.decrypt($cipher);
$gpg.decrypt($cipher, out => 'filename');
$gpg.decrypt($cipher, out => $*OUT);
Stores the DecryptResult.
If the signature was verified with the :verify option, the
VerifyResult is also available.
A signature can contain signatures by one or more keys. The set of
keys used to create a signatures is contained in a context, and is
applied to all following signing operations in this context (until the
set is changed).
They can be set either at
GPGME creation with the :signers object,
or with the
.signers method later.
my $signed = $gpg.sign('My message');
$gpg.sign($*IN, out => $*OUT);
my $signature = $gpg.sign('My message', :detach); # Detached signature
The SignResult will be available after signing.
$message = $gpg.verify($signed);
put $gpg.verify($signature, $message).status; # Detached signature
The VerifyResult will be available after
GPGME actions (particularly key generation with very long keys)
rely on the OS ability to generate a great deal of entropy. Things
may appear to hang on entropy starved hosts. Tools like
haveged can help the OS capture
entropy. Even doing something simple like running
sudo dd if=/dev/sda of=/dev/zero in the background can help speed things up.
You must install
libgpgme which usually has the right dependencies
on GPG as well.
- For debian or ubuntu:
apt install libgpgme11
- For alpine:
apk add gpgme
- For CentOS:
yum install gpgme
If you get locale errors on CentOS, you may need to run this:
yum install glibc-locale-source glibc-langpack-en
localedef -i en_US -f UTF-8 en_US.UTF-8
This work is subject to the Artistic License 2.0.
See LICENSE for more information.