Generating a primary key uses the create_key method in a Context. It contains multiple arguments and keyword arguments, including: userid, algorithm, expires_in, expires, sign, encrypt, certify, authenticate, passphrase and force. The defaults for all of those except userid, algorithm, expires_in, expires and passphrase is False. The defaults for algorithm and passphrase is None. The default for expires_in is 0. The default for expires is True. There is no default for userid.

If passphrase is left as None then the key will not be generated with a passphrase, if passphrase is set to a string then that will be the passphrase and if passphrase is set to True then gpg-agent will launch pinentry to prompt for a passphrase. For the sake of convenience, these examples will keep passphrase set to None.

import gpg c = gpg.Context() c.home_dir = "~/.gnupg-dm" userid = "Danger Mouse <dm@secret.example.net>" dmkey = c.create_key(userid, algorithm="rsa3072", expires_in=31536000, sign=True, certify=True)

One thing to note here is the use of setting the c.home_dir parameter. This enables generating the key or keys in a different location. In this case to keep the new key data created for this example in a separate location rather than adding it to existing and active key store data. As with the default directory, ~/.gnupg, any temporary or separate directory needs the permissions set to only permit access by the directory owner. On posix systems this means setting the directory permissions to 700.

The temp-homedir-config.py script in the HOWTO examples directory will create an alternative homedir with these configuration options already set and the correct directory and file permissions.

The successful generation of the key can be confirmed via the returned GenkeyResult object, which includes the following data:

print(""" Fingerprint: {0} Primary Key: {1} Public Key: {2} Secret Key: {3} Sub Key: {4} User IDs: {5} """.format(dmkey.fpr, dmkey.primary, dmkey.pubkey, dmkey.seckey, dmkey.sub, dmkey.uid))

Alternatively the information can be confirmed using the command line program:

bash-4.4$ gpg --homedir ~/.gnupg-dm -K ~/.gnupg-dm/pubring.kbx ---------------------- sec rsa3072 2018-03-15 [SC] [expires: 2019-03-15] 177B7C25DB99745EE2EE13ED026D2F19E99E63AA uid [ultimate] Danger Mouse <dm@secret.example.net> bash-4.4$

As with generating keys manually, to preconfigure expanded preferences for the cipher, digest and compression algorithms, the gpg.conf file must contain those details in the home directory in which the new key is being generated. I used a cut down version of my own gpg.conf file in order to be able to generate this:

bash-4.4$ gpg --homedir ~/.gnupg-dm --edit-key 177B7C25DB99745EE2EE13ED026D2F19E99E63AA showpref quit Secret key is available. sec rsa3072/026D2F19E99E63AA created: 2018-03-15 expires: 2019-03-15 usage: SC trust: ultimate validity: ultimate [ultimate] (1). Danger Mouse <dm@secret.example.net> [ultimate] (1). Danger Mouse <dm@secret.example.net> Cipher: TWOFISH, CAMELLIA256, AES256, CAMELLIA192, AES192, CAMELLIA128, AES, BLOWFISH, IDEA, CAST5, 3DES Digest: SHA512, SHA384, SHA256, SHA224, RIPEMD160, SHA1 Compression: ZLIB, BZIP2, ZIP, Uncompressed Features: MDC, Keyserver no-modify bash-4.4$