docs: python bindings howto

* Updated official doc (the org-mode file) with the instructions on
  importing and exporting both public and secret keys.
This commit is contained in:
Ben McGinnes 2018-06-28 18:33:51 +10:00
parent 6573eb339a
commit fa1a4e0b25

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@ -454,6 +454,364 @@
literals with the fingerprint when getting a key in this way.
** Importing keys
:PROPERTIES:
:CUSTOM_ID: howto-import-key
:END:
Importing keys is possible with the =key_import()= method and takes
one argument which is a bytes literal object containing either the
binary or ASCII armoured key data for one or more keys.
The following example retrieves one or more keys from the SKS
keyservers via the web using the requests module. Since requests
returns the content as a bytes literal object, we can then use that
directly to import the resulting data into our keybox.
#+begin_src python
import gpg
import os.path
import requests
c = gpg.Context()
url = "https://sks-keyservers.net/pks/lookup"
pattern = input("Enter the pattern to search for key or user IDs: ")
payload = { "op": "get", "search": pattern }
r = requests.get(url, verify=True, params=payload)
result = c.key_import(r.content)
if result is not None and hasattr(result, "considered") is False:
print(result)
elif result is not None and hasattr(result, "considered") is True:
num_keys = len(result.imports)
new_revs = result.new_revocations
new_sigs = result.new_signatures
new_subs = result.new_sub_keys
new_uids = result.new_user_ids
new_scrt = result.secret_imported
nochange = result.unchanged
print("""
The total number of keys considered for import was: {0}
Number of keys revoked: {1}
Number of new signatures: {2}
Number of new subkeys: {3}
Number of new user IDs: {4}
Number of new secret keys: {5}
Number of unchanged keys: {6}
The key IDs for all considered keys were:
""".format(num_keys, new_revs, new_sigs, new_subs, new_uids, new_scrt,
nochange))
for i in range(num_keys):
print(result.imports[i].fpr)
print("")
else:
pass
#+end_src
*NOTE:* When searching for a key ID of any length or a fingerprint
(without spaces), the SKS servers require the the leading =0x=
indicative of hexadecimal be included. Also note that the old short
key IDs (e.g. =0xDEADBEEF=) should no longer be used due to the
relative ease by which such key IDs can be reproduced, as
demonstrated by the Evil32 Project in 2014 (which was subsequently
exploited in 2016).
** Exporting keys
:PROPERTIES:
:CUSTOM_ID: howto-export-key
:END:
Exporting keys remains a reasonably simple task, but has been
separated into three different functions for the OpenPGP
cryptographic engine. Two of those functions are for exporting
public keys and the third is for exporting secret keys.
*** Exporting public keys
:PROPERTIES:
:CUSTOM_ID: howto-export-public-key
:END:
There are two methods of exporting public keys, both of which are
very similar to the other. The default method, =key_export()=,
will export a public key or keys matching a specified pattern as
normal. The alternative, the =key_export_minimal()= method, will
do the same thing except producing a minimised output with extra
signatures and third party signatures or certifications removed.
#+begin_src python
import gpg
import os.path
import sys
print("""
This script exports one or more public keys.
""")
c = gpg.Context(armor=True)
if len(sys.argv) >= 4:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = sys.argv[3]
elif len(sys.argv) == 3:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = input("Enter the GPG configuration directory path (optional): ")
elif len(sys.argv) == 2:
keyfile = sys.argv[1]
logrus = input("Enter the UID matching the key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
else:
keyfile = input("Enter the path and filename to save the secret key to: ")
logrus = input("Enter the UID matching the key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
if homedir.startswith("~"):
if os.path.exists(os.path.expanduser(homedir)) is True:
c.home_dir = os.path.expanduser(homedir)
else:
pass
elif os.path.exists(homedir) is True:
c.home_dir = homedir
else:
pass
try:
result = c.key_export(pattern=logrus)
except:
result = c.key_export(pattern=None)
if result is not None:
with open(keyfile, "wb") as f:
f.write(result)
else:
pass
#+end_src
It is important to note that the result will only return =None=
when a pattern has been entered for =logrus=, but it has not
matched any keys. When the search pattern itself is set to =None=
this triggers the exporting of the entire public keybox.
#+begin_src python
import gpg
import os.path
import sys
print("""
This script exports one or more public keys in minimised form.
""")
c = gpg.Context(armor=True)
if len(sys.argv) >= 4:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = sys.argv[3]
elif len(sys.argv) == 3:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = input("Enter the GPG configuration directory path (optional): ")
elif len(sys.argv) == 2:
keyfile = sys.argv[1]
logrus = input("Enter the UID matching the key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
else:
keyfile = input("Enter the path and filename to save the secret key to: ")
logrus = input("Enter the UID matching the key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
if homedir.startswith("~"):
if os.path.exists(os.path.expanduser(homedir)) is True:
c.home_dir = os.path.expanduser(homedir)
else:
pass
elif os.path.exists(homedir) is True:
c.home_dir = homedir
else:
pass
try:
result = c.key_export_minimal(pattern=logrus)
except:
result = c.key_export_minimal(pattern=None)
if result is not None:
with open(keyfile, "wb") as f:
f.write(result)
else:
pass
#+end_src
*** Exporting secret keys
:PROPERTIES:
:CUSTOM_ID: howto-export-secret-key
:END:
Exporting secret keys is, functionally, very similar to exporting
public keys; save for the invocation of =pinentry= via =gpg-agent=
in order to securely enter the key's passphrase and authorise the
export.
The following example exports the secret key to a file which is
then set with the same permissions as the output files created by
the command line secret key export options.
#+begin_src python
import gpg
import os
import os.path
import sys
print("""
This script exports one or more secret keys.
The gpg-agent and pinentry are invoked to authorise the export.
""")
c = gpg.Context(armor=True)
if len(sys.argv) >= 4:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = sys.argv[3]
elif len(sys.argv) == 3:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = input("Enter the GPG configuration directory path (optional): ")
elif len(sys.argv) == 2:
keyfile = sys.argv[1]
logrus = input("Enter the UID matching the secret key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
else:
keyfile = input("Enter the path and filename to save the secret key to: ")
logrus = input("Enter the UID matching the secret key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
if homedir.startswith("~"):
if os.path.exists(os.path.expanduser(homedir)) is True:
c.home_dir = os.path.expanduser(homedir)
else:
pass
elif os.path.exists(homedir) is True:
c.home_dir = homedir
else:
pass
try:
result = c.key_export_secret(pattern=logrus)
except:
result = c.key_export_secret(pattern=None)
if result is not None:
with open(keyfile, "wb") as f:
f.write(result)
os.chmod(keyfile, 0o600)
else:
pass
#+end_src
Alternatively the approach of the following script can be
used. This longer example saves the exported secret key(s) in
files in the GnuPG home directory, in addition to setting the file
permissions as only readable and writable by the user. It also
exports the secret key(s) twice in order to output both GPG binary
(=.gpg=) and ASCII armoured (=.asc=) files.
#+begin_src python
import gpg
import os
import os.path
import subprocess
import sys
print("""
This script exports one or more secret keys as both ASCII armored and binary
file formats, saved in files within the user's GPG home directory.
The gpg-agent and pinentry are invoked to authorise the export.
""")
if sys.platform == "win32":
gpgconfcmd = "gpgconf.exe --list-dirs homedir"
else:
gpgconfcmd = "gpgconf --list-dirs homedir"
a = gpg.Context(armor=True)
b = gpg.Context()
c = gpg.Context()
if len(sys.argv) >= 4:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = sys.argv[3]
elif len(sys.argv) == 3:
keyfile = sys.argv[1]
logrus = sys.argv[2]
homedir = input("Enter the GPG configuration directory path (optional): ")
elif len(sys.argv) == 2:
keyfile = sys.argv[1]
logrus = input("Enter the UID matching the secret key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
else:
keyfile = input("Enter the filename to save the secret key to: ")
logrus = input("Enter the UID matching the secret key(s) to export: ")
homedir = input("Enter the GPG configuration directory path (optional): ")
if homedir.startswith("~"):
if os.path.exists(os.path.expanduser(homedir)) is True:
c.home_dir = os.path.expanduser(homedir)
else:
pass
elif os.path.exists(homedir) is True:
c.home_dir = homedir
else:
pass
if c.home_dir is not None:
if c.home_dir.endswith("/"):
gpgfile = "{0}{1}.gpg".format(c.home_dir, keyfile)
ascfile = "{0}{1}.asc".format(c.home_dir, keyfile)
else:
gpgfile = "{0}/{1}.gpg".format(c.home_dir, keyfile)
ascfile = "{0}/{1}.asc".format(c.home_dir, keyfile)
else:
if os.path.exists(os.environ["GNUPGHOME"]) is True:
hd = os.environ["GNUPGHOME"]
else:
hd = subprocess.getoutput(gpgconfcmd)
gpgfile = "{0}/{1}.gpg".format(hd, keyfile)
ascfile = "{0}/{1}.asc".format(hd, keyfile)
try:
a_result = a.key_export_secret(pattern=logrus)
b_result = b.key_export_secret(pattern=logrus)
except:
a_result = a.key_export_secret(pattern=None)
b_result = b.key_export_secret(pattern=None)
if a_result is not None:
with open(ascfile, "wb") as f:
f.write(a_result)
os.chmod(ascfile, 0o600)
else:
pass
if b_result is not None:
with open(gpgfile, "wb") as f:
f.write(b_result)
os.chmod(gpgfile, 0o600)
else:
pass
#+end_src
* Basic Functions
:PROPERTIES:
:CUSTOM_ID: howto-the-basics