fix some pylint errors/warnings

create-gpg-shadow-key-from-x509-cert-req.py

@@ -1,11 +1,19 @@
 #!/usr/bin/env python3
 
+"""
+create a shadowed-private-key in sexp format
+for gnupg's private-keys-v1.d folder
+containing the public key of a
+X.509 certificate signing request or a public key
+"""
+
+import ctypes
+import math
+
 import binascii
 import cryptography.hazmat.backends
 import cryptography.hazmat.primitives.serialization
 import cryptography.x509
-import ctypes
-import math
 
 DEFAULT_KEY_OUTPUT_PATH_PATTERN = '{keygrip_hex}.key'
 DEFAULT_SMARTCARD_APP_ID_HEX = 'D2760001240102010001234567890000'
@@ -43,8 +51,8 @@ def keygrip_from_key_sexp(key_sexp_data):
 
 def load_public_key(input_path):
     backend = cryptography.hazmat.backends.default_backend()
-    with open(input_path, 'rb') as f:
-        input_data = f.read()
+    with open(input_path, 'rb') as input_file:
+        input_data = input_file.read()
     try:
         return cryptography.hazmat.primitives.serialization.load_pem_public_key(
             input_data,
@@ -56,7 +64,8 @@ def load_public_key(input_path):
         return req.public_key()
 
 
-def create_gpg_key(input_path, gpg_key_output_path_pattern, smartcard_app_id_hex, keygrip_hex_output_path):
+def create_gpg_key(input_path, gpg_key_output_path_pattern,
+                   smartcard_app_id_hex, keygrip_hex_output_path):
     pubnums = load_public_key(input_path).public_numbers()
     key_data = ['shadowed-private-key', [
         'rsa',
@@ -68,17 +77,19 @@ def create_gpg_key(input_path, gpg_key_output_path_pattern, smartcard_app_id_hex
     keygrip = keygrip_from_key_sexp(key_sexp_data)
     keygrip_hex = binascii.hexlify(keygrip).upper().decode()
     if keygrip_hex_output_path:
-        with open(keygrip_hex_output_path, 'w') as f:
-            f.write(keygrip_hex + '\n')
-    with open(gpg_key_output_path_pattern.format(keygrip_hex=keygrip_hex), 'wb') as f:
-        f.write(key_sexp_data)
+        with open(keygrip_hex_output_path, 'w') as keygrip_file:
+            keygrip_file.write(keygrip_hex + '\n')
+    with open(gpg_key_output_path_pattern.format(keygrip_hex=keygrip_hex), 'wb') as sexp_file:
+        sexp_file.write(key_sexp_data)
 
 
 def _init_argparser():
     import argparse
     argparser = argparse.ArgumentParser(
-        description='create a shadowed-private-key in sexp format for gnupg\'s private-keys-v1.d folder'
-            + ' containing the public key of a PEM-encoded X.509 certificate signing request (CSR)',
+        description='create a shadowed-private-key in sexp format'
+                    ' for gnupg\'s private-keys-v1.d folder'
+                    ' containing the public key of a'
+                    ' PEM-encoded X.509 certificate signing request (CSR)',
     )
     argparser.add_argument(
         'input_path',
@@ -90,8 +101,8 @@ def _init_argparser():
         metavar='path-pattern',
         default=DEFAULT_KEY_OUTPUT_PATH_PATTERN,
         help='path to sexp-encoded shadowed-private-key to be created.'
-            + ' if specified, {keygrip_hex} will be substituted.'
-            + ' (default: "%(default)s")',
+             ' if specified, {keygrip_hex} will be substituted.'
+             ' (default: "%(default)s")',
     )
     argparser.add_argument(
         '--smartcard-app-id',
@@ -105,7 +116,7 @@ def _init_argparser():
         metavar='path',
         default=None,
         help='path where to save keygrip in hex format'
-            + ' (default: no output)',
+             ' (default: no output)',
     )
     return argparser
 
@@ -116,6 +127,7 @@ def main(argv):
     create_gpg_key(**vars(args))
     return 0
 
+
 if __name__ == '__main__':
     import sys
     sys.exit(main(sys.argv))