'How to get attribute value from Extension object (Python cryptography)?

I want to access name attribute from Extension object.

from cryptography import x509
from cryptography.x509.oid import ExtensionOID

l_certificate = rgetattr(self.l_config_json, 'web_interface.certificate.certificate')
d_certificate = x509.load_pem_x509_certificate(str.encode(l_certificate))
ext = d_certificate.extensions.get_extension_for_oid(ExtensionOID.EXTENDED_KEY_USAGE)
extendedKeyUsage = ext.value
print(extendedKeyUsage)

Result:

<ExtendedKeyUsage([<ObjectIdentifier(oid=1.3.6.1.5.5.7.3.2, name=clientAuth)>, <ObjectIdentifier(oid=1.3.6.1.5.5.7.3.1, name=serverAuth)>])>

How to access name attributes(clientAuth and serverAuth) from result??

pythoncryptographyx509certificatepythonpython-3.xfiledirectorymove


Solution 1:[1]

If I understand the goal, you are just wondering how to access the attribute values? These can be derived by looking at the class definitions in site-packages/cryptography/x509/extensions.py and is a foundational skill (i.e. read the source code).

What I do is pretty straight forward:

# common to cryptography.x509.extensions.ExtensionType
data = {
    'critical': ext.critical,
    'name': ext.oid._name
}
# extension specific attributes
if isinstance(ext.value, cryptography.x509.extensions.ExtendedKeyUsage):
    data['key_usages'] = [x._name for x in ext.value or []]

which produced

 {'critical': False,
  'key_usages': ['serverAuth', 'clientAuth'],
  'name': 'extendedKeyUsage'}

instead of the repr you have, and cannot parse I guess?

Solution 2:[2]

The response you are getting and storing in 'ext' is a list. Access the individual items in the list by either iterating through it or by directly referencing its location. For eg: for "clientAuth" try using ext[0].value

extendedKeyUsage = ext[0].value

print(extendedKeyUsage)

Solution 3:[3]

I hope below code is the solution for your problem. Please note that I have use os.mkdirs() to create new directory. but you can try with Path.mkdir()

I have created four text file. out of 4, three text file have strings 2012. and one text file contains string 2020 and three text file contains 2012

Input files:

  1. ff1.txt (contains string "2012")
  2. ff2.txt (doesn't contains string "2012")
  3. ff_blah1.txt (contains string "2012")
  4. ff_blah1_blah2.txt (contains string "2012")

I have broken down problem statement in steps

  1. find the files which has name starts with "ff"
  2. after finding files, open all the files and search string "2012"
  3. create new folder "2012" if it doesn't exists
  4. move all files that we find at step2 into new created folder "2012"
import os
import shutil

source_path = '/Users/MacJJ271123/Desktop/PY_Script/'
list_of_files = os.listdir(source_path)

def move_file():
    for file in list_of_files:
        if file.startswith("ff"):
            if '2012' in open(file).read():
                if not os.path.exists(os.path.join(source_path, "2012")):
                    os.mkdir(os.path.join(source_path, "2012"))
                shutil.move(os.path.join(source_path,file), os.path.join(source_path,"2012",file))
                print(file)

move_file()

Output:

MacJ271123-MacBook-Air~  # python3 move_files_stack_oveflow.py
ff_blah1_blah2.txt
ff_blah1.txt
ff1.txt
MacJJ271123-MacBook-Air~  #

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Dharman
Solution 2 Surendranatha Reddy T
Solution 3 Jignesh23

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