Simple py2 implementation of PAN-OS masterkey encryption/decryption

mkcrypt.py

from hashlib import md5, sha1
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends import default_backend
from base64 import b64encode, b64decode

class PanCrypt():
    def __init__(self, key='p1a2l3o4a5l6t7o8'):
        backend=default_backend()
        key=self._derivekey(key)
        self.c=Cipher(algorithms.AES(key), modes.CBC('\0'*16), backend=backend)
    def _derivekey(self,key):
        return md5(key+md5("pannetwork").digest()).digest()*2
    def _pad(self, d):
        plen=16-(len(d)%16)
        return d+(chr(plen)*plen)
    def _unpad(self,d):
        return d[:-(ord(d[-1]))]
    def _encrypt(self,data):
        e=self.c.encryptor()
        return e.update(self._pad(data)) + e.finalize()
    def _decrypt(self,data):
        d=self.c.decryptor()
        return self._unpad(d.update(data)+d.finalize())
    def encrypt(self, data):
        v=b64encode('\x01')
        hash=b64encode(sha1(data).digest())
        ct=b64encode(self._encrypt(data))
        return '-'+v+hash+ct
    def decrypt(self, data):
        v=b64decode(data[1:5])
        hash=b64decode(data[5:33])
        pt=self._decrypt(b64decode(data[33:]))
        return (v,hash,pt)

encryption:

>>> pc=PanCrypt()
>>> ciphertext=pc.encrypt("AAAA")
>>> print(ciphertext)
'-AQ==4lEhcqv4zJ9n/dSetsrPLfcbutM=X6AkSo4yvy4V9F78nMz4rg=='

verifying the ciphertext string matches the ciphertext returned by cryptod:

sh-4.2# sdb -P3 'sw.cryptod.runtime.api.encr={"ptext-len":4,"plain-text":'AAAA'}'
""""sw.cryptod.runtime.api.encr: { 'encrypted-text': <LUFRPT00bEVoY3F2NHpKOW4vZFNldHNyUExmY2J1dE09WDZBa1NvNHl2eTRWOUY3OG5NejRy
Zz09>, 'etext-len': 57, 'plain-text': <QUFBQQ==>, 'ptext-len': 4, }
sh-4.2# echo 'LUFRPT00bEVoY3F2NHpKOW4vZFNldHNyUExmY2J1dE09WDZBa1NvNHl2eTRWOUY3OG5NejRyZz09'|base64 -d
-AQ==4lEhcqv4zJ9n/dSetsrPLfcbutM=X6AkSo4yvy4V9F78nMz4rg==

decrypting data:

>>> pc.decrypt(ciphertext)
('\x01', '\xe2Q!r\xab\xf8\xcc\x9fg\xfd\xd4\x9e\xb6\xca\xcf-\xf7\x1b\xba\xd3', 'AAAA')

this tuple contains the version code (should be \x01 in valid ciphertexts), the SHA-1 hash of the plaintext, and the plaintext.