Implementing Laravel crypt and decrypt functions in python - python-3.x

Question

I was able to find the decrypt function with a few researches, and now
I am trying to write laravel encrypt function using python.
I can decrypt using it:
class decrypter:
def __init__(cls, key):
cls.key = key
def decrypt(cls, text):
decoded_text = json.loads(base64.b64decode(text))
iv = base64.b64decode(decoded_text['iv'])
crypt_object = AES.new(key=cls.key, mode=AES.MODE_CBC, IV=iv)
decoded = base64.b64decode(decoded_text['value'])
decrypted = crypt_object.decrypt(decoded)
return unpad(decrypted, 16).decode('utf-8')
def decrypt_string(str):
try:
key = b"xxxx+xxxxxx+x+xxxx+xxxxx"
key = base64.b64decode(key)
msg = str
obj = decrypter(key)
decrypted = obj.decrypt(msg)
return decrypted
except Exception as e:
logla.logla(e, "decrypt_string")
print(e)
But I couldn't find a source for the encrypt method. There is a source I could find, but I couldn't run it.
enter link description here

Answer 1

For encryption, proceed in the opposite direction:
Create an IV
Pad plaintext
Save IV and ciphertext to JSON
Encode JSON with Base64
For encryption as in the linked code, additionally the MAC has to be generated and the PHP serialization has to be used:
import json
import base64
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad, unpad
from Crypto.Random import get_random_bytes
from Crypto.Hash import HMAC, SHA256
from phpserialize import loads, dumps
class encrypter:
def __init__(cls, key):
cls.key = key
def encrypt(cls, text):
text = dumps(text)
msg = pad(text, 16)
iv = get_random_bytes(16) # b'0123456789012345'
crypt_object = AES.new(key=cls.key, mode=AES.MODE_CBC, IV=iv)
encrypted = crypt_object.encrypt(msg)
ivB64 = base64.b64encode(iv)
encryptedB64 = base64.b64encode(encrypted)
mac = HMAC.new(cls.key, digestmod=SHA256).update(ivB64+encryptedB64).hexdigest()
json_string = json.dumps({'iv': ivB64.decode(), 'value': encryptedB64.decode(), 'mac': mac})
return base64.b64encode(json_string.encode())
def encrypt_string(str, key):
try:
msg = str.encode()
obj = encrypter(key)
encrypted = obj.encrypt(msg)
return encrypted
except Exception as e:
print(e)
# Test
keyB64 = b'MDEyMzQ1Njc4OTAxMjM0NTY3ODkwMTIzNDU2Nzg5MDE='
key = base64.b64decode(keyB64)
plaintext= 'This is a test plaintext'
encrypted = encrypt_string(plaintext, key)
decrypted = decrypt_string(encrypted, key)
print(encrypted)
print(base64.b64decode(encrypted))
For the test-IV b'0123456789012345' the output is:
b'eyJpdiI6ICJNREV5TXpRMU5qYzRPVEF4TWpNME5RPT0iLCAidmFsdWUiOiAiTlE1djFpaWU1QnFoTWNwRlhNdUFSZ2N3YVlrNG5CZlJyYmRKUGRna3FDcUN6NEZ6ZDhSOHhIUy95N1N3TWlQTyIsICJtYWMiOiAiYmYwNGJjMWEyN2NhNWUzMGFlYTdjZTI4Y2FkYTBlZGVjOGEwMzc3NWZhODVhMDc2MGRhODUzNDc1OTBmYmNmZCJ9'
b'{"iv": "MDEyMzQ1Njc4OTAxMjM0NQ==", "value": "NQ5v1iie5BqhMcpFXMuARgcwaYk4nBfRrbdJPdgkqCqCz4Fzd8R8xHS/y7SwMiPO", "mac": "bf04bc1a27ca5e30aea7ce28cada0edec8a03775fa85a0760da85347590fbcfd"}'
The linked code produces the same output using the same plaintext, key, and test-IV.