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mirror of synced 2024-11-24 14:30:11 +01:00
bemaniutils/bemani/common/aes.py

41 lines
1.3 KiB
Python

import base64
import hashlib
from Crypto import Random
from Crypto.Cipher import AES
class AESCipher:
"""
Simple AES cipher used to provide cookie support to the frontend.
"""
def __init__(self, key: str) -> None:
self.__padamt = 16
self.__key = hashlib.sha256(key.encode("utf-8")).digest()
def _pad(self, s: str) -> str:
intermediate = f"{len(s)}.{s}"
while len(intermediate) % self.__padamt != 0:
intermediate = intermediate + "-"
return intermediate
def _unpad(self, s: str) -> str:
length, string = s.split(".", 1)
intlength = int(length)
return string[:intlength]
def encrypt(self, raw: str) -> str:
raw = self._pad(raw)
random = Random.new()
iv = random.read(AES.block_size)
cipher = AES.new(self.__key, AES.MODE_CBC, iv)
return base64.b64encode(
iv + cipher.encrypt(raw.encode("utf-8")), altchars=b"._"
).decode("utf-8")
def decrypt(self, encoded: str) -> str:
enc = base64.b64decode(encoded.encode("utf-8"), altchars=b"._")
iv = enc[: AES.block_size]
cipher = AES.new(self.__key, AES.MODE_CBC, iv)
return self._unpad(cipher.decrypt(enc[AES.block_size :]).decode("utf-8"))