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66 lines
2.1 KiB
Python
66 lines
2.1 KiB
Python
import base64
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from hashlib import sha256
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from Cryptodome import Random
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from Cryptodome.Cipher import AES
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BLOCK_SIZE = 16
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class AESCipher:
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"""This class is compatible with crypto-js/aes.js
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Encrypt and decrypt in Javascript using:
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import AES from "crypto-js/aes.js";
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import Utf8 from "crypto-js/enc-utf8.js";
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AES.encrypt(decrypted, password).toString()
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AES.decrypt(encrypted, password).toString(Utf8);
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"""
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def __init__(self, key: str, description=""):
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self.key: str = key
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self.description = description + " "
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def pad(self, data):
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length = BLOCK_SIZE - (len(data) % BLOCK_SIZE)
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return data + (chr(length) * length).encode()
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def unpad(self, data):
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return data[: -(data[-1] if isinstance(data[-1], int) else ord(data[-1]))]
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def bytes_to_key(self, data, salt, output=48):
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# extended from https://gist.github.com/gsakkis/4546068
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assert len(salt) == 8, len(salt)
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data += salt
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key = sha256(data).digest()
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final_key = key
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while len(final_key) < output:
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key = sha256(key + data).digest()
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final_key += key
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return final_key[:output]
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def decrypt(self, encrypted: str) -> str: # type: ignore
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"""Decrypts a string using AES-256-CBC."""
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encrypted = base64.urlsafe_b64decode(encrypted) # type: ignore
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assert encrypted[0:8] == b"Salted__"
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salt = encrypted[8:16]
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key_iv = self.bytes_to_key(self.key.encode(), salt, 32 + 16)
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key = key_iv[:32]
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iv = key_iv[32:]
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aes = AES.new(key, AES.MODE_CBC, iv)
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try:
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return self.unpad(aes.decrypt(encrypted[16:])).decode() # type: ignore
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except UnicodeDecodeError:
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raise ValueError("Wrong passphrase")
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def encrypt(self, message: bytes) -> str:
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salt = Random.new().read(8)
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key_iv = self.bytes_to_key(self.key.encode(), salt, 32 + 16)
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key = key_iv[:32]
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iv = key_iv[32:]
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aes = AES.new(key, AES.MODE_CBC, iv)
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return base64.urlsafe_b64encode(
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b"Salted__" + salt + aes.encrypt(self.pad(message))
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).decode()
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