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kangfend/decrypt.py

Created June 22, 2022 23:43
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  1. kangfend created this gist Jun 22, 2022.
    17 changes: 17 additions & 0 deletions decrypt.py
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    Original file line number Diff line number Diff line change
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    from binascii import unhexlify
    from hkdf import Hkdf
    import hashlib


    from base64 import b64decode
    from Crypto.Cipher import AES
    from Crypto.Util.Padding import unpad


    def decrypt(encryption_key, text):
    encryption_key = unhexlify(encryption_key)
    key_length = len(encryption_key)
    kdf = Hkdf(b"\0" * 64, encryption_key, hash=hashlib.sha512)
    data = b64decode(text[128:])
    cipher = AES.new(kdf.expand(b"encryption", key_length), AES.MODE_CBC, data[:AES.block_size])
    return unpad(cipher.decrypt(data[key_length:]), AES.block_size)