52 lines
1.3 KiB
Python
52 lines
1.3 KiB
Python
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import os
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import sys
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from Crypto.Cipher import AES
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from Crypto.Hash import SHA256
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def main(args=None):
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if len(args) < 2:
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print("Usage: python aes_decipher.py <file> <key>")
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return
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fname = args[0]
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if not os.path.exists(fname) or os.path.isdir(fname) or not os.path.isfile(fname):
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print("File does not exist or is not a file")
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return
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key_arg: str = args[1]
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if len(key_arg) < 16:
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h = SHA256.new()
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h.update(key_arg.encode('utf-8'))
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key = h.digest()[0:16]
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cipher = AES.new(key, AES.MODE_ECB)
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else:
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key = key_arg[0:16]
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cipher = AES.new(bytes(key.encode('utf-u')), AES.MODE_ECB)
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fsize = os.path.getsize(fname)
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with open(fname, 'rb') as file:
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run = True
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while run:
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block = file.read(AES.block_size)
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text = cipher.decrypt(block)
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if file.tell() == fsize:
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has_padding = True
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i = AES.block_size - text[-1]
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while has_padding and i < len(text):
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has_padding = text[i] == text[-1]
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i += 1
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if has_padding:
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text = text[:AES.block_size - text[-1]]
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run = False
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os.write(1, text)
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if __name__ == '__main__':
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main(sys.argv[1:])
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