The use of SHA-2-224 is kinda weird. Based on a quick skim: * no kdf on the password, just SHA-2-224(password) * uses the same key and iv (which always start

The use of SHA-2-224 is kinda weird. Based on a quick skim: * no kdf on the password, just SHA-2-224(password) * uses the same key and iv (which always starts as 0) in both directions * uses CFB mode without a MAC, which has malleability issues (IIRC you can flip bits in a ciphertext block, and the same bits will be flipped in the plaintext, but the rest of the stream will be garbage). * the authentication used is pretty sketchy (the key is fixed at 16 bytes and PW_LEN 15, so ljust shouldn't be doing anything): if tmp_data[:len(self.key)].ljust(PW_LEN,'0') != self.key.ljust(PW_LEN, '0'): log.msg("Remote unauthorized", logLevel=logging.INFO) Reminds me of this: https://www.cs.auckland.ac.nz/~pgut001/pubs/linux_vpn.txt https://www.cs.auckland.ac.nz/~pgut001/pubs/linux_vpn.txt