In this exercise you have to brute force the key given one plaintext ciphertext pair encrypted with TC01. In the file *Specification* a short specification of the cipher is given, the file *Reference Implementation [python]* contains a reference implementation of the cipher written in Python.

The key will be 64 bit of the form: `0x0000 0000 000* ****`

. Where a * signifies that this part of the key is unknown. In this case this means that the 20 least significant bits are unknown (and the 44 most significant bits are 0).

**Note:** All in/output to this website is given in hexadecimal notation in python you can easily interpret a hex as an integer by using:
`int(0x0123AFF, 16)`

.
And you can output an integer in hexadecimal format by using a string format:
`"%016X"%(123456)`