How to work enc function:

1. Encode string to base64

2. Create a new string from the encoded one by applying xor to each character:

   new [i] = base64_encoded [i] ^ base64_encoded [i + 1]

3. Convert the result to hex

How to work decode:

1. Convert the hex string to bytes (binascii.unhexlify)

2. Know first char

   1. If you don't know it just repeat algorithm for each base64 alphabet's chars

3. base64_encoded [i + 1] = base64_encoded [i] ^ new [i]

solution script: solution.py

flag is flag{tyrannosauras_xor_in_reverse}

Original writeup (https://github.com/wetox-team/writeup/blob/master/hacktivitycon/tyrannosaurus_rex/).