HackTheBox AHS512 Challenge

#!/usr/bin/python3
from hashlib import sha512
from random import randint
from pwn import remote
import sys

class ahs512:
    def __init__(self, message):
        self.message = message
        self.key = self.generateKey()

    def generateKey(self):
        while True:
            key = randint(2, len(self.message) - 1)
            if len(self.message) % key == 0:
                break
        return key

    def transpose(self, message):
        transposed = [0 for _ in message]
        columns = len(message) // self.key
        for i, char in enumerate(message):
            row = i // columns
            col = i % columns
            transposed[col * self.key + row] = char
        return bytes(transposed)

    def rotate(self, message):
        return [((b >> 4) | (b << 3)) & 0xff for b in message]

    def hexdigest(self):
        transposed = self.transpose(self.message)
        rotated = self.rotate(transposed)
        return sha512(bytes(rotated)).hexdigest()

def main():
    if len(sys.argv) != 2:
        print(f"Usage: {sys.argv[0]} <ip:port>")
        sys.exit(1)
    host, port = sys.argv[1].split(':')
    p = remote(host, int(port))
    p.recvuntil(b'Find a message that generate the same hash as this one: ')
    target = p.recvline().strip().decode()
    original_message = b"pumpkin_spice_latte!"
    modified_message = original_message.replace(b'_', b'\xdf')
    while True:
        p.sendlineafter(b'Enter your message: ', modified_message.hex().encode())
        p.recvline()
        answer = p.recvline()
        if b'Conditions not satisfied!' not in answer:
            break
    print(answer.decode().strip())
    p.close()

if __name__ == "__main__":
    main()