from pwn import *

def run():
    #r = process(["python", "./server.py"])
    r = remote("babypad.be.ax", 1337)
    enc = bytes.fromhex(r.readline().decode().strip())
    print(enc.hex())

    def trial(s):
        if isinstance(s, str):
            s = s.encode()
        r.readuntil("> ")
        r.sendline(s.hex())
        result = r.readline().decode().strip()
        return int(result) == 1

    known_content = bytearray([0] * len(enc))

    def run_test(position):
        npads = 16 - (position % 16)
        for x in range(256):
            if x == npads:
                continue
            test = bytearray(xor(enc, known_content))
            test[position] ^= x ^ npads
            for z in range(position + 1, position + npads):
                test[z] ^= npads

            if trial(test[:position + npads]):
                return x
        raise Exception("none found for", position)

    # actual_pad = run_test(len(enc) - 1)
    # print("found pad", actual_pad)
    actual_pad = 4
    known_content[-4:] = b"\x04\x04\x04\x04"

    i = len(enc) - 5
    while i >= 0:
        result = run_test(i)
        print(known_content)
        known_content[i] = result
        i -= 1

    return known_content

if __name__ == "__main__":
    run()