from typing import List


def xor_buf(b1: List, b2: List) -> bytes:
    """
    xor_buf - xor two lists

    Args:
        b1: List
        b2: List

    Returns:
        bytes: the result

    """
    return bytes([b1[i] ^ b2[i] for i in range(0, min(len(b1), len(b2)))])