padding.py 文件源码

def _byte_unpadding_check(buffer_, block_size, checkfn):
    if buffer_ is None:
        raise AlreadyFinalized("Context was already finalized.")

    if len(buffer_) != block_size // 8:
        raise ValueError("Invalid padding bytes.")

    valid = checkfn(buffer_, block_size // 8)

    if not valid:
        raise ValueError("Invalid padding bytes.")

    pad_size = six.indexbytes(buffer_, -1)
    return buffer_[:-pad_size]