Think of a question to which the answer is known only to you and your contact. Enter the question and answer, then wait for your contact to enter the answer. If the answers do not match, the communication channel you are using may be under surveillance.
想一个只有您和要联系的人知道答案的问题。输入问题与答案，然后等待对方回答。若答案不正确，则代表你们之间的通信渠道可能正被监听。