Islam teaches and obliges Muslims to be honest and truthful, so the Prophet (peace and blessings be upon him) is reported to have said, “Stick to truthfulness, for it leads one to righteousness, and the latter leads to Paradise. Thus, when one sticks to truthfulness and shows keenness in it, Allah considers him as an absolutely truthful man. And avoid telling lies, for it leads to excessiveness, and this leads to Hellfire. Thus, when one persists in telling lies, Allah considers him as a liar” (Al-Bukhari).
Thus, if one is sure that he does not tell lies while dealing with people in work or outside it, there is nothing wrong to be diplomatic for the purpose of hiding secrets for necessity.