明修栈道，暗渡陈仓
míng​xiū​zhàn​dào'àn​dù​chén​cāng

to feign one thing while doing another

明修栈道，暗渡陈仓 明修棧道，暗渡陳倉 míng​xiū​zhàn​dào'àn​dù​chén​cāng
to feign one thing while doing another
Literally meaning to repair the plank road by day while secretly crossing at Chencang, this idiom describes using a diversion to hide one's true intentions or activities.