French to English Tech/Engineering IT (Information Technology) passwords and online security

This follows on from a previous question. I am translating a training manual for employees of a large firm on the subject of online security. The text is peppered with proverbs and pearls of wisdom from various French notables, this time, I believe, from Jacques Amyot. So far, I have been unable to uncover a translation for this (sometimes it's best to go with what's gone before rather than attempt one's own, when dealing with proverbs etc.)... so any sources or daring originals would be most gratefully received.
For a bit of extra context, the scene used to illustrate the advice is this: a man sitting in an airport waiting area with his busines laptop on his knees (preparing his presentation) is approached by an external business acquaintance, who then sits next to him and delcares that his is attending the same seminar. Oh la, la, what should he do? : shut his laptop, not worry, he knows the guy (decent sort etc.) or cover his work with his hand?! (Can you imagine the latter!?) No prizes for guessing the right answer but big points prizes for the best suggestion for this context!