I had CNN on earlier today, and they kept going on about how U.S. Intelligence agencies can’t decrypt messages on phones and whatnot. They mentioned it so often I thought ‘The lady doth protest too much, methinks.’
AFAIK, they’re not lying. But if I were a spy, I wouldn’t tell the opposition, ‘Hey, guess what? I can read what you wrote!’ (Which may be why Coventry wasn’t warned about the 11/14/1940 raid.)