It was sententious nonsense when Harry Stinson said it in 1929, when he yanked the State Department's share of funding for the U. S. Government's first official cryptographic effort (and arguably, one of the first super-secret Bureaus: the Cipher Bureau operated behind a front as a legitimate commercial-code business. The NSA got those sneaky-pete genes more-or-less legitimately).
Stinson was quick to recant in deed if not word when the U. S. got kicked into WW II; the military had never given up.
In the real world, "gentlemen" have been verifiably reading one another's mail since the late 1500s.
You'll excuse me if I find the current flap about NSA peering over the shoulders of world leaders -- even ones with whom our government is pinky-swear BFFs -- a few centuries late and staggeringly naive.
In the eyes of the jaded spooks of Britain and the Continent, the intelligence services of the United States have long had a reputation for unsubtlety despite super-1337 electronic-spying skills; their latest missteps have been something of a return-to-standard, as Elint merges with Humint as the smartphone in your pocket turns into an untrustworthy constant companion and their need for ever-better geekery outstrips the number of men and women who will keep even the most dire of secrets.
1 month ago