Okay, conspiracy freaks, here’s a fun new technology: A scientist has developed a way to spy on what you’re typing — by listening to the sound of your keystrokes. Every key on your keyboard produces a noise, and IBM research scientist Dmitri Asimov suspected that the sounds were probably quite distinct. As SearchSecurity.com reports, he recently decided to test his hypothesis. It succeeded beyond his wildest dreams:

Asonov found that by recording the same sound of a keystroke about 30 times and feeding it into a PC running standard neural networking software, he could decipher the keys with an 80% accuracy rate. He was also able to train the software on one keyboard to decipher the keystrokes on any other keyboard of the same make and model.

Good sound quality is not required to recognize the acoustic signature or frequency of the key. In fact, Asonov was able to extract the audio captured by a cellular phone and still decipher the signal.

Pretty mind-blowing, eh? The thing is, it reminded me of an old detective story I’d read as a kid. I was a fan of the “Thinking Machine” stories written by Jacques Futrelle. They detailed the adventures of Dr. Augustus S. F. X. Van Deusen (can you dig that crazy name?), an arrogant brainiac who liked to go around boasting about how he could solve any crime with his machinelike logic. Anyway, there’s one story called “The Mystery of the Silver Box”, in which Van Deusen is hired by a rich CEO — “Mr. Grayson” — to help figure out how his most important business plans are being leaked to his competitor. Grayson is particularly puzzled because the only person who ever hears his plans is his secretary, Miss Winthrop; he dictates his letters and she types ‘em up. Since she sits at a desk within eyeshot of Grayson, the CEO knows that she doesn’t call anyone to leak information. He can’t figure out how the hell the information is getting out.

But Van Deusen, since he is The Thinking Machine, figures it out. He notices that Miss Winthrop keeps a little silver box on her desk next to her phone. He deduces her scheme: She uses it to prop the phone receiver up a little bit and open up a line to Grayson’s competitor. Then, while she types one of Grayson’s letters, she hits the keys in a rhythm that spells out the content of the letter in Morse code. The competitor deciphers the Morse code and, presto, learns of Grayson’s secret plans. As Van Deusen notes at the end of the story:

“Miss Winthrop is a tremendously clever woman,” replied The Thinking Machine. “She never told you that besides being a stenographer-typist she is also a telegraph operator. She is so expert in each of her jobs that she combined the two. In other words, in writing on the typewriter, she was clever enough to be able to tap her keys in a pattern that is exactly like the Morse telegraphic code. Any other telegraph operator at the other end of the phone could translate the clicks of the keys into words.”

This completely fried my noodle when I read it back in grade four. And now some IBM scientist is using A.I. to do almost the same thing!

By the way, you can read “The Mystery of the Silver Box” here — at a web site that has full-text copies of all of the “Thinking Machine” stories. While you’re at it, check out “The Problem of Cell 13”, the most famous of the tales. In it, Van Deusen escapes from a high-security prison in only four days. The stories were all written between 1905 and 1912, so there are some wonderfully dated moments; I just reread it myself and cracked up at this exchange:

“Nothing is impossible,” declared The Thinking Machine with equal emphasis. He always spoke petulantly. “The mind is master of all things. When science fully recognizes that fact a great advance will have been made.”

“How about the airship?” asked Dr. Ransome.

“That’s not impossible at all,” asserted The Thinking Machine. “It will be invented some time. I’d do it myself, but I’m busy.”

(Thanks to Slashdot for this one!)