Doctor Curmudgeon: Delilah…Shush!

By Diane Batshaw Eisman, M.D. FAAP Doctor Eisman is in Family Practice in Aventura, Florida with her partner, Dr. Eugene Eisman, an internist/cardiologist

Delilah is a musical sounding name. It comes from the Hebrew and Arabic. And it means “delicate” or “to hang low.”

And these adjectives beautifully describe a top secret WW II project.

Delilah was the brilliant voice encoding system developed by the logician, mathematician, cryptanalyst, philosopher, and computer pioneer Alan Turing.

Jack Copeland reported in IEEE Spectrum that a few months ago some papers were auctioned off for almost half a million dollars in London. These were not art or antiques, but documents from the Delilah project.

British charitable and private sectors combined their funds to purchase the documents. Turing’s surviving notebooks and papers now reside at King’s College in Cambridge.

Like their biblical namesake, the Delilah project was meant to deceive. The Turing papers documented research on a secret prototype for a portable voice encryption system.

A secure voice communication system could be of great use for the military.

Before Delilah, the wartime cipher machines were not easy to use. Commanders needed to get information sent quickly and securely. Text was written and then encrypted. In wartime, that was just too slow. The military dreamt of a way to speak and have their message immediately encrypted and sent securely.

The United States Army had contracted Bell Labs to come up with voice encryption. And they did. But it was huge, filled an entire room and weighed more than fifty thousand kilograms.
Turing was well aware of this project and he felt there had to be a way to make speech encryption units much smaller.

Hidden at Hanslope Park, somewhere in England, there dwelt a military facility. This is where Turing worked on Delilah.

And it was there that champagne corks popped with success! Delilah was composed of three units, and each one was about the size of a shoebox. With her power pack, she weighed 39 kilograms.

Delilah was similar to our modern method for digitizing sound. The machine went from analog to digital by breaking down sound signals into numbers. Each number corresponded to the voltage of the sound signal. Random keys were generated and the message was sent.

And so, you could speak into a microphone and your analog voice signal was changed into an electrical signal. Then, the machine added a key which was a bunch of random numbers. The receiver’s key generator was synchronized with that of the sender.

Then, Delilah would distort the frequencies of your voice signal and if there was anybody listening, your voice would sound like a nonsensical mess.

The garbled message would be sent out over telephone lines or radio waves.

Sounds so simple! I can only vaguely imagine the mathematics, logic, and engineering that went into this project.

Turing had given lectures to engineers about the project. He had put his thoughts into notebooks, but very few have survived. Some were saved by Donald Bayley, an electrical engineer who worked with Turing. Baylay had also kept loose notes from Turing’s lectures along with diagrams.

Secret Delilah—a brilliant combination of mathematics and engineering. And it has been forgotten for decades. Thanks go to Turing’s right hand man, Donald Baylay, for preserving these documents.

And so, the forgotten notebooks and papers have had a happy ending safely preserved at King’s College in Cambridge, London.

AUTHOR’S NOTE: My thanks to my feline cousin, Renpet, who is a former CIA officer. when she Learned that the Turing Delilah papers were safe at King’s College, she told me to look it up. I asked her for more information, but she turned her tail to me and padded into her office.

Dr. Curmudgeon suggests “Bitter Medicine”, Dr. Eugene Eisman’s story of his experiences–from the humorous to the intense—as a young army doctor serving in the Vietnam War.
Bitter Medicine by Eugene H. Eisman, M.D. –on Amazon

Doctor Curmudgeon® is Diane Batshaw Eisman, M.D., a physician-satirist. This column originally appeared on SERMO, the leading global social network for doctors.
SERMO www.sermo.com

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