The Low-Stakes Race to Crack an Encrypted German U-Boat Message

“What am I supposed to see?” Krutzler asks, staring at his screen and bouncing his knee like he has a baby on it. His T-shirt reads “Defense Nuclear Weapons School.”

“You’re supposed to see a little ladder,” explains Koeth. “Like DNA strands.”

A few minutes go by before the transmission begins again. This time, it sounds a bit different. Koeth gives the thumbs up. Holly Wilson, a student of Koeth’s who graduated with a bachelor’s in physics in 2023, gets enlisted to transcribe the code into a yellow-lined legal pad. She’s wearing a faded Fleetwood Mac T-shirt and has a massive tattoo of an octopus wrapping her arm. Wilson writes down OKTOBER 7 and DBK WSE before the signal fades.

“That’s it, that’s it!” shouts Koeth. He consults the page from the German Army Staff Machine Key Number 28 book, provided by MRHS in a link on its website. He’ll need to obtain the key setting for the Enigma machine, the first step in decoding the message. The team has been at it for almost an hour.

At last, Koeth opens the wood cover of the Enigma. Although it’s possible to purchase one for between $300,000 to $500,000, Koeth received his as a loan from a collector in California, a WWII buff who has an exact replica of Little Boy, the atomic bomb dropped on Hiroshima, in his backyard. (Ensuing calls from concerned neighbors.)

Koeth’s own workplace might be cause for similar concern. A faculty member at UMD since 2009, his second-floor office holds an impressive collection of radiological antiquities such as Fiestaware, Vaseline glass, and, under lock and key, some Lone Ranger Atomic Bomb Rings, cereal prizes from the 1950s that contained a small amount of polonium 210.

Koeth removes two rotors from the machine, turns one to 6 and the other to 12, and plops them back inside.

“We gotta do the plugboard next,” Koeth announces before closing the lid. He begins to plug and unplug a series of tubes in a way that recalls Ernestine, Lily Tomlin’s immortal phone operator.

“No wonder the Germans lost the war,” says Larry Westrick, an electrical engineer from Opelika, Alabama. “It takes too long to communicate.”

Luckily, tenacity is part of Koeth’s job description. When he was 10, Koeth laid out plans to build a nuclear reactor in his parents’ basement in Piscataway, New Jersey.

Next, entering the code in cyphertext, Koeth pushes some of Enigma’s buttons, which in turn moves the rotors like the inner workings of a clock; a lampboard lights up a corresponding letter in plaintext. “It’s a guessing game,” he says, turning quiet. “Just think,” he says after a while, “they had to do this every day.”

Krutzler, Westrick, and a few newcomers gather around Koeth and his machine. There are 100 letters in the message and so far, none of them seem to make any sense.

“Something is wrong,” they say in unison. A joke goes around that the secret message is “Drink more Ovaltine.”

Koeth refers to a set of instructions. “Basically, you key in the first set of letters, and they should match the second set of letters. Which they don’t.”