News | Nov. 15, 2021

Cracking Zendia’s Codes Safeguarded America

The National Cryptologic Museum operates as the National Security Agency’s principal gateway to the public, holding within its archives a treasure trove of cryptologic equipment. Its mission is to educate visitors in person and online about the role of cryptology in shaping history, from the ancient world to the present. In this occasional series, we highlight some of the rarest and most interesting artifacts found in its collection. Enjoy!

FORT MEADE, Md. - If the punchline to the famous joke, “How do you get to Carnegie Hall?” is practice, the same theory applies to National Security Agency staff who aspire to join the ranks of the best cryptanalysts in the world.

Over decades, cryptanalysts were trained by a world famous concert flautist who made it to Carnegie himself before entering the halls of the NSA to teach hundreds how to crack codes. Lambros Callimahos, born in Cairo to Greek parents, created musical history with an all-flute recital in New York’s most famous concert hall in 1938. After that he then pursued another of his passions, cryptology.  He entered the Army cryptologic service in 1941 and went on to teach cryptology at the Army Security Agency and later the NSA.
 
Callimahos’s students crossed the classroom threshold under a sign that said “Through these doors pass the Agency’s best cryptanalysts.” A master of languages, speaking 9 fluently and reading several more, he made up his own language and country to train his students. He imbued his fictional island nation of Zendia, not only with its own language, but a distinct culture, history, and a ruler, Salvo Salasio, whose picture bore more than a passing resemblance to a young Callimahos.

Salvo Salasio
Salvo Salasio, the fictional ruler of the island nation of Zendia, bears a remarkable resemblance to a young Lambros Callimahos. Photo: National Cryptologic Museumlasio
Salvo Salasio
Salvo Salasio
Salvo Salasio, the fictional ruler of the island nation of Zendia, bears a remarkable resemblance to a young Lambros Callimahos. Photo: National Cryptologic Museumlasio
Photo By: NSA
VIRIN: 211115-D-IM742-1235

Recently the National Cryptologic Museum (NCM) uncovered long-lost materials from the course, which help tell the story of the NSA’s early training in cryptanalysis.

“These artifacts illustrate the attention to detail that Callimahos put into developing the training program provided to early NSA Cryptanalysts. The story of this program adds to the already rich history of American Cryptology,” said NCM Collections Manager Spencer Allenbaugh.

Callimahos’ course, which he taught for more than 20 years, was known as CA-400. It was an expansion of William Friedman’s original senior cryptanalytic course, and is still legendary around the Agency. Friedman was the NSA’s chief cryptologist in its earliest days.

The teaching materials used in CA-400 increased over the years, and by the mid-1970’s a student was expected to read over sixty books and documents. However, it was the “Zendian Problem” at the end of the course that needed solving before graduation.

Zendia represented Callimahos’s almost overwhelming thoroughness and creativity. Students were tasked with decoding radio intercepts from the fictional island. U.S. Army cartographers even drew up a map placing the small island in the Pacifika Ocean, right where some would say God forgot to put it. Students had to decipher 375 Zendian military messages, essentially Morse code intercepts in the Zendian language. The messages were enciphered by a variety of manual and machine systems. Over two weeks, students were tasked to decrypt and translate all the exploitable messages. If they could crack the made-up language, they could crack any other on earth.

The recent discoveries associated with the CA-400 course are the Zen-45 and Zen-50 cipher machines that students used to break the Zendian codes. The bright green machines mimicked real-world tools such as the SIGABA, and help tell the story of the NSA’s early cryptanalysis training.

“The National Cryptologic School (NCS) is enthusiastic over the museum’s discovery,” said Diane Janosek, Commandant of the NCS.

Diane Janosek with ZEN cipher machine
Diane Janosek poses alongside one of the newly discovered ZEN cipher machines used by Lambros Callimahos to teach National Security Agency staff to become cryptalnalysts. Photo by NSA
Diane Janosek with ZEN cipher machine
Diane Janosek with ZEN cipher machine
Diane Janosek poses alongside one of the newly discovered ZEN cipher machines used by Lambros Callimahos to teach National Security Agency staff to become cryptalnalysts. Photo by NSA
Photo By: NSA
VIRIN: 211115-D-IM742-1234

“The Zen devices provide us the opportunity to reflect on the rich history of the school and its immense value in contributing over five decades toward a well-educated and prepared workforce to defend our nation,” said Janosek.

Visitors to the NCM can look forward to seeing these treasured ZEN machines on exhibit when museum renovations are completed and the collection reopens in the Spring of 2022.