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Here’s what you’ll learn in this story:

• Last month, two journalists decoded part of the famous Kryptos sculpture in front of the CIA building.

• It’s the latest news in the cryptography world, as ciphers continue to attract code crackers in the CIA—and beyond.

• The Beale Cipher has attracted perhaps the most decryption enthusiasts of all time. Tens of thousands of people have tried to solve it, to get to the supposed location of a massive treasure.

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Just as sculptor Jim Sanborn was getting ready to auction off the solution to an encrypted code he carved into his Kryptos sculpture, he was thwarted by two people who claimed to have solved part of it, in an email they sent him on September 3.

Standing before the CIA headquarters in Virginia since 1988, Sanborn’s S-shaped copper screen is meant to evoke the theme of “intelligence gathering.” For nearly four decades, members of the public have been trying to solve the code and have succeeded in cracking the first three of five passages. The last two passages, known as K4 and K5, have remained unsolved, but now two people—beside the artist himself— know the solution to K4.

Ciphers connected to great treasure or consequences can be impossible to resist, and the tougher they are to solve, the more would-be decrypters seem to obsess over them. Whether mathematical, symbolic, or word-based, a cipher is a system for encrypting data, a way to encode a message and then decode it. Such coding systems have been used throughout history to carry private war messages and secret spy messages.

The CIA’s Kryptos sculpture with its unsolved cipher represents some of the work being done inside the organization: code cracking. But some of the most famous ciphers have stumped even CIA agents. So, outsiders figuring out the Kryptos solution before it was auctioned off is extra ironic.

A more gruesome example of public fascination with coded messages is the “Zodiac” serial killer’s letters about his crimes in the San Francisco Chronicle in 1969 and 1970. They stumped both the CIA and FBI, neither agency finding out the killer’s identity even after the deaths of five people. Researchers from three different continents joined the code-cracking efforts. Finally, a mathematician solved one of the killer’s ciphers, but no one ever identified and caught the killer, and the case has never been officially closed.

Cryptoanalysts from the CIA and National Security Agency also tried to work on the Beale cipher. This is perhaps the most tantalizing case to ever attract decryption efforts, this time in the form of a treasure hunt that has so far lasted 140 years. Tens of thousands of people have searched for the location of a massive collection of precious metals dating back to about 1819. That’s when a party of explorers—whose leader was Thomas Jefferson Beale—supposedly found the stash near what is now Santa Fe, New Mexico. Today the gold alone in the collection is purportedly worth more than $60 million. According to the story, the group buried the treasure in Virginia.

Making the story even more incredible is that the full hoard is said to include nearly 3,000 pounds of gold and 5,100 pounds of silver, among other highly valuable items. And the Declaration of Independence is believed to be a key to one of the three ciphers involved in the decryption.

Some think the treasure is on Machias Seal Island, off the coast of northern Maine. Others, like longtime searcher Ken Bauman—who figures he’s spent three-quarters of his life trying to find the Beale treasure—are convinced that it’s scattered across four different locations, including the island and Mount Pleasant mansion in Philadelphia.

Over the decades, treasure hunters have been “hunkering in libraries, driving bulldozers, wielding shovels, digging countless holes across the Virginia countryside, and in the process becoming so ubiquitous that some Roanoke-area farmers took to shooting at trespassers,” Popular Mechanics reported in 2024.

This search has been “one of the largest and most costly treasure hunts in U.S. history, baffling the finest mathematical minds in the country and defeating their computers ... while inducing frustration, despair and bankruptcy,” according to Smithsonian magazine in 1981.

However, some people believe the entire legend is more likely a hoax that leads to vexation and a waste of time and money, rather than real buried treasure.

But after nearly a century and a half, it’s unlikely treasure hunters and cipher enthusiasts will give up anytime soon. Nor will they give up on cracking the final section of the Kryptos passages.

Two journalists, Jarett Kobek and Richard Byrne, took advantage of an accidental information leak to solve the K4 passage. According to amateur cryptographer and journalist Kobek, RR Auction made a mistake. Kobek noticed that the company’s auction listing for the K4 solution mentioned that “coding charts” for the encryption were located at the Smithsonian’s Archives of American Art in Washington, D.C. Byrne, who lived in D.C., then found and photographed the charts, which turned out to contain K4’s plaintext, or decrypted message. Together, the two were able to assemble its 97 characters in the correct order.

Sanborn meant to auction off the original text of the fourth part of his Kryptos code, plus related artifacts, including handwritten charts, for an estimated $300,000 to $500,000. He planned to use the funds from the auction to “help manage medical expenses for possible health crises, and to fund programs for people with disabilities,” according to The New York Times story about the decryption. Years earlier, Sanborn had inadvertently included scraps of paper with the solution on it in the Smithsonian archives, according to Scientific American. At the time, he’d been compiling documents while undergoing cancer treatment.

Now, things were tense: it was entirely possible the cipher’s solution could be exposed before the sale.

However, since revealing the solution to Sanborn, Kobek and Byrne have promised not to release it to anyone else. The Smithsonian Institution has sealed the records for 50 years, at Sanborn’s request. Now the auction buyer may not know the answer first, but will still get Sanborn’s official documents, method of solution, and other materials included with the sale.

And even though K4’s text solution was discovered, the method that Sanborn used to decode it is still a mystery to everyone but him. For cryptography enthusiasts, that may count as the ultimate sacred treasure, and still worth the hunt.

Before joining Popular Mechanics in 2022, Manasee Wagh worked as a science journalist, a newspaper reporter, a technical writer, and an engineer. She has a bachelor’s degree in computer engineering and a master’s degree in journalism. Her favorite stories are about the discoveries that unearth even deeper mysteries, and she enjoys helping people understand the science behind the remarkable world we live in. She lives in the Northeast with her two favorite people and one curious, feisty feline, but always seeks to combine her love of food, nature, and travel into memorable journeys away from home.