> Kryptos: The Puzzle the CIA Still Hasn't Confirmed
There's a sculpture standing on actual CIA grounds that stumped the agency's own cryptanalysts for years. Then, in 2025, its answer reportedly turned up in a completely different archive, and the man who built it still won't just tell everyone.
The sculpture
Kryptos is a copper-and-granite installation by artist Jim Sanborn, dedicated on November 3, 1990, at the George Bush Center for Intelligence, CIA headquarters, Langley, Virginia. Sanborn collaborated with Ed Scheidt, a retiring CIA cryptographic officer, to design the actual encryption. Carved into the sculpture's curved copper screen are four separate encoded passages, roughly 869 characters combined, labeled K1 through K4.
Three down
K1 and K2 use a Vigenère cipher run through a keyed, non-standard alphabet ("KRYPTOSABCDEFGHIJLMNQUVWXZ"), with the keywords PALIMPSEST and ABSCISSA respectively. K3 is a transposition cipher. All three were actually solved quietly, more than once, before anyone outside a small circle knew it. An NSA team led by Ken Miller cracked them internally in late 1992, and CIA analyst David Stein solved them by hand in 1998, but neither disclosure went public. Credit usually goes to computer scientist Jim Gillogly, who solved and published all three independently in 1999, making him the first to actually tell anyone. K2's decoded text is its own small reward. It includes a set of geographic coordinates pointing to a spot roughly 174 feet from the sculpture itself.
The one that wouldn't crack
K4 is short, about 97 characters, and that's part of what makes it brutal. Its cipher method has never been publicly confirmed, and it resisted every serious public attempt for more than three decades, making it one of the most famous unsolved ciphertexts in the world, sitting in plain view of an intelligence agency that specializes in exactly this.
The 2025 wrinkle
In September 2025, journalists Jarett Kobek and Richard Byrne reported finding documents in the Smithsonian's own archives that appeared to contain K4's plaintext. Sanborn didn't confirm it publicly. Instead, that November, he auctioned off his personal archive, his own working notes on the piece, for just over $962,000, well above its estimated value, rather than simply releasing the answer. He's also stated that a fifth message, K5, exists and won't surface until K4 is publicly acknowledged as solved. As of this writing, nothing has been officially confirmed by Sanborn or the CIA, so "unsolved" is still technically the accurate word for K4. It's just not a clean one anymore.
