CIA’s Kryptos mystery solution heads to auction after 35 years

The CIA’s Kryptos sculpture, a cryptographic artwork created by Jim Sanborn and installed at the agency’s Langley headquarters in 1990, is nearing the end of its decades-long mystery. While the first three of its four coded panels have been solved, the final panel, known as K4, has resisted all decoding attempts despite limited hints from Sanborn. In November 2025, Sanborn plans to auction the handwritten plaintext solution to K4, along with related papers and a copper proof-of-concept plate, with an expected winning bid between $300,000 and $500,000. Sanborn hopes the buyer will maintain the secret and potentially oversee future verification of code-breaking attempts. Over the years, Kryptos has attracted thousands of solvers, including persistent individuals and renewed interest fueled by popular culture references such as Dan Brown’s novels. However, the rise of artificial intelligence has led to many inaccurate attempts, which partly motivated Sanborn’s decision to sell the final solution. Pro