BOSTON (AP) — When Jim Sanborn was commissioned to create a sculpture at CIA headquarters, he aimed to embody the world of spies and secret codes.


The result was 'Kryptos,' a 10-foot-tall, S-shaped copper sculpture resembling a piece of paper coming out of a fax machine, with encrypted messages on one side.


“At that time, codes and encoding seemed esoteric,” Sanborn reflects. “I wanted to make it accessible and fun... Any artist wishes to hold the viewer's attention for as long as possible.”


Initially, the first three messages on the sculpture were cracked relatively swiftly after its dedication in 1990. However, 35 years later, the fourth message remains elusive and has drawn a cult following of codebreakers and fans passionately trying to decode it.


Sanborn, now 79 and battling health issues, is auctioning the solution to K4, hoping the future keeper will continue the interaction with Kryptos enthusiasts. The auction, which runs until November 20, is already attracting substantial bids, currently exceeding $200,000.


“Since its 1990 installation, Kryptos has garnered widespread attention,” says Bobby Livingston, Executive Vice President at RR Auction. “K4 has stumped both professionals and amateurs alike.”


The auction includes essential documentation to crack K4, emptying a treasure chest of coded secrets. However, Sanborn was rocked by an accidental early revelation when researchers discovered original texts, leading him to seal access to his archival materials for 50 years.


With K4's enigma at stake, audiences are left in suspense, as most fans express a desire for its solution to stay under wraps, fearing that revealing it could diminish the allure.


As the auction draws near, Sanborn's emotional journey reflects both pride and regret, knowing the key to his artistic marvel could change hands, yet weigh heavily on his legacy.