Well, this is interesting: The auction, which will include other items related to cryptology, will be held Nov. 20. RR Auction, the company arranging the sale, estimates a winning bid between $300,000 and $500,000. Along with the original handwritten plain text of K4 and other papers related to the coding, Mr. Sanborn will also be providing a 12-by-18-inch copper plate that has three lines of alphabetic characters cut through with a jigsaw, which he calls “my proof-of-concept piece” and w...| Schneier on Security