Introduction

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"When asked about the solutions that have been sent to him (Jim Sanborn), and whether any of them were close, Jim said he got one from Germany about a year ago that was “kind of scary”, that the first part had started to look right, but then the rest didn’t." From the CNN documentary about Kryptos: A making-of report with many photographs.

After all, what is known, the encryption seems to consist of 2 levels or layers. It looks like one layer is used to mask the statistics of the ciphertext. If it is true that the encryption consists of 2 unknown steps and the only thing that would be available are 97 letters, then the message can not be broken. This does not mean that the encryption process must subsequently prove to be secure; on the contrary, it may well be, when all the information about it is known, it turns out to be very insecure or inappropriate. History has shown that keeping the encryption algorithm secret is not a good idea. A principle of modern cryptography formulated in 1883 by Auguste Kerckhoff states that the security of a cryptosystem should depend only on the secrecy of its cryptographic key rather than the secrecy of the algorithm. William F. Friedman, the inventor of the index of coincidence, broke the Japanese encryption system "PURPLE" during World War II, without ever having seen one of the machines used or knowing the algorithm behind it. But he had a ton of intercepted messages to work with, partly even in plaintext due to the intelligence service. What do we have? Only 97 letters. With only 97 letters, Friedman would never have been able to complete this work. It is almost certain that Jim Sanborn was aware of this, or at least Ed Scheidt, who was teaching him. So there was a need, should the message ever be decrypted, to give an indication of the procedure. It is known that Jim Sanborn has said that the 4th message is solvable without knowing the contents of the other messages (thekryptosproject.com).

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