I am inclined to believe that the 4th piece is written in a foreign language or otherwise multiply-encoded, or that Sanborn made a drastic error in the cryptography. The other 3 sections were solved independently in a much shorter time. For instance, the NSA was the first to crack the first three parts of the sculpture, and they did it in only 2 days. The fact that nobody has made any progress on the 4th section in well over a decade even with a known clue is hard to reconcile.
> Then “within two days of receiving the information tasking from Chief, Z,” they had solved parts one through three of the puzzle. They spent another day on the fourth section, but very quickly “a decision was made to stop any further work” on it. “Given the suspected cryptography, the last section is too short to solve without diverting a great deal of effort from operational problems,” they wrote in the memo.
Elonka Dunin is the maintainer of the well-known Yahoo Kryptos group, and maintains the primary reference page.
Apparently a mistake exists in Part 2 of the sculpture so it's plausible that there's more. From the Wikipedia article:
> There are also a few incorrect letters in the ciphertext which Sanborn has said were intentional, and a few letters near the beginning of the bottom half have been displaced from their normal positions, apparently intentionally... One of the lines of the tableau is one character too long, which Sanborn has indicated was accidental.
It's tough to imagine how to start such a problem when you can't even rely on the ciphertext being correct.
"It's tough to imagine how to start such a problem when you can't even rely on the ciphertext being correct."
That's a common problem in the real world. A lot of ciphertext, at least historically, comes from radio signals and if your receiver doesn't get a good copy of the signal you've got what you've got.
Unless, of course, those are clues? From the FAQ on Elonka's page:
Q: Why are words misspelled in Parts 1 and 2? Is that a mistake?
No. Sanborn has said that those two errors -- iqlusion and undergruund -- are deliberate, but he didn't say exactly why. He did say that it wasn't what they were that was so important, as their orientation or positioning.
If there's something critical about their positioning, and given that the coordinates are for a location in the same courtyard as the sculpture, it seems reasonable that one would need more than just the ciphertext to solve it.
> Sanborn realized he had also made an inadvertent error, a missing “x” that he mistakenly deleted from the end of a line in section two
I can't imagine the horror that accompanied that realization. I get anxiety when I notice a typo after an e-mail goes out. A typo into an encrypted sculpture that's so high profile must have been upsetting...
> Then “within two days of receiving the information tasking from Chief, Z,” they had solved parts one through three of the puzzle. They spent another day on the fourth section, but very quickly “a decision was made to stop any further work” on it. “Given the suspected cryptography, the last section is too short to solve without diverting a great deal of effort from operational problems,” they wrote in the memo.
Elonka Dunin is the maintainer of the well-known Yahoo Kryptos group, and maintains the primary reference page.
http://elonka.com/kryptos/
Wired ran an interesting article about the NSA's original crack of the scultpure, which I have quoted from above.
http://www.wired.com/2013/07/nsa-cracked-kryptos-before-cia/