Thanks for doing the interview. I think I've read almost everything available from the media now published on the sculpture and I'm not often surprised by new quotes.

I think what you got was versions of what Sanborn said before, perhaps rhyming not repeating. The new part was about the thinking around releasing EAST NORTH EAST in parts.

I think to get the full picture, it'd be best to interview Ed Scheidt as well.

You have quotes in the interview like: Sanborn wanted to "make it as difficult as possible" and he hoped "the [K4 code] would outlive him".

This would seem to imply Sanborn doesn't want K4 solved, or doesn't care.

But the consistently stated intention of Scheidt in many interviews has been that it would be difficult, but solvable within 5, 7, or 10 years. This is really _quite different_ to what Sanborn said.

Right from the start (January 1990) the media articles stated "The secret phrase has been inscribed using two codes - one invented in 1586 by Blaise de Vigenere, a French diplomat, and the other devised by an unidentified cryptographer especially for the sculpture.".

In 1991, Scheidt said he didn't know what the sculpture said; later in 2015, he said he'd gone back and checked K1-3 but not K4.

Would-be solvers are starting to realize that with so much plaintext released and nobody seemingly closer to a solution 

(a) it seems more likely that Sanborn could release the whole plaintext without the method becoming any clearer; 
(b) the encryption method must be quite complex if knowing 25% of the plaintext doesn't appear to help; 
(c) the timeline is absolutely defying the Scheidt expressed intention particularly with so many "hints"

And following on from (c), computer power, networks, storage, and algorithms for solving classical ciphers have improved massively in the last 30 years.

So given all those, plus the continued attention of many crypto experts I've been in touch with, plus the Scheidt expressed intention, we seriously wonder if there's been a mistake in K4 encryption.
Or if Sanborn has "accidentally" made solution impossible by cooking up a new system that can't be solved at this length of cipher. (This is the theory of one of the best contributors here, Jim Melichar).

We see accidental mistakes in the other sections (IQLUSION based on accidentally misspelling the PALIMPSEST keyword once, UNDERGRUUND fixed on another "version" of Kryptos, Antipodes).

Scheidt said in 2005 he was "confident" the encryption had been done correctly; does he still think that?

Because given computer power now, if anybody had guessed the method, the search would be done in an instant...

And was Scheidt's intention that the encryption method could be derived from statistical properties of the K4 ciphertext? This is the working assumption.

(I understand he often deflects that kind of very specific question by saying it's a "Jim question")

People spend time on this because of the reputation of Scheidt. Not Sanborn.

Thanks again