So if we accept the possibility of null ciphers then is it possible that if we force a Caesar shift will the plaintext be revealed through the masking gibberish.

No.

Using K for E and then shifting the rest of the alphabet as well (6 places), we get little more than a variation of the current gibberish.

If there is a substitution cipher intermixed with null letters then it is not a Caesar shift of 6.

Kryptos Fan

Advertisements