In classical cryptography a null is intended to confuse the cryptanalyst. Typically, a null will be a character which decrypts to obvious nonsense at the end of an otherwise intelligible phrase. In a null cipher, most of the characters may be nulls.
An example follows:
- News Eight Weather: Tonight increasing snow. Unexpected precipitation smothers eastern towns. Be extremely cautious and use snowtires especially heading east. The [highway is not] knowingly slippery. Highway evacuation is suspected. Police report emergency situations in downtown ending near Tuesday.
Taking the first letter in each word successively yields the real message: “Newt is upset because he thinks he is President.”
If we take the K4 text:
And extract the letters in an orderly fashion, we can see if there is a simple null cipher at work, such as every other letter being important.
Every 2nd letter:
Every 3rd letter:
Every 4th letter:
Every 5th letter:
Every 6th letter:
Every 7th letter:
Every 8th letter:
Every 9th letter:
Every 10th letter:
I tried anagramming the last 3 sets of letters at 1, 2, and 3 word segments but only saw gibberish.
At this point I feel it is safe to shelve this idea at least in its current form. It is not impossible that there are null ciphers in Kryptos but in my limited search of K4 I did not find anything significant.