After a long, tedious battle with this thing, I’ve pretty much got it narrowed down to what I believe to be the only option. As I noted before, there are many multiples of the same number, even up to four times for the same number (“1”, for example). Furthermore, I believe we have compiled all the data we can regarding Code D, and that there isn’t much left to discover in regards to solving this cipher. In other words, if we have all the data we need, there can’t be that much info needed to solve the cipher. That said, I really doubt it’s a VIC cipher by any means.
I have also delved into some of the other cipher options, eliminated a few, and cross-referenced through a couple of programs. So far, they all pretty much make a 1:1 match with the Tri-Digital Cipher. For those of you that don’t know what that is, here is a brief overview: Tri-Digital Cipher
As you can see from the overview, it’s possible to derive up to three letters from each number; therefore, even with four of the same number in a row, there are different possibilities. The key to this cipher is two codewords that can be used–the first is a ten-digit codeword that can reuse letters. You assign it numbers that correspond to the alphabetical order of the letters, with 0 counting as “10”. So:
D O C T O R H O R N
2 5 1 0 6 8 3 7 9 4
You would then create a checkerboard with the numbers at the top, assign the letters of a second key word (9 characters, excluding repeat letters, with the last column left blank). Then, simply fill in the unused letters. This can then be used to solve the cipher. The good thing about this is that there are generally only 2 / 3 viable options since the bottom row is rarely used letters. Furthermore, you would obviously need the vowel equivalent in certain spots.
I’ve done a count of the characters in the cipher, and I’m fairly certain that either 9 or 8 is the space number above the blank column. One thing I’m not clear on is if a doubling of the number above this last column denotes a sentence break or if that is not factored into the cipher.
Anyway, if this is the cipher we need, there should be a slightly obvious 10-digit keyword and a keyword or phrase that can be narrowed down into 9 digits.