SECOM Cipher Attempt

As I mentioned on the forums, the SECOM is very similar to the VIC cipher and also uses an extended straddling checkerboard (which ties in with the Code C message).  Anyway, what follows is an attempt to determine the two transpositions utilizing the key phrase "Superbus Via Inscientiae":

• I took the first twenty characters of the phrase and split them into two groups of ten:

 S U P E R B U S V I          A I N S C I E N T I

• I then assigned numbers to each letter corresponding to alphabetical order, with 0 being last:

 S U P E R B U S V I          A I N S C I E N T I

   6 8 4 2 5 1 9 7 0 3           1 4 7 9 2 5 3 8 0 6

• I then added the number of the second group to the numbers of the first group.  When you do this step, it's important NOT to carry the tens column--in other words, if you get 5 + 8 = 13, you drop the ten and use only the 3:

 6842519703

+ 1479253806  

------------------

  7211762509 

• I then create a block composed of 50 NEW numbers by using chain addition.  In other words, I take the 7 + 2 = 9 and write the 9 below the 7.  Then I take 2 + 1 = 3 and write the 3 below the 2 . . . so on and so forth.  Once again, the tens column is not carried:

7211762509

----------------

9328387598

2501152470

7512676177

2638336849

8911694237

• Then, take these last 10 digits and assign numbers to them much like you did with the letters above; except of course, that you will be going in order of the numbers rather than the alphabetical order of the letters:
  
  
  8911694237
  ---------------
  8912605347
  • This final 10-digit number should be the header for our straddling checkerboard.
    
    
    What I'm including next is a couple of charts depicting the first and second transpositions I derived from the separate halves of the key phrase and the cipher text we've been provided.  As long as the key phrase is "Superbus Via Inscientiae", then these transpositions will work, and all that's left to do is find a valid straddling checkerboard to apply to them.  For an explanation of how I got these transpositions, visit this site.
    
    
    In the long run, the only chart that really matters is the first transposition, because if the key phrase is right, then this is considered the "original" cipher text encoded directly from the straddling checkerboard.
    
    
    Both transpositions, in the order that I completed them (reverse order due to decoding process):
    
    
    Second Transposition
    
    

    3	0	9	2	5	3	1	5	8	8	3	3	3	4	9
    1	7	8	9	1	3	8	5	9	9	4	8	1	9	0
    4	5	9	9	1	3	4	1	5	1	9	4	5	7	9
    1	5	4	2	8	8	7	1	3	9	6	4	2	9	0
    6	0	3	3	1	1	9	9	0	8	1	1	9	7	2
    5	9	8	8	9	9	9	8	1	9	0	1	6	7	1
    1	9	6	9	9	8	8	3	9	8	1	8	3	8	1
    4	4	4	8	3	8	9	2	3	8	9	1	7	4	8
    9	4	9	7	1	7	9	1	1	7	3	8	7	1	9
    1	7	3	3	5	7	4	8	4	8	6	3	6	1	7
    6	7	3	5	9	1	7	9	9	2	8	9	2	1	3
    1	1	2	7	9	1	8	9	7	9	3	1	1	3	1
    9	7	3	1	7	1	4	1	3	9	9	1	2	9	9
    7	1	0	3	0	1	3	1	1	0	3	1	9	3	8
    9	1	4	8	9	8	9	9	3	5	9	1	5	9	0
    9	5	2	5	2	2	1	2	0	9	9	9	3	5	4
    8	2	0	3	3	2	3	7	0	0	8	5	3	1	9
    4	2	9	7	1	6	2	1	1	9	5	6	3	9	7
    3	8	3	1	5	1	7	9	4	4	5	2	9	3	1
    0	9	6	5	1	1	7	4	9	1	9	7	9	4	7
    8	9	4	3	2	9	6	8	4	8	0	4	4	9	8
    9	1	3	9	2	3	7	4	4	4	5	8	4	4	1
    1	9	8	5	9	9	9	5	8	9	9	9	5	9	9
    1	1	8	8	8	0	4	1	4	9	1	9	3	9	9
    9	3	9	1	3	9	0	6	1	2	2	4	4	3	1
    3	1	9	1	4	5	7	0	3	8	2	9	9	5	9
    3	3	2	9	3	2	0	1	9	9	8	3	7	5	9
    1	9	5	9	9	3	3	5	9	3	9	0	3	9	8
    3	9	0	2	4	1	1	8	9	1	3	1	4	3	5
    9	3	1	8	1	3	8	3	1	3	8	9	1	5	9
    3	1	2	0	0	1	0	5	9	2	4	9	6	1	3
    7	8	9	5	9	7	4	1	5	7	4	8	8	7	1
    4	7	3	0	3	8	3	3	3	8	9	4	0	7	4
    8	8	1	3	1	8	1	8	1	1	9	8	9	1	9
    4	7	4	9	4	0	9	1	9	0	8	0	5	0	1
    9	3	3	0	6	8	1	7	0	4	8	5	9	9	9
    1	3	9	4	1	X	X	X	X	X	X	X	X	X	X

    
    
    
    
    First Transposition
    
    

    9	9	3	4	0	3	1	3	3	8
    1	1	0	7	3	8	7	1	1	9
    3	4	9	4	3	1	9	3	5	9
    9	9	2	9	1	8	9	8	1	3
    0	1	5	4	1	9	2	9	7	5
    6	9	3	0	5	1	8	1	9	9
    3	3	1	9	9	7	9	3	4	1
    1	9	5	1	8	4	1	1	4	5
    9	9	8	9	8	8	1	2	5	9
    1	1	8	0	9	3	2	0	2	9
    4	2	3	8	9	8	7	0	9	5
    5	2	3	9	9	7	9	1	3	2
    7	4	1	3	1	1	1	0	1	5
    0	4	7	3	9	9	8	5	5	2
    3	3	8	0	6	3	9	9	1	2
    3	1	9	6	9	6	7	2	1	1
    3	8	1	8	9	1	9	4	7	2
    2	2	3	1	8	7	3	9	4	0
    9	9	8	7	8	2	1	6	9	9
    3	9	5	0	3	1	1	1	1	9
    2	5	9	4	4	3	9	7	9	9
    0	9	9	8	4	3	7	8	7	3
    1	8	4	5	4	1	3	9	9	5
    9	3	8	1	8	9	1	5	4	4
    9	7	1	3	3	0	7	9	7	4
    1	5	4	9	8	8	1	7	2	3
    9	9	5	4	9	2	4	4	9	8
    5	0	9	1	2	0	1	1	6	0
    9	3	9	3	3	3	3	5	8	9
    9	9	1	4	9	3	9	7	4	6
    3	8	3	9	4	2	9	4	8	8
    3	4	4	9	9	3	1	8	0	9
    5	3	1	0	7	7	2	8	4	4
    9	5	5	9	1	0	9	7	4	3
    3	5	1	9	7	0	7	1	9	9
    9	9	9	9	9	8	1	4	8	1
    3	3	4	0	1	5	0	7	3	3
    9	8	5	8	1	3	3	3	7	9
    0	9	7	1	7	1	0	0	4	2
    2	4	1	1	1	9	1	3	4	1
    4	0	5	9	7	2	3	8	4	9
    1	7	4	7	3	9	1	3	5	8
    1	4	2	2	3	7	1	3	8	5
    8	9	8	8	5	1	0	3	4	9
    9	8	8	1	7	6	3	8	4	9
    1	9	7	9	4	2	1	8	1	1
    3	1	1	0	8	1	9	1	9	1
    1	9	3	1	4	1	3	3	5	8
    9	0	9	6	8	9	8	1	8	8
    3	5	6	7	6	5	9	8	9	8
    1	0	4	1	6	6	1	1	9	0
    8	1	2	9	7	3	4	8	9	4
    1	9	9	8	3	9	8	1	5	9
    3	9	0	1	5	7	9	1	9	3
    8	9	6	8	9	X	X	X	X	X

    
    
    Once again, this text would be the "original" encoded text as long as the key phrase is right.  Although these may not be the correct transpositions due to the key phrase being wrong, hopefully it gives you all an idea of how we can reverse engineer the cipher to get at what we need.