155. Are you a spymaster? Can you crack this code?

Do you enjoy cracking codes? I’ve been fascinated by codes and ciphers since I was a kid. Now, I have the chance to include a cipher in the novel I’m working on, Boundarising.  Here it is:

1455   2324   1341   5115   3224   2345   2543   1351   1221   5231   4324   5434

3415  5333   3324   1455   1521   2433   4145   5322   5333    2324   4115   3335

2423   1431   2532   2544   3321   4324   4135   5333   2133    2111   3323   3313 

2433   4415   4433   2423   4135   3442   4411   4145   2454    3335   1251   3135  

2324   4423   1513   4531   4234   4235   3135   5545   1223    1221   4135   3313  

2433   2513   5314   5544   3321   3531   4324   5132   3353    2153   3353   5322  

1242   4134   5545   3545   1431   2442   3255   3335   2123    3442   2531   4223  

1431   2322   3135   3424   4234   3135   5534   1254   4222    1332   3531   5312  

2443   4135   3255   5545   4415   4433   4135   3442   5545    3415   4113   2152  

1431   4115   2124   1415   4235   4145   3313   2513   4254    2443   3231   1513  

2142   1544   1213   1322   2354   2534   4441   5444   3255    3335   5545   2341  

2113   4235   3524   1441   5545   4453   4135   1541   3442    2341   2423   3312  

1322   1431   2312   1441   2423   3135   5321   4233   2234    1214   1322   1415  

4415   3533   1145   3345   4115   3544   2114   2541   5322    1112   5214   1541  

3353   4324   1333   3242   3224   3152   3353   4234   3135    4114   3224   2324  

2224   4241   3331   4454   3135   1541   4555   1213   1452    4321   4445   3135  

1213   3531   4325   4211   2113   4324   1532   3134   1421    4325   4445   3215  

3321   3442   1214   4233   2135   4315   3455   1415   4125    1431   2333   3242  

2354   2234   2411   1542   1431   3212   4222   1432   3313    2423   3321   1142  

5545   4324   4355   4215   2233   3114   1352   1311   5214    3155   3323   4222 

1452

Can you crack this? This isn’t just an empty challenge. I need to be able to demonstrate that a teenage boy, armed only with paper and pencil could do it, so I really need to know how easy this is to solve.

My protagonist, Sol, has been dispatched by his parents to live during wartime with his uncle, Zand in the countryside where he should be safe from enemy bombing, Many children were sent out of danger in this way in Britain during the second world war.

Just before he gets on the train, Sol’s father, William, presses an envelope into his hands and asks him to give it to Zand.

But Sol is a curious boy, opens the envelope and discovers the coded message. He spend many months trying to crack it. To give you a running start, Sol, recognizes that because there are no numbers greater than five, this code is probably created in a 5×5 grid. This would be sufficient to store all the letters of the alphabet, if two (such as I and J) are doubled up.

 12345
1ABCDE
2FGHI/JK
3LMNOP
4QRSTU
5VWXYZ

So, Sol reasons that the numbers code for letters (where 11 is A, 12 is B and so on). But, there are groups of four numbers, while two would be sufficient to code for a letter. So, Sol thinks the code involves pairs of letters. There must be some coding rules for relating the members of the pair to each other.

He readily sees that the grid above doesn’t decode the message, so he decides the letters cannot be arranged simply from A to Z. He thinks it’s unlikely the arrangement is random. That’s as far as he gets for some time.

Can you break the code? If so, please let me know how you did it. The first reader to do so will get a free copy of the book when it’s published.

6 thoughts on “155. Are you a spymaster? Can you crack this code?

  1. Neil, Just to let you know I am working on this code. So far my attempt at frequency analysis and fitting the best matches has fallen flat. If as you suggest there is a relationship between two letters in the pair, that suggests two tables with a letter/alphabet shift. The trick is finding the starting points.

    Liked by 1 person

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