T-9 Cypher Is Solved

[Doppelgänger]

After a few hours of intense brute-forcing this cypher, I have been left with a mountain of crumpled paper and the decrypted message.

+81

638433687387-7825328744445444833-
46737678-44-6636384327684377-
4273433233673-932685373224446-
46843228853-843684374778455-
285274346843-2489

First off, this is what is known as a T9 Cypher. I reached this conclusion by noticing the +81 at the beginning of the message. At first I was unsure what this meant, until I realised that is was a dialing code. For example, the dialing code for Australia is +61. When I researched this, I found that the dialing code at the start of the cypher was actually, coincidentally, the dialing code for Japan. Now, the cypher works much like old phone keypads did. Where the numbers also acted as letters. The '2' key gave you the letters; A, B and C, the '3' key gave you the letters; D, E and F, and so on.

Now, to the cypher. In the first line of numbers we have, 6384336878378. This means the first letter is either; M, N or O. The second, being 3, with gives up the possibility of D, E or F being the second letter. Continuing on, checking each and every number for their respective letters yields; Of the four test-. It was at this point where I assumed, by context, what the next set of letters would come together to form. Which I thought was 'subjects'. After checking, I found I was correct, and was able to remove a huge bit of work out of the way, and was able to continue on.

Also interesting to note, is that I could block words from crossing over from their respective number groups by looking at the dashes throughout the message. This meant that every group of numbers HAD to be either an entire word, or a group or words that fit into that line.

Now, I did get stuck when I reached the number 44. Taking the rule I mentioned in the previous paragraph, this meant that these two numbers had to be two letters. Considering the dashes mean we can't carry words over, I could only get GG, GH, GI, HG, HH, HI, IG, IH and II. Of course these would make no sense if put into the message as 'HI' is the only word we can pull from this. It was then when I realised that on the old phone keypads, if one wished to use a number in their text message, they would had to keep skipping through the letters until they reached the numbers. So, seeing that the word prior to the 44 was 'report' it made sense that it was indeed, "Report 44". I went through the rest, checking nearly every single possible combination and finally managed to pull the entire message from the cypher, which reads:

Of the four test subjects highlighted in Report 44, one of the brothers has died before we could reach him in the battle. The other is still at large in the city.

[Kalinine]

Well done!

[certainpersonio]

@Doppelgänger Oh well done! I also recognized the Japanese country code, but i was hung up on the "-" representing words separations. Great insight.

Also, what a cool message. If you've seen the Vigenere that @Nieno69 solved, then the city mentioned here is the same "city in flames" there, Stalingrad. 

[AlphaSnake]

Nice work & fast too.

Brains for you.

Regards Alpha.

[anonymous]

Just like the other code this leads to Stalingrad. Im so happy Gersch returns

[NaBrZHunter]

Brains, DG, my freind! Way to smash it!!!

[Tac]

Nice man!!

[Guest]

This and the cipher with Gersch in mentioning a fiery city next to a river tells me that Stalingrad is gonna be good. Nikolai and his brother were notorious in battle? I wonder who his brother is?