An encrypted clue for the police

A well known German drug dealer contacted his accomplice through an encrypted note. The police caught the accomplice during a drug deal and found the note in his backpack.

Note:

(For those who can't open images, it says: STTLBSTBFDBSFDRQCBODBSCBQGGQJLTSTDL)

Police Notes [Alt + Shift + T word]:

STTLBSTBFDBSFDRQCBODBSCBQGGQJLTTDL
B = ? TT = ?

interview information 13.06.2019:
-american accomplice can't speak any german.
-education: information technologist
-usual communication via email. why note?
-accomplice talked to the german drug dealer before

The police failed to decrypt the message. Can you?

Hint 1:

Hint 2:

The German didn't use a common encrypting method, he created his own with the things he had access to.

Hint 3:

The police isn't any use in this case.

Hint 4:

The German isn't a great inventor, he based his method on something simple he spotted in his apartment - an object he used daily.

Hint 5:

The object is a peripheral device.

Hint 6:

The encryption involves shifting letters on an object.

• Are the "[Alt + Shift + T word]" and "b" bits deliberate? Oct 8, 2019 at 14:56
• @Nati Could you write out what the picture says? I can't open images. How can the accomplice talk to the German if he can't speak German?? Oct 8, 2019 at 17:41
• @Neo1009: The image shows the letters in the Police Notes, handwritten in red throwaway ballpen on crumpled graph paper. Highlighting the TT's and B's must have been done by the police, the letters in the image all have the same weight. (Some Germans speak English, but the two could also communicate in French or Russian, for example.) Oct 8, 2019 at 17:59
• @MOehm Touché. I didn't think about that. Oct 8, 2019 at 22:23
• Is the "c" intentionally left out of the word "encrypted" in the title?
– JLee
May 24, 2022 at 15:13

After much unsuccessful messing around with

Shifting keyboard letters via umpteen different algorithms,

I went back to my instinctive approach of making some assumptions about how the message would likely begin. The regular occurrence of the letter

B makes it a good candidate for a space.

"MEET ME"

or something similar, so I assigned the first letters those values, and also made a big assumption that each letter always maps to the same value. That got me this:

MEET ME __ M_____ __ M_ _____TEME_T

Which looked promising, and led me to guess "ON" for the next word, giving me

MEET ME ON MON___ N M _____TEMENT

Sorry the formatting is weird in the last 2 spoilers. It has a mind of its own.

By this point I was excited, knowing I was probably on the right track. The obvious choice to finish the next word was

"DAY",

giving me 3 more letters to plug in, yielding

MEET ME ON MONDAY _N MY A__A_TEMENT

I then quickly realized that the German had misspelled the word

"apartment" with 2 P's and an extra E.

But also concluded that the message must be

MEET ME ON MONDAY IN MY APPARTEMENT

Then I went back to the

Keyboard

to try to reverse engineer the encryption method that the German had used

Thx to @moehm for the comment about the german keyboard. Below is the encryption table used:

• On the one hand, that seems like it must be the solution... On the other hand I feel like it's pretty disappointing if that's it. Just a simple substitution cipher? Were all the other details irrelevant? Or is it possible that your solution is actually a red herring and you haven't actually solved it yet (which would be really cool)? May 24, 2022 at 21:34
• @SQLnoob Quite a red herring if it is. I guess we will see. I'm a bit surprised no one stumbled on this in over 2.5 years though.
– JLee
May 24, 2022 at 21:39
• @user39583 The German keyboard was one of my first ideas when I first saw this puzzle a few weeks back, but I can't make anything of it.
– JLee
May 25, 2022 at 9:55
• There are three extra umlaut letters on a German keyboard, which extend the top and middle rows. The substitution cipher just enumerates the rows on a German keyboard with the basic Latin alphabet plus three extra characters, the first of which must be a space. Jul 25, 2022 at 5:12
• Nice! :) Finally someone figured it out! Well done. @JLee
– Nati
Nov 25, 2022 at 13:22

I don't have the full answer yet, but here's what I'm thinking

The peripheral mentioned in hint 5, in my opinion, is the keyboard. The man has access to a computer, but no internet, and his specialty is in information technology.

I'm not sure why the TT and B were Bolded, except to maybe indicate a row shift or a period.

• HI and welcome Lucas! Please take the tour and read How to Answer to make yourself familiar with the site. While I have you, can I advise you not to make posting partial answers too much of a habit, as per this meta post? Mar 31, 2022 at 18:24
• Hello :) you're on the right track! Isn't a full answer though.
– Nati
May 24, 2022 at 13:56