You've been known to your government to be an expert in decrypting messages for years so you're not really surprised when a man in a black suit knocks on your door one rainy afternoon.
“Good afternoon, your country needs you.”
Much later, somewhere you’ve never been and would never know how to get to – or get out of, for that matter – you’re sitting in front of a grey-haired elderly man with a semi-permanent smile on his face which never seems quite honest.
“Fact is, we know they are using an encryption relying on a code word they change every other week, and while we have been able to intercept all their messages, we’ve never found the keyword to decipher them. But this time, we’ve got close. We’ve observed a suspect for several months, and we are pretty sure he’s the one receiving the keyword every other week, and passing it on to their network. Last night, the suspect was followed when he entered a shabby hotel, and also when he left it only 20min later. We’ve managed to arrange… and incident, which allowed us to go through his things without giving away that he’s followed. The only remarkable thing we discovered was a handwritten crossword-like paper of letters which we successfully copied down. It has presumably been written by the suspect while he was in the hotel, and we are sure it’s the keyword. Unfortunately, we have not at all been able to discover the keyword. And this is where you come into the game. We’ll update you with any intelligence we get, and you may ask us any question you think relevant, but right now, there really isn’t more to go on than this handwritten crossword… Oh, and the analysts of the messages tell me, that it is mathematically required that the keyword consists of at least 5 and at maximum 7 letters, and that all of those need to be unique.”
Can you find the keyword? The paper found with the suspect is shown below.
Your ‘friend’ might give further possible information over the next few days. You may also ask specific questions, if you think that useful, and your friend will answer to the best of his knowledge.
Technical notes and answers to comment-questions
This is only my second attempt making a puzzle here, and tagging it properly is a bit difficult. I can assure you that there is a single answer and that it is clearly the answer (once found). I will add clues over time (if unsolved), and if you have specific questions, please ask them "in story" and you'll receive answers "in story" (when suitable) Those questions might make things easier, but they are not essential.
The image letters typed out as ASCII text (as requested):
FiPwUFrsWcQBaBnyI TmtsoOpzfgkKnBCRu lBAmGyJoUXATuwrxQ iVYHKrCkNijmaczvY iSOUeFUrKeEfEnDWt mkcnqjDmnGNaajryH AIotSrqOPadGKckYi HuTHOrZpgpaMYIBCg ukrbjiZSkwMdGVaKh LiAVEtDimanxuXhJw nrTABFdckbAmnfBKA wBsKeysEEttdubkjY FunkyrKuAmhCntPmC kxAijZbIXiMVFwGun HfBjeVdTXDrmARFtb mtkAEJrUbwKYbaHam RwXyaujKhavnIYJpG LiMTuzvFWyQJiRuAR xGqUeekGJRjEeZHIj bJYpmiTByrjihIwrJ RyNWHmkHanfzfJXxt LIiLjHyatXlabrAtZ ywqHawrivQuickgXQ
Alignment of characters within the boxes:
The original note was handwritten with the characters not all being perfectly aligned in the boxes. (However, it's a cross-hatched paper, so the boxes are accurate.)
Hints & Solution-Cross-checking
First clue. (If you're stuck. You can solve the puzzle without it.)
A bit later that night a clerk opens the door and tells you: "Any new ideas already I'm sorry to tell you, that the first few words you've given us to try didn't seem to do the trick. For what it's worth: We've now searched the hotel room the message was received in, and it is now clear to us, that the message was transmitted using Morse code. We've found an automatic Morse-code writer hidden behind a panel. A tiny scrap of paper was still in there - either from the beginning or the end of the transmission. It reads: " · − − − − | − − · · · | − · · − | · · − − − | · · · − −"
Second clue. (If you're stuck. You can solve the puzzle without it. This clue is stronger than the first.)
It is not long after, that the same clerk knocks on your door again. "We have just witnessed the suspect handing over the keynote to another man. We think we have positively identified him as the one-eyed spy, who we are trying to nail down for a long time. Anyway, the exchange was quite cleverly done in a Staples store and we nearly have missed it. The spy came in, asked the shop keeper for a packet of colourful pencils and, just after paying, picked up the crossword note our suspect had left in the packing area, and went out. For whatever reason - and to our luck - the one-eyed spy came back 5 minutes later and exchanged - rather angrily - the packet of pencils for another one, before leaving again. We have of course spoken with the shop-keeper. According to him, the spy asked for "a pack of 30 coloured pencils" the first time, which the shopkeeper gave him. The spy returned, because the pack consisted of pencils in red, blue, green, yellow, pink and orange - 5 of each - but he wanted the pack containing 30 different colours."
Once you have a keyword... (Solving the one below will verify your solution.)
Your grey-haired friend crashes into the room and startles you out of your thoughts. "We really have to hurry now. We think we have just intercepted a message send to the one-eyed man. It was stored on one of those cheap label-printers of all things! When we tried to arrest the man, he could escape, but at least he had to leave behind the device. The message was still in memory! It's an endless mess of letters, of course, but we have all confidence in you, that you can turn this into a message..." He hands you a long stripe printed from the label machine (It is a single long piece like in the first image.) Typed out for copy & paste convenience: "dSmAmcptscAbypOetIoaweorRoaLexdrrevmmiusVtFNnkneeenrsExyieatnXdgxpDKCgrvyxHxxQoxiMHxeXdnaTTruNWtaXieoJJXttn" ( The solution is a message consisting of 12 English words. )