# A strange Letter

1: Hey, could you please give me your car tomorrow? I have to go to the movie.
2: No, I don't think so.
1: Hey c'mon. You're my brother. You must help me. You ain't using it anyway.
2: Of course, I am not using it. But let me see if you could crack my puzzle to own the car.
1: Hey it is just a car man.
2: You must earn it anyway. You can't get anything easily. It will be tasteless. A little hardwork should do. If everything you wish comes just like that, it won't be interesting would it?
1: I will take father's car then.
2: It was given for service, remember?
1: Ok, all right. Gimme the puzzle.
2: You take all the time you want. But you must go to the movies "tomorrow" right?
1: Yeah. I will try.
2: I will give you a letter where you should find who were mentioned in that letter.

Crack this and find them and you'll get your keys right away. Good luck :)

Source: This is my own puzzle

• Your homemade encryption is broken. It has lost all information about each word except for that word's length and its first letter. Commented Feb 9 at 3:18

A partial answer, because I'm stuck.

From the = at the end, and the combination of upper & lower case numbers and letters, this looks like

it has been Base 64 encoded. Using Base 64 Decoding we get: Date : 29.01.2009 Place : Santa Claus Village

Dear Morty, Rd o_~ C eKVlY CFLXpaaCFL BDH iSf EJThQb [vm[v _~ iSf o_~}{ O^| iSfMZtti iS gO^|y iSfMZ YreKVl MZtiSffM _~ iSf ]zukWnn aCFLXp BDH _~ iSfM o_~} QbEJTh SfMZtiiSfMZt KVlYreeK Sf GN\xqccGN\xqc [vm[vmm[vm[v CFL Sf CFL iSf gO^|yssg iSfM QbEJTh Wn]z CF iSfM iSfMZ B gO^| MZtiSf gO^|ys CFL CFLXpaaCFL iSf [vm CFL gO^|ys iSf MZtiSffMZ hQb MZtiSff SfMZtii YreKVll SfMZtiiSfM _~ KVlYreeKVl [vm[v hQb MZtiSffM KVlYreeKVl Sf EJTh KVlYreeKVl [vm[v Sf o_~ QbEJTh IRdIRddI hQb GN\xqccGN\xq QbEJTh kW CFL [vm[ KVlY gO^|yss iS o_~}{w Sf iSfMZ MZtiSffM o_~} KVlY o_~}{ _~ iSfMZ [vm[ sgO^| _~ o_~}{ reKV iSfM [vm[ aCFLXppa fMZ iSf [vm[vmm eKVlYrre hQbE GN\xqccG O^| _~} _~ iSf SfMZtiiSfM _~ iSf MZtiS aCFLXp CFL iSfM gO^|yss iS MZtiSff hQbEJT iSfMZt gO^|yssgO^ iSfMZ iSfM gO^|yss iS aCFLXpp iSfMZ MZtiSffM o_~} kWn]zu GN\xqccGN\x hQbE MZti iSfM iSfM QbEJThh GN\x CFL iSf o_~ QbEJ iS jUjUj [vm[ iSfMZ MZtiSffM iS EJ YreKVll CFL hQbE MZti iSfM [vm[ aCFLX iSfMZ aCFLX iS CF KVlYre iSfM iSfM [vm[ C YreKVllYreKV SfMZtiiSfMZ

so it appears

we need a second decryption for the body of the letter. Because the remaining text has characters like }{ and ^, my thought was an ASCII shift, but I've run through all possible ones, and haven't been able to convert the body of the letter into anything either readable, or a string without special characters. I'm not sure what other cipher techniques to use here.

Since the puzzle says

"Crack this and find them and you'll get your keys right away", it's possible the header information is a key to decrypt the rest, but I've tried using the date, SANTA, SANTA CLAUS, SANTA CLAUS VILLAGE, MORTY, and ROVANIEMI (the location of the Santa Claus Village) as keys for an XOR cipher on the remaining text with no joy.

Minor update:

As @Lukas Rotter helpfully points out in the comments, all words in the body of the letter belong to one of twelve groups: CFLXpa, EJThQb, iSfMZt, YreKVl, ]zukWn, GN\xqc, gO^|ys, o_~}{w, IRd, [vm, jU, BDH. Of these, BDH appears to be special, as it is the only one that starts at the same point in the cycle each time it appears (meaning there are no strings starting with D or H) and doesn't concatenate (there are no BDHB strings, etc)

Hopefully this helps someone more clever to at least eliminate some options.

• I've noticed that there are a few groups of characters, and each word has only characters from that one group. (e.g. iSfMZt are all only in words with each other.) There are also a lot of repeated patterns, especially if you make correspondences between the different groups. Not sure what relevance this has, though. (The sets aren't shifts of each other - the correspondences seem relatively arbitrary.)
– Deusovi
Commented Jan 6, 2021 at 2:35
• Yeah, I spent time working on the vm strings that also repeat a lot, but no luck. Commented Jan 6, 2021 at 3:34
• All words are part of one of these sequences: CFLXpa, EJThQb, iSfMZt, YreKVl, ]zukWn, GN\xqc, gO^|ys, o_~}{w, IRd, [vm, jU, BDH. Sixth letter always repeats if word is >= 7 chars, afterwards sequence wraps around and repeats itself again. In essence, each word can be simplified to it's first letter and length, everything else is predetermined by these sequences, since there are no duplicate characters between them. Commented Jan 6, 2021 at 14:52
• This doesn't seem to quite hold for all words, unless I'm misunderstanding? For example, the first word is Rd, which starts in the middle of the IRd sequence you identified, and I'm not seeing how to fit eKVlY into this set either. Commented Jan 6, 2021 at 16:02
• @JProblems Just start at the position within the sequence where the letter appears. R is within the IRd sequence, so next letter is d. e is in the YreKVl sequence, so next letter is K, then V, then l, then wrap around to Y. The sequences I presented should be thought of as circles. Starting point is irrelevant (at least for the sequence itself), next letter is always predetermined. Commented Jan 6, 2021 at 16:07

Rd o_~ C eKVlY CFLXpaaCFL BDH iSf EJThQb [vm[v ~ iSf o~}{ O^| iSfMZtti iS gO^|y iSfMZ YreKVl MZtiSffM ~ iSf ]zukWnn aCFLXp BDH ~ iSfM o~} QbEJTh SfMZtiiSfMZt KVlYreeK Sf GN\xqccGN\xqc [vm[vmm[vm[v CFL Sf CFL iSf gO^|yssg iSfM QbEJTh Wn]z CF iSfM iSfMZ B gO^| MZtiSf gO^|ys CFL CFLXpaaCFL iSf [vm CFL gO^|ys iSf MZtiSffMZ hQb MZtiSff SfMZtii YreKVll SfMZtiiSfM ~ KVlYreeKVl [vm[v hQb MZtiSffM KVlYreeKVl Sf EJTh KVlYreeKVl [vm[v Sf o~ QbEJTh IRdIRddI hQb GN\xqccGN\xq QbEJTh kW CFL [vm[ KVlY gO^|yss iS o~}{w Sf iSfMZ MZtiSffM o_~} KVlY o_~}{ _~ iSfMZ [vm[ sgO^| ~ o~}{ reKV iSfM [vm[ aCFLXppa fMZ iSf [vm[vmm eKVlYrre hQbE GN\xqccG O^| _~} ~ iSf SfMZtiiSfM ~ iSf MZtiS aCFLXp CFL iSfM gO^|yss iS MZtiSff hQbEJT iSfMZt gO^|yssgO^ iSfMZ iSfM gO^|yss iS aCFLXpp iSfMZ MZtiSffM o~} kWn]zu GN\xqccGN\x hQbE MZti iSfM iSfM QbEJThh GN\x CFL iSf o~ QbEJ iS jUjUj [vm[ iSfMZ MZtiSffM iS EJ YreKVll CFL hQbE MZti iSfM [vm[ aCFLX iSfMZ aCFLX iS CF KVlYre iSfM iSfM [vm[ C YreKVllYreKV SfMZtiiSfMZ

This is because

The encoding seemed to be a base64 encoded text file with the = sign at the end being the padding, so after decoding it, the above is the key. It also says "Place : Santa Claus Village" so it must be somewhere there. It doesn't seem to mean anything right now yet...