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Unanswered Questions

130 questions with no upvoted or accepted answers
47
votes
1answer
4k views

Unsolved Mysteries: D'Agapeyeff cipher

The D'Agapeyeff cipher is an as-yet unbroken cipher that appears in the first edition of "Codes and Ciphers", an elementary book on cryptography published by the cryptographer Alexander D'Agapeyeff in ...
32
votes
1answer
4k views

Binary cryptogram from a friend

My friend sent me a "puzzle" in binary, and said that there are multiple steps to solving the puzzle, all of them including decryption. I translated the binary into text and he said that was a good ...
29
votes
0answers
1k views

One 'double agent' two-step on a waltzing floor

I'm in a jam – cornered I am! – No clue 'bout where to go Here's what went down, a pretty gown Some wine, a French chateau She whispered underneath her breath "Come dance with me and ...
18
votes
0answers
989 views

BFTIODFTTWKBCSC

This is my first self-developed cryptographic puzzle. I hope it is neither too hard nor too easy for you to break, and that you enjoy it. Please do not only post the answer, but also your way towards ...
18
votes
0answers
7k views

The Beale Papers

The background to this one's given here. NB: These may not be a genuine cryptograms (current thinking is that these are gibberish); but I though it interesting to share these in case they're genuine /...
15
votes
0answers
1k views

Deus Ex crypto puzzle

There is an encrypted email in the recent Deus Ex: Mankind Divided game: From the game files, this appears to be the string: ...
15
votes
0answers
1k views

Is there a more efficient way to rotate the centre pieces on the Octo-Star?

I'm looking for a more efficient algorithm to rotate the center column of the Octo-Star puzzle 45 degrees. The situation below occurs when four properly-oriented edges are next to each other, ...
14
votes
0answers
285 views

The Brief Puzzle Hunt

Recently, I was invited to give a speech during the kickoff phase of a local puzzlehunt. I’ve almost finished writing my first draft, but I just can’t figure out the best way to end it off. Can you ...
14
votes
0answers
613 views

Peaceful Encampments

This math puzzle is due to Donald Knuth (as far as I know; maybe he got it from someone else) circa 2014. Consider a plain represented by the unit square. On this plain we want to “peacefully ...
13
votes
1answer
735 views

Creepy video on Youtube, with secret cipher built in

This showed up in r/deepintoyoutube: https://www.youtube.com/watch?v=j1ExfbH4Jew I've posted it around, and no one has solved it. I believe it is a cipher for a couple of reasons, at the end 26 ...
11
votes
0answers
290 views

Rethinking this series on the syllabus

I assigned each person in my class the task of creating a number-sequence, however, 4 of the guys I usually consider to be leaders came back with baffling results. Can you make sense of their work ...
11
votes
0answers
277 views

Find the place, find the palace

A part of me was a mode of transportation in the past. A part of me is the mode of transport in the present. A part of me is an important place in two fictional novels. A part of me has acted in the ...
11
votes
0answers
420 views

Never Completed Game - Difficult Riddle

The seventeenth of the primes. Its twin is twentynine. Po. Let’s drive. Bye, Alfonsín. Add seven triangular. Sweet. It named the Valley. This riddle is taken from https://www.nevercompletedgame....
11
votes
0answers
461 views

Alternate, complex potions puzzle from HP fanfic

A long narrow room. The entrance is blocked by purple flame, the path onward blocked by black flame. On a table, the only thing in the room, are two dozen potions in opaque bottles. Half green glass, ...
11
votes
0answers
947 views

Decrypting the Key

So I've been trying to solve this Riddle called "Phage is Spreading.." ...

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