During the summit, IOHK hosted a live cryptopuzzle competition that was available exclusively to registered attendees. The prize was awarded at the summit’s closing remarks by Charles Hoskinson and Jeremy Wood to winners: Michal Petro, Rafael Korbas and Peter Perešíni (a team from Vacuum Labs) who solved 5 out of 6 puzzles!
We’re sharing the cryptopuzzle with the Cardano community today for fun to see if any of you can solve all 6! The first puzzle was displayed on the IOHK Summit 2019 t-shirt, with the rest on posters scattered around the summit – all you need is a little curiosity and some basic knowledge of computer science and blockchain technology. Each piece of the puzzle, when solved, will yield an English BIP39 keyword.
Puzzle 1
Puzzle 2
Puzzle 3
Puzzle 4
Puzzle 5
Puzzle 6
We’ll post the answers in two week’s time on Thursday May 9
Happy puzzling! 
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SPOILER ALARM: If you are interested in the solutions, click: https://twitter.com/AdaLiteWallet/status/1119747528755433473
IOHK Summit 2019 Puzzle Solutions
Hidden in case anyone is trying to still solve. Click to see answers
Puzzle 1: nature
Take all letters contained in “Run Proofs of Stake” and remove those in “Fork Spoofs” by exact number of occurence. This yields the letters “a”, “e”, “n”, “r”, “t”, “u”, and, each of them exactly once. The only BIP39 keyword that can be composed using these letters exactly once is “nature”.
Puzzle 2: actor
Take the Cardano block from Slot 1294 of Epoch 80 and extract the first five symbols of its hash which is “daf0e”. The most famous person with a matching name is (probably) Willem Dafoe, who is an actor.
Puzzle 3: jaguar
Each logo symbol encodes a lower-case ASCII character (codes 97 (for ‘a’) to 122 (for ‘z’)) in 9-bit binary whereas the least significant bit is encoded in the top pair of branches and the most significant bit is encoded in the bottom (ninth) pair of branches. The number of filled red dots in each logo indicates the encoded letter’s position in the final keyword. Each logo’s letter code is obtained by XORing the black and the red dots on each of the nine levels — 0 if both dots are filled or both dots are empty, and, 1, otherwise. In particular, the red pattern can be seen as a one-time pad whereas the black pattern is the respective encryption of the wanted letter. For example, the first logo represents the 5-th keyword letter encoded as binary ‘001100001’ (reading the XORs from bottom to top) which is 97 in decimal, thus encoding an ‘a’.
Puzzle 4: saddle
Each Daedalus logo encodes a letter from the word “Daedalus” by clockwise rotation by a multiple of 45° degrees from its original form whereas rotation by (k-1) times 45° refers to the k-th letter in the string. For example, the rotation of the first logo is 7ᐧ45°, thus encoding the 8-th letter of “Daedalus” which is ‘s’.
Puzzle 5: retreat
The given string is the concatenation of seven SHA256 digests. Each digest is produced from a single lower-case letter followed by a newline. The keyword is obtained by appending the respective letters in order of occurrence of the given hashes.
Puzzle 6: note
The picture depicts a Merkle tree as hinted by the six nodes in the top center of the (original) figure. In order to obtain the keyword, the witness nodes of a “Merkle proof” for the node marked on the bottom left of the figure have to be extracted. Sorting the witness nodes from top to bottom yields the keyword. The Merkle tree with the respective witness nodes is depicted below.
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