ADVENT CALENDAR PUZZLE 2

Solution: decode using standard cryptography ciphers

Each line gives two words in order:

1. (plunge begin): this is plaintext (plunge begin)
2. (soy tusk): the second letter has been changed, the only matching BIP39 words are say task.
3. (bmuht siht): words are written in the reverse order (thumb this)
4. (fasion tile): one letter of each word is missing, the only words that can work are fashion title
5. (464 1999): those are indices of 'delay' and 'what' in the BIP39 list
6. (vacances typiques): the two words are the French translations of holiday and typical
7. (vwdps wrs): take the 3rd previous letterin the alphabet, d becomes a, to get stamp top
8. (70 68 70 65 68 75, 6c 71 70 64 77 68): decode from hexadecimal, then do the same as 7 to get member inmate
9. (01100100 01111010 01100100 01110101 01101000, 01101010 01101111 01110010 01111001 01101000): decode from binary then do the same as 7 to get aware glove
10. (anVuZ2xl cGlnZW9u): decode from base64 to get jungle pigeon
11. (lead ref, sly mob): Rearrange the letters to get (federal symbol)
12. Hidden in the page source (Ctrl-F5) you will see 'such j', try all possible BIP39 word starting with J, the right one is the second, you get such jaguar

HIDDEN MNEMONIC

plunge begin say task thumb this fashion title delay what holiday typical stamp top member inmate aware glove jungle pigeon federal symbol such jaguar