ZeroNights Mnemonic split quest
All the necessary details are here.
Each conference participant badge has a scratch sticker that contains 24 words of a mnemonic phrase, as well as a color tag with an additional word. Each mnemonic phrase is unique and is part of a shared secret (original mnemonic phrase) on a 6 of 250 threshold secret schema.
Each secret (original mnemonic phrase) has its own color that corresponds to the color tag. In order to restore the secret mnemonic phrase, it is enough to collect 6 shares of the same color.
Details about the used implementation of the Shamir secret scheme you can find here.
Having restored the mnemonic secret phrase, you can get access to the private key from the bitcoin address located along the derivation path m/84’/0’/0’/0/0
All 6 secret mnemonic phrases of the corresponding colors are shares of the main secret. The extra word on the colored marker is the share name. The main secret is splited according to a threshold scheme of 4 of 6.
In each phrase, it is necessary to replace the last word with a word with the name of the corresponding share color (word on a colored tag) and restore the main secret from the received shares. The private key and the main reward are located along a non-standard derivation path. The derivation path will be published at 14:00.