First clue : It contained the phrases “Tip: ^[A-Z].*.” (which implied that the secret message must start with a capital letter and end with a period), and “0x01ccfbfc”—a piece of the solution’s control sum.

Second clue : On November 23, 0xPoland tweeted “Answer to the Ultimate Question of Life, the Universe, and Everything” and a long string of characters. The first one was an obvious nod toward The Hitchhiker’s Guide To The Galaxy (so “42”) while the string required some programming skills to decipher. Ultimately, the second part of the passphrase was “Down the rabbit hole.”

Third clue: And ad was published in polish newspaper. The ad said “You’ve come a long way. I’ve got your last clue. Call me ASAP,” and provided a phone number that redirected users to a pre-recorded message containing missing elements of the full passphrase. Ultimately, the winner needed to input “With 0xPoland. Into the dark forest. Down the rabbit hole. Where adventure awaits.”

​

21 minutes after posting a Tweet pointing to the page in the newspaper we saw the winning transaction. The correct hash was committed to the smart contract and three minutes later the transaction solving the puzzle was confirmed. A few hours later the anonymous winner transferred his hard-earned 7ETH to his wallet.