Bitcoiners are still trying to solve a four-year-old puzzle now worth $1 million.

The challenge is not your traditional “find five bitcoin hidden in this painting.” Rather, it’s a fiendishly difficult series of wallets loosely tied together that only a select few are ever likely to crack. But that hasn’t stopped intrigued bitcoin experts from giving it a go.

The puzzle is a group of bitcoin addresses that hold incremental amounts of bitcoin. If you can crack the private keys in each one, your prize is the bitcoin held inside. Now, normally cracking a private key would take longer than the lifespan of the universe (or 0.65 billion billion years according to one estimation), but in this case, the addresses are connected in such a way that makes it easier to solve.

The group of addresses was originally noticed on bitcoin forum BitcoinTalk back in 2015 by a pseudonymous user known as Bulista. On previous threads, Bulista claimed to have created a bot that was designed to brute force bitcoin addresses—although he acknowledged that this would take nearly forever to do, because they are protected by strong cryptography.


However, with these particular addresses, they were created in such a way that narrows down the possible list of solutions (i.e. the private key that can unlock each address). And according to other forum posts, the mysterious creator designed the task in order to see if they can be unlocked–although this can’t be verified.

At the time the challenge was discovered in 2015, the addresses held 32 bitcoin, worth $13,000 at the time. Some of the wallets have been cracked and the bitcoin taken. But more money has been added to the remaining uncracked addresses and the total treasure chest now sits at 102 bitcoin, worth just shy of a million dollars.

According to a forum user called racminer, there are 160 address in total with 90 remaining to be broken into—with 102.66 bitcoin left to be claimed. Each address holds between 0.62 and 1.60 bitcoin.

For hapless developers, the game is on. But needless to say, for those of us who don’t know our SHA-256 algorithms from our elliptic curve cryptography need not apply.


Stay on top of crypto news, get daily updates in your inbox.