By Nick Marinoff
A lot has been happening with the “friendly” bitcoin hacker “johoe.”
Speculation first began last week when he swiped approximately 250 bitcoins from blockchain.info following a security lapse that took place during the early hours of Monday, December 8th. In a strange sort of twist, johoe later returned the bitcoins, explaining that he was merely protecting them against malware attacks, and that if users could prove themselves as the owners, he would gladly return them.
Now, johoe has struck again, this time stealing about 300 bitcoins from what blockchain.info feels are secure bitcoin wallets.
Following his first “attack” on the site, johoe explained:
“Every bitcoin transaction is signed by two values – ‘R’ and ‘S’ – which prove that the sender knows the private key. If the same R value is used twice, the private key can be easily computed from the signatures alone.”
Johoe found a large number of broken bitcoin addresses, which he was later able to isolate. He says his intention was never to actually steal the bitcoins, but to simply send out the message that security needed to be heightened, and that he had every intention of returning the bitcoins once the issue had been addressed:
“I decided this beforehand. I make enough money with my day job that I can live on it. Also this way I don’t have to worry that someday someone will find it out. In hindsight, this was a very good decision.”
Apparently, johoe doesn’t feel the first event was effective enough, which prompted his decision for the second hacking. He suggests that bitcoin users’ upgrade to hardware wallets, which he feels are much more secure.