John Cantrell, the Bitcoin and Lightning Network project developer, has said that Bitcoin is still safe even after he successfully hacked a Bitcoin wallet by explaining and ensuring people in a tweet thread on June 19.
It has been reported that according to Cantrell, Bitcoins stored in a wallet generated from a 12-word mnemonic is secure, as the only reason why he was able to hack the Bitcoin wallet was that the wallet’s owner publicly exposed eight words from his 12-word mnemonic seed.
“It would take the same system that brute forced the last 4 words of his mnemonic 837 quintillion millennium to brute force all possible 12 word mnemonics […] if you know as few as 5 words. To brute force all 12 words (just to break even on your $100B investment, assuming you can actually liquidate all the BTC) still takes 422 TRILLION YEARS.”
However, the only way Bitcoin is not secure is when seed words are revealed.
Thus, he concluded:
“Your bitcoin is safe. 2^128 is a REALLY big number. Just don’t let anyone near your seed words.”