BitMEX Research has identified a suspected double-spend transaction valued at 0.00062063 BTC or roughly $21 — and it doesn’t appear to be an instance of that popular replace-by-fee wallet hack. On Jan. 20, BitMEX’s ForkMonitor noted that “multiple blocks were produced at height 666833.” BitMEX Research tweeted:Satoshi Nakamoto’s Bitcoin Whitepaper is credited with having solved the double-spend problem in 2009. The challenge of ensuring that a decentralized network can autonomously verify that the same coins have not been transferred more than once had stymied earlier attempts at digital cash. In July, crypto ... (full story)