Chinese blockchain news site Jinse Caijing is reporting that the Bitcoin cold wallet for cryptocurrency exchange OKEx is single-signature, with founder Xu Mingxing holding the private key.
That is problematic for OKEx users, given that Xu was “taken away by police” in China several weeks ago. As a result, on October 16, OKEx said it had halted withdrawals, which continue to be unavailable.
In a statement at that time, the company explained, "One of our private key holders [presumably Xu] is currently cooperating with a public security bureau in investigations where required. We have been out of touch with the concerned private key holder. As such, the associated authorization could not be completed."
Jinse Caijing’s reporting cites people close to senior management. Assuming its reporting is accurate, Xu is either the only key holder for the exchange’s Bitcoin wallet or the exchange is sharing one private key among its staff rather than use a multi-sig wallet or other solution.
That's the equivalent of sharing one's Netflix password, but with more at stake than someone seeing your browsing history. Glassnode estimates that OKEx holds 200,000 Bitcoin (worth roughly $2.65 billion today) in its vaults.
According to our data, around 200,000 BTC (1.1% of the circulating #bitcoin supply) are currently held in #OKEx wallets.