The hack is publicized for at least a hour, but from reporting I saw they still continue to drain funds as for now. I wonder why large CEX do not have any safety measures for this kind of hacks, they could withdraw everything to newly generated wallets and minimize damage that way. It is certainly not the first time CEX wallets get hacked.
You don’t even have to do that, have deposits go to offline keys directly, that way there’s only ever cold > hot wallet movement and a big deposit can’t cause your hot wallet to be too risky.
The point of cold wallet is to minimize movements, if there is high frequency of funds moved from a wallet then it is likely can not be called cold any more. Plus CEX in any case still needs to have large buffer of funds on some wallet to support day trading.
You can move money into a crypto wallet without that wallet needing to do anything, or being online at all, or even having a private key that physically exists anywhere in the universe. It's just a public/private keypair; send it to the public key of a private key that's offline and it still exists on the blockchain, you just can't do anything until the matching private key comes online.
The point of a cold wallet is to keep the private key physically offline. That way you know it cannot be stolen by electronic means, because the physical device containing the key needed to authorize transactions is locked up and not powered on. Then you only power it on during very specific, audited times and conditions when it's needed to fund the hot wallet, which does all the actual automated trading and transfers.
GP's point is to have all incoming transactions to an exchange go to a cold wallet, which becomes a one-way sink, and then periodically the exchange powers up the cold wallet to sign transactions transferring assets to the hot wallet, which then funds all outgoing transactions. This isn't a bad architecture, though I'm not sure it'd save all that much here.
I was taking it that your bitcoin bank would have a SHTF lever that would immediately dump ALL your hot wallets into an offline cold-wallet.
Then when things calm down you go and find ... the keys under the birdbath are lost, and you're fucked in a different way.
But at least it might work.
Until the SHTF lever was hacked to divert all hot wallets into somebody else's cold wallet
The words you are using are very confusing.
You can't "move money into an offline crypto wallet that is not online at all."
If "money" i.e. crypto "currency" is in a crypto "wallet" then it is online. Anyone with the key and an Internet connection can transfer it at any time.
The wording is confusing because to someone who doesn't know how cryptocurrencies work it sounds like you can simply "take the crypto offline and put it into a physical device" as if it was a file. But that's not how it works. The physical key merely contains the actual key for the always-online wallet.
It's true that anyone with the key and an Internet connection can move money out of a crypto wallet at any time, but the point of the cold wallet is that they don't get the key because it's kept on a computer (or other storage medium) that is physically offline and disconnected from the Internet. Same reason government intelligence agencies use a SCIF for any important information work: you keep the information physically disconnected from the Internet.
of course you can move crypto currency to an offline wallet and by offline I mean its private key is held in some physical form/device that is not connected to the network.
Only spending from that wallet needs online access to private key - depositing to it does not.
For a large CEX like Binance, $5B might just qualify as a hot wallet.
There are lots of measures in place at these exchanges - the rub is that cold storage is by design slow. To service withdrawal requests in a timely fashion a percent is kept “warm” or hot and used to process withdrawals. Usually this is where the leaks happen.
Yeah, they should have a way to move all funds into a new wallet so guys like this one don't have to go one by one ...