If someone were to start a new exchange today, what are the steps they should take to ensure their private keys are as secure as can be?
Public Cold Storage Address and Proof Of Keys is the minimum.
E.G: Poloniex Old Cold Storage Address
https://www.blockchain.com/btc/address/17irB8xLxhVRerCoUyypnmpoak3QBpVp2zMoved into Multi-Sigs
https://bitcointalk.org/index.php?topic=1432482.0https://www.blockchain.com/btc/address/39TDhgfAg4oRXo1TLfEb5yZBN45hBKVYjaWith a test now and then
Or Listed on a service
https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html1 3D2oetdNuZUqQHPJmcMDDHYoqkyNVsFk9r 3-of-6
wallet: Bitfinex-coldwallet 138,661 BTC ($471,705,994 USD) 0.7914% 2017-01-05 05:34:15 2019-02-04 09:24:55 5609 2017-01-06 03:29:06 2018-10-22 07:45:07 4541
2 385cR5DM96n1HvBDMzLHPYcw89fZAXULJP
wallet: Bittrex-coldwallet 130,005 BTC ($442,259,707 USD) 0.7420% 2018-12-20 18:16:25 2019-02-03 12:40:50 9 2019-01-09 15:58:55 2019-01-09 15:58:55 1
3 3Nxwenay9Z8Lc9JBiywExpnEFiLp6Afp8v 3-of-5
wallet: Bitstamp-coldwallet 108,848 BTC ($370,287,511 USD) / +8000 BTC 0.6212% 2015-10-16 08:43:06 2019-02-04 09:42:42 226 2015-10-29 04:44:26 2019-01-03 05:57:01 61
4 3Cbq7aT1tY8kMxWLbitaG7yT6bPbKChq64 3-of-5
wallet: Huobi-wallet 108,135 BTC ($367,859,839 USD) 0.6172% 2017-09-08 10:41:05 2019-02-04 13:39:02 230 2017-09-09 05:18:35 2018-04-25 01:53:53 9
5 3AweAnU1qYSUCJ5Hvy9DFEB7dVqUebZw5i
wallet: Binance-coldwallet 107,432 BTC ($365,469,601 USD) / +107432 BTC 0.6131% 2019-01-14 19:19:40 2019-02-03 12:40:50 6
The next step is Proof of Ability to Move Funds on occasion or signed message and a few people holding the keys example in 3 of 5
5 people each hold 1 Key (1 Dies we still have 4/5)
Otherwise we could end up with another Quadriga Situation ...
Rating Wise
https://icorating.com/exchanges/centralized/As an indicator
Quadriga was a B
Cryptopia was a B
Poloniex is an A-
Binance is a B+
Only A+ is Kraken
Not even Coinbase got A+