Coinbase seems to be the major player, but is their tech really safe? The fact that they are so large concerns me -- they are more likely to be attacked.<p>What is the consensus nowadays?
Coinbase is legitimate. The vast majority of the company's Bitcoin stockpile is stored on hardware encrypted offline hard drives.<p>I think Coinbase could thwart off a targeted attack, with the worst case being an interruption in service due to DDoS. It is far more likely that an individual account is compromised by an attacker who learns the user's password. Coinbase mitigates the impact of this scenario by:<p>1. Forcing all accounts to use two-factor authentication<p>2. Providing users with a vault that provides additional security options. It's meant to hold the bulk of a user's BTC, similar to a savings account at a traditional bank. Withdrawals are subject to a 48 hour delay and can be configured to require multiple co-signers.<p>The time delay accomplishes two things. One, it prevents an attacker from instantly draining a compromised account. Two, it provides Coinbase with ample time to retrieve the BTC from its offline storage (it's a sign that they're telling the truth about their massive offline storage strategy).<p>More info on vault can be found here:
<a href="https://coinbase.com/vault" rel="nofollow">https://coinbase.com/vault</a>