One of the major concerns surrounding virtual currencies like Bitcoin is security. Because cryptocurrencies aren't backed by a central bank, there's nobody to complain to should someone steal your holdings.

That's prompted a number Bitcoin exchanges to offer insurance programs as an incentive to do business with them. But according to a recent post from one of the largest exchanges, they've been offering insurance free of charge for nearly a year now.

In a surprise blog post, Coinbase said they've maintained insurance coverage since November 2013 through Aon, the world's largest insurance broker. The insurance covers losses due to breaches in physical or cyber security, accidental loss and employee theft.

It doesn't cover Bitcoins lost or stolen as a result of an individual user's negligence to maintain secure control over their login credentials.

Coinbase adds that they are insured against theft and hacking in an amount that exceeds the average value of Bitcoin they hold in online storage at any given time. That last bit about "online storage" is of particular importance, especially if PandoDaily's claim of them holding just three to five percent of all deposits in online wallets at any given time is accurate.

That means that 95 to 97 percent of all deposits are stored offline and therefore wouldn't be covered under their insurance policy in the event of theft or loss. Whether or not that's a game breaker would depend on the level of security guarding Coinbase's offline storage.