When I was considering buying Casascius coins, it was basically because I saw them as a negotiable, easily-verifiable instrument for transferring BTC in the real world. If I wanted to tip someone in BTC, or buy a burrito, or whatever, it would make it easier than asking them to set up a wallet and so forth; I could treat it like money, and the hologram and Mike's reputation would back up that it could be redeemed if the payee so desired.

These days, when a 1BTC Casascius coin has a higher face value than the biggest US bills, that's less feasible than it once was.

Quote from: Gerco on April 05, 2013, 12:11:57 AM

Quote from: stephwen on April 04, 2013, 01:13:34 PM

Doesn't Mike know the private key to all casascius coins he produced?

His statement of controls says that he doesn't, we take his word for it.

Is it possible that he kept a copy of all private keys? Sure, but as he explains on his website: He can easily be held legally accountable. Whether the current legal system will do anything? I don't know, but he didn't make it very easy for himself to hide if he misbehaves.

My confidence in Casascius coins stems from this line of thinking:

For Mike to steal the reserve balances of his coins, it would be necessary that he have been planning to do so from the beginning, without any changes of heart along the way.

If he was trustworthy at the beginning, he didn't save the private keys and no matter how much he might want to steal the reserve today, he has already lost the power.

If he was untrustworthy (intending to steal) at the beginning, but had a change of heart at any time, he would have deleted the private keys, and similarly be unable to steal the reserve today.

That leaves the case that he's untrustworthy, and has always been so, and is waiting for the right moment to steal the reserve. Today, 1BTC is worth over $100, and there are about 30000 BTC stored in Casascius instruments. In other words, over 3 million dollars in BTC. If Mike intends to steal the reserve, why hasn't he done it yet?