Quote from: cunicula on January 26, 2012, 03:10:52 AM

Would this make it easier to lose coins from human error? What happens if you lose your phone? Is it possible to allow very slow draining of a wallet with access to just one of the two private keys (e.g. max of 1 coin sent every 100 blocks)?

This way coins could be recovered even if one of the two factors is lost. It would also reduce user inconvenience for cases where security is not as essential. However, it would still be possible to steal very slowly.

Yes, this actually would be possible. To do what you asked, specifically, you would create 2-of-3 multisig transaction addresses where the third key is owned by a third party (likely web-based) service. When you lose access to one of your two private keys, you could use this service to recover your funds at whatever predetermined rate you chose. Such a service could require a login, or not, depending on the security you desire.

Alternatively, you could put the third private key in a safe and you would have immediate access to all of your funds should you lose a private key. Of course, this is no different than just storing a backup of both keys, but it's a little neater.

Quote from: cunicula on January 26, 2012, 03:10:52 AM

Residing in a country where you need two factor authentication for everything. I suspect that this modification (while very useful) could impose serious inconveniences on users if poorly implemented.

That's why it'll be encouraged for people to use 2-of-3 transactions instead of 2-of-2.