Bitcoin Forum

I'm pretty sure this has already been discussed, but am wondering why it isn't done yet:
Here's a spin off the Casascius Coins and Bit Bills. Let's call the website "Rainy Day Savings." Joe creates a key pair and sends the public key to the website and orders a Rainy Day Bill. April at Rainy Day Savings prints a Bill and applies a tamper resistant hologram that conceals a private key. April then generates a 2 of 2 multisig address based on the public key sent to the website and the public key that goes to the hidden private key. That address is printed on the note. April then mails the note to Joe and advises him to carefully write or print the private key paired to the public key that was sent to the website. Joe then sends an amount to the multisig address and writes the value of the note on its face. Joe can then spend the note as physical Bitcoin and because it is multisig signed, nobody has both addresses to spend it until the tamper-proof sticker is removed and both private keys are imported to a wallet.

https://bitcointalk.org/index.php?topic=92969.0 (https://bitcointalk.org/index.php?topic=92969.0)

Since Joe is untrusted, every receiver of the coin will have to verify that the combined address indeed has coins, so it's not as easy to use as a Casascius physical coin. Also, it's not much more secure than a normal CPC - assuming the coin is to be used multiple times, nobody can be sure that April and Joe aren't the same person and thus have both private keys.

I don't think it's the same thing.

Yeah, I was talking about using multisig to sign a checkbook type bill there, but the second private key would be kept elsewhere. On this one, both signatures would be on the same bill, but one would be hidden by a sticker.

If more than one person is in control or even has knowledge of a private key at the same time, the instrument is already corrupted.

Of course, that is why it would have to be a Mensch like Casascius to create the note and apply the sticker. The person spending the note would have no incentive to corrupt the note because the value would be lost for everyone.

A document like this could be issued by Nefario and authenticated by Casascius, for instance. They could be used as stock dividend certificates and could be traded offline.

+1 I am still interested in this topic!

Thats an interesting idea...

Wouldn't that be a Bitcoin Bearer Bond?

Thank you. That is a much better term. I will change the title of this thread. Per Investopedia http://www.investopedia.com/terms/b/bearer_bond.asp#axzz22gFW0oRT (http://www.investopedia.com/terms/b/bearer_bond.asp#axzz22gFW0oRT)

This will work much much better is the bearer bond is based upon a financial instrument (a portion of bonds) listed on a stock exchange. Bearer bonds are tried and tested and work well. They however got stopped lately since it facilitates money laundry, but none the less, bearer bonds are still possible through Panama corporations and structures.

I'm not sure what you mean by basing this on a listed instrument. Bitcoin has actual cash value. Besides, the current model for stock exchanges is obsolete. Bitcoin is the Extinction Level Event for these dinosaurs.

I'm thinking that you would have to be careful about the public key provided by the end user. They would not be able to use just an address from the Bitcoin client unless they also have access to the private key. It might be a good idea to use bitaddress.org to generate the key pair.

Too good an idea (one had and discussed by too many) not to happen.