Quote from: casascius on September 07, 2011, 02:34:41 PM

Quote from: Sultan on September 07, 2011, 01:43:25 PM

1 - How does one verify that it was you who made the coin?
2 - How does one verify that there is, indeed 1 bitcoin loaded in without 'destroying' the coin?
3 - Once the bitcoin is redeemed what happens to the coin? (just seems a terrible waste of preciois metal)
(4) Next just a discussion, alot of people are suggesting QR codes. Would using them make any difference? Apart from making it harder?
I love this idea, though! (5) Will you be making coins of smaller amounts?
Many thanks

1 - I chose a hologram with the name Casascius on it, because that would be prohibitively expensive ($thousands) for someone else to duplicate. And if they're going to go to the effort, they may as well make their own legitimate coins (clearly there's a demand) rather than perpetrating a fraud that would get quickly found out.

2 - Each coin has the first 8 characters of the bitcoin address on it, which is enough for Block Explorer to find it. When I load bitcoins on coins, the transactions are fairly distinct - lots of outputs of 1 BTC to lots of addresses wrapped into a single transaction. So if someone were to vanitygen one (the odds of it happening purely at random are 2.2 trillion to 1) you could find the right transaction.

3 - it becomes a piece of metal, not quite as desirable, but still cool nonetheless.

4 - I could probably put together QR codes, but I favor readable codes for several good reasons, the most significant being that most people don't know how to scan them into a program without retyping them anyway (typical joe will scan with his iphone and type into his computer what he sees on the screen, defeating the purpose). And second, if the code gets torn or damaged, your eyeball will do a much better job of piecing it back together than a phone that will just say it can't read the code.

5 - Probably no smaller amounts. Maybe bigger amounts (such as 10 or 50 BTC in larger, more ornate coins). This is fairly time consuming for me as it is, and I fear that demand could outstrip my ability to supply them. It's hard to want to delegate it, as I can make sure that all of the codes are legible and correct and match the address on the outside, but somebody else might not take that so seriously.

6 - Others have asked about durability. I don't know yet - haven't had them that long. The adhesive is quite strong and they will probably resist water just fine, but what would really ruin them is if they sat in your pocket and got jingled around with your keys. I would treat them as delicate until proven otherwise. I am experimenting with spraying on a layer of polyacrylate which adds significant protection to the hologram, particularly at the edges, but it will take me several days to really know for sure how that will end up. Seriously though, I hope somebody copies my idea and does a better job and makes a wash-proof key-proof bullet-proof coin for less

Thanks for your your prompt reply! Just to continue the discussion further, if I may...

1 - Just to clarify, each of the holograms are exactly the same? If this is the case, I feel this may be a bit of a risk because, agreex, the initial investment in duplicating the pattern will be huge, but if they mass-produce this and put it into 1,000 coins, the criminals would make their money back in no time. My humble suggestion would be to digitally sign each address which could be verified online. That way each hologram is different, although I am not sure if this would incur higher costs.

2 - Forgive me, I am not sure I understand the security feature of "lots of inputs wrapped into one transaction? Could you explain this a little more simply? Surely if I knew the address on the coin I could find out how many bitcoins are assigned to it?

3 - Will you buy spent coins to make new coins? Cheesy

4 - Wholeheartedly agree with you. Readable is better than QR in this case .

5 - I guess without smaller coins the intention is for the coin not to be used in small trades?

Once again thank you for your quick response!