

Bitcoins get physical - kitcar
https://www.casascius.com/
"Each Casascius Bitcoin is a collectible coin backed by real Bitcoins embedded inside.  They come in two denominations: 1 bitcoin, and 25 bitcoins.  Each piece has its own Bitcoin address and a redeemable "private key" on the inside, underneath the hologram."<p>One big weakness is they seem to be "single use" though, as they need to be torn open to be used.
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0x12
A private key that someone else printed out and stored in a coin is no longer
private.

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soapdog
I think they have value for collectors and for playing poker with friends.

I think that at this moment, bitcoins have potential for eCommerce but not
much penetration on real shops and retailers.

I don't see people going Scrooge McDuck crazy and piling these coins in huge
vaults but still, the inception of physical coins and bills make bitcoin more
flexible. For example, they can be traded when there is no connection
available.

Maybe in the future you will be climbing the Himalayas and a little monk will
be there selling hot tea and enlightenment but he only accepts bitcoins since
Buddhists are keen on the "money is an illusion" thing. Unfortunately, your
AT&T iPhone 18S will have no coverage and you will be thankful for your
bitcoin coins... (and, yes, this is a joke).

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steve8918
It's an interesting souvenir and definitely nice to look at, but once you
spend your BTC online, the intrinsic value (the BTC) and the store of value
(the coin) become separated, and the coin becomes worthless. In fact, I don't
even know how money would get exchanged... if you gave someone the coin, it
still doesn't confer ownership. It's essentially an anonymous IOU, meaning it
has no value.

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iliis
_> if you gave someone the coin, it still doesn't confer ownership_

It does because the coin has the private key. Maybe it's better to think of it
as a key to a (public) safe. The key represents the right to open this safe.
So, by giving you the key, I give you the ownership to the content of the
safe. (However, if I have another copy of the key it get's problematic.)

 _> It's essentially an anonymous IOU_

Which is exactly the same as normal cash. The only difference is that you can
destroy them without really loosing the money. So you have a worthless piece
of metal. You can do the same with your normals coins (eg. melt them down),
but then the worth is just gone ;)

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gerggerg
except I can't write down the serial number of my hundred dollar bills, give
the bills to you and then spend them myself.

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Periodic
I think this is why you don't load them yourself. Essentially it is this
company backing the coin, not you. When they send you a loaded coin it
probably won't be loaded with the coin you bought it with.

Another interesting property is that unlike a bank they cannot issue more
money than they have assets, as each coin is linked to a unique private key.
(assumes they are not just a one-time scam)

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gerggerg
Casascius makes no mention of backing the coin whatsoever. You have to verify
it upon receiving it unless you don't really care.

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exit
wow, economics aside, i _love_ the motto "vires in numeris" (= "strength in
numbers")

whatever becomes of bitcoins, for the first time in a long time i've felt like
i live in the future.

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sneak
Even if you trust the coin issuer 100% to not keep a copy of the private key,
these sorts of schemes only work until anyone anywhere counterfeits the first
BitBill or Casascius coin.

At that point, it becomes necessary that all of the other physical tokens in
the world must then be immediately destroyed on redemption and validated as a
normal network spend... Which defeats the purpose of these transferable tokens
to begin with.

The tamper seal doesn't help. You might as well just print out your own
private keys as QR codes, the person accepting them will need Internet access
to verify+transfer them, just as now with these "tamper-evident" systems.

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baddox
What do you mean by counterfeiting? Do you mean selling coins online that
don't have real codes? Because you certainly couldn't pay for goods with a
counterfeit coin, since they're instantly verifiable.

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sneak
I could buy one of these coins, then make a thousand coins with the public key
of that one coin on it, with nothing inside the tamper-seal.

The moment I start circulating them, this now means that everyone who wants to
accept these coins needs to destroy them, reveal the private key, and transfer
those coins.

That defeats the purpose of the whole tamper-evident system - the idea behind
it is so that they DON'T need to be redeemed.

<http://lesswrong.com/lw/ne/the_parable_of_the_dagger/>

They are _not_ instantly verifiable without destroying the coin.

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skeltoac
Good for casascius (profit), good for bitcoin (new users). Poor choice for
meaningful commerce (hassle, dubious, costly).

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RobertKohr
The main problem is that you have to trust the person who minted the coin not
to extract the value of the coin while it is in circulation. Eventually it
should leave circulation, be converted back to virtual, and transferred to a
safe address that minter doesn't have access to.

So, the thing that it is printed on should be really cheap, like card stock or
just paper. It shouldn't be considered currency, but more like a check. People
accept a check on the assumption it won't bounce because they know the person
who signed the check to them.

When you get one, it should be off the person who wrote the check, and you
should cash it immediately (transfer it to an address you trust).

I could see keeping a few business cards in my real wallet with public and
private keys on them with empty addresses. I can load them on demand from my
cell phone, and write the amount and sign them when I hand them to someone.
This way I can give them money without them needing a digital device handy. I
could even do this in advance in a few denominations for completely offline
access, but it would still require the trust of two individuals on the same
level as writing them a check.

In this case, obscuring the private key would be pointless since both people
would have access to it.

Here is a good resource for printing address: <https://www.bitaddress.org> It
has QR codes on it, so you can use the Android app to scan the pub key and
transfer money to it. The addresses are generated client side with your
browser, so they should be safe from snooping.

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drKarl
What's the point? That just defeats the whole philosophy of anonymous
cryptocurrency and... 25 physical BTC = 29.50BTC!! You loose money if you buy
physical coins...

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ryandickherber
> You loose money if you buy physical coins...

Gold and silver coins also cost more than spot.

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drKarl
That's why gold and silver isn't used for coins anymore (except for special
limited editions). Nowadays fiat money coins face value is much more than the
material of which the coins itself are made.

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Someone
Not always:
[http://en.wikipedia.org/wiki/Penny_debate_in_the_United_Stat...](http://en.wikipedia.org/wiki/Penny_debate_in_the_United_States#Arguments_for_elimination)

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narcissus
Similar to bitbills.com, but definitely prettier :)

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aidso
It'd need some encryption+verification like a QR code that can easily be
scanned with a phone, which would open up a website, contain an encrypted key
and then decrypt and run block explorer to verify without revealing the key.

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GigabyteCoin
The simple fact that "people like to peel stickers" will be this project's
demise.

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sneak
I wish he'd invested the time/effort into producing something useful or cool
that I could buy with bitcoins instead of these. I like the checkout system -
just address and bitcoin payment.

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omid
This just feels wrong. Physical coins provide peer-to-peer non-anonymous
transactions instead of distributed anonymous ones, that is what Bitcoin is
about.

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brador
FYI: Bitcoin is not anonymous unless you are a miner or pay cash. Even then,
you can still be tracked and located if necessary.

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munin
this seems to open a whole new door for double-spending and other forms of
counterfeiting. nothing seems to stop me from buying a physical coin, then
transferring the digital coin to my mtgox account but still spending the
physical "coin".

to guard against this, you need to check block explorer for every coin that
you were going to spend with a physical merchant, I think?

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Periodic
The private key is stored under a special hologram sticker, which is tamper
evident. It should be obvious if the coin was digitally transferred.

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munin
obvious if you have an internet-connected computer present at every point of
sale? -- oh nevermind I was mistaken, I get it now. neat.

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mhb
Obvious if the hologram has been tampered with.

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runn1ng
I don't get it. If I recieve a physical bitcoin, how do I know it was not
previously "redeemed"?

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chwahoo
To redeem the coin, you have to peel back a sticker. The hologram for peeled
coins takes on a honeycomb appearance according to the link.

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runn1ng
Oh, that makes sense.

So it is sort of "centralized" with the hologram makers, right?

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ThaddeusQuay2
Does a pile of eight bitcoins equal a bytecoin? If so, then a single bitcoin
would indeed be "a bit", because: "In the U.S., the "bit" as a designation for
money dates from the colonial period, when a common unit of currency was the
Spanish milled dollar worth 8 Spanish reales. As a way of making change, these
dollars were cut into eight pie-slice shaped pieces which were called "bits".
(For this reason, the whole coin was known as a "piece of eight".) Each
eighth-dollar bit was then worth 12.5 cents, "two bits" was a quarter of a
dollar (25 cents), "four bits" was a half-dollar (50 cents) and "six bits" was
75 cents."

<http://en.wikipedia.org/wiki/Bit_(money)#United_States>

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skeptical
I don't care about technicalities, the coins look awesome.

Is this really meant to have any practical use? Looking good is the main
purpose IMHO. I'm ok with that.

