Casascius physical bitcoins

Various views of Casascius coins


Casascius physical bitcoins, also called Casascius coins, are physical metal coins created by Bitcoin user Casascius (Mike Caldwell, Sandy, Utah, USA) and sold until Nov 26, 2013[1], that contain an embedded piece of paper with digital Bitcoin value, covered by a tamper-resistant hologram. Casascius coins are available in 1, 10, 25, 100, and 1000 BTC increments. They can be purchased at Casascius's website, https://www.casascius.com (only Bitcoin accepted), or at http://www.MemoryDealers.com (PayPal and credit cards accepted).

The coins are designed such that they could be circulated in face-to-face transactions. The first person to redeem its private key gets the value on the coin, and afterwards, the coin no longer has any Bitcoin value. It is difficult or impossible to read the private key on the coin without damaging or destroying the hologram, which exposes a honeycomb-like tamper-evidence pattern when peeled.

The piece of paper inside each coin has a private key which forms the backing for the Bitcoin value represented by the coin. Redeeming the private key back into digital Bitcoins is currently available with a patched reference client and many of the alternative clients.

Casascius coins are similar to Bitbills in that they are an object that contains a redemption code that serves as a bearer item for digital bitcoins.

There are 2 independent websites that track the status of all Casascius coins in circulation, based on information from the block chain:

Casascius Bitcoin Analyzer (http://casascius.uberbills.com/)
Casascius Physical Bitcoins Database (http://casascius.appspot.com/)
Contents [hide]
1 History
1.1 Suspension of sale
2 Releases of Casascius coins
2.1 Original series 1 BTC coin
2.2 Second series 1 BTC coin
2.3 10 BTC silver round
2.4 25 BTC coin
2.5 100 BTC gold plated bar
2.6 1000 BTC gold plated bar
2.7 1000 BTC 1 troy ounce gold coin
3 See also
4 References
History
Originally, Mike Caldwell imagined placing a private key on a piece of paper inside a washer with a tamper-evident hologram on each side. However, he found it was more economical to have a real coin minted with a hologram on one side than to have two different hologram designs, and so the first Casascius coins were customized brass coins ordered from a mint that makes car wash tokens.[2]

Suspension of sale
As of Nov 27, 2013, Mike Caldwell suspended sales of items that contain digital bitcoins.[1] The Financial Crimes Enforcement Network (FinCEN), a branch of the Treasury Department, informed him before, that minting physical bitcoins qualifies him as a money transmitter business, which means he needs to register at the federal level and probably get state licenses too.[3]

Releases of Casascius coins
Original series 1 BTC coin
1.125 inches in diameter
Solid brass
Year printed on coins: 2011
Approximately 0.24 ounces
Eight-digit "firstbits" inkjetted onto surface of hologram sticker
First appeared in September 2011[4].
Private key: 22 character string inside the coin, the 256-bit private key is SHA256(string)
Approximate number produced: 3,500 as of November 2011
A spelling error can be found in the small lettering of the hologram: "CASACIUS" instead of "CASASCIUS"
Casascius has stated that no more than 11,000 may be produced
All 11,000 Bitcoin addresses pre-generated for the series have been published as a signed text file
Second series 1 BTC coin

The hologram and the private key is different, the metal part of the coin is the same as the first series.

1.125 inches in diameter
Solid brass
Year printed on coins: 2011
Approximately 0.24 ounces
Denomination ("ONE BTC") appears on the hologram
Eight-digit "firstbits" visible through a small transparent window that allows limited visibility of one side of the private key paper
Private key: 30 character string inside the coin, the 256-private key is SHA256(string)
First appeared in November 2011
No spelling error in hologram
10 BTC silver round
First available on Dec 1, 2011
39mm diameter
1 troy ounce .999 Fine Silver
Uses second series holograms marked TEN BTC
Comes in a clear plastic capsule
Zeroes and ones on the back encode the message "Bitcoin: an idea too big to fail"
25 BTC coin

1.75 inches in diameter, about 3mm thick
Gold-plated alloy
Approximately 1.2 ounces
Printed year: 2011
Uses same holograms and private key scheme as original series 1 BTC coin
First appeared in October 2011
Zeroes and ones on the back encode the message "You asked for change, we gave you coins"
100 BTC gold plated bar
Weight: 4.2oz
Dimensions: 8cm x 4cm x 0.6cm
Printed year: none
Indented features: "100 BTC", Bitcoin logo, "gold plated bearer bar"
Hologram: V1 or V2
1000 BTC gold plated bar
Weight: 4.2oz
Dimensions: 8cm x 4cm x 0.6cm
Hologram: V1
Printed year: none
Lasered overprinting on the hologram to indicate the denomination
This is a non-denominated bar that has been engraved with a 1000 BTC denomination. It is indented with the Bitcoin logo and the words "gold plated bearer bar" like the 100 BTC bar, but is not indented with a denomination. The denomination is applied via laser engraving.
This item is presently listed for sale only through MemoryDealers.com
1000 BTC 1 troy ounce gold coin
Available as of Dec 16, 2011
Printed year: 2012
Diameter: 30mm
Special order item, 3 business day lead time
Hologram: V1 with Bitcoin address lasered at top instead of inkjetted across middle
Availability: Purchase from MemoryDealers.com, or directly from Casascius with BTC, or USD bank wire
For more visit
https://en.bitcoin.it/wiki/Casascius_physical_bitcoins