Various views of Casascius coins

Redeemed Casascius coin

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:

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

Second series 1 BTC Casascius 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

Casascius 25BTC 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

See also