An analysis of Casascius coins

Mike Caldwell, a long-time Bitcoin enthusiast, wanted a way to create physical representations of bitcoins. In 2011, Caldwell started producing and selling Casascius coins, one of the best-known “physical bitcoins” available on the market.

Casascius is a word made up by Caldwell, derived from an acronym for “Call a Spade a Spade.” To create a Casascius coin, Caldwell would embed a private key on a card inside a coin. This card would be protected by a tamper-evident hologram. To redeem the bitcoins in a Casascius coin, users would have to remove the hologram to reveal the private keys and import them into a Bitcoin wallet.