Frequently asked questions about Casascius Physical Bitcoins

Q. Couldn't someone just use an iron / hairdryer / a solvent / whatever to remove and replace the hologram?

A. Try it.  The holograms were made by a premier manufacturer who understands they are in the business of making tamper-evident labels, and it looks to me like they did a really good job.  It's pretty difficult to remove the hologram without exposing an obvious "honeycomb" tamper evident pattern.  The tamper pattern is extremely sensitive and not concealable once exposed - so sensitive in fact, I ruin over 10% of the holograms just preparing the coins and have to discard them.  I don't know of a way, and I'd be interested to hear if you do.

Q. Do you keep a copy of the private key?  Who has had access to the private keys?

A. I did not keep the private keys, and I am the only person who has ever had control over the private keys.  I have either inserted the private keys into the coins myself, or have directly supervised others doing the same.  On the series 1 coins, the hologram manufacturer pre-printed the addresses onto the hologram labels, but they were only given the 8 characters you see, not the private keys themselves.

Q. It's impossible to prove you didn't keep the private keys, and with all the Bitcoin scams lately, why should I believe you?

A.  I have given out my real-world identity and have digitally signed a list of the Bitcoin addresses used in this project.  I have made it so that it if I were to perpetrate a scam, it would be possible to prove it and to hold me legally accountable - something no scammer wants to do.  You should demand the same from anyone handling your cryptocurrency.

Q. How did you generate the private keys?  Was this done securely? What was your entropy source?  How can I be sure the keys are properly random?

A. Detailed answers to questions like these can be found on my Statement of Controls.


Near the end of October 2011, Casascius Physical Bitcoins were featured on CNet, and I had to raise the price on the original 1 BTC Casascius Physical Bitcoin due to overwhelming demand.  This only applied to the 1 BTC coin, not the 25.


When I introduced Casascius Physical Bitcoins, part of the motivation was to introduce a proof of concept, a conversation piece to help people talk to others about Bitcoin and perhaps to be the first to market to make a real "coin" out of Bitcoins - something I perceive as being of historical significance given my enthusiasm for the project.  What I didn't expect in the beginning, is that a large part of the interest in Casascius Physical Bitcoins is from people wanting to collect the coin, who see it as a token of the same historical significance I see.  Needless to say, I am flattered that what is arguably a hobby project of mine is demanded as a collectible.

My plan is to preserve the collectible value of the original series for those interested in collecting it.  Other than to accommodate variations in the BTC exchange rate, I do not intend to lower the price on the original series, only the new series.

There will never be more than 11,000 of the original series coins, probably much fewer than this. This coin can be identified by a misspelling of "CASASCIUS" in the small background print (the middle S is missing).  As of December 2011 I have made about 3500, and the final count will be further limited by other factors: the percentage of the uniquely numbered holograms that get ruined from the start, many of the sold coins have been opened and redeemed, some of the holograms have gone into the 25 BTC coins, and am not sure if I will keep doing them by hand myself if I can manage series 2 better.  I have published a list of all the Bitcoin addresses pre-generated for the original project, and maybe someone out there can take this list and scan the block chain and tell us just how many unspent ones there are out there.

There are 7.5 million digital Bitcoins as of October 2011 - if I were to make 11,000 1BTC coins, I will still have coined less than 0.2% of all the Bitcoins out there.

Return to main page