Bitcoin Forum

https://en.bitcoin.it/w/images/en/thumb/a/a9/Casascius_25btc.jpg/535px-Casascius_25btc.jpg
https://en.bitcoin.it/w/images/en/thumb/e/e1/Casascius_25btc_size_compare.jpg/800px-Casascius_25btc_size_compare.jpg

Weight: About 34 grams, or 1.2 ounces.
Size: About 45 mm, or 1.75 inches.
Thickness: About 3mm
Plated with real gold.  Text on front is painted black.
Each coin comes individually wrapped in a clear plastic pouch.

Cost: 28 BTC if you order 1-4.
27.50 BTC if you order 5+.
Percentage wise, this is a more favorable premium than the 1 BTC coin.

These are not on my website yet, but USA customers, you can still order if you calculate send the correct amount, and mention in the notes field.  (I do all these manually anyway, so it won't be missed).  The flat rate shipping is the same.

International customers, please wait until I have the site updated.  (Or, at your own risk, I am willing to send ONE coin in a DVD mailer sent via regular letter mail for 1 BTC). Due to the value, I am looking into other shipping methods that provide better tracking and delivery.  It'll probably be DHL, UPS, or USPS Express, and in some cases registered mail.  Also, I plan to provide a lower-cost lettermail international shipping option for very small orders (up to 5 BTC worth of coins).  Stay tuned.

https://www.casascius.com

EDIT: P.S. For the 25 BTC coin, I am offering an "unspoil" service, so you never need to choose between destroying your physical coin and gaining electronic access to your funds.  If at any time you need to tear open your 25BTC physical bitcoin to get your funds, you can send it back at a later date and have it cleaned and restickered with a new 25 BTC private key for only 25.5 BTC plus return shipping.

Awesome, definitely ordering one of these!!

Look into shipping via UPS Mail Innovations. http://www.upsmailinnovations.com/
It's basically a cooperation btwn UPS and USPS. You get a USPS tracking number, but everything is picked up by UPS. UPS delivers it to the customers post office and the USPS delivers it locally.

They ship anything under 1 lb. We use UPS MI for small packages, perfect for these.
Just an example of some of my rates

3oz = $1.49
60z = $1.93
10 oz = $2.58
13 oz = $2.99
15.99 oz = $4.41

if you have any questions, or want my reps #, send me a PM

Charlie

Very cool!  :D

pretty cool. Any possibility of minting one in .999 Fine Silver?  Of course it would cost the value of the silver plus the embedded bitcoins, but I'd buy one in pure silver for sure

When you say gold plated alloy, are you referring to gold as in the color, or gold as in metallic content?

Both.  The surface is gold metal.

So in short gold colored paint, but it looks nice though :D
Silver or Gold coins would trigger attention from governements and can not be freely traded, especially gold is not allowed these days
Some people was thinking of walking over our border with 200 krugerrands mounted in their jackets and belts....
And guess who has the gold now .... indeed the governement, so i do not expect such coins have an actual gold plating and to be honest you do not want that either.

No, not paint.  They are really gold plated.  (edited my prior posts to make this more clear)

???

Beautiful!  Is there any significance to the pattern of 1's and 0's on the back?

Yes, they are binary-coded ASCII for: "YOU ASKED FOR CHANGE" "WE GAVE YOU COINS".  Four little dots on the bottom tell you where to start reading.

I really need to post another picture of how it looks under can lights.  Not only does that bring the hologram to life, those 0's and 1's sparkle in a way that make the back coin look encrusted with diamonds.

Very nice!  BTW, I just received my order of 11 one-BTC coins from you today - I would like to compliment you on your fast delivery.  

What is the process for importing the private key on the back of the hologram into a wallet?
[EDIT: Never mind, I found StrongCoin.]

Simple with MtGox. Login to your MtGox account and Add Funds using a private key :)
More info- https://bitcointalk.org/index.php?topic=46908.0;topicseen

Good to know, thanks!

Blanks, as in the peeled-open shells?  Or blanks as in ... intact, just with no value?  Even though I wouldn't accept one of these as payment without first verifying the code I wouldn't want the potential for there to be "blanks" floating around.

Love the new coin!

Nice idea!  Diversification in a single coin...make it 1oz and 10 BTC and you have close to an equivalent value in silver and BTC.

Really?  What country has banned gold?

well the US made private ownership of gold illegal for many years, however now it is perfectly legal.  You are only allowed to carry $10,000 worth of precious metals across the border without declaring it though.

I am willing to sell the blanks at the same price as the coin minus the face value.  They will arrive with no hologram, the same as if you ordered them with the full value, peeled the hologram, redeemed the BTC, and then cleaned off the residue with a solvent (it comes completely off with Goof-off etc.).

For the 1 BTC coins, I am willing to sell torn open ones for 0.15 BTC on an as-available basis.  These have a real private key and bitcoin address, but nothing has been loaded on them, the sticker has been peeled and restuck (so it shows tamper marks), and the private key has been lightly crossed out.  At the moment I probably have 50 such coins available.

(The offer for 0.15 BTC generally are "mistake" coins, since a percentage always get messed up for one reason or another, such as if I accidentally smudge the label and make the tamper dots appear.  On the other hand, there are no 25 BTC mistake coins, because the coins are worth enough that it's worthwhile to clean them off and redo them in the event of a mistake.)

If you don't mind, go to https://casascius.com and fill out your order, but just put in the notes that you want blanks, and subtract the face value off the total, then you'll get an address and all your info will be in my shipping system.  So I can print the customs form and shipping label straight from the database all in one step.

I find these physical coins very interesting, but I just want to make sure I understand some of the technical aspects. I have some understanding of the basics of crypto, but not enough to really evaluate this.

The private key you generate is an SHA-256 hash of these letters that you generate and put on the back of the hologram. So, I assume that you are generating these random letters with a good random data source, and there's at least 256 bits of randomness in there, so in theory using the hash of it as a private key is "as random" as an address generated by the standard client in the usual way? Do i have that right?

And so, in addition to trusting you specifically that you don't keep any records of the private keys that you've loaded onto your coins (intentionally or not), we also need to trust that you've used a good random data source. Could you describe and explain your process to ensure that your generation of private keys is random and secure? (Or please point me in the right direction if you've already done so and I've missed it.)

Thank you.

There's no such thing as random....

There's no more than 123 bits of entropy due to the abbreviated length.  Bitcoin addresses themselves have no more than 160 bits of entropy because they are based on ripemd160.  I chose this as a tradeoff for space versus time.  It's still quite expensive to brute force 123 bits, especially when the payoff is that you might bump into a 1 BTC coin sometime before the end of the world, and especially considering that each iteration of any attack requires a relatively slow elliptic curve multiplication operation.  Mining is far more lucrative by several orders of magnitude to say the least.  

My source of entropy is the cryptographic secure random number generator in the .NET Framework, in the System.Security.Cryptography namespace, XORed with the SHA256 hash of (mash + incrementing number).  Mash is a constant string produced by me mashing gibberish (was probably 60-70 chars) on the keyboard and is meant as extra entropy against Microsoft's implementation.  (I'm familiar with Debian SSL flaw and thought that this would mitigate the possibility if there were something similar).

This was done on an airgapped machine, the OS installation dedicated just for this purpose, private keys have never touched any machine on the internet.  The hard drive was strictly controlled, and after the private keys were printed on 33 sheets of paper (each individually checked for accuracy), has since been zeroed over in its entirety (with linux) and a new OS installed over top of it.

I recognize and appreciate the importance of generating these keys securely.  It would be an epic fail for me to say "Whoops!  Hacker found your private keys in my temp directory... SORRY" and fortunately I know how not to do that.

Thank you, casascius, for that great explanation. Perhaps you could include some description of it on your ordering page?

I assume the papers are shredded or similar after their keys are put onto coins?

The papers are what literally go in to the coin under the sticker. So nothing to shred.

Perhaps include the motto "In Casascius We Trust"  :D

You should sell them on tv ! Remember the $20 from Liberia to commemorate 9/11.

http://forums.commercialsihate.com/9-11-commmemorative-20-dollar-ad_topic1328.html

The 25 BTC coin is now available online.

I am also offering the piece for sale with no BTC value for 3.5 BTC.  Of course, it has no hologram on the back.  It looks the same as if you bought the full coin, redeemed the BTC, and cleaned off the hologram residue.

(Consider this:  Even though they won't be true "Casascius Coins", you could buy my blank coins and sticker them yourself with generic 1" circle hologram security labels off the Internet.  Even though you might not be able to circulate them, if all you care is to collect them or to give them to a loved one, you may not care.  This eliminates the risk of mailing real BTC.)

From a different thread Casascius wrote:

So just to clarify -- it is possible that these could be circulated without having the hologram tampered with but having no bitcoin funds loaded, correct?  I.e., if I were to accept one of these as payment or purchase one, I should first check the address to confirm it has the bitcoins loaded?

I know that when a miner generates, the 50 BTC reward (or portion thereof) can go to a specific address.  Eligius, for instance, does this:
 - http://blockchain.info/tx-index/11312776/f46dd33fe4397cbba04bc7b25560ac3c715c6b4cd1371f61dba04a639cec98a7
As does P2Pool.  Eligius even offered to do this for non-miners on a contract basis.

I think one of these 25 BTC with the 25 bitcoins coming as generated coin would make it even more valuable.  Because there are only about 60 thousand 50 BTC blocks remaining, a pair of these collectibles each with 25 BTC from the same block would make them even more valuable as that is something that cannot be done again after about a year from now when the 50 BTC reward drops to 25 BTC.

Incidentally, I showed the physical 25 BTC coin at my monthly coin collector meeting.  Out of 40 (including many that are octogenarians or close to that) there were four who were interested in these.

Not exactly.  I'm willing to ship them unloaded and load them on receipt so they aren't as valuable while they're being processed for customs.  But I am not willing to allow them to circulate unloaded.  If they are in the wild, they are either already loaded, or going to be loaded.  Also, any coins shipped that way would be shipped with a method that offers international tracking and a signature, because I intend to load the value whether the coins arrive or not.

That is a satisfactory response.

maybe i missed this, but how is this coin secured from 2x spend attack.  that is the issuer (Casasious) could also have a copy of teh coin's a privkey.  i know there is a tamper evident seal and a code to check with the issuer its authenticity.

Lastly, how is this secure from counterfeit?  couldn't i just copy the verification code of a legit coin and try to pass one off?  people accepting these will likely not redeem them, so the counterfeit may not have the right privkey inside, but its outer check number thingy would be right...

maybe i dont understand.  but if you can explain this to me i'd love to buy a 25 btc for my 3 year old nephew, just like i've been buying him silver eagles every b-day since.

did you select an ink and paper that could withstand the test time?  injet printer ink evaporates.  laser is better...  just curious if in 20 years it would have faded away b/c you used a crappy lexmark inkjet.

In a theoretical sense, I could scam my customers.  In a practical sense, seeing as how I give away my real life identity and have PGP signed the list of addresses I have prepared for my coins, those I scammed would have fairly strong recourse against me.


Sure, if anyone wants to spend four figures to get custom holograms done, only to be able to perpetrate a scam that will probably be figured out in days if not weeks.  It's been discussed in the past.  If someone goes to the effort of doing it, that'll be unfortunate.  Hopefully they'd see it as just as lucrative to generate real legit coins (i mean, I'm already charging a 20-25% premium over face value, isn't that good enough?).  Same argument as it applies to mining: it pays more to be an honest miner, and therefore have reasonable faith that miners are honest.


Buy one, and buy a billy club with it.  If I scam you, come to Utah and beat my ass.  My real address is on my website.  If I don't scam you, you've just given a great gift that hopefully will appreciate.


I deliberately chose inkjet.  Laser toner is relatively thick and can be read from the outside with radiation or ultrasound.  Inkjet may fade in the same sense old photos become slightly off color, but you don't see them fading into oblivion like the photos turning into blank paper.  That said, I used an off-black color to ensure that C+M+Y+K ink all contribute to the color, so they would all have to fade to blank for this to be an issue.

If nothing else, I think Cassies will be collectable if not museum pieces in 50 years  ;D

Wow, you thought this thru...as soon as some stuff clears i'll buy a few

Utah eh,?  R U a mormon?  If so its a deal.  Never met a crooked mormon (except for the ones in politics and Rick Koerber (https://secure.wikimedia.org/wikipedia/en/wiki/Rick_Koerber)).

i received this stuff! Very, very good product. Playing with it like a kid now )))


http://img3.imageshack.us/img3/4868/45578936.jpg (http://imageshack.us/photo/my-images/3/45578936.jpg/)

http://img196.imageshack.us/img196/9618/73855977.jpg (http://imageshack.us/photo/my-images/196/73855977.jpg/)

http://img546.imageshack.us/img546/1958/70212540.jpg (http://imageshack.us/photo/my-images/546/70212540.jpg/)

I got my 25 BTC coin today...wow...as a hobbyist coin collector, I must say, this one was pressed with gusto...it's more like a mini 3D sculpture than a plain coin...the relief (in numismatic terms) is ultra high. It feels great in the hand...as does the gold plated bar!

Well done again, casascius!

Does anyone know the quantity of blanks there were made/available?
This would be a good figure to add to the encyclopedia since there is no mention of these in there.

https://www.talkimg.com/images/2023/07/26/QEGSq.png

This is a good question Miner Jones. I don't know personally but I am watching for the answer.

  I have been looking for awhile but never have come across how many blanks were sodl.

  I do know I only came across one for sale thru the years and that is the one that is part of my collection.

  I think they are harder to find than the loaded ones. But I could be wrong.