Physical Bitcoin and Tamper Evident

[Medic]

Hey Tamper Evident folks,

I picked up a Casascius physical bitcoin at DEFCON last year from Bodo for the novelty and forgot about it until now. They contain the full private key of a bitcoin address under the holographic seal, so if you can remove the seal and replace it, you can still spend the coin in the physical world.. It seems like a perfect fit for this contest.

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.

From: https://www.casascius.com/faq.aspx
Pictures: https://www.casascius.com/photos.aspx

--Medic

[kallahar]

Re: Physical Bitcoin and Tamper Evident

That's pretty cool, and I was just reading about these...

Is it a sticker, or is it imprinted directly onto the material?

Do we have the ability to make the holograms? or is it some super secret or expensive process?

How does the receiver verify the hologram? would any hologram that looks fancy enough maybe pass muster?

Kallahar

[Medic]

Re: Physical Bitcoin and Tamper Evident

It's a brass coin with a hologram sticker over it.

I'm sure you (someone?) can create a competing physical bitcoin representation like http://bitbills.com/ or something, so go ahead and create the holograms. :)

As far as validation of the hologram, I went off of the high-resolution pictures on his site to attempt to verify the authenticity. Since it shows the first 8 digits of the address, I was able to search for it in the block chain and verify it still has a balance of 1 BTC: http://blockexplorer.com/address/1Cc...ABjkvPqrwkY8TB .

I'd imagine the more people use it, the better known the hologram will get and the more anti-counterfeiting technology will have to be added. The Tamper Evident contest looked like a good place to start that back and forth. :)

--Medic

[datagram]

Re: Physical Bitcoin and Tamper Evident

I've been wanting to look at these but don't know anyone who's willing to give me a few to play with :( I'm reasonably certain that I could beat the hologram but I'd need at least a dozen to test everything. So...who wants to give me a bag of them at DC 21 ? I'd be happy to do all tests live in the Tamper-Evident Village!

Can anyone provide info on what material the seal backing, adhesive (or other bonding method), card, card printing method, etc are?

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[mfp]

[snideology]

Re: Physical Bitcoin and Tamper Evident

I'd like to play with one myself.

Is there going to be a te contest at DC21?

[TheCotMan]

Re: Physical Bitcoin and Tamper Evident

I'd like to play with one myself.

Is there going to be a te contest at DC21?

I believe Jeff said there are plans to have a "TE" (Tamper Evident) contest this year again. Also, there are plans to have a "Tamper Evident Village"