Opendime is a small USB stick that allows you to spend Bitcoin like a dollar bill. Pass it along multiple times. Connect to any USB to check balance. Unseal anytime to spend online.

Hopefully everyone who needed an Opendime for Christmas has got it under the tree already, because we are now out of stock! But the big news is we’ve redesigned the hardware and improved it. Same price, same concept, but some useful improvements:


  • we’ve added a special security chip, the sole purpose of which is to defeat any attempt at building counterfeit or cloned Opendime
  • a new “unseal” mechanism: stick a paperclip into the hole to break, instead of the tab
  • lanyard hole added, corners rounded, and 5mm shorter
  • lots of decoration on PCB to celebrate Bitcoin and make it look like a precious object that can hold unlimited monetary value… because it is, and it can.

Order now to get in on the first build of the V2 product at pre-sale prices. We plan to be shipping them March 2017!

To everyone who’s supported us and helped educate the masses about our product: Thank you! Without you Opendime would not be possible. Let’s show the world how to do Bitcoin with the privacy and immediacy of cash.

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Anti-Counterfeiting Chip

We’ve added the Atmel ATECC508A to our board. This little chip is very powerful and does SHA-256 hashing, true random number generating (TRNG) and public key signing (ECDSA) on the NIST 256-bit curve named “P256”. (As Bitcoiners, we say it works on the ‘wrong’ curve, and not the one true curve that Satoshi so wisely picked… but it’s just as secure and exactly the same math.)

This chip holds a number of secret keys that are impossible to extract, and we will be publishing a whitepaper to describe everything it does in great detail. At a high level, the important point is this security chip holds a “factory key” that only the Coinkite factory knows. We will publish the public part of this key, and you can use the signatures that this chip makes to verify that you are connected to a real Opendime. It will also verify that it’s a unique device and that it’s paired to the microprocessor that it was originally built with.

This additional chip does not affect how you use the Opendime and it’s completely optional to verify it, but if you do verify the signature from that chip, you can be 100% sure that you are talking to a genuine Opendime.

Unseal By Poking

We call the Opendime a digital piggy-bank, because to get the Bitcoin out, you have to break it. The original version used a long tab in the middle of the board. This was a little wasteful of space and could be hard to break. To unseal the new Opendime you have to stick a paperclip (or other similarly-sized wire) into a small hole clearly marked on the back side. With a firm jab, you will break the seal that’s on the other side and unlock the Bitcoin in the device.

The main reason for this change is to save space and, at the same time, be sure the Opendime is not accidentally unsealed.

Other Physical Changes

With the long tab removed, we had space to spare and based on your feedback, made the design slightly more human. We’ve rounded the corners and added a lanyard hole for hanging or mounting. It works well on keyrings and hooks now.



Since we love Bitcoin and hard currency, we wanted to add some design elements from old-style metal currency. We added the Bitcoin logo, Opendime logo and the word “Bitcoin” to the board. Some radial lines and curved text also add to the “coin” aesthetic.

Other Changes

Not much! We wanted to keep the software interface the same, so we have minimized changes to the files in the virtual filesystem. We will update our github repo with the updated image files before the boards ship out.


We will be updating reseller prices in February, contact

Enjoy the ride!