Opendime® is a read-only USB flash drive that contains the private key to bitcoin strictly on the device itself and works like a bearer bond – allowing you to perform crypto transactions offline. It works on any computer, laptop, tablet, or phone using a QR image and text files which contains a bitcoin address. The private key is generated inside the device and is never known to any human, not even you. It can be given to anyone, and the recipient never has to worry that the funds can be accessed. The person holding the credit stick holds the bitcoin.
How It Works
Opendime® is delivered without any private key. You must give it entropy (random numbers generated by dragging a file to the device) the first time you use it. Once it’s gotten enough numbers, it will hash them all together and use that to pick a random number for use as the private key. The payment address is generated and set in stone. When plugged into any USB capable port the device shows a QR code image and text Bitcoin address. You send bitcoins in any amount to that address and the Opendime® is loaded. You give the device to a recipient who “unseals” it to reveal the private key, see the amount it holds, and spend the bitcoin or move it to their own wallet of choice.
Opendime® transactions are a little different from blockchain transactions. Whenever two people meet and trade goods or services for an Opendime®, you could say a transaction has occurred, and yet there is nothing recorded on the blockchain. This is different from a normal Bitcoin wallet which makes blockchain records continuously and can create a complex web of connections that can later be explored by anyone.
This device is expected to be loaded once, probably with a round number of bitcoins, and unloaded exactly once to the recipient’s wallet of choice. It can be used to gift bitcoins to someone, pay for something that has a given amount (like a car), load with various denominations of bitcoin and sold to friends, or instead of a paper wallet. Opendime® is a very safe and effective way of generating uncompromised private key. There is no password, nor seed phrase, as the device is locked in until physically unsealed. Any bitcoin wallet that is monitoring the blockchain can be used with Opendime®, and it carries a simple python program that can be used to verify balance and spend funds (once unsealed).
The newest hardware (V2) includes a dedicated anti-counterfeiting chip which holds a secret key assigned by the Opendime factory. Opendime® publishes the matching public key, and so it’s easy to verify that you have a genuine Opendime in your hands. They also use clear packaging, so any tampering or other funny business is very easy to see before buying the device.
It is safe to setup, verify and load an Opendime® on an untrusted computer. The private key is generated inside, and does not leave the Opendime® itself regardless of any malware and keyloggers that may be present on the attached computer. It can also be used on iPads and tablets, which typically see the Opendime® as a single photo of a QR code, ready for scanning.
We recommend using a trusted computer after it is unsealed since the private key is in the open at that point. You would need to trust that computer anyway, since you are sending the funds from the Opendime® to some other Bitcoin wallet address and you don’t want that to be manipulated.