[jbrr25]

You can download a java app which generates the key pair taking mouse movement as entropy and then you to go to a SAT(IRS equivalent) office with the key in a USB drive, they take your biometrics and save the public key to your profile. However, as most people only bring the USB drive, they usually create the key pair in the in the office. If your key is compromised or lost, you have to go to the office and they change it in very much the same way.

It's a somewhat tedious process, but if you keep the key safe, which they very much advice, most of the procedures, including tax fillings, are pretty easy and fast.