Enroll a Security Key
A security key is a hardware device that plugs into a computer via a USB slot. When it is plugged in, you can tap it to satisfy authentication requests from the college's two-factor authentication system. You need to enroll a security key before you can use it.
Purchasing a Security Key
Duo Security supports U2F security keys. A search of Google or Amazon brings up many options. The top vendor is Yubico.
Your security key should fit the USB ports on your computer, so if you have USB-A, buy a USB-A key; if USB-C, then get a USB-C key. If you move between computers that have both kinds of ports, then you should get a USB-A key and use it with a USB A-to-C adapter.
Note that USB-A keys cost $20 or less, while USB-C keys can cost $50 or more. If you need USB-C it is more cost effective to buy a USB-A key along with an A-to-C adapter.
Here are some suggestions:
Preparation
Take your security key out of its packaging and, if necessary, attach an A-to-C adapter.
Step by step
Launch a supported browser(Chrome 70, Firefox 60, Safari 13, Edge 79, or any higher version of these browsers) and open a new Private Browsing or Incognito window. Go to the Amherst website, and select Login from the Tools & Resources menu (the wrench icon).
Enter your username and password on the login screen and press Login. DO NOT choose an authentication method. (If you've set up Duo to use your default method automatically, press Cancel). Instead, click the link "Add a new device."
Once you're on the Add a new device screen you should choose your authentication method. Note that unlike other Duo screens, the push option is listed last when you add a new device. You may have to scroll down to see it.
Indicate that you are adding a security key and click Continue.
You're now shown the "Enroll Your Security Key" window.
When the pop-up window appears, insert your security key into a USB port. When the key flashes, tap it with your finger. The word "Success" will flash momentarily, then the pop-up window will close.
You'll be returned to the My Settings and Devices window, where your Security Key will have be labelled "JUST ADDED."
You can now finish the login to the Amherst website by clicking Finish Login and employing one of your authentication methods. Note that when your security key is in a USB port, you always have the option of tapping the key to authenticate.