There are two ways you can generate one-time passcodes for two-factor authentication. Both of these options are free of charge.
The Duo Mobile app will generate new passcodes every 30 seconds that can be used for authentication. Note: the passcodes generated by the Duo Mobile app are not sufficient for enhanced authentication. If you plan to use the Duo Mobile passcodes for two-factor authentication, you must have a more secure two-factor authentication method available if you are asked to perform an enhanced authentication. These codes can be used in cases where you do not have Wi-Fi or cellular access on your phone or other registered devices to help you gain authentication approval. For example, you may find passcodes most useful when traveling abroad in remote areas with intermittent cell reception or while on an airplane.
You may download 10 single-use passcodes from 2fa.uchicago.edu.
To use passcodes, open the Duo app and select the gray icon in the upper right-hand side of the app for iOS and Android (pointed by the red arrow in the image below) or the Generate Passcode button on Microsoft OS devices. A six-digit numeric code will be generated that you will enter when a UChicago website requests 2FA. This feature does not use any data services and can be used with or without internet access. It can be used as many times as required.
To use passcodes from the 2FA website, log on to the 2FA website. Navigate to the Manage Devices section, and select the Print One-Time Passcodes button that appears above Your Registered Devices. Once printed or written down, you may keep this list with you to use as one-time passcodes in situations where you do not have reliable access to other forms of authentication. NOTE: These passcodes can be used for enhanced authentication. If you choose to use the Duo Mobile app passcode generation as your main form of authentication, printing a set of these one-time passcodes can be a viable backup in case of enhanced authentication.