Second factor selection criteria

Factors to consider

There are a number of criteria to consider in selecting a second-factor, including:

  • Assurance levels

  • Ease of use

  • Cost

  • Sensitivity of systems and data

Second-factor assurance levels

Any 2FA protection provides a higher assurance level than a static password alone affords. Within the realm of 2FA options, some options provide a higher level of security than others. The threshold for the security level appropriate for a given application that is protected with 2FA will vary with the risk posed to that application. As such, for applications that require a sufficiently high assurance level, less secure 2FA options will not be allowed.

Preferred second-factor option

The preferred option is the Duo Mobile app.

  • The app is available for iOS and Android devices, with or without cellular access

  • While an Internet connection is required for adding the device to a user’s Duo account, the app can be used to generate OTP codes even when cellular data or Wi-Fi networks are not available

  • The app is simple to register and use. It functions, in various modes, with or without cellular data or Wi-Fi connection

  • Any Duo protected application can be authenticated with the app. It is not necessary to disclose the phone number for a smartphone to use the app



Duo Mobile System Requirements

  • Android: the current version of Duo Mobile supports Android 7.0 and greater. Duo recommends upgrading to the most recent version of Android available for your device. We cannot ensure compatibility of Duo Mobile with custom variants or distributions of Android.

  • iPhone: The current version of Duo Mobile supports iOS 11.0 and greater. Support for older Duo Mobile versions on iOS 10.0 ended July 28, 2019.

Alternative options

Hardware tokens

Tokens for students

  • A U2F token is a good option for Duo authentication for web applications

  • A U2F token will not work with the University's virtual private network (VPN)

  • The U2F standard is currently well supported by Google Chrome

  • U2F tokens are relatively inexpensive, with prices starting below $20

  • Most Yubikey are compatible with Duo, see this page for details

  • It is easy for a user to add a U2F token to your Duo account in the self-service portal

Tokens for employees

Phone call

  • Phone call authentication can be used for any Duo protected application that supports push authentication

  • A user can add a phone number to their Duo account for phone call authentication in the self-service portal

SMS

  • Any phone that can receive SMS messages can receive an OTP code via text message

  • These codes can be used to authenticate with any Duo protected application

  • A user can add a cell phone to their Duo account in the self-service portal

Device management instructions

For steps on enrolling in Duo 2FA using one of the above alternate second-factor methods, please see the Device management instructions page.

Second-factor criteria comparison 

Second-factor option

Self-serve enrollment?

Phone number required?

Cellular network connection required?

Wi-Fi connection required?

Second-factor option

Self-serve enrollment?

Phone number required?

Cellular network connection required?

Wi-Fi connection required?

Duo Mobile app

Yes

No

No

No (only for enrollment)

U2F token

Yes

No

No

Yes

OTP token

No 

No

No

No

Combined U2F/OTP token

Yes (U2F)

No

No

No

SMS

Yes

Yes

Yes

No

Phone call

Yes

Yes

Yes (or landline)

No

Assurance levels

Second-factor option

Assurance level

Second-factor option

Assurance level

Duo Mobile App

High

U2F token

High

OTP token

Moderate - high

SMS

Low

Phone call

Low

 

Need help?

Contact the IST Service Desk online or 519-888-4567 ext. 44357.

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