Authelia: Configurable TOTP Window Size

[zjzeit]

I have a TOTP device (Protectimus Slim Mini) but the problem is the clock on the device has skewed just outside the boundaries defined by the TOTP spec. Is it possible to set a configurable window size value as an option in configuration.yml to increase the window size of acceptable TOTP values?

In this case, window is defined as the number of 60-second intervals the TOTP value is accepted and passes authentication.

I did this in Authelia v3 by modifying the WINDOW: value in the file ./server/src/lib/authentication/totp/TotpHandler.js

I am using the docker image authelia/authelia:4.8.0

[james-d-elliott]

@zjzeit I am implementing an example of this until we decide how this is best implemented, feel free to try it, but expect the functionality to change in the future. Docker image is: authelia/authelia:feature-topt-tuning

See here for the config example: https://github.com/authelia/authelia/blob/feature-topt-tuning/config.template.yml#L38-L45

[james-d-elliott]

This has been released in 4.9.0. Enjoy @zjzeit

Here are the docs. I'd recommend changing skew to 2 in your case it will allow for up to 60+ seconds in either direction. https://docs.authelia.com/configuration/one-time-password.html

[zjzeit]

Thank you for the quick resolution!