Brazilian citizens can download the Mudamos app on their smartphones and register with their electoral identification number, name and address, which are verified with the country’s electoral body. The app then issues a cryptographic key, half of which is stored on the phone; the other is kept with Mudamos and used to verify a signature as authentic.
https://rollcall.com/2021/04/20/tech-tools-help-deepen-citizen-input-in-drafting-laws-abroad-and-in-u-s-states/