Secure Information Technology Center – Austria

Browser Addon for Certificate Validation using EU Trust Lists

Intended for demonstration purposes, A-SIT realised an addon for Mozilla Firefox capable of verifying and displaying the trust status of a website certificate according to the EU Trust List (TL). The extension adds a symbol to the browser’s address bar, indicating the trustworthiness of certificates on HTTPS-protected websites according to the eIDAS regulation via TL. Inspired by common usage of a coloured lock icon in order to signalize the trust status in browsers, the addon displays a blue EU flag for trustworthy, a crossed out flag for untrustworthy domains after completion of the browser-specific handshake validation. Besides, the user has the ability to learn more about the validation results by clicking onto the icon. As a result, certificate characteristics as well as TL-specific attributes are denoted.

Addon screenshot Addon screenshot


Having downloaded the browser extension and unpacked the ZIP file, the resulting .xpi file can be moved to an active browser window via drag & drop. After confirming the installation, the plugin is ready to use.


Title Version Date
Firefox addon 1.0.0 2017-02-10
Documentation   2017-02-10
Source code   2017-02-10

Posted 10.02.2017, Kategorie: Electronic signatures, IT-Security.