Ilkan Esiyok (CISPA Helmholtz Center for Information Security), Pascal Berrang (University of Birmingham & Nimiq), Katriel Cohn-Gordon (Meta), Robert Künnemann (CISPA Helmholtz Center for Information Security)
The Internet is a major distribution platform for web applications, but there are
no effective transparency and audit mechanisms in place for the web. Due to the ephemeral nature
of web applications, a client visiting a website has no guarantee that the
code it receives today is the same as yesterday, or the same as other visitors
receive. Despite advances in web security, it is thus challenging to audit
web applications before they are rendered in the browser. We propose
Accountable JS, a browser extension and opt-in protocol for accountable
delivery of active content on a web page. We prototype our protocol,
formally model its security properties with the Tamarin Prover, and
evaluate its compatibility and performance impact with case studies
including WhatsApp Web, AdSense and Nimiq.
Accountability is beginning to be deployed at scale, with Meta’s recent announcement of Code Verify
available to all 2 billion WhatsApp users, but there has been little formal analysis of such protocols.
We formally model Code Verify using the Tamarin Prover and compare its properties to our Accountable JS protocol. We also compare Code Verify’s and Accountable JS extension's performance impacts on WhatsApp Web.