InfoGuard: A Design and Usability Study of User-Controlled Application-Independent Encryption for Privacy-Conscious Users

Abstract: Billions of secure messaging users have adopted end-to-end encryption (E2EE). Nevertheless, challenges remain. Most communication applications do not provide E2EE, and application silos prevent interoperability. Our qualitative analysis of privacy-conscious users' discussions of E2EE on Reddit reveals concerns about trusting client applications with plaintext, lack of clear indicators about how encryption works, high cost to switch apps, and concerns that most apps are not open source. We propose InfoGuard, a system enabling E2EE for user-to-user communication in any application. InfoGuard allows users to trigger encryption on any textbox, even if the application does not support E2EE. InfoGuard encrypts text before it reaches the application, eliminating the client app's access to plaintext. InfoGuard also incorporates visible encryption to make it easier for users to understand that their data is being encrypted and give them greater confidence in the system's security. The design enables fine-grained encryption, allowing specific sensitive data items to be encrypted while the rest remains visible to the server. Participants in our user study found InfoGuard usable and trustworthy, expressing a willingness to adopt it.