SOAP: A Social Authentication Protocol

Social authentication has been suggested as a usable authentication ceremony to replace manual key authentication in messaging applications. Using social authentication, chat partners authenticate their peers using digital identities managed by identity providers. In this paper, we formally define social authentication, present a protocol called SOAP that largely automates social authentication, formally prove SOAP's security, and demonstrate SOAP's practicality in two prototypes. One prototype is web-based, and the other is implemented in the open-source Signal messaging application.
Using SOAP, users …

applications authenticate authentication called chat cs.cr digital digital identities identities identity identity providers key managed messaging partners protocol prove security soap social