Protecting Web Passwords from Rogue Servers using Trusted Execution Environments

摘要

Passwords are undoubtedly the most dominant user authentication mechanism onthe web today. Although they are inexpensive and easy-to-use, security concernsof password-based authentication are serious. Phishing and theft of passworddatabases are two critical concerns. The tendency of users to re-use passwordsacross different services exacerbates the impact of these two concerns. Currentsolutions addressing these concerns are not fully satisfactory: they typicallyaddress only one of the two concerns; they do not protect passwords from rogueservers; they do not provide any verifiable evidence of their (server-side)adoption to users; and they face deployability challenges in terms of the costfor service providers and/or ease-of-use for end users. We present SafeKeeper, a comprehensive approach to protect theconfidentiality of passwords in web authentication systems. Unlike previousapproaches, SafeKeeper protects user passwords against very strong adversaries,including rogue servers and sophisticated external phishers. It is relativelyinexpensive to deploy as it (i) uses widely available hardware securitymechanisms like Intel SGX, (ii) is integrated into popular web platforms likeWordPress, and (iii) has small performance overhead. We describe a variety ofchallenges in designing and implementing such a system, and how we overcomethem. Through an 86-participant user study, and systematic analysis andexperiments, we demonstrate the usability, security and deployability ofSafeKeeper, which is available as open-source.