arXiv:1810.04660cs.CR
True2F: Backdoor-resistant authentication tokens
Early discovery. Linked by one identifiable commenter. This paper is outside the main ranking; a mention is not an endorsement.
Abstract
We present True2F, a system for second-factor authentication that provides the benefits of conventional authentication tokens in the face of phishing and software compromise, while also providing strong protection against token faults and backdoors. To do so, we develop new lightweight two-party protocols for generating cryptographic keys and ECDSA signatures, and we implement new privacy defenses to prevent cross-origin token-fingerprinting attacks. To facilitate real-world deployment, our system is backwards-compatible with today's U2F-enabled web services and runs on commodity hardware tokens after a firmware modification. A True2F-protected authentication takes just 57ms to complete on the token, compared with 23ms for unprotected U2F.
It's possible to rule out some (but not necessarily all) cross-protocol attacks with a simple and cheap tweak. I have not proved that this rules out everything, but it appears to be no weaker than the scheme sans tweak, and proofs shouldn't be too hard. The high-level idea is to…
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