International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Shay Gueron

Publications

Year
Venue
Title
2021
JOFC
Selfie: reflections on TLS 1.3 with PSK
Nir Drucker Shay Gueron
TLS 1.3 allows two parties to establish a shared session key from an out-of-band agreed pre-shared key (PSK). The PSK is used to mutually authenticate the parties, under the assumption that it is not shared with others. This allows the parties to skip the certificate verification steps, saving bandwidth, communication rounds, and latency. In this paper, we identify a vulnerability in this specific TLS 1.3 option by showing a new “reflection attack” that we call “ Selfie .” This attack uses the fact that TLS does not mandate explicit authentication of the server and the client, and leverages it to break the protocol’s mutual authentication property. We explain the root cause of this TLS 1.3 vulnerability, provide a fully detailed demonstration of a Selfie  attack using the TLS implementation of OpenSSL, and propose mitigation. The Selfie  attack is the first attack on TLS 1.3 after its official release in 2018. It is surprising because it uncovers an interesting gap in the existing TLS 1.3 models that the security proofs rely on. We explain the gap in these model assumptions and show how it affects the proofs in this case.
2018
JOFC
2018
JOFC
2016
ASIACRYPT
2009
ASIACRYPT
2009
FSE
2002
CHES

Program Committees

Crypto 2020
CHES 2019
CHES 2018
CHES 2013