RT Journal Article T1 A Key for John Doe: Modeling and Designing Anonymous Password-Authenticated Key Exchange Protocols A1 González Vasco, María Isabel A1 Pérez Del Pozo, Angel A1 Soriente, Claudio AB Anonymous Password-Authenticated Key Exchange (APAKE) can be seen as the hybrid offspring of standard key exchange and anonymous password authentication protocols. APAKE allows a client holding a low-entropy password to establish a session key with a server, provided that the client's password is in the server's set. Moreover, no information about the password input by the client or the set of valid passwords held by the server should leak to the other party-beyond whether the client's password lies or not in the server's password database. To the best of our knowledge, all APAKE proposals to date either assume client storage or force the client to remember the index assigned to its password in the server's database. Furthermore, earlier works either provide only informal definitions or fail in some sense to properly model the primitive. In this paper, we provide a formal security model for APAKE, capturing security and anonymity provisions for both clients and servers. In addition, we present two APAKE protocols that only require clients to remember a password and that attain our sought key secrecy and anonymity guarantees. Our first protocol leverages oblivious pseudo-random functions, while the second one builds upon a special type of identity-based encryption scheme. PB IEEE SN 1545-5971 YR 2021 FD 2021-05-01 LK https://hdl.handle.net/10016/39070 UL https://hdl.handle.net/10016/39070 LA eng NO This work is partially supported by the NATO Science for Peace and Security program (grant G5448), as well as by the MINECO grant MTM2016-77213-R. DS e-Archivo RD 17 jul. 2024