A Secure Two-factor Authentication Key Exchange Scheme

Two-factor authentication key exchange (AKE) is an effective way to strengthen the security of password-authenticated key exchange. Most two-factor AKE schemes using smart cards as the second factor require users to have the second factor with them any time, which causes users inconveniences. Biometrics provide a user-friendly manner to achieve two-factor AKE since they need not be carried. However, biometrics may have less entropy than expected and would suffer from offline guessing attacks. In this paper, we propose a secure two-factor authentication key exchange scheme TAKE that resists offline guessing attacks against biometrics and passwords. In TAKE, a user generates a combined factor of his/her biometrics and password. To protect the combined factor, the user and the server leverages secure two-party computation to blind it with a key which is protected in a trusted execution environment. Thus, TAKE prevents an adversary from eavesdropping on the combined factor, and simultaneously guarantees that he cannot recover the combined factor from blinded one to undertake offline guessing attacks even if he compromises the server and obtains the blinded combined factor. We provide the formal security proof of TAKE. The experiments show that TAKE is efficient in terms of storage, computation, and communication overhead.