A Modular Framework for Multi-Factor Authentication and Key Exchange

Multi-Factor Authentication (MFA), often coupled with Key Exchange (KE), offers very strong protection for secure communication and has been recommended by many major governmental and industrial bodies for use in highly sensitive applications. Over the past few years many companies started to offer various MFA services to their users and this trend is ongoing. The MFAKE protocol framework presented in this paper offers a la carte design of multi-factor authentication and key exchange protocols by mixing multiple types and quantities of authentication factors in a secure way: MFAKE protocols designed using our framework can combine any subset of multiple low-entropy (one-time) passwords/PINs, high-entropy private/public keys, and biometric factors. This combination is obtained in a modular way from efficient single-factor password-based, public key-based, and biometric-based authentication-only protocols that can be executed in concurrent sessions and bound to a single session of an unauthenticated key exchange protocol to guarantee forward secrecy. The modular approach used in the framework is particularly attractive for MFAKE solutions that require backward compatibility with existing single-factor authentication solutions or where new factors should be introduced gradually over some period of time. The framework is proven secure using the state-of-the art game-based security definitions where specifics of authentication factors such as dictionary attacks on passwords and imperfectness of the biometric matching processes are taken into account.