One-Time Password Generation and Two-Factor Authentication Using Molecules and Light.

Herein, we report the first example of one-time password (OTP) generation and two-factor authentication (2FA) using a molecular approach. OTPs are passwords that are valid for one entry only. For the next login session, a new, different password is generated. This brings the advantage that any undesired recording of a password will not risk the security of the authentication process. Our molecular realization of the OTP generator is based on a photochromic molecular triad where the optical input required to set the triad to the fluorescent form differs depending on the initial isomeric state.