Systems and methods for One-Time Password (OTP) authentication with infinite nested hash chains are described. In one aspect, a methodology includes a client device that provides a one-time password (OTP) authentication server with certain registration information. The client device generates, via the OTP authentication server, an authenticated OTP with infinite nested hash chains, These generating operations use a first hash function (hA (−)) for updating a seed chain, a second hash function (hB (•)) for OTP production, an OTP seed number stOTP for a tth authentication, and two authentication seeds of numbers s2t−1Auth and s2tAuth, for the tth authentication.