A solution is proposed for performing authentications. A corresponding method comprises storing a verification string corresponding to applying a one-way function iteratively starting from a secret string. An authentication request is received in association with an authentication string (or more) being generated by applying the one-way function iteratively starting from the secret string for a lower number of times. A result of the authentication request is determined by comparing the verification string with a comparison string being generated by applying the one-way function to the authentication string (or a few times iteratively). Corresponding computer programs and a computer program products for performing the method are also proposed. Moreover, corresponding systems for implementing the method are proposed.