A token value is generated for a user to submit to an authentication service of an electronic system. The token value represents that the user is in possession of an electronic item known to the authentication service, where the electronic item is capable of two-way communications with the authentication service and has thereon an authenticator application transmitted from the authentication service to the electronic item. The authenticator application obtains a current time value from a clock of the electronic item or an authentication value from the authentication service, retrieves predetermined indicia of the electronic item from a location thereon, and combines the obtained value and the retrieved indicia of the electronic item to generate the token value. The authentication service essentially performs the same steps based on information already available at such authentication service to generate a verification token value, and compares the submitted token value to the verification token value.