Abstract: A method, apparatus and/or system generates a challenge for user authentication, having a challenge data element from a stored pool of challenge data elements. The challenge is based on rule data and stored usage data associated with at least some of the challenge data elements in the stored pool of challenge data elements. The generated challenge is sent for use in an authentication of a user to a sender. A method, apparatus and/or system also generates sender authentication and corresponding location information, having a data element from a stored pool of challenge data elements. Selection of the data elements is based on rule data and stored usage data associated with at least some of the data elements in the stored pool of data elements.

Abstract: A method, apparatus and/or system generates a challenge for user authentication, having a challenge data element from a stored pool of challenge data elements. The challenge is based on rule data and stored usage data associated with at least some of the challenge data elements in the stored pool of challenge data elements. The generated challenge is sent for use in an authentication of a user to a sender. A method, apparatus and/or system also generates sender authentication and corresponding location information, having a data element from a stored pool of challenge data elements. Selection of the data elements is based on rule data and stored usage data associated with at least some of the data elements in the stored pool of data elements.

Abstract: A method and system for validating a certificate maintains a multi-subscriber root certificate store, containing subscriber identification data for a plurality of subscribers along with data representing a plurality of root certificates, such as an index to root certificates or the root certificates themselves, associated with each of the plurality of subscribers. In one example, a table is stored containing specified root CA certificates for a plurality of subscribers in a network such as stored by a network element in a wireless radiotelephone network, or any other suitable wireless network. Subscriber units do not have a root CA store that contains pre-stored root CA certificates. Accordingly, memory is saved in the subscriber units. In addition, a separate server that stores the multi-subscribers root certificate store preferably carries out certificate path validation on behalf of the mobile units so that the wireless mobile unit need not carry out certificate path construction.

Abstract: A RSA encryption scheme includes a modulus in which at least one set of bits is of a predetermined configuration. The configuration may be selected to replicate the identity of the recipient or other information normally transmitted between the parties or may be information stored by the sender to allow only the balance of the modulus to be transmitted with the sender subsequently reconstructing the modulus.

Abstract: A RSA encryption scheme includes a modulus in which at least one set of bits is of a predetermined configuration. The configuration may be selected to replicate the identity of the recipient or other information normally transmitted between the parties or may be information stored by the sender to allow only the balance of the modulus to be transmitted with the sender subsequently reconstructing the modulus.