Abstract: Method and apparatus for secure transmissions. Each user is provided a registration key. A long-time updated broadcast key is encrypted using the registration key and provided periodically to a user. A short-time updated key is encrypted using the broadcast key and provided periodically to a user. Broadcasts are then encrypted using the short-time key, wherein the user decrypts the broadcast message using the short-time key.

Abstract: A method of transforming a set of signals representing a message comprising the steps of first encoding one of the set of signals according to a first keyed transformation, a second encoding of the one of the set of signals in accordance with at least one additional keyed transformation, a third encoding of the one of the set of signals according to a self inverting transformation in which at least one of the set of signals is altered, a fourth encoding of the one of the set of signals according to at least one additional inverse keyed transformation wherein each of the at least one additional inverse keyed transformation is a corresponding inverse of at least one additional keyed transformation, and fifth encoding the one of the set of signals according to first inverse keyed transformation wherein the first inverse keyed transformation is the inverse of the first keyed transformation.

Abstract: Methods and apparatus are presented for providing local authentication of subscribers travelling outside their home systems. A subscriber identification token 230 provides authentication support by generating a signature 370 based upon a key that is held secret from a mobile unit 220. A mobile unit 220 that is programmed to wrongfully retain keys from a subscriber identification token 230 after a subscriber has removed his or her token is prevented from subsequently accessing the subscriber's account.

Abstract: Methods and apparatus are presented for providing local authentication of subscribers travelling outside their home systems. A subscriber identification token 230 provides authentication support by generating a signature 370 based upon a key that is held secret from a mobile unit 220. A mobile unit 220 that is programmed to wrongfully retain keys from a subscriber identification token 230 after a subscriber has removed his or her token is prevented from subsequently accessing the subscriber's account.

Abstract: In a communications system, a method of transforming a set of message signals representing a message comprising the steps of first encoding one of the set of message signals in accordance with a first keyed transformation, a second encoding of the one of the set of message signals in accordance with at least one additional keyed transformation, a third encoding of the one of the set of message signals in accordance with a self inverting transformation in which at least one of the set of message signals is altered, a fourth encoding of the one of the set of message signals in accordance with at least one additional inverse keyed transformation wherein each of the at least one additional inverse keyed transformation is a corresponding inverse of at least one additional keyed transformation, and fifth encoding the one of the set of message signals in accordance with first inverse keyed transformation wherein the first inverse keyed transformation is the inverse of the first keyed transformation.

Abstract: A method and apparatus for generating encryption stream ciphers. The recurrence relation is designed to operate over finite fields larger than GF(2). The linear feedback shift register used to implement the recurrence relation can be implemented using a circular buffer or sliding a window. Multiplications of the elements of the finite field are implemented using lookup tables. A non-linear output can be obtained by using one or a combination of non-linear processes. The stream ciphers can be designed to support multi-tier keying to suit the requirements of the applications for which the stream ciphers are used.

Abstract: A method and apparatus for generating encryption stream ciphers. The recurrence relation is designed to operate over finite fields larger than GF(2) and is maximal length. An output equation generates the output based on a plurality of elements in the shift register used to implement the recurrence relation. The recurrence relation and the output equation are selected to have distinct pair distances such that, as the shift register shifts, no particular pair of elements of the shift register are used twice in either the recurrence relation or the output equation.

Abstract: In a communications system, a method of transforming a set of message signals representing a message comprising the steps of first encoding one of the set of message signals in accordance with a first keyed transformation, a second encoding of the one of the set of message signals in accordance with at least one additional keyed transformation, a third encoding of the one of the set of message signals in accordance with a self inverting transformation in which at least one of the set of message signals is altered, a fourth encoding of the one of the set of message signals in accordance with at least one additional inverse keyed transformation wherein each of the at least one additional inverse keyed transformation is a corresponding inverse of at least one additional keyed transformation, and fifth encoding the one of the set of message signals in accordance with first inverse keyed transformation wherein the first inverse keyed transformation is the inverse of the first keyed transformation.

Abstract: An apparatus for providing authentication of a mobile station in a wireless communication system. The present invention takes the number dialed by the mobile station user and computes the 24 bit number (AUTH.sub.-- DATA) for authentication in accordance with a hashing function that has the following characteristics. The hashing function takes as its input at least the entire dialed digit string contained in the request for service and the number of digits. In a preferred embodiment, the ordering of the digits affects the result, as well as, the values of the digits. The preferred embodiment of the hashing function also accepts some or all of the mobile station identifier data. The function provides as output a number of suitable size for input to a second calculation of an authentication signature, such as the 24 bits required for AUTH.sub.-- DATA. The output number is created in such a way that there is a minimum likelihood that other sets of dialed digits may create the same result.