# US 5,708,716 A · Fraud detection and user validation system for mobile earth terminal communication device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,716 A - Document ID: US5708716A - Status: Granted - Kind: A - Application number: 08/601,912 - Filed: 1996-02-15 - Granted: 1998-01-13 - Earliest claimed: 1995-11-30 - Assignees: AMSC Subsidiary Corporation - Inventors: William R. Tisdale; Charles E. Sigler - Web page: https://patentgrep.com/patent/US5708716A ## CPC - H04B 7/18565: {Arrangements for preventing unauthorised access or for providing user protection (arrangements for secret or secure communication H04L9/00)} - H04B: TRANSMISSION ## Abstract An authentication system authenticates a mobile communication system each time it attempts to register or communication in a mobile satellite system. The authentication system stores a first security key to establish communication in the mobile communication network system. The system generates a second security key having first and second components using a first process having first and second input signals. The first input signal includes the first security key, and the second input signal includes at least one of a transmit frequency and a receive frequency. The system generates a third security key using a second process having third and fourth input signals. The third input signal includes the second component of the second security key and the fourth input signal is a random number. Advantageously, the system verifies that the mobile communication system is authorized to establish communication using at least one of the first, second, third and fourth components of the second and third security keys. This complex procedure is difficult to circumvent, thereby preventing unauthorized use of the mobile satellite system. ## Claims ### Claim 1 In a mobile communication network system including a communication switching office having an antenna for receiving/transmitting a message from/to a vehicle using a mobile communication system, an interface system, a central controller receiving/transmitting the message from/to the communication switching office issued from the vehicle via the interface system, a method of authenticating a mobile communication system storing a first security key to establish communication in the mobile communication network system, said method comprising the steps of: (a) requesting, by a user, to become a subscriber in the communication network system using the mobile communication system; (b) determining, by the central controller, a transmit frequency and a receive frequency for establishing communication between the user and a destination; (c) generating, by the central controller, a second security key having first and second components using a first process having first and second input signals, the first input signal comprising the first security key and the second input signal comprising at least one of the transmit frequency and the receive frequency; (d) generating, by the central controller, a third security key using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key and the fourth input signal being a random number; (e) transmitting, by the central controller, the transmit frequency and the receive frequency to the mobile communication system; (f) independently generating, by the mobile communication system, the second and third security keys in accordance with said generating steps (d) and (e); and (g) verifying, by the central controller, that the mobile communication system is authorized to establish communication using the second and third security keys. ### Claim 2 (depends on 1) A method according to claim 1, wherein said verifying step (g) is performed in real-time. ### Claim 3 (depends on 1) A method according to claim 1, wherein the first process comprises a data encryption algorithm. ### Claim 4 (depends on 3) A method according to claim 3, wherein the data encryption algorithm comprises the DES encryption algorithm. ### Claim 5 (depends on 1) A method according to claim 1, wherein the second process comprises a logic operation of the third and fourth input signals. ### Claim 6 (depends on 5) A method according to claim 5, wherein the logic operation is an exclusive OR logic operation. ### Claim 7 (depends on 1) A method according to claim 1, wherein the at least one of the transmit frequency and the receive frequency comprises both the transmit and receive frequencies. ### Claim 8 (depends on 1) A method according to claim 1, wherein the second input signal further comprises fill bits received from a communication bulletin board in the mobile communication network system. ### Claim 9 (depends on 1) A method according to claim 1, wherein the second input signal further comprises a personal identification number entered by the user each time the mobile communication system initiates a call. ### Claim 10 (depends on 1) A method according to claim 1, wherein said verifying step (g) further comprises the step of verifying that the mobile communication system is authorized to establish communication by comparing the second and third security keys of the mobile communication system and the central controller to each other for correspondence. ### Claim 11 (depends on 1) A method according to claim 1, wherein said verifying step (g) further comprises the step of verifying that the mobile communication system is authorized to establish communication by comparing the first components of the second and third security keys of the mobile communication system and the central controller to each other for correspondence. ### Claim 12 (depends on 1) A method according to claim 1, wherein the first security key is generated during commissioning of the mobile communication system. ### Claim 13 (depends on 1) A method according to claim 1, wherein the first security key is generated by the steps of: (1) generating a first key using a first data encryption algorithm having first and second data inputs generated by respective first and second random number generating methods; and (2) generating the first security key using a second data encryption algorithm having third and fourth data inputs, the third data input comprising the first key and the fourth data input comprising the at least one of the transmit and receive frequencies utilized by the mobile communication system. ### Claim 14 In a mobile communication network system including a communication switching office having an antenna for receiving/transmitting a message from/to a vehicle using a mobile communication system, an interface system, a central controller receiving/transmitting the message from/to the communication switching office, a method of authenticating a mobile communication system storing a first security key to establish communication in the mobile communication network system, said method comprising the steps of: (a) generating a second security key having first and second components using a first process having first and second input signals, the first input signal comprising the first security key and the second input signal comprising at least one of a transmit frequency and a receive frequency; (b) generating a third security key having third and fourth components using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key and the fourth input signal being a random number; and (c) verifying that the mobile communication system is authorized to establish communication using at least one of the first, and second components of the second security key and the third and fourth components of the third security key. ### Claim 15 In a mobile communication network system including a communication switching office having an antenna for receiving/transmitting a message from/to a vehicle using a mobile communication system, an interface system, a central controller receiving/transmitting the message from/to the communication switching office issued from the vehicle via the interface system, an authentication system for authenticating a mobile communication system storing a first security key to establish communication in the mobile communication network system, comprising: a mobile communication system requesting for a user to become a subscriber in a communication system; a central controller for the communication system responsively connected to said mobile communication system, receiving the request from said mobile communication system, said central controller performing the following functions: determining a transmit frequency and a receive frequency for establishing communication between the user and a destination, generating a second security key having first and second components using a first process having first and second input signals, the first input signal comprising the first security key and the second input signal comprising at least one of the transmit frequency and the receive frequency, generating a third security key having third and fourth components using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key and the fourth input signal being a random number, transmitting the transmit frequency, the receive frequency and the third input signal to the mobile communication system, wherein the mobile communication system receives the transmit frequency, and the receive frequency from the central controller, and independently generates the second and third security keys, and wherein the central controller verifies that the mobile communication system is authorized to establish communication using at least one of the first, and second components of the second security key and the third and fourth components of the third security key. ### Claim 16 (depends on 15) An authentication system according to claim 15, wherein said central controller verifies that the mobile communication system is authorized to establish communication in real-time. ### Claim 17 (depends on 15) An authentication system according to claim 15, wherein the first process comprises a data encryption algorithm. ### Claim 18 (depends on 17) An authentication system according to claim 17, wherein the data encryption algorithm comprises the DES encryption algorithm. ### Claim 19 (depends on 15) An authentication system according to claim 15, wherein the second process comprises a logic operation of the third and fourth input signals. ### Claim 20 (depends on 19) An authentication system according to claim 19, wherein the logic operation is an exclusive OR logic operation. ### Claim 21 (depends on 15) An authentication system according to claim 15, wherein the at least one of the transmit frequency and the receive frequency comprises both the transmit and receive frequencies. ### Claim 22 (depends on 15) An authentication system according to claim 15, wherein the second input signal further comprises fill bits received from a communication bulletin board in the mobile communication network system. ### Claim 23 (depends on 15) An authentication system according to claim 15, wherein the second input signal further comprises a personal identification number entered by the user each time the mobile communication system initiates a call. ### Claim 24 (depends on 15) An authentication system according to claim 15, wherein said central controller verifies that the mobile communication system is authorized to establish communication by comparing the second and third security keys of the mobile communication system and the central controller to each other for correspondence. ### Claim 25 (depends on 15) An authentication system according to claim 15, wherein said central controller verifies that the mobile communication system is authorized to establish communication by comparing the first components of the second and third security keys of the mobile communication system and the central controller to each other for correspondence. ### Claim 26 (depends on 15) An authentication system according to claim 15, wherein the first security key is generated during commissioning of the mobile communication system. ### Claim 27 (depends on 15) An authentication system according to claim 15, wherein the first security key is generated by the central controller performing the following functions: (1) generating a first key using a first data encryption algorithm having first and second data inputs generated by respective first and second random number generating methods; and (2) generating the first security key using a second data encryption algorithm having third and fourth data inputs, the third data input comprising the first key and the fourth data input comprising the at least one of the transmit and receive frequencies utilized by the mobile communication system. ### Claim 28 In a mobile satellite system including a satellite communication switching office having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to a vehicle using a mobile communication system, a satellite interface system, a central controller receiving/transmitting the satellite message from/to the satellite communication switching office issued from the vehicle via the satellite and the satellite interface system, the mobile communication system comprising: a user interface system providing a user interface through which a user has access to services supported by the mobile satellite system; an antenna system providing an interface between the mobile communication system and the mobile satellite system via the satellite interface system, and receiving a first satellite message from the satellite and transmitting a second satellite message to the satellite; a logic and signaling system, operatively connected to said transceiver, controlling initialization of the mobile communication system, obtaining an assigned outbound signaling channel from which updated system information and commands and messages are received, said logic and signaling system configuring said transceiver for reception and transmission of at least one of voice, data, fax and signaling messages, and controlling protocols between the mobile communication system and the mobile satellite system, and validating a received signalling messages and generating codes for a signaling message to be transmitted, wherein the mobile communication system requests for a user to become a subscriber in the satellite communication system, wherein the central controller receives the request from said mobile communication system, said central controller performing the following functions: determining a transmit frequency and a receive frequency for establishing communication between the user and a destination, generating a second security key having first and second components using a first process having first and second input signals, the first input signal comprising the first security key and the second input signal comprising at least one of the transmit frequency and the receive frequency, generating a third security key having third and fourth components using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key and the fourth input signal being a random number, transmitting the transmit frequency, the receive frequency and the third input signal to the mobile communication system, wherein the mobile communication system receives the transmit frequency, and the receive frequency from the central controller, and independently generates the second and third security keys, and wherein the central controller verifies that the mobile communication system is authorized to establish communication using at least one of the first, and second components of the second security key and the third and fourth components of the third security key. ### Claim 29 A method of authenticating a mobile communication system storing a first security key including an Access Security Key (ASK) to establish communication in the mobile communication network system, said method comprising the steps of: (a) requesting, by a user, to become a subscriber in the communication network system using the mobile communication system; (b) determining, by the central controller, a transmit frequency and a receive frequency for establishing communication between the user and a destination; (c) generating, by the central controller, a second security key having first and second components using a first process having first and second input signals, the first component including an authentication security check field (ASCF) and the second component including a secondary security check field (SSCF), the first input signal comprising the first security key including the ASK and the second input signal comprising at least one of the transmit frequency and the receive frequency; (d) generating, by the central controller, a third security key including a call count variable check field (CCVCF) using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key including the SSCF and the fourth input signal being a random number; (e) transmitting, by the central controller, the transmit frequency and the receive frequency to the mobile communication system; (f) independently generating, by the mobile communication system, the second and third security keys in accordance with said generating steps (d) and (e); and (g) verifying, by the central controller, that the mobile communication system is authorized to establish communication using the second and third security keys. ### Claim 30 A method of authenticating a mobile communication system storing a first security key to establish communication in the mobile communication network system, said method comprising the steps of: (a) generating a second security key having first and second components using a first process having first and second input signals, the first component including an authentication security check field (ASCF) and the second component including a secondary security check field (SSCF), the first input signal comprising the first security key including the ASK and the second input signal comprising a first random number; (b) generating a third security key, the third security key including a call count variable check field (CCVCF) using a second process having third and fourth input signals, the third input signal comprising the second component of the second security key including the SSCF and the fourth input signal being a second random number; and (c) verifying, by the central controller, that the mobile communication system is authorized to establish communication using the second and third security keys.