Method and apparatus for a wireless mobile device with SIM challenge modification capability

1. A wireless mobile device for providing challenge/response based authentication comprising:

a wireless transceiver operative to receive a first portion of a challenge from an external authentication unit;

an internal partial challenge generator, operatively coupled to the wireless transceiver, operative to provide internally, a second portion of the challenge and to provide the internally generated second portion of the challenge without the first portion to the wireless transceiver for transmission for the authentication unit;

combiner logic, operatively coupled to the internal partial challenge generator, and operative to combine the externally received first portion of the challenge with the internally produced second portion of the challenge to produce a complete challenge; and

a response generator, operatively coupled to the wireless transceiver, and operative to produce a response from the complete challenge for transmission to the external authentication unit, wherein the response for transmission is the same response generated from the complete challenge.

2. The wireless mobile device of claim 1 wherein the internal partial challenge generator provides the second portion of the challenge by generating a random number as the second portion of the challenge and wherein the combiner logic combines the random number with the first portion of the challenge to produce the complete challenge and wherein the response generator generates the response based on an application of a cryptographic algorithm using both the complete challenge and secret wireless mobile device identification information.

3. The wireless mobile device of claim 1 wherein the received external first portion of the challenge had a first bit length and wherein the internally generated second portion of the challenge has a second and different bit length.

4. The wireless mobile device of claim 1 comprising a counter operative to count a number of times that a same second portion of the challenge has been used to generate a response and wherein the internal partial challenge generator generates a new second portion of a challenge in response to the count.

5. The wireless mobile device of claim 1 wherein the transceiver sends both the response and the second portion of the challenge to the authentication unit in response to the received first portion of the challenge.

6. The wireless mobile device of claim 1 wherein the wireless transceiver is operative to send the response and the second portion of the challenge to effect authorization by the external authentication unit.

7. A wireless mobile device for providing challenge/response based authentication comprising:

a secure subscriber identity module (SIM) comprising:

an internal partial challenge generator operative to provide internally, a second portion of a challenge in response to receiving an external first portion of the challenge and to provide the internally generated second portion of the challenge without the first portion for transmission to the authentication unit;

combiner logic, operatively coupled to the internal partial challenge generator, and operative to combine the externally received first portion of the challenge with the internally produced second portion of the challenge to produce a complete challenge; and

a response generator to produce a response from the complete challenge for transmission to the external authentication unit with the second portion, wherein the response for transmission is the same response generated from the complete challenge.

8. A method for providing challenge/response based authentication comprising:

providing internally, via a wireless mobile device, a second portion of a challenge;

combining, by the wireless mobile device, an externally received first portion of the challenge with the internally produced second portion of the challenge to produce a complete challenge;

producing, by the wireless mobile device, a response from the complete challenge for transmission to an external authentication unit, wherein the response for transmission is the same response generated from the complete challenge; and

sending, by the wireless mobile device, the response and the internally produced second portion of the challenge to an external authentication unit without the first portion.

9. The method of claim 8 comprising providing the second portion of the challenge by generating a random number as the second portion of the challenge and combining the random number with the first portion of the challenge to produce the complete challenge and generating the response based on an application of a cryptographic algorithm using both the complete challenge and secret wireless mobile device identification information.

10. The method of claim 8 wherein the received external first portion of the challenge had a first bit length and wherein the internally generated second portion of the challenge has a second and different bit length.

11. The method of claim 8 comprising determining a number of times that a same second portion of the challenge has been used to generate the response and generating a new partial challenge in response to the number of times that a same second portion of the challenge has been used.

12. A method for providing challenge/response based authentication comprising:

wirelessly transmitting a first portion of a challenge to a wireless mobile device;

receiving the first portion of the challenge and providing internally, a second portion of the challenge in response to receiving the first portion of the challenge;

combining the received first portion of the challenge with the internally produced second portion of the challenge to produce a complete challenge;

producing a response from the complete challenge for transmission to the external authentication unit, wherein the response for transmission is the same response generated from the complete challenge;

wirelessly sending the response produced from the complete challenge and the second portion of the challenge without the first portion to an external authentication unit;

receiving the sent response and the second portion of the challenge; and

generating an expected authentication response based on a locally stored first portion of the challenge and the received second portion of the challenge and comparing the generated expected authentication response to the received response to determine whether to verify the wireless mobile device.

13. The method of claim 12 comprising providing the second portion of the challenge by generating a random number as the second portion of the challenge and combining the random number with the first portion of the challenge to produce the complete challenge and generating the response based on an application of a cryptographic algorithm using both the complete challenge and secret wireless mobile device identification information.

14. The method of claim 12 wherein the received external first portion of the challenge had a first bit length and wherein the internally generated second portion of the challenge has a second and different bit length.

15. The method of claim 12 comprising determining a number of times that a same second portion of the challenge has been used to generate the response and generating a new partial challenge in response to the number of times that a same second portion of the challenge has been used.

16. The method of claim 12 comprising generating a challenge/expected response pair based on the first portion of the challenge and the received second portion of the challenge and generating a future challenge/expected response pair based on a received future second portion of a challenge and a generated future first portion of the challenge.

17. The method of claim 16 further comprising sending the challenge/expected response pair and the future challenge/expected response pair to a remote unit operative to compare the received response with the expected response to determine if authentication should be granted.

18. A method for providing challenge/response based authentication comprising:

wirelessly transmitting a first portion of a challenge to a wireless mobile device;

generating an expected response based on a locally stored first portion of the challenge and a received second portion of the challenge from the wireless mobile device without the transmitted first portion;

generating a future expected response based on a received future second portion of a challenge; and

sending the expected response and the future expected response to a remote unit for comparison with at received response.

19. The method of claim 18 comprising generating a challenge/expected response pair based on the first portion of the challenge and the received second portion of the challenge and generating a future challenge/expected response pair based on the received future second portion of a challenge and a generated future first portion of the challenge.

20. The method of claim 19 further comprising sending the challenge/expected response pair and the future challenge/expected response pair to a remote unit operative to compare the received response with the expected response to determine if authentication should be granted.