Secure session communication between a mobile device and a base station

1. A computing system comprising:

a main telematics module,

a connectivity module comprising antenna(s), processor(s), the connectivity module configured to:

(a) authenticate a mobile device via a vehicle-access-key (VAK);

(b), if (a), issue an ephemeral-session-key (DSK) to the mobile device;

(c), if (b), establish an active session with the mobile device;

(d) encrypt messages to the mobile device with the VAK during (a) and with the DSK during (c); and

(e) maintain the active session with the mobile device only when a signed challenge message periodically transmitted by the connectivity module is satisfied with a signed response from the mobile device within a countdown, the countdown resetting each time the signed response is received from the mobile device.

2. The computing system of claim 1 , wherein the connectivity module is configured to automatically revoke the DSK.

3. The computing system of claim 2 , wherein the connectivity module is configured to automatically revoke the DSK upon expiration of a predetermined time interval.

4. The computing system of claim 3 , wherein the time interval begins during (b).

5. The computing system of claim 4 , wherein the connectivity module is configured to during (c), reject messages from the mobile device encrypted with the VAK but accept messages from another mobile device encrypted with a different VAK.

6. The computing system of claim 1 , wherein the connectivity module is configured to begin (a) upon receiving an unencrypted message comprising a valid VAK ID and a valid VAK hash.

7. The computing system of claim 1 , wherein the connectivity module is configured to include an unencrypted VAK authentication code in messages including VAK encrypted data.

8. The computing system of claim 7 , wherein the connectivity module is configured to include an unencrypted DSK hash in messages including DSK encrypted data.

9. The computing system of claim 1 , wherein the connectivity module is configured to break the DSK into a first block (DSK 1 ) and a second block (DSK 2 ).

10. The computing system of claim 9 , wherein both of DSK 1 and DSK 2 are necessary to compute DSK.

11. The computing system of claim 9 , wherein the connectivity module is configured to break the DSK by factoring the DSK such that DSK 1 is a first factor and DSK 2 is a second factor.

12. The computing system of claim 9 , wherein the connectivity module is configured to transmit DSK 1 in a first message and DSK 2 in a later second message.

13. The computing system of claim 12 , wherein the connectivity module is configured to transmit DSK 2 in reply to a valid response from the mobile device.

14. The computing system of claim 13 , wherein the connectivity module is configured to transmit an encrypted nonce to the mobile device.

15. The computing system of claim 14 , wherein to be valid, the response must include a value based on the nonce.

16. The computing system of claim 15 , wherein the connectivity module is configured to transmit DSK assembly instructions with DSK 1 or DSK 2 .

17. The computing system of claim 16 , wherein the connectivity module is configured to increment the nonce and transmit the incremented nonce to the mobile device prior to (c).

18. The computing system of claim 1 , wherein the VAK is a first VAK, the DSK is a first DSK and the connectivity module is configured to store multiple VAKs and multiple DSKs.

19. The computing system of claim 1 , wherein the connectivity module is configured to revoke the DSK upon receiving a message from the mobile device encrypted with the VAK during (c).

20. The computing system of claim 1 , wherein the connectivity module is configured to include unencrypted mobile device metadata in each message to the mobile device, the metadata enabling the mobile device to route the message.