PROCESSING SECURE SMS MESSAGES

1 . A method of processing an SMS message transmitted between a vehicle telematics unit and a call center, comprising the steps of:

(a) receiving an SMS message having security data, wherein both a header and a payload of the SMS message carry the security data;

(b) attempting to authenticate the security data;

(c) accepting the SMS message if the security data is authenticated; and

(d) ignoring the contents of the SMS message if the security data is not authenticated.

2 . The method of claim 1 , wherein the security data is associated with a time of expiration (TOE) of the SMS message.

3 . The method of claim 1 , wherein the security data carried by the payload is encrypted.

4 . The method of claim 1 , wherein the SMS message carries a vehicle command, the method further comprising step (e): executing the vehicle command if the SMS message is authenticated in step (c).

5 . The method of claim 1 , further comprising receiving a system time from the telematics unit and evaluating the validity of the security data using the system time.

6 . The method of claim 5 , wherein the evaluating step occurs prior to step (b), wherein if the security data is determined to be invalid the SMS message is ignored and steps (b) and (c) are omitted.

7 . The method of claim 1 , further comprising, prior to step (b), comparing the SMS message to previously received SMS messages, wherein if the SMS message is the same as one of the previously received SMS messages, the SMS message is ignored and at least the accepting step (c) is omitted.

8 . The method of claim 1 , further comprising, prior to step (b), comparing the time of expiration of the current SMS message with the time of expirations of other previously received SMS messages, wherein if the time of expiration of the current SMS message is less than any of the time of expirations associated with the previously received SMS messages, the current SMS message is ignored and at least the accepting step (c) is omitted.

9 . The method of claim 1 , further comprising transmitting an error report to the call center when the SMS message is ignored.

10 . The method of claim 1 , further comprising transmitting a success report to the call center when the SMS message is accepted.

11 . A method of processing an SMS message, comprising the steps of:

(a) receiving at a vehicle telematics unit an SMS message having a vehicle instruction, wherein the SMS message includes security data carried by a header of the SMS message, wherein an encrypted version of the security data is also carried by a payload of the SMS message;

(b) determining whether a telematics unit system time is accurate;

(c) when in step (b) the system time is determined to be accurate, evaluating the validity of the security data using the system time, wherein if security data is evaluated to be invalid, compiling an SMS error report and at least omitting the executing step (g);

(d) determining whether a duplicate of the SMS message was previously received at the telematics unit, wherein if a duplicate was previously received, compiling an SMS error report and at least omitting the executing step (g);

(e) decrypting the encrypted version of the security data;

(f) authenticating the security data carried by the header using the decrypted security data, wherein if the security data carried by the header is not authenticated, compiling an SMS error report and omitting step (g); and

(g) if the security data carried by the header is authenticated, executing the vehicle instruction.