Authenticating a short message service (SMS) message
View Patent ↗A vehicle telematics unit or other electronic hardware in a vehicle authenticates an incoming SMS message and provides additional security features above and beyond those inherent to the SMS protocol. A call center uses a mathematical function to derive a security code, and then sends an SMS message to the vehicle. The telematics unit can utilize the transmitted information to authenticate the sender of the SMS message and/or its contents. One group of suitable mathematical functions utilizes keyed-hash message authentication codes (HMACs).
1. Vehicle hardware for authenticating an SMS message received in a vehicle, comprising a processor and electronic memory that is accessible by the processor and that has stored thereon a program which is operable upon execution by the processor to carry out the steps of:
(a) determining a vehicle key for the vehicle telematics unit;
(b) wirelessly receiving an SMS message at the telematics unit, wherein the SMS message includes a payload section having information related to a security code;
(c) generating a security code using a mathematical function and the vehicle key; and
(d) comparing the payload section information received in step (b) with the security code generated in step (c) to authenticate the SMS message;
wherein the mathematical function utilizes a keyed-hash message authentication code (HMAC).
2. Vehicle hardware as defined in claim 1 , wherein the HMAC includes at least one function selected from the group consisting of: HAVAL, MD4, MD5, SHA-0, SHA-1 or SHA-256.
3. Vehicle hardware as defined in claim 1 , wherein step (c) further includes generating the security code using the mathematical function, the vehicle key, and one or more additional component(s) that are located in the payload section and are wirelessly received with the SMS message.
4. Vehicle hardware as defined in claim 3 , wherein the one or more additional component(s) includes a component that is related to a message segment.
5. Vehicle hardware as defined in claim 3 , wherein the one or more additional component(s) includes a component that is related to a features segment field.
6. Vehicle hardware as defined in claim 5 , wherein the features segment field is selected from the group consisting of: a version field, a sequence field, a priority field, an expiration field, a display timer field, and a random field.
7. Vehicle hardware as defined in claim 5 , wherein the one or more additional component(s) includes a first component that is related to a random field, and a second component that is related to an expiration field.
8. Vehicle hardware as defined in claim 1 , wherein the payload section further includes a features segment, a message segment, and a padding segment.
9. Vehicle hardware as defined in claim 8 , wherein the features segment includes at least one field selected from the list consisting of: a version field, a sequence field, a priority field, an expiration field, a display timer field, and a random field.
10. Vehicle hardware as defined in claim 8 , wherein the padding segment includes one or more filler characters that: i) cause the payload section to fully use its allotment of characters, ii) are recognizable as filler characters, and iii) are not used in step (c) to generate the security code.
11. Vehicle hardware as defined in claim 1 , wherein the payload section consists of a plurality of seven-bit ASCII characters.
12. Vehicle hardware as defined in claim 1 , wherein the payload section consists of a plurality of eight-bit binary bytes.
13. Vehicle hardware as defined in claim 1 , wherein steps (a) through (d) operate as an initial authentication gate; and wherein if the SMS message passes the authentication gate then a subsequent decryption method is applied by the telematics unit to the SMS message, and if the SMS message does not pass the authentication gate then the SMS message is deleted.
14. Vehicle hardware as defined in claim 1 , further comprising a telematics unit that includes the processor and electronic memory.