Systems, methods, software, and components using tamper-proof real-time clock

Abstract

The write-access control line for an RTC is combined with a clear line for an RTC signature register, so that changes to the RTC will cause subsequent reads to return an invalidity flag.

1 . A device, comprising:
 a real-time clock configured to maintain and provide a system time; and   signature storage having an invalidation control line connected to the real-time clock,   wherein the signature storage includes a digital signature that is compared to a signature input for determining whether the invalidation control line forces the signature storage into an invalid state.   
     
     
         2 . The device of  claim 1 , wherein the digital signature is not available as data output. 
     
     
         3 . The device of  claim 1 , wherein if the digital signature is equal to the signature input, the signature storage is forced into a valid state. 
     
     
         4 . The device of  claim 1 , wherein if the digital signature is not equal to the signature input, the signature storage is forced into an invalid state. 
     
     
         5 . The device of  claim 1 , further comprising instruction execution logic operable to execute a plurality of software instructions. 
     
     
         6 . The device of  claim 1 , further comprising validation logic to check the digital signature. 
     
     
         7 . The device of  claim 1 , wherein the digital signature is generated based on a unique hardware-encoded value. 
     
     
         8 . A method comprising
 generating a digital signature for a real-time clock configured to maintain and provide a system time;   storing the digital signature in signature storage having an invalidation control line connected to the real-time clock, and   comparing the digital signature to a signature input for determining whether the invalidation control line forces the signature storage into an invalid state.   
     
     
         9 . The method of  claim 8 , wherein the digital signature is not available as data output. 
     
     
         10 . The method of  claim 8 , wherein if the digital signature is equal to the signature input, the signature storage is forced into a valid state. 
     
     
         11 . The method of  claim 8 , wherein if the digital signature is not equal to the signature input, the signature storage is forced into an invalid state. 
     
     
         13 . The method of  claim 8 , wherein the comparing is performed via validation logic. 
     
     
         14 . The method of  claim 8 , wherein the digital signature is generated based on a unique hardware-encoded value. 
     
     
         14 . The method of  claim 8 , wherein the digital signature is generated based on a real-time clock value. 
     
     
         15 . A non-transitory computer readable medium comprising instructions for:
 generating a digital signature for a real-time clock configured to maintain and provide a system time;   storing the digital signature in signature storage having an invalidation control line connected to the real-time clock, and   comparing the digital signature to a signature input for determining whether the invalidation control line forces the signature storage into an invalid state.   
     
     
         16 . The non-transitory computer readable medium of  claim 15 , wherein the digital signature is not available as data output. 
     
     
         17 . The non-transitory computer readable medium of  claim 15 , wherein if the digital signature is equal to the signature input, the signature storage is forced into a valid state. 
     
     
         18 . The non-transitory computer readable medium of  claim 15 , wherein if the digital signature is not equal to the signature input, the signature storage is forced into an invalid state. 
     
     
         19 . The non-transitory computer readable medium of  claim 15 , wherein the digital signature is generated based on a unique hardware-encoded value. 
     
     
         20 . The non-transitory computer readable medium of  claim 15 , wherein the digital signature is generated based on a real-time clock value.