Staged Control Release In Boot Process

Abstract

Integrity validation of a network device may be performed. A network device comprising a secure hardware module, may receive a root key. The secure hardware module may also receive a first code measurement. The secure hardware module may provide a first key based on the root key and the first code measurement. The secure hardware module may receive a second code measurement and provide a second key based on the first key and the second code measurement. The release of keys based on code measurements may provide authentication in stages.

What is claimed: 
     
         1 . A method to perform integrity validation of a network device, the method comprising:
 receiving a measurement of first code stored in a memory of the network device;   generating a first key based on a root key stored in a secure memory of the network device and the first code measurement, and wherein the first key relates to a first stage of trust associated with a first function of the network device, and wherein the first key is capable of being used by a first stakeholder to access the first function;   receiving a measurement of second code stored in the memory of the network device; and   generating a second key based on the first key and the second code measurement, wherein the second key relates to a second stage of trust associated with a second function of the network device, and wherein the second key is capable of being used by a second stakeholder to access the second function.   
     
     
         2 . The method of  claim 1 , further comprising preventing access to the first function when the first code measurement is invalid. 
     
     
         3 . The method of  claim 2 , further comprising preventing access to the second function when the second code measurement is invalid. 
     
     
         4 . The method of  claim 1 , further comprising:
 receiving a nonce; and   sending a signed message in response to the nonce, wherein the signed message indicates an untrustworthy state, a partial trustworthy state, or a trustworthy state.   
     
     
         5 . The method of  claim 4 , further comprising providing a last valid credential when the partial trustworthy state is indicated, wherein the last valid credential includes a last valid key associated with a last valid code measurement. 
     
     
         6 . The method of  claim 4 , wherein the signed message further indicates a freshness of a boot state, and wherein the nonce is derived locally via at least one of a sequence counter or a date and time stamp function. 
     
     
         7 . The method of  claim 1 , wherein the root key is stored in the secure memory at a time of manufacture or a time of provisioning. 
     
     
         8 . The method of  claim 1 , wherein the secure memory is part of a secure hardware module and wherein the root key is not visible to software outside of the secure hardware module.