Method and apparatus for compliance checking in a trust-management system

Abstract

A method and apparatus are provided for compliance checking in a trust-management system. A request r, a policy assertion (ƒ 0 , POLICY), and n−1 credential assertions (ƒ 1 , s 1 ) . . . , (ƒ n−1 , s n-1 ) are received, each credential assertion comprising a credential function ƒ i and a credential source s i . Each assertion may be monotonic, authentic, and locally bounded. An acceptance record set S is initialized to {(Λ, Λ, R)}, where Λ represents a distinguished null string, and R represents the request r. Each assertion (ƒ i , s i ), where i represents the integers from n−1 to 0, is run and the result is added to the acceptance record set S. This is repeated mn times, where m represents a number greater than 1, and an acceptance is output if any of the results in the acceptance record set S comprise an acceptance record (0, POLICY, R).

What is claimed is:  
     
         1 . A method of compliance checking in a trust-management system, comprising: 
 a) receiving a request r, a policy assertion (ƒ 0 , POLICY) associated with the request r, and n−1 credential assertions (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ), each credential assertion comprising a credential function ƒ i  and a credential source s i ;    b) initializing an acceptance record set S to {(Λ, Λ, R)}, where Λ represents an empty portion of the acceptance record set S, and R represents the request r;    c) running assertion (ƒ i , s i ) on the acceptance set S for each integer i from n−1 to 0 and adding the result of each assertion (ƒ i , s i ) to the acceptance record set S;    d) repeating step (c) mn times, where m represents a number greater than 1; and    e) determining if the acceptance record set S includes (0, POLICY, R).    
     
     
         2 . The method of    claim 1   , further comprising: 
 f) determining whether an assertion (ƒ i , s i ) is ill-formned;    wherein step (c) is only performed for assertions (ƒ i , s i ) that are not ill-formed.    
     
     
         3 . The method of    claim 2   , further comprising: 
 g) initializing a set I to an empty set; and    h) adding any ill-formed assertions (ƒ i , s i ) to set I.    
     
     
         4 . The method of    claim 1   , wherein a request r is a request to access a data object.  
     
     
         5 . The method of    claim 1   , wherein a request r is a request to make a copy of a data object.  
     
     
         6 . The method of    claim 1   , wherein a request r is a request to play a data object that includes audio content.  
     
     
         7 . The method of    claim 1   , wherein a credential function includes a subject, an action, and an object.  
     
     
         8 . The method of    claim 1   , wherein the request r is a string encoding an action for which a calling application seeks a proof of compliance.  
     
     
         9 . The method of    claim 1   , wherein R represents an action string corresponding with the request r.  
     
     
         10 . The method of    claim 9   , wherein the action string R includes a subject, an action and an object.  
     
     
         11 . The method of    claim 1   , wherein a credential assertion includes one of a public key, a uniform resource locator and a name.  
     
     
         12 . The method of    claim 1   , wherein credential function ƒ i  is correlated with a credential source s i  by cryptographically signing the credential function ƒ i  with a private cryptographic key belonging to credential source s i .  
     
     
         13 . The method of    claim 1   , wherein each assertion is monotonic, authentic, and locally bounded.  
     
     
         14 . A method of compliance checking in a trust-management system, comprising: 
 a) receiving a request;    b) receiving a policy associated with the request;    c) receiving a number of credentials, the policies and credentials comprising a number of monotonic, authentic, and locally bounded assertions; and    d) deciding whether the credentials prove that the request complies with the policy.    
     
     
         15 . The method of    claim 14   , wherein a monotonic assertion approves an action when provided with a set of evidence if the assertion would approve the action when provided with a subset of that evidence.  
     
     
         16 . The method of    claim 14   , wherein an authentic assertion produces acceptance records that do not impersonate another assertion.  
     
     
         17 . The method of    claim 14   , wherein a locally bounded assertion is bounded in terms of a maximum runtime and a maximum size of acceptance sets that can be produced.  
     
     
         18 . The method of    claim 14   , wherein the policy comprises a function ƒ 0  encoded in a programming system  
     
     
         19 . A method of compliance checking in a trust-management system, comprising: 
 receiving (i) a request r to perform an action R and (ii) assertions (ƒ 0 , POLICY), (ƒ 1 , s i ), . . . , (ƒ n-1 , s n-1 );    executing, mn times, assertion (ƒ i , s i ) for each integer i from n−1 to 0, the execution being performed using any information generated by previously executed assertions, m representing a number greater than 1; and    determining if (0, POLICY, R) has been generated.    
     
     
         20 . An apparatus for compliance checking in a trust-management system, comprising: 
 a processor; and    a memory storing instructions adapted to be executed by said processor to receive a request R to perform an action and assertions (ƒ 0 , POLICY), (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ) initialize an acceptance record set S to {(Λ, Λ, R)}, where A represents a distinguished null string, iteratively run, mn times, assertion (ƒ i , s i ) on the acceptance set S for each integer i from n−1 to 0 and add the result of each assertion (ƒ i , s i ) to the acceptance record set S, where m represents a number greater than 1, and determine if the acceptance record set S includes (0, POLICY, R).    
     
     
         21 . A trust management platform, comprising: 
 an input port configured to receive a request, a policy assertion (ƒ 0 , POLICY), and credential assertions (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ), each credential assertion comprising a credential function ƒ i  and a credential source s i ; and    a compliance checking unit coupled to said input port and configured to: 
 a) initialize an acceptance record set S to {(Λ, Λ, R)}, where Λ represents a distinguished null string and R represents information corresponding with the request,  
 b) run assertion (ƒ i , s i ) on the acceptance set S for each integer i from n−1 to 0 and add the result of each assertion (ƒ i , s i ) to the acceptance record set S,  
   c) repeat step (b) mn times, where m represents a number greater than 1, and    d) determine if acceptance record set S includes an acceptance record (0, POLICY, R).    
     
     
         22 . A trust-management system, comprising: 
 means for receiving a request to perform an action r and a set of assertions (ƒ 0 , POLICY), (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ); and    means for proving that the request r is consistent with the set of assertions.    
     
     
         23 . A medium storing instructions adapted to be executed by a processor to perform steps including: 
 a) receiving a request r, a policy assertion (ƒ 0 , POLICY) associated with the request r, and n−1 credential assertions (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ) each credential assertion comprising a credential function ƒ i  and a credential source s i ;    b) initializing an acceptance record set S to {(Λ, Λ, R)}, where Λ represents a distinguished null string and R represents the request r,    c) running assertion (f i , s i ) on the acceptance set S for each integer i from n−1 to 0 and adding the result of each assertion (ƒ i , s i ) to the acceptance record set S;    d) repeating step (c) mn times, where m represents a number greater than 1; and    e) determining whether the acceptance record set S includes (0, POLICY, R).    
     
     
         24 . A method of compliance checking in a trust-management system, comprising: 
 a) receiving a request r, a policy assertion (ƒ 0 , POLICY) associated with the request r, and n−1 credential assertions (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ), each credential assertion comprising a credential function ƒ i  and a credential source s i ;    b) initializing an acceptance record set S to {(Λ, Λ, R)}, where Λ represents a distinguished null string and R represents the request r;    c) for each integer i from n−1 to 0: 
 running assertion (ƒ i , s i ) against the acceptance set S and adding the result to the acceptance record set S,  
 determining if the acceptance record set includes (0, POLICY, R), and  
 if the acceptance record set includes (0, POLICY, R), then stopping said method; and  
   d) repeating step (c) mn times, where m represents a number greater than 1.    
     
     
         25 . A method of compliance checking in a trust-management system, comprising: 
 a) receiving credential assertions (ƒ 1 , s 1 ), . . . , (ƒ n-1 , s n-1 ), each credential assertion comprising a credential function ƒ i  and a credential source s i ;    b) initializing an acceptance record set S to {(Λ, R) }, where Λ represents an empty portion of the acceptance record set S, and R represents a request;    c) running assertion (ƒ i , s i ) on the acceptance set S for each integer i from n−1 to 0 and adding the result of each assertion (ƒ i , s i ) to the acceptance record set S;    d) repeating step (c) mn times, where m represents a number greater than 1.