Tethered device systems and methods

Abstract

Systems and methods are described for applying digital rights management techniques to tethered devices. In one embodiment, a host device is operable to translate a relatively sophisticated license into a simpler format for use on a relatively low-capability device. In another embodiment, a method of using extended SCSI commands to communicate over a USB connection is provided.

What is claimed is: 
     
         1 . A method of exporting a license from a host device to a target device, the license for use in governing access to or other use of a piece of electronic content, the method comprising:
 accessing a license associated with a piece of electronic content;   generating a simple validity statement data structure associated with the piece of electronic content based, at least in part, on the license, wherein generating the simple validity statement data structure comprises:
 encrypting a content key configured to decrypt the piece of electronic content using a first key; 
 identifying, based on the license, one or more conditions relating to use of the piece of electronic content; 
 generating a simple validity statement record based on the identified one or more conditions; and 
 including the encrypted content key and the simple validity statement record in the simple validity statement data structure; 
   digitally signing at least part of the simple validity statement data structure using a second key; and   transmitting the simple validity statement data structure to the target device.   
     
     
         2 . The method of  claim 1 , wherein the method further comprises determining that the license allows for the piece of electronic content to be transmitted to the target device. 
     
     
         3 . The method of  claim 1 , wherein the first key and the second key comprise a same key. 
     
     
         4 . The method of  claim 1 , wherein the first key and the second key comprise a pairing key. 
     
     
         5 . The method of  claim 4 , wherein the method further comprises:
 generating, as part of a pairing operation between the host device and the target device, the pairing key; and   transmitting the pairing key to the target device.   
     
     
         6 . The method of  claim 1 , wherein generating the simple validity statement data structure further comprises determining that the identified one or more conditions make reference to at least one node. 
     
     
         7 . The method of  claim 6 , wherein generating the simple validity statement data structure further comprises:
 generating one or more link validity statement records; and   including the one or more link validity statement records in the simple validity statement data structure.   
     
     
         8 . The method of  claim 1 , wherein the one or more link validity statement records further provide an indication of whether the at least one node is reachable from at least another node. 
     
     
         9 . The method of  claim 7 , wherein the one or more link validity statement records further comprises an indication of a condition that must be satisfied in order for the one or more link validity statement records to be valid. 
     
     
         10 . The method of  claim 9 , wherein the condition that must be satisfied in order for the one or more link validity statement records to be valid comprises a condition relating to the state of a domain membership of the target device. 
     
     
         11 . The method of  claim 1 , wherein the simple validity statement records further comprise an indication of at least one condition that must be satisfied for the simple validity statement record to be valid. 
     
     
         12 . The method of  claim 11 , wherein the at least one condition that must be satisfied for the simple validity statement record to be valid comprises a condition relating to a state variable. 
     
     
         13 . The method of  claim 12 , wherein the condition relating to the state variable comprises a condition that the state variable is set to a predefined value before access to the piece of electronic content is granted. 
     
     
         14 . The method of  claim 11 , wherein the at least one condition that must be satisfied for the simple validity statement record to be valid comprises a condition relating to an output of the target device. 
     
     
         15 . The method of  claim 11 , wherein the at least one condition that must be satisfied for the simple validity statement record to be valid comprises a condition relating to a first predefined time value before which access to the piece of electronic content may be granted. 
     
     
         16 . The method of  claim 15 , wherein the at least one condition that must be satisfied for the simple validity statement record to be valid further comprises a condition relating to a second predefined time value after which access to the piece of electronic content may be granted. 
     
     
         17 . A non-transitory computer-readable storage medium storing instructions that, when executed by a processor of a trusted system, cause the processor to:
 access a license associated with a piece of electronic content;   generate a simple validity statement data structure associated with the piece of electronic content based, at least in part, on the license, wherein generating the simple validity statement data structure comprises:
 encrypting a content key configured to decrypt the piece of electronic content using a first key; 
 identifying, based on the license, one or more conditions relating to use of the piece of electronic content; 
 generating a simple validity statement record based on the identified one or more conditions; and 
 including the encrypted content key and the simple validity statement record in the simple validity statement data structure; 
   digitally sign at least part of the simple validity statement data structure using a second key; and   transmit the simple validity statement data structure to the target device.   
     
     
         18 . The non-transitory computer-readable storage medium of  claim 17 , wherein generating the simple validity statement data structure further comprises determining that the identified one or more conditions make reference to at least one node. 
     
     
         19 . The non-transitory computer-readable storage medium of  claim 18 , wherein generating the simple validity statement data structure further comprises:
 generating one or more link validity statement records; and   including the one or more link validity statement records in the simple validity statement data structure.   
     
     
         20 . The non-transitory computer-readable storage medium of  claim 19 , wherein the one or more link validity statement records further provide an indication of whether the at least one node is reachable from at least another node. 
     
     
         21 . The non-transitory computer-readable storage medium of  claim 19 , wherein the one or more link validity statement records further comprises an indication of a condition that must be satisfied in order for the one or more link validity statement records to be valid. 
     
     
         22 . The non-transitory computer-readable storage medium of  claim 21 , wherein the condition that must be satisfied in order for the one or more link validity statement records to be valid comprises a condition relating to the state of a domain membership of the target device. 
     
     
         23 . The non-transitory computer-readable storage medium of  claim 17 , wherein the first key and the second key comprise a pairing key. 
     
     
         24 . The non-transitory computer-readable storage medium of  claim 17 , wherein the pairing key is generated as part of a pairing operation between the host device and the target device.