Tethered device systems and methods
View Patent ↗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.
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;
determining that the identified one or more conditions make reference to at least one node;
generating a simple validity statement record based on the identified one or more conditions;
including the encrypted content key and the simple validity statement record in the simple validity statement data structure;
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;
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 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.
7. The method of claim 1 , 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.
8. The method of claim 7 , 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.
9. 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.
10. The method of claim 9 , 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.
11. The method of claim 10 , 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.
12. The method of claim 9 , 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.
13. The method of claim 9 , 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.
14. The method of claim 13 , 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.
15. 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;
determining that the identified one or more conditions make reference to at least one node;
generating a simple validity statement record based on the identified one or more conditions;
including the encrypted content key and the simple validity statement record in the simple validity statement data structure;
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;
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.
16. The non-transitory computer-readable storage medium of claim 15 , 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.
17. The non-transitory computer-readable storage medium of claim 15 , 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.
18. The non-transitory computer-readable storage medium of claim 17 , 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.
19. The non-transitory computer-readable storage medium of claim 15 , wherein the first key and the second key comprise a pairing key.
20. The non-transitory computer-readable storage medium of claim 15 , wherein the pairing key is generated as part of a pairing operation between the host device and the target device.