Copy count for DTCP with an abbreviation hash used for check in copy
A Digital Rights Management (DRM) system is provided that reduces time for a move transaction using DTCP-IP when a copy is moved back or checked back in to an originating Personal Video Recorder (PVR). During a DTCP MOVE transaction, instead of transferring the full asset in a check back in operation to the PVR, a unique and abbreviated representation of the original copy of the asset would be made for the transfer. This abbreviated representation takes the form of a hash constructed from a hashing function which uses characteristics of the asset as inputs. This hash will have to be a unique and near guaranteed indicator of the original content, to a high probability, so that the copy control system could live up to the spirit of the DTCP spec and the DLNA interoperability guidelines.
1. A method for controlling copy count using a Digital Transmission Content Protection (DTCP) standard, the method comprising:
maintaining an original master copy of a first video content in a personal video recorder (PVR);
maintaining a maximum copy count number;
copying the original master copy as a copy asset and transferring the copy asset from the PVR to a second video device on request for check out by the second video device and marking the transferred copy asset as Copy No More (CNM), and decrementing the copy count, and further creating and storing an abbreviated representation of the copy asset;
receiving the copy asset checked back in to the PVR from the second video device in response to a MOVE command, the received copy asset being an externally created version of the abbreviated representation of the checked-out copy;
comparing the checked in copy asset with the original master copy to determine if the copy asset and the master copy are from the identical first video content, and if so incrementing the copy count,
wherein the abbreviated representation takes the form of a hash constructed from a hashing function.
2. The method of claim 1 ,
wherein a transfer from the PVR occurs under a Sync n' Go command and the transferred copy is bound with the original copy so that the copy count is decremented when either the copy asset or the original master copy are transferred.
3. The method of claim 1 ,
wherein the copy asset checked into the PVR occurs under a Sync n' Go command, and
wherein both the original copy and the copy asset are maintained in storage in the PVR.
4. The method of claim 1 ,
wherein a Max Copy Count value is not a defined DTCP parameter, and an alternative operator controlled delivery mechanism is provided for the copy count as the Max Copy Count value in DTCP.
5. The method of claim 4 ,
wherein the Max Copy Count is included in the restriction list for DTCP and provided with a channel identifier that can be applied to all assets recorded from a channel indicated by the channel identifier.
6. The method of claim 1 , wherein the abbreviated representation comprises at least one of (a) a CRC based hash function; (b) a cryptographic hash; and (c) an additive arithmetic hash operation.
7. The method of claim 1 , wherein the copy asset is a transcoded version of the original master copy.
8. The method of claim 1 , wherein the hash function is created using an algorithm provided from or identified by the PVR to the second video device.
9. A personal video recorder (PVR) configured for controlling copy count using a Digital Transmission Content Protection (DTCP) standard, the PVR comprising:
a processor; and
a memory device connected to the processor, the memory device storing code executable by the processor to perform the following steps:
storing an original master copy of a first video content in the memory;
maintaining a maximum copy count number;
copying the original master copy as a copy asset and transferring the copy asset from the PVR to a second video device on request for check out by the second video device and marking the transferred copy asset as Copy No More (CNM), and decrementing the copy count, and further creating and storing an abbreviated representation of the copy asset;
receiving the copy asset checked back in to the PVR from the second video device in response to a MOVE command, the received copy asset being an externally created version of the abbreviated representation of the checked-out copy;
comparing the checked in copy asset with the original master copy to determine if the copy asset and the master copy are from the identical first video content, and if so incrementing the copy count,
wherein the abbreviated representation takes the form of a hash constructed from a hashing function.
10. The PVR of claim 9 ,
wherein a transfer from the PVR occurs under a Sync n' Go command and the transferred copy is bound with the original copy so that the copy count is decremented when either the copy asset or the original master copy are transferred.
11. The PVR of claim 9 ,
wherein the copy asset checked into the PVR occurs under a Sync n' Go command, and
wherein both the original copy and the copy asset are maintained in storage in the PVR.
12. The PVR of claim 9 ,
wherein a Max Copy Count value is not a defined DTCP parameter, and an alternative operator controlled delivery mechanism is provided for the copy count as the Max Copy Count value in DTCP.
13. The PVR of claim 12 ,
wherein the Max Copy Count is included in the restriction list for DTCP and provided with a channel identifier that can be applied to all assets recorded from a channel indicated by the channel identifier.
14. The PVR of claim 9 , wherein the abbreviated representation comprises at least one of (a) a CRC based hash function; (b) a cryptographic hash; and (c) an additive arithmetic hash operation.
15. The PVR of claim 9 , wherein the copy asset is a transcoded version of the original master copy.
16. The PVR of claim 9 , wherein the hash function is created using an algorithm provided from or identified by the PVR to the second video device.
17. A video player and storage device for receiving and transmitting a copy asset made from a master copy stored by a personal video recorder (PVR) using a Digital Transmission Content Protection (DTCP) standard, the video player and storage device comprising:
a processor; and
a memory device connected to the processor, the memory device storing code executable by the processor to perform the following steps:
receiving upon request of a check out operation a copy asset transferred from the PVR, the copy asset copied from the original master copy stored by the PVR;
receiving information about an algorithm for generating a hash function from the PVR and applying the hash function algorithm to the copy asset to create an abbreviated representation of the original master copy; and
transmitting the abbreviated representation in a DTCP move operation back to the PVR in a check in operation.
18. The video player and storage device of claim 17 , wherein the abbreviated representation comprises at least one of (a) a CRC based hash function; (b) a cryptographic hash; and (c) an additive arithmetic hash operation.
19. The video player and storage device of claim 17 , wherein the copy asset is a transcoded version of the original master copy.
20. The video player and storage device of claim 17 , wherein the copy asset is encrypted before creation of the abbreviated representation.