Method and apparatus for use of a time-dependent watermark for the purpose of copy protection

Claim 3

The method of protecting content as claimed in claim 1 , wherein said step of calculating said watermark comprises the steps: combining said seed data and said time data; and computing at least one, one-way function on said combined seed and time data.

Claim 4

The method of protecting content as claimed in claim 1 , wherein said step of calculating said ticket comprises the steps: combining said seed data and said time data; and computing at least one, one-way function on said combined seed and time data.

Claim 5

The method of protecting content as claimed in claim 1 , wherein said step of comparing said ticket and said watermark comprises the steps: combining said ticket and said time data; computing at least one, one-way function on said combined ticket and time data to produce a result; and comparing said result to said watermark.

Claim 6

The method of protecting content as claimed in claim 2 , further comprising the step of selecting said one-way function to be a hashing function.

Claim 7

A copy protection system for protecting content wherein a ticket and a watermark indicates a copy protection status of the content, the system comprising: a source device for producing said ticket and said watermark using a first time reference and a one-way function, and for providing a data stream containing said content, said ticket, said watermark, and said first time reference; and a receiver device for receiving said. data stream, wherein if said first time reference is contained within a time window determined by a second time reference, said receiver further compares said ticket to said watermark using said first time reference and said one-way function, and produces a signal indicating the copy protection status of the content.

Claim 8

A copy protection system for protecting content wherein a ticket and a watermark indicates a copy protection status of the content, the system comprising: a source device for producing said ticket and said watermark using a first time reference and a one-way function, and for providing a data stream containing said content, said ticket, said watermark, and said first time reference; and a receiver device for receiving said. data stream, wherein if said first time reference is contained within a time window determined by a second time reference, said receiver further compares said ticket to said watermark using said first time reference and said one-way function, and produces a signal indicating the copy protection status of the content.

Claim 9

The copy protection system as claimed in claim 6 , wherein said source device further produces said ticket and watermark using seed data.

Claim 10

The copy protection system as claimed in claim 6 , wherein said one-way function is a hashing function.

Claim 11

A source device for protecting content wherein a ticket and a watermark indicate a copy protection status of the content, said source device comprising: a time reference device for producing a time reference signal; and a processor for receiving said time reference signal, for producing said ticket and said watermark using said time reference signal and a one-way function, and for providing digital data containing said content, said ticket, said watermark, and said time reference signal.

Claim 12

A source device for protecting content wherein a ticket and a watermark indicate a copy protection status of the content, said source device comprising: a time reference device for producing a time reference signal; and a processor for receiving said time reference signal, for producing said ticket and said watermark using said time reference signal and a one-way function, and for providing digital data containing said content, said ticket, said watermark, and said time reference signal.

Claim 13

The source device for protecting content as claimed in claim 9 , wherein said processor further produces said ticket and said watermark using seed data.

Claim 14

The source device for protecting content as claimed in claim 9 , wherein said one-way function is a hashing function.

Claim 15

A receiver device for receiving digital data containing content, a ticket, a watermark, and a first time reference, wherein said ticket and said watermark together indicate a copy protection status of the content, said receiver comprising: a time reference device for producing a second time reference signal; and a processor, wherein if said first time reference is contained within a time window determined by said second time reference signal, said processor receives said digital data, combines said ticket with said first time reference to produce a first result, performs a one-way function on said first result to produce a second result, and compares said second result to said watermark to determine said copy protection status of said content.

Claim 16

A receiver device for receiving digital data containing content, a ticket, a watermark, and a first time reference, wherein said ticket and said watermark together indicate a copy protection status of the content, said receiver comprising: a time reference device for producing a second time reference signal; and a processor, wherein if said first time reference is contained within a time window determined by said second time reference signal, said processor receives said digital data, combines said ticket with said first time reference to produce a first result, performs a one-way function on said first result to produce a second result, and compares said second result to said watermark to determine said copy protection status of said content.

Claim 17

The receiver device as claimed in claim 12 , wherein said one-way function is a hashing function.

Claim 18

A copy protection system for protecting content wherein a ticket and a watermark indicates a copy protection status of the content, wherein the copy protection system comprises: a source device comprising: means for producing said ticket and said watermark using a first time reference and a one-way function; means for combining said content, said ticket, said watermark, and said first time reference into a data stream; and means for outputting said data stream, and wherein the copy protection system further comprises: a receiver device for receiving said data stream, said receiver device comprising: means for receiving said data stream; means for producing a second time reference and for generating a time window; means for determining if said first time reference is contained within said time window; and means for comparing said ticket to said watermark using said first time reference and said one-way function, and for producing a signal indicating the copy protection status of the content, if said determining means determines that said first time reference is contained within said time window.

Claim 19

A copy protection system for protecting content wherein a ticket and a watermark indicates a copy protection status of the content, wherein the copy protection system comprises: a source device comprising: means for producing said ticket and said watermark using a first time reference and a one-way function; means for combining said content, said ticket, said watermark, and said first time reference into a data stream; and means for outputting said data stream, and wherein the copy protection system further comprises: a receiver device for receiving said data stream, said receiver device comprising: means for receiving said data stream; means for producing a second time reference and for generating a time window; means for determining if said first time reference is contained within said time window; and means for comparing said ticket to said watermark using said first time reference and said one-way function, and for producing a signal indicating the copy protection status of the content, if said determining means determines that said first time reference is contained within said time window.