Digital video recorder anti-skip system
View Patent ↗A method for producing scrambled content (FIG. 6 A), the method including providing content ( 600 ) to be scrambled, identifying a first portion of the content ( 620 ), identifying a second portion of the content ( 630 ), computing a disguising function of at least part of the first portion ( 620 ) of the content and producing a result, and scrambling the second portion ( 630 ) of the content, the scrambling being based in part, on the result. Related apparatus and methods are also described.
1. A method for permitting a viewer to view content, the method comprising:
providing the content, where at least part of the content is scrambled;
identifying a first portion of the content as “must see” content based on meta-data in the content that indicate a beginning and an end of the “must see” content, the “must see” content comprising a plurality of “n” adjacent sub-portions;
identifying a second portion of the content as “dependent” content based on meta-data in the content that indicate a beginning and an end of the “dependent” content, the “dependent” content being scrambled, the “dependent” content comprising a series of more than “n” sub-portions;
descrambling the “must see” content, only if the “must see” content-is scrambled;
only if the “must see” content is played back in a normal mode as opposed to a trick mode, separately producing “n” respective sub-results by computing a hash for each of the “n” sub-portions of the “must see” content, descrambling each one of a first “n” sub-portions of the series of sub-portions of the “dependent” content utilizing a respective one of the “n” sub-results, and descrambling each one of the remaining sub-portions of the series of sub-portions of the “dependent” content, utilizing a sub-result that is different from an immediately preceding sub-result utilized to descramble an immediately preceding sub-portion in the series so that each sub-portion in the series is descrambled; and
if the “must see” content is not played back in the normal mode, preventing the “dependent” content from being descrambled.
2. The method according to claim 1 and wherein the “dependent” content is adjacent to the “must see” content.
3. The method according to claim 1 and wherein the content comprises at least one of the following: video content; audio content; and audio-video content.
4. The method according to claim 1 and wherein the hash function comprises SHA-1.
5. The method according to claim 1 and wherein the descrambling of the “dependent” content comprises descrambling using an exclusive-or (XOR) method.
6. The method according to claim 1 and wherein the descrambling of the “dependent” content comprises descrambling using a DES method.
7. The method according to claim 1 and wherein the descrambling of the “dependent” content comprises descrambling using an AES method.
8. The method according to claim 1 and wherein each of the “n” sub-portions of the “must see” content comprises exactly one byte.
9. The method of claim 1 and wherein the computing is performed in real-time.
10. The method of claim 1 and wherein the computing is performed before the sub-results are required for descrambling.
11. The method according to claim 1 , wherein each of the sub-portions of the “dependent” content comprises exactly one byte.
12. The method according to claim 1 , wherein each one of the “n” sub-portions of the “must see” content is equal in size, respectively, to each corresponding sub-portion of the “dependent” content, a particular sub-portion of the “dependent” content corresponding to a particular sub-portion of the “must see” content” if descrambling of the particular sub-portion of the “dependent” content utilizes a particular sub-result produced by computing a hash for the particular sub-portion of the “must see” content.
13. Apparatus for viewing content, the apparatus comprising:
a discriminator for identifying a first portion of the content as “must see” content based on meta-data in the content that indicate a beginning and an end of the “must see” content, the “must see” content comprising a plurality of “n” adjacent sub-portions; and for identifying a second portion of the content as “dependent” content based on meta-data in the content that indicate a beginning and an end of the “dependent” content, the “dependent” content being scrambled, the “dependent” content comprising a series of more than “n” sub-portions; and
an anti-skip descrambler for:
descrambling the “must see” content, only if the “must see” content of the content is scrambled;
only if the “must see” content is played back in a normal mode as opposed to a trick mode, separately producing “n” respective sub-results by computing a hash for each of the “n” sub-portions of the “must see” content, descrambling each one of a first “n” sub-portions of the series of sub-portions of the “dependent” content utilizing a respective one of the “n” sub-results, and descrambling each one of the remaining sub-portions of the series of sub-portions of the “dependent” content, utilizing a sub-result that is different from an immediately preceding sub-result utilized to descramble an immediately preceding sub-portion in the series so that each sub-portion in the series is descrambled; and
if the “must see” content is not played back in the normal mode, preventing the “dependent” content from being descrambled.
14. Apparatus according to claim 13 and also comprising:
a normal descrambler for descrambling another portion of the content without utilizing any of the sub-results.