Patent EP0345952A2 successfully refreshed from Google Patents.
EP0345952A2
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Method and apparatus for encrypting and decrypting time domain signals
Assignee: Adeia Media LLC
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Filing: 1989-05-11
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Granted: —
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Expires: 2009-05-11
Abstract
Abstract Time sequential information signals, such as color video signals having a line timing reference and an active video portion, are encrypted by time shifting the active video signal portion towards and away from the line timing reference signal in psuedo-random fashion prior to broadcasting or recording on tape or disk and transmittal to the user. The signals are decrypted by an inverse time shifting technique. By limiting the amount of time shifting between lines, potential signal degradation for color video signals is minimized, and drop out compensation processing is minimally affected, so that the color resolution and picture quality are substantially unaffected. Various levels of security are attainable, ranging from a simple security technique in which the intra field time shifting information is encoded along with the active video to a relatively sophisticated, high security level in which the number of decryption signal processing attempts and the time period within which decryption processing is permitted are limited.
Inventors
- 👤 John O. Ryan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:52
CPC Classifications
G; G11; G11B; G11B20/00; H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/169; H04N7/1693; H04N5/00; H04N5/76; H04N5/91; H04N5/913; H04N2005/91357; H04N2005/91364
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
82 words
A method of encrypting information signals to prevent unauthorized use thereof, said signals being normally arranged as a succession of lines of active information, each line having a line timing reference, said method comprising the steps of: (a) individually time shifting the active information portion of at least some of the lines of said signals with respect to the line timing reference by selected amounts; and (b) providing an indication of the time shifting performed in step (a) to enable subsequent decrypting.
Claim 2
Independent Claim
82 words
A method of encrypting information signals to prevent unauthorized use thereof, said signals being normally arranged as a succession of lines of active information, each line having a line timing reference, said method comprising the steps of: (a) individually time shifting the active information portion of at least some of the lines of said signals with respect to the line timing reference by selected amounts; and (b) providing an indication of the time shifting performed in step (a) to enable subsequent decrypting.
Claim 3
Dependent Claim
41 words
The method of claim 1 wherein said information signals are video information signals containing a line sync signal portion, and wherein said step (a) includes the step of inhibiting time shifting of the line sync signal portion of the individual lines.
Claim 4
Dependent Claim
41 words
The method of claim 1 wherein said information signals are video information signals containing a color reference signal portion, and wherein said step (a) includes the step of inhibiting time shifting of the color reference signal portion of the individual lines.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein said step (a) further includes the step of limiting the accumulated amount of time shifting in each temporal direction to a predetermined maximum value.
Claim 6
Dependent Claim
24 words
The method of claim 4 wherein the maximum value in one temporal direction is different from the maximum value in the opposite temporal direction.
Claim 7
Dependent Claim
45 words
The method of claim 5 wherein the maximum value in said one temporal direction is 6T and the maximum value in said opposite temporal direction is -2T, where T is a predetermined time period substantially less than the temporal duration of one line of information.
Claim 8
Dependent Claim
38 words
The method of claim 6 wherein said information signals are video information signals having a color reference signal portion of a predetermined frequency; and wherein T equals the duration of one cycle of said color reference signal portion.
Claim 9
Dependent Claim
38 words
The method of claim 1 wherein said information signals are video information signal containing a plurality of lines of non-active video, and wherein said step (a) includes the step of inhibiting time shifting of the non-active video lines.
Claim 10
Dependent Claim
34 words
The method of claim 1 wherein said selected amounts are limited to +T, -T, and zero, where T is a predetermined time period substantially less than the temporal duration of one line of information.
Claim 11
Dependent Claim
38 words
The method of claim 9 wherein said information signals are video information signals having a color reference signal portion of a predetermined frequency; and wherein T equals the duration of one cycle of said color reference signal portion.
Claim 12
Dependent Claim
18 words
The method of claim 1 wherein said step (a) of time shifting is performed in a predetermined sequence.
Claim 13
Dependent Claim
11 words
The method of claim 11 wherein said predetermined sequence is pseudo-random.
Claim 14
Dependent Claim
28 words
The method of claim 11 wherein said step (a) of time shifting includes the step of changing said predetermined sequence to another sequence as a function of time.
Claim 15
Dependent Claim
43 words
The method of claim 11 wherein said information signals are arranged in groups of lines; and wherein said step (a) of time shifting includes the step of changing said predetermined sequence to another sequence as a function of the number of groups time-shifted.
Claim 16
Dependent Claim
54 words
The method of claim 11 wherein said information signals are grouped into at least two sub-groups; and wherein said step (a) of time shifting includes the steps of using a first predetermined sequence to time shift lines in one sub-group, and using a second predetermined sequence to time shift lines in a second sub-group.
Claim 17
Dependent Claim
37 words
The method of claim 15 wherein said step (a) of time shifting includes the step of changing at least one of said first and second predetermined sequences to a third predetermined sequence as a function of time.
Claim 18
Dependent Claim
41 words
The method of claim 15 wherein said step (a) of time shifting includes the step of changing at least one of said first and second predetermined sequences to a third predetermined sequence as a function of the number of sub-groups time-shifted.
Claim 19
Dependent Claim
49 words
The method of claim 1 wherein said step (a) includes the steps of: (i) storing successive samples of a selected line in a memory device; (ii) time shifting said samples by a selected amount corresponding to the selected line; and (iii) outputting the delayed samples from the memory device.
Claim 20
Dependent Claim
33 words
The method of claim 18 wherein said information signals are analog signals, and wherein said step (i) of storing is preceded by the step of converting said signals from analog to digital form.
Claim 21
Dependent Claim
25 words
The method of claim 19 wherein said step (iii) of outputting is followed by the step of converting said samples from digital to analog form.
Claim 22
Independent Claim
118 words
A method of decrypting previously encrypted information signals to permit use thereof, said encrypted information signals comprising encrypted versions of original information signals arranged as a succession of lines of active information, each line having a line timing reference, said encrypted signals having been produced by time shifting at least some of the lines of the original information signals with respect to the line timing reference by selected amounts and the direction and magnitude of the time shifting having been established, said decrypting method comprising the steps of: (a) providing an indication of the time shifting performed on a given line; and (b) restoring the original time relationship between the line timing reference and the line of information.
Claim 23
Independent Claim
118 words
A method of decrypting previously encrypted information signals to permit use thereof, said encrypted information signals comprising encrypted versions of original information signals arranged as a succession of lines of active information, each line having a line timing reference, said encrypted signals having been produced by time shifting at least some of the lines of the original information signals with respect to the line timing reference by selected amounts and the direction and magnitude of the time shifting having been established, said decrypting method comprising the steps of: (a) providing an indication of the time shifting performed on a given line; and (b) restoring the original time relationship between the line timing reference and the line of information.
Claim 24
Dependent Claim
44 words
The method of claim 21 wherein said encrypted information signals are video information signals containing line sync portions which were not time shifted during the encryption process; and wherein said step (b) of restoring includes the step of leaving the line sync portions undisturbed.
Claim 25
Dependent Claim
46 words
The method of claim 21 wherein said encrypted information signals are video information signals containing color reference signal portions which were not time shifted during the encrypting process; and wherein said step (b) of restoring includes the step of leaving the color reference signal portions undisturbed.
Claim 26
Dependent Claim
140 words
The method of claim 21 wherein said encrypted information signals are video information signals containing a plurality of lines of non-active video which were not time shifted during the encryption process; and wherein said step (b) of restoring includes the step of leaving the non-active video lines undisturbed. succession of lines of active information, each line having a line timing reference, said encrypted signals having been produced by time shifting at least some of the lines of the original information signals with respect to the line timing reference by selected amounts, and the direction and magnitude of the time shifting having been established during encryption, said system comprising: means for providing an indication of the time shifting performed on a given line; and means for restoring the original time relationship between the line timing reference and the line of information.
References Cited (Backward Citations)
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