`
`I
`Ulllted States Patent
`
`[19]
`
`Gilliousen et a1,
`
`[11] Patent Number:
`
`4,613,901
`
`[45] Date of Patent:
`
`Sep. 23, 1986
`
`358/123
`.. 358/ 114
`358/117
`.. 353/54
`358/86
`350/120
`
`..........
`.. 358/122
`358/122
`170/2216
`455/4
`173/2203
`ITS/22.11
`...... 353/122
`173/2203
`1711/2200
`358/122
`353/122
`358/122
`
`.
`
`
`
`A system and method for scrambling and selectively
`descrarribling television signals that are transmitted to
`subscribers’ descramblers in a subscription television
`system. A working key signal is generated by process-
`ing an “initialization vector” signal in accordance with
`the DES algorithm upon the algorithm being keyed by
`-th
`t
`k
`-
`th
`k
`c.‘ 3’ 3 Como“ ca cg”? Cy “31ml 01.5mm 0 er 5y
`slgnal. A unique encrypnon keystream is generated by
`processing the initialization vector signal in accordance
`with the DES algorithm upon the algorithm 1161.113
`keyed by the working key signal. A television signal is
`scrambled in accordance with the unique encryption
`keystream to provide a scrambled television signal. A
`plurality of unique encrypted category key signals‘indi-
`vidually addressed to different selected subscribers’
`358/36
`I122 descramblers are generated by processing the initial
`__ 357,1”
`common category key signal in accordance with the
`550/122
`DES alsonflgm upon the 41301111191 being keyed by 3
`.. 179/15 BV
`plurality of different “unit key" Signals umque to differ-
`353/122
`ent selected descramblers. The scrambled television
`113/22
`signal, the initialization vector signal, and the plurality
`353/114
`of encrypted cate 0
`he si
`215 are broadcast to the
`358 122
`g W y '5“ '
`'
`3581:”:
`descramblers. A corresponding tier of DES algorithms
`178/22
`are employed at the descrambler to reproduce the -
`"'"350/124
`S‘WPt‘O“ hymen“; “Fl “"5 TV 5’3” is “scramwa
`358/122
`in accordance therewnh. Each descrambler has its
`353,122
`unique unit key signal stored in a secure memory for use
`358/114
`in reproducing the common category key signal when
`358/123
`the descrambler is addressed by its unique encrypted
`358/86
`category key signal,
`......... .. 235/379
`ITS/22.06
`
`[54] SIGNAL ENCRYPTION AND
`DISTRIBUTION SYSTEM FOR
`NTR I I 1};
`CR um]: [N “am
`RSMSOTE DESCREMBLING 0F
`ION SIGNALS
`
`ELF.
`
`V15
`Inventom:
`
`S. Gilliam“, San Diego;
`Chg-“est, Newby Jr El Cajon. Karl
`d‘
`P
`’
`f
`E
`M0" 91',
`owaYt
`°
`'-
`inks o
`_
`-
`,
`[73} “Sign” EteroggliifL
`I)“, Inc" 83“
`g ’
`'
`2
`A I. No; 498 00
`pp
`’8
`I]
`[
`{22] Filed:
`May 27, 1983
`
`Int. 01.4 ...................... .. H0419 ‘1/167;H04L 9/00
`[51]
`[52] U.S.Ci. ............................... ..358/122;178/22.07;
`178/221; ITS/22.16
`[58] Field of Search ..................... 353/122; 178/2207,
`1781/22.] 2114 2116
`’
`’
`
`[56]
`
`References Cited
`
`[57]
`
`ABSTRACT
`
`3/1982 Saeki et a1.
`4,322,745
`4/1982 Gnillou ..............
`4,323,921
`4,323,922 4/1982 den Toonder et a1.
`4,331,913
`5/1982 Eskin et a1.
`4,331,974 5/1982 Cogswell et al.
`4,336,553
`6/1932 den Toonder et a1.
`P331115 et 81.
`..........
`4.354.201 10/1982 Sechet et a1.
`..
`4,338,643 6/1983 Aminelzal'l
`4,450,109
`7/1934 Mueller-Schloer
`4,461,032
`1/1984 Skerlos ............ ..
`4.467.139
`8/1984 Mollie:
`4,471,164 9/1984 Henry .
`.......
`4,484,021 11/1984 Lee et a].
`.........
`4,531,011
`7/1935 Bluesteiii et a].
`4,531,020 7/1935 Wechselberger et a1.
`4,533,943
`8/1985 McNamara et al,
`4,533,949
`3/1935 Fujimma e; 3L
`4,535,355
`3/1935 Arnet a1.
`.
`.
`.
`,
`“’3‘”? Emm’”e’—St'?l’h°“ 0' Emma“
`Asststant Examiner—Lmda J. Wallace
`Attorney, Agent, or Firm—Edward W. Callan
`
`.
`
`
`
`_
`..
`
`U.S. PATENT DOCUMENTS
`3,233.29; 3,955 paw!“ et aL _
`3,663.30?
`6/1972 Face at 31.
`.
`3,729,581
`4/1973 Anderson
`33117053 12/1973 Wiflig 9‘ 31-
`33937359 3/1974 1:315:31
`3,803,491
`4/1974 Osbom
`3,886,302 5/1975 Kosco
`3,894,176 1/1915 Mellon _________n
`3,399,633
`3/1975 Sermon at 31'
`3,916,091 10/ 1975 Kirk. Jr. et a1.
`3,919,462 11/1975 Hanung et at.
`3,936,593 2/1976 Aaronson et al-
`i-ggl'g:
`391‘s” 3‘ al-
`4'025’948 5:19.”
`""""""
`4'053’330 11/19.” Gmnet
`4:063:26,
`1/1973 Fires
`4.0911417
`5/1973 meson
`..
`4,112,464 9/1973 Cruifet a].
`4,115,662
`9/1918 Guinet et a]
`4,115,801
`9/1978 Piles ......... ..
`4.160.120 7/1979 Barnes 61 31
`411511751
`7/1979 05‘
`4163254 7/1979 Bl
`k
`a]
`4' 1631255
`filmy
`.99 ct
`
`4‘1”;13 10”91,9
`Imueseg'gt";i“"
`4'215 366 7/1930 Davidson
`4'225’334
`9/1930 Block at
`4:250:524
`21/1981 Tomizawa
`4,253,114 2/1981 Tang et a].
`4,292,650 9/1931 Hendrickson .
`4,302,771 11/1931 Gargini
`4,304,990 12/1981 Atalla
`4.316.055 2/1982 Feistal
`
`
`
`173/22
`173/56
`ITS/6.8
`178/511
`-- 173/22
`325/53
`170/51
`173Al
`173/11
`178/51
`173/51
`173/5-1
`3173/5-3
`
`26 Claims, 3 Drawing Figures
`
`mum" we
`svirtu
`
`
`
`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 1
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 1
`
`

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`
`Apple v. PMC
`|PR2016-01520
`
`Page 2
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 2
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`
`U. S. Patent
`
`Sep. 23, 1986
`
`Sheet 2 of 8
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`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 3
`
`
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`U.S. Patent
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`Sep. 23, 1986
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`PMC Exhibit 2201
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`Apple v. PMC
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`Page 4
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`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 4
`
`
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`

`

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`
`US. Patent
`
`Sep. 23, 1986
`
`Sheet4of8
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`4,613,901
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`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 5
`
`
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 5
`
`

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`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 6
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`
`U.S. Patent
`
`Sep. 23, 1986
`
`Sheet 6 of 8
`
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`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 7
`
`
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 7
`
`

`

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`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 8
`
`
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 8
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`

`

`US. Patent
`
`Sep. 23, 1986
`
`SheetSofS
`
`4,613,901.
`
`227
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`8
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`
`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 9
`
`PMC Exhibit 2201
`Apple v. PMC
`IPR2016-01520
`Page 9
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`

`

`
`
`1
`
`4,613,901
`
`SIGNAL ENCRYPTION AND DISTRIBUTION
`SYSTEM FOR CONTROLLING SCRAMBLING
`AND SELECTIVE RENIOTE DESCRANIBLING 0F
`TELEVISION SIGNAIS
`
`BACKGROUND OF THE INVENTION
`
`The present invention generally pertains to subscrip-
`tion television systems and is particularly directed to a
`system for controlling Scrambling and selective, remote
`descrambling of television signals.
`There are many schemes for controlling scrambling
`and selective, remote descrambling of television signals
`available for use in subscription television systems, in-
`cluding schemes wherein only selected subscribers’
`descramblers are addressed to be enabled to descramble
`scrambled television signals. These schemes heretofore
`have not provided the degree of security against unau-
`thorized descrambling that is desired by the subscrip-
`tion television industry.
`
`SUMMARY OF THE INVENTION
`
`The present invention is characterized by a key signal
`encryption and distribution system for scrambling and
`selective, remote descrambling of television signals.
`The present
`invention utilizes advanced crypto-
`graphic techniques to provide a video scrambling and
`selective descrambling system that
`is highly secure
`against unauthorized descrambling.
`Such security is based in part upon the use of an
`encryption algorithm, such as the DES (Data Encryp-
`tion Standard) algorithm. The DES algorithm is keyed
`by a 56-bit key signal. Without knowing the content of
`the key signal, a DES encrypted message cannot be
`decrypted unless all 72,057,590,[DD,000,000 possible key
`signals are tested by trial and error. Such a task would
`require an incredibly expensive and powerful computer.
`Since there is no such thing as an "unbreakable" deter-
`ministic cipher generator, the best one can hope for is to
`make the cryptanalysis process vastly more expensive
`than the value of the information that one is trying to
`protect. The DES algorithm succeeds in this endeavor
`quite nicely for subscription TV systems. The DES
`algorithm is the one commercially available crypto-
`graphic algorithm that has been most thoroughly ana-
`lyzed and tested under attack and which is now be-
`lieved to provide an extremely high level of security. At
`least three levels of encryption algorithms are used in
`scramng and descrambling the television signal in the
`system of the present invention.
`The following functions are performed in the system
`of the present invention.
`A subsystem in each descrambler provides a sub-
`scriber key signal that is unique to the descrambler.
`A control computer stores a list of the unique sub~
`scriber key signals for the descramblers of the system.
`The control computer also stores a list defining a hierar-
`chy of common category key signals corresponding to a
`hierarchy of address groups defined on the basis of
`subscribers having a common grade of service or other
`attributes that makes it desirable to address a group of
`subscribers’ descramblers in common.
`The control computer generates from the stored hier-
`archy list, a common category key signal corresponding
`to a selected address group in the hierarchy of address
`groups. The computer further generates from the stored
`subscriber key signal list, a group of unique subscriber
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`key signals corresponding to the selected address
`group.
`The scrambler generates a group of unique encrypted
`category key signals individually addressed to different
`selected subscribers’ descramblers by processing the
`generated common category key signal in accordance
`with a first encryption algorithm upon the first algo-
`rithm being keyed by the generated group of unique
`subscriber key signals; generates a working key signal
`by processing an initialization vector signal in accor—
`dance with a second encryption algorithm upon the
`second algorithm being keyed by either the generated
`common category key signal or some other key signal;
`generates a unique keystream by processing the initial-
`ization vector signal in accordance with a third encryp-
`tion algorithm upon the third algorithm being keyed by
`the working key signal; and scrambles a television sig-
`nal in accordance with the unique keystream to provide
`a scrambled television signal.
`Preferably, a new working key signal is generated
`every few TV frames. The initialization vector signal is
`a signal derived from real time that is communicated to
`the descrambler as a synchronization control signal.
`Preferably it provides a time-based repetitive sequen-
`tially varying count of TV frames.
`The category membership of a subscriber defines the
`grade of service that a subscriber receives. Preferably
`the category key signal is varied from time to time, such
`as weekly, or whenever the subscriber’s grade of ser-
`vice is changed.
`Preferably the control computer stores a list defining
`a plurality of channel key signals respectively corre-
`sponding to different time blocks for different television
`channels in the system, and generates a selected channel
`key signal from said channel key signal list; and the
`scrambler generates an encrypted channel key signal by
`processing the selected channel key signal in accor-
`dance with a fourth encryptiOn algorithm upon the
`fourth algorithm being keyed by the generated common
`category key signal; and generates the working key
`signal by processing the initialization vector signal in
`accordance with the second encryption algorithm upon
`the secOnd algorithm being keyed by the selected chan-
`nel key signal.
`the initialization
`The scrambled television signal,
`vector signal, and the group of unique encrypted cate-
`gory key signals are communicated to the subscribers’
`descramblers.
`Each descrambler reproduces the common category
`key signal, when the descrambler receives the unique
`encrypted category key signal addressed thereto, by
`processing the encrypted category key signal addressed
`to the descrambler in accordance with the first algo-
`rithm upon the first algorithm being keyed by the
`unique subscriber key signal provided in the addressed
`descrambler; reproduces the working key signal, when
`the common category key signal is reproduced in the
`descrambler, by processing the initialization vector
`signal in accordance with the second algorithm upon
`the second algorithm being keyed by either the com-
`mon category key signal that is reproduced in the de-
`scrambler in relation to the reproduced commoa cate-
`gory key signal (such as the selected charmel key sig-
`nal), consistent with which key signal was used to key
`the second algorithm in the scrambler; reproduces the
`unique keystream, when the working key signal is re-
`produced in the descrambler, by procassing the initial-
`ization vector signal in accordance with the third algo-
`
`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 10
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`3
`rithm upon the third algorithm being keyed by the
`working key signal that is reproduced in the descram-
`bler; and descrambles the scrambled television signal.
`when the unique keystream is reproduced in the de-
`scrambler, by descrambling the scrambled televisiou
`signal in accordance with the unique keystream that is
`reproduced in the descrambler.
`A given descrambler cannot decrypt an encrypted
`category signal unless the unique subscriber key signal
`for the given descrambler was used to encrypt the com-
`mon category signal.
`Each descrambler includes a secure memory for stor-
`ing information that is used for providing the unique
`subseriber key signal in the descrambler. The secure
`memory makes the system of the present invention
`additionally secure. Even if a cryptanalyst were
`equipped with an Operable descrambler. a complete set
`of drawings, and advanced cryptographic equipment he
`would not be able to descramble the television signal
`unless the descrambler memory contained information
`essential to providing a key signal identical to one of the
`unique subscriber key signals used in encrypting the
`category key signal. Only unique subscriber key signals
`of authorized subscribers are used in encrypting the
`category key signal. The information for providing the
`unique subscriber key signal is stored in a secure inter-
`nal read only memory (ROM) of a microprocessor chip
`having internal architecture that prohibits the ROM
`from being read off-chip. Since the ROM can only be
`read by the microprocessor, a high level of security
`against disclosing the unit key signal to signal process-
`ing methods of analysis is assured.
`In the preferred embodiment, a subscriber key gener-
`ation number that is common to all of the subscribers‘
`descramblers corresponding to selected address group
`is generated by the control cornputer and communi-
`cated to the subscribers‘ descramblers together with the
`group of unique encrypted category key signals. In such
`embodiment the subscriber key subsystem in each de-
`scrambler combines the communicated subscriber key
`generation number with a unique subscriber address
`signal stored in the secure memory of the descrambler
`to provide a unique subscriber key generation signal.
`The subsystem provides the unique subscriber key sig-
`nal by processing the subscriber key generation signal in
`scoordance with an encryption algorithm upon the
`algorithm being keyed by a subscriber key seed signal
`that is unique to the descrambler. The subscriber key
`seed signal preferably is stored in the secure memory of 59
`the descrambler and is retrieved therefrom to key the
`encryption algorithm in response to a predetermined
`seed address included in a given position in the sub-
`scriber key generation number.
`Although the present invention is described herein as
`being applicable to a subscription television system, it
`also is broadly applicable to other types of communica-
`tions systems.
`Additional features of the present invention are de-
`soribed in relation to the description of the preferred
`embodiment.
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`BRIEF DESCRIPTION OF THE DRAWING
`
`FIG. 1 is a block diagram of a scramng system
`according to the present invention.
`FIG. 2 is a block diagram of a preferred embodiment
`of the scramqu key distribution system included in the
`system of FIG. 1.
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`FIG. 3 is a block diagram of the scrambler signal
`processor included in the system of FIG. 1.
`FIG. 4 is a block diagram of the audio processor
`included in the scrambler signal processor of FIG. 3.
`FIG. 5 is a block diagram of a preferred embodiment
`of a descrambling system according to the present in-
`vention.
`FIG. 6 is a block diagram of the descrambler key
`distribution system included in the system of FIG. 5.
`FIG. ’7 is a block diagram of the descrambler signal
`processor included in the system of FIG. 5.
`FIG. 8 is a block diagram of the audio processor
`included in the descrambler signal processor of FIG. 7.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`Referring to FIG. 1, a preferred embodiment of a
`scrambling system according to the present invention
`includes a scrambler signal processor 10, a scrambler
`key distribution system 11 and a control computer 12.
`The control computer 1|] stores a list of subscriber
`key signals that are unique to the different descramblers
`of the subscription television system.
`The control computer 12 also stores a list defining a
`hierarchy of address groups defined on the basis of
`subscribers having a common grade of service or other
`attributes that makes it desirable to address a group of
`subscribers' descramblers in common. From the stored
`hierarchy list, the control computer 12 generates a 56-
`bit common category key signal on line 13 correspond-
`ing to a selected address group in the hierarchy of ad-
`dress groups.
`From the stored subscriber key signal list, the control
`computer 12 generates a group of unique 56-bit sub-
`scriber key signals on line 14 corresponding to the se-
`lected address group.
`The control computer 12 further stores a list defining
`a plurality of channel key signals respectively corre-
`sponding to different time blocks for different television
`channels, and generates a selected 56-bit channel key
`signal from the channel key signal list onto line 15.
`Together with the channel key signal on line 15. the
`control computer 12 generates a selected 16-bit cate-
`gory address signal on line 16 corresponding to the
`selected address group.
`The control computer 11 generates a 32-bit sub-
`scriber key generation number on line 17 that is com-
`mon to all of the subscribers’ descramblers.
`The control computer additionally stores a list of
`32‘bit subscriber address signals that are unique to the
`different descramblers of the subscription television
`system, and generates a group of unique 32-bit sub-
`scriber address signals corresponding to the Selected
`address group from the unit address signal list. The
`unique subscriber address signals on line 18 are gener-
`ated on line 18 by the control computer 12 together
`with the respective unique subscriber key signals gener-
`ated by the control computer on line 14.
`In addition. the control computer 12 generates a 24-
`bit initialization vector (IV) frame count signal on line
`19 and process control signals on litres 20. The IV signal
`on line 19 is a time-based signal indicating a repetitive
`sequentially varying count. In an alternative preferred
`embodiment (not shown) the IV frame count signal is
`produced in the scrambler signal processor 10 and pro-
`vided therefrom to the scrambler key distribution sys-
`tem 11.
`
`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
`Page 11
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`5
`The process control signals on lines 2|] effect control
`of various processes in the scrambler signal processor
`10 and the descrambling system of FIG. 5.
`Referring to FIG. 2, the scrambler key distribution
`system 11 includes a keystream generator 21, a working
`key signal generator 22, an encrypted channel key sig-
`nal generator 23 and an encrypted category key signal
`generator 24. The scrambler key distribution system of
`FIG. 2 further includes five expansion function ele-
`ments 25, 26, 2?, 23 and 29 for expanding the signals
`respectively received from the control computer 12 on
`lines 19, 15, 16, 13 and 18 to 64 bits. Expansion is accom-
`plished by adding various sets of predetermined bit
`combinations to the end of each of the respectively
`received signals so that the word lengths match. Such
`expansion is implemented by programmed operation of
`a microprocessor. Accordingly a 24-bit initialization
`vector signal on line 19 is expanded to a 64—bit signal on
`line 30; the 56-bit channel key signal on line 15 is ex-
`panded to a 64—bit signal on line 31; the 16-bit category
`address signal on line 16 is expanded to a 64-bit signal on
`line 32; the 56-bit category key signal on line 13 is ex-
`panded to a 64-bit signal on line 33; and the 32-bit sub-
`scriber address signal on line 18 is expanded to a 64-bit
`signal on line 34.
`In addition, the scrambler key distribution system of
`FIG. 2 includes two exclusive-OR logic elements 35
`and 36. The logic element 35 exclusive-OR’s the se-
`lected channel key signal on line 31 with the category
`address signal on line 32 to provide a scrambled selected
`channel key signal on line 3?. The logic element 36
`exclusive-OR's the common category key signal on line
`33 with the subscriber address signal on line 34 to pro-
`vide a scrambled common category key signal on line
`38.
`
`The encrypted category key signal generator 24 gen-
`erates a group of unique 64-bit encrypted category key
`signals individually addressed to different selected sub-
`scribers’ descramblers by processing the scrambled
`common category key signal on line 38 in accordance
`with the DES encryption algorithm upon the DES
`algorithm being keyed by the group of unique sub-
`scriber key signals received on line 14 from the control
`computer 12. The group of encrypted category key
`signals are provided sequentially on line 39 to the
`scrambler signal processor 10 (FIGS. 1 and 3).
`The encrypted channel key signal gerator 23 gen-
`erates a 64-bit encrypted channel key signal by process-
`ing the scrambled selected channel key signal on line 37
`in accordance with the DES encryption algorithm upon
`the DES algorithm being keyed by the generated com-
`mon category key signal received on line 13 from the
`control computer 12. The encrypted channel key signal
`is provided on line 40 to the scrambler signal processor
`1|].
`The working key signal generator 22 generates a
`64-bit working key signal by processing the initializa-
`tion vector signal on line 30 in accordance with the
`DES encryption algorithm upon the DES algorithm
`being keyed by the generated channel key signal on line
`15. The generated working key signal is provided on
`line 41 and truncated by a truncation function element
`42 to a 56-bit signal on line 43. Truncation is accom-
`plished by deleting the last eight bits from the 64-bit
`signal. In the preferred embodiment, a new working
`key is generated every four TV frames or at a 7.5 Hz
`rate.
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`The keystream generator 21 generates a unique 64-bit
`keystream by processing the initialization vector signal
`on line 30 in accordance with the DES encryption algo-
`rithm upon the DES algorithm being keyed by the
`working key signal on line 43. The unique keystrearn is
`provided on line 44 to the scrambler signal processor
`10.
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`Referring to FIG. 1, the scrambler signal processor
`10 scrambles a video signal received on line 45 and an
`audio signal received on line 46 in accordance with the
`unique keystream received on line 44 to provide a
`scrambled television signal on line 4?.
`Referring to FIG. 3, the scrambler signal processor
`1|] includes a control processor 48, an audio processor
`49, a video amplifier 50, a sync detection circuit 51, an
`analog-to-digital (A/D) converter 52, a video line
`buffer memory 53, address counters 54, an address
`FIFO (first-in/frrst—out) queue 55, a line buffer control-
`ler 56, a waveshaping filter 57, a burst generator 58, a
`sync generator 59, a reference pattern generator 60, a
`multiplexer (MUX) 61 and a digital-to—analog fD/A)
`converter 62. The operation of the control processor 48
`is controlled by process control signals provided on line
`20 by the control computer 12.
`The video signal on line 45 is scrambled in accor-
`dance with one portion of each frame of the unique
`keystream on line 44. The audio signal on line 46 is
`scrambled by the audio precessor 49 in accordance with
`a different portion of each frame of the unique keys—
`trearn from line 4-4 that is provided to the audio proces-
`sor on line 63.
`The video amplifier 50 amplifies the video signal on
`line 45 and filters the same to remove any extraneous or
`harmonic signals. The amplified and filtered video sig-
`nal is provided on line 63 to the A/D converter 52 and
`the sync detection circuit 51. The sync detection circuit
`51 detects the vertical and horizontal synchronization
`signals in the video signal on line 63 and responds
`thereto by providing synchronization control and
`clocking signals on lines 64 to the control processor 48.
`Among these clocking signals is a 14.32 MHz signal,
`which is at four times the color subcarrier frequency of
`an NTSC video signal, and which is also provided by
`the sync detection circuit 51 on line 64a to clock the
`A/D converter 52.
`The A/D converter 52 converts the amplified video
`signal on line 63 into a digital video information signal
`on line 65 at the sampling rate of 14.32 MHz to provide
`910 8-bit samples per video line. The active video infor-
`mation corresponds to 744 samples in each line.
`The video line buffer memory 53 stores the digital
`video signal on line 65 in four groups of four video
`information lines each. Each stored video information
`line includes T44 8-bit samples of active video informa-
`tion. A first group includes four consecutive odd-num-
`bered lines from the same video field. A second group
`includes the next four consecutive odd numbered lines
`from the same video field. A third group includes four
`consecutive even—numbered lines from the same video
`field, and the fourth group includes the next four con-
`secutive even-numbered 11am from the same video field.
`One group of odd-numbered lines is stored in the mem-
`ory 53 while the information from the previously-stored
`group of odd-numbered lines is retrieved from the mem-
`ory 53 to form a four—line group of odd-numbered
`scrambled video information line on line 66. Likewise,
`one group of even-numbered lines is stored in the mem-
`ory 53 while the information from the previously stored
`
`PMC Exhibit 2201
`
`Apple v. PMC
`|PR2016-01520
`
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`group of even-numbered lines is retrieved from the
`memory to form a four-line group of even-numbered
`scrambled video information lines on line 66. Video
`scrambling is accomplished by retrieving the active
`video information from the mory in a sequence dif-
`ferent from that in which it was stored.
`The address counters 54 provide the respective ad-
`dresses on line 67 to the memory 53 for storing and
`retrieving video information. These addresses are pro-
`vided to the address counters 54 on line 68 via the ad-
`dress FIFO queue 55 and line 69 from the control pro-
`cessor 48 in accordance with the unique keystrearn
`provided to the control processor 48 on line 44.
`The line buffer controller 56 prevides clocking and
`control signals on lines 70 for synchronizing the opera-
`tions of the address FIFO queue 55, the address count-
`ers 54 and the memory 53 in accordance with clocking
`and synchronizatiou control signals provided on line 71
`by the control processor 48. The control processor 48
`provides the clocking and synchronization control sig-
`nals on lines 71 in response to the clocking and synchro-
`nization control signals received on lines 64 from the
`sync detection circuit 51.
`Scrambling is accomplished Within four-line groups.
`Two control bits of the keystream on line 44 designate
`which lines within a given, stored four-line group are to
`be paired for forming a corresponding pair of scrambled
`video information lines. The relative lengths of the
`retrieved portions in each pair of scrambled lines is
`designated by six control bits in the keystream, which
`indicate a cutpoint as being after a given number of
`segments from the beginning of the line.
`Another five control bits of the keystream on line 44
`designate the sequence within a four~line group in
`which the scrambled lines are formed. Twenty-four
`different sequences are possible. Thus nineteen bits of
`the keystream are used every four video line times to
`select one of 3x62><24=276,768 possible scrambling
`patterns. Descrambling requires local generation of the
`identical keystream in the descrambler.
`To further obscure the location of the cutpoint, the
`waveshaping filter 57 adjusts the values of the adjacent
`extremities of the retrieved portions of each scrambled
`line to smooth over any fast rise-time edges.
`The waveshaping filter 57 provides a smooth transi-
`tion between two nine—bit samples in a digital data
`stream separated by six clock periods. The process in-
`volves generating a plurality of interpolated values
`between the two selected samples in different adjacent
`retrieved portions of each scramb