United States Patent [19]
`Gilhousen et al.
`
`[II] Patent Number:
`[45] Date of Patent:
`
`4,613,901
`Sep. 23, 1986
`
`[54] SIGNAL ENCRYPTION AND
`DISTRIBUTION SYSTEM FOR
`CONTROLLING SCRAMBLING AND
`SELECTIVE REMOTE DESCRAMBLING OF
`TELEVISION SIGNALS
`
`[75]
`
`Inventors: Klein S. Gilhousen, San Diego;
`Charles F. Newby, Jr., El Cajon; Karl
`E. Moerder, Poway, all of Calif.
`
`[73] Assignee: M/ A-COM Linkabit, Inc., San
`Diego, Calif.
`
`[21] Appl. No.: 498,800
`
`[22] Filed:
`
`May 27, 1983
`
`Int. Cl.4 ........................ H04N 7/167; H04L 9/00
`[51]
`[52] u.s. Cl •................................. 358/122; 178/22.07;
`178/22.1; 178/22.16
`[58] Field of Search ..................... 358/122; 178/22.07,
`178/22.1, 22.14, 22.16
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`3,238,297 3/1966 Pawley eta!. ........................ 178/22
`3,668,307 6/1972 Face eta!. ........................... 178/5.6
`3,729,581 4/1973 Anderson ............................. 178/6.8
`3,777,053 12/1973 Wittig et al .......................... 178/5.1
`3,798,359 3/1974 Feistel ................................... 178/22
`3,803,491 4/1974 Osborn .................................. 325/53
`3,886,302 5/1975 Kosco .................................. 178/5.1
`3,894,176 7/1975 Mellon ................................. 178/5.1
`3,899,633 8/1975 Sorenson eta!. .................... 178/5.1
`3,916,091 10/1975 Kirk, Jr. et al ...................... 178/5.1
`3,919,462 11/1975 Hartung et al. ...................... 178/5.1
`3,936,593 2/1976 Aaronson et al. ................... 178/5.1
`3,997,718 12/1976 Ricketts et al ....................... 178/6.8
`4,024,574 5/1977 Nieson ................................. 358/117
`4,025,948 5/1977 Loshin ................................. 358/122
`4,058,830 11/1977 Guinet eta!. ......................... 358/86
`4,068,264 1/1978 Pires .................................... 358/122
`4,091,417 5/1978 Nieson ................................. 357/117
`4,112,464 9/1978 Guif eta!. ........................... 358/122
`4,115,662 9/1978 Guinet et al. .................. 179/15 BV
`4,115,807 9/1978 Pires .................................... 358/122
`4,160,120 7/1979 Barnes eta!. ......................... 178/22
`4,161,751 7/1979 Ost ...................................... 358/114
`4,163,254 7/1979 Block et al .......................... 358/122
`4,163,255 7/1979 Pires .................................... 358/122
`4, 172,213 10/1979 Barnes et a!. ......................... 178/22
`4,215,366 7/1980 Davidson ............................ 358/124
`4,225,884 9/1~80 Block et al. ......................... 358/122
`4,250,524 2/19~1 Tornizawa ........................... 358/122
`4,253,114 2/1981 Tang et al. .......................... 358/114
`4,292,650 9/1981 Hendrickson ....................... 358/123
`4,302,771 11/1981 Gargini ................................. 358/86
`4,304,990 12/1981 Atalla .................................. 235/379
`4,316,055 2/1982 Feistal .............................. 178/22.06
`
`4,322,745 3/1982 Saeki et al. .......................... 358/123
`4,323,921 4/1982 Guillou ............................... 358/114
`4,323,922 4/1982 den Toonder eta!. ............. 358/117
`4,331,973 5/1982 Eskin eta!. ........................... 358/84
`4,331,974 5/1982 Cogswell et al. ..................... 358/86
`4,336,553 6/1982 den Toonder et al. ............. 358/120
`4,338,628 7/1982 Payne et al. ........................ 358/120
`4,354,201 10/1982 Sechet et al ........................ 358/122
`4,388,643 6/1983 Aminetzah .......................... 358/122
`4,458,109 7/1984 Mueller-Schloer .............. 178/22.16
`4,461,032 7/1984 Skerlos .................................... 455/4
`4,467,139 8/1984 Mollier ............................. 178/22.08
`4,471,164 9/1984 Henry ............................... 178/22.11
`4,484,027 11/1984 Lee et al ............................. 358/122
`4,531,011 7/1985 Bluestein et al. ................ 178/22.08
`4,531,020 7/1985 Wechselberger eta!. ....... 178/22.08
`4,533,948 8/1985 McNamara et al. ................ 358/122
`4,533,949 8/1985 Fujimura eta!. ................... 358/122
`4,535,355 8/1985 Am et a!. ............................ 358/122
`
`Primary Examiner-Stephen C. Buczinski
`Assistant Examiner-Linda J. Wallace
`Attorney, Agent, or Firm-Edward W. Callan
`ABSTRACT
`[57]
`A system and method for scrambling and selectively
`descrambling television signals that are transmitted to
`subscribers' descramblers in a subscription television
`system. A working key signal is generated by process(cid:173)
`ing an "initialization vector" signal in accordance with
`the DES algorithm upon the algorithm being keyed by
`either a common category key signal or some other key
`signal. A unique encryption keystream is generated by
`processing the initialization vector signal in accordance
`with the DES algorithm upon the algorithm being
`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(cid:173)
`vidually addressed to different selected subscribers'
`descramblers are generated by processing the initial
`common category key signal in accordance with the
`DES algorithm upon the algorithm being keyed by a
`plurality of different "unit key" signals unique to differ(cid:173)
`ent selected descramblers. The scrambled television
`signal, the initialization vector signal, and the plurality
`of encrypted category key signals are broadcast to the
`descramblers. A corresponding tier of DES algorithms
`are employed at the descrambler to reproduce the en(cid:173)
`cryption keystream; and the TV signal is descrambled
`in accordance therewith. Each descrambler has its
`unique unit key signal stored in a secure memory for use
`in reproducing the common category key signal when
`the descrambler is addressed by its unique encrypted
`category key signal.
`
`26 Claims, 8 Drawing Figures
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 1
`
`

`

`VIDEO
`
`AUDIO
`
`40[
`
`46\
`
`12)
`
`PROCESS CONTROL
`
`SUBSCRIBER KEY
`GENERATION NUMBER
`
`20(
`
`17(
`
`SCRAMBLEr'
`SIGNAL
`PROCESSOR
`
`10
`
`1
`
`I
`
`SCRAMBLED TV
`47}
`
`39\
`
`401.
`
`44\
`
`~
`tfj .
`~ a ('t) =
`,_VJ -""' 00
`
`f""'t-
`
`til
`(!)
`1='
`N
`
`0"\
`
`CONTROL
`COMPUTER
`
`nz: FRAME COUNT
`
`CHANNEL KEY
`
`CATEGORY ADDRESS
`
`CATEGORY KEY
`
`19)
`
`15)
`
`l61
`
`13)
`
`SUBSCRIBER ADDRESSES
`
`I B)
`
`SUBSCRIBER KEYS
`
`14)
`
`-
`-
`
`-
`-
`
`II 1
`
`KEYSTREAM
`
`SCRAMBLER
`KEY
`DISTRIBUTION
`SYSTEM
`
`ENCRYPTED CHANNEL KEY
`
`ENCRYPTED CATEGORY KEYS
`
`FIG I
`
`til
`t:r'
`(!)
`
`~ -g,
`00 .. ...
`
`0'\
`~
`...
`(j..)
`\0
`0
`
`~
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 2
`
`

`

`KEYSTREAM
`
`GENERATOR
`
`~I
`
`64 -t-
`
`24 I
`
`•
`
`).
`I
`19) I
`
`TI[
`FRAME
`COUNT
`
`EXPAND
`
`I 164 I I
`
`•
`
`'
`[~()
`
`56 -I-
`
`E
`CHANN L )
`KEY
`
`\
`/ ·-
`
`l I
`
`., EXPAND
`
`I ~ )) )I v~
`\
`·nJ
`
`KEYSTREAM
`
`.,
`
`44J
`
`6~
`1
`
`43
`
`r------4_2_..___,
`
`TRUNCATE
`
`W 0 R K I N G
`KEy
`
`I CHANN~ ENCRYPTED
`
`23
`
`•
`
`KEY
`GENERA
`
`CHANNEL
`KEY
`
`cATEGoRY
`ADDRESS
`
`)
`
`I
`
`.~J \
`
`·1 ExPAND 14-J-32
`I \
`
`,.-..,..... _____ __.
`
`56 1
`
`CATEGORY
`KEY
`
`(
`
`"')
`} I
`
`•
`
`)
`
`....
`
`I
`
`EXPAND
`
`lvl~
`\
`
`oJ<J{
`
`•
`-~
`
`./1
`
`I
`I)) 'J
`
`u\•
`
`I
`
`)
`--
`
`I CATEGORY
`
`KEY
`GENERATOR
`
`:J4
`
`•
`
`6: 391
`
`I
`
`ENCRYPTED
`., CATEGORY
`KEY
`
`~u~DSRC~~:sR:)
`~ 5S
`
`;'.
`
`;
`
`SUBSCRIBER
`KEYS
`
`IOJ ·I EXPAND . p
`
`14)
`
`FIG 2
`
`r56
`
`-
`
`c .
`
`C/l
`~
`~
`ft
`t:S
`«""+-
`
`.g
`r.l.l
`N
`w
`
`... -1..0
`
`~
`
`r.l.l
`g"
`a
`N
`~
`OO
`
`+;;..
`-..
`~
`\o
`0
`~
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 3
`
`

`

`Fl L TER
`
`92
`
`FIG 3
`
`~
`C/) .
`~ a ('D a
`
`Vl
`
`.p
`N w
`
`~ -1..0
`
`00
`0\
`
`20
`
`PROCESS CONTROL
`nz: FRAME COUNT
`ENCRYPTED CHANNEL KEY
`CATEGORY ADDRESS
`ENCRYPTED CATEGORY KEYS
`SUBSCRIBER KEYGENERATION NUMBER
`KEY STREAM
`
`AUDIO
`
`46
`
`CONTROL
`PROCESSOR
`
`98
`
`PATTERN
`GENERATOR
`
`95
`
`Vl
`~
`~
`w
`~
`00
`
`+;:...
`....
`0"\
`~ w
`....
`\0
`0
`
`~
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 4
`
`

`

`U.S. Patent Sep. 23, 1986
`
`Sheet4 of8
`
`4,613,901
`
`KEYSTREAM
`
`114
`
`8
`
`141
`
`118
`Q-BIT
`CONVERTER
`
`142
`
`CONTROL DATA
`101
`
`·FJG. 4
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 5
`
`

`

`SCRAMBLED TV
`
`1'-152
`
`150
`
`FIG 5
`
`1511
`
`DESCRAMBLER
`SIGNAL
`PROCESSOR
`
`IV FRAME COUNT
`
`153~
`
`ENCRYPTED CHANNEL KEY 154l
`
`CATEGORY ADDRESS
`
`155?
`
`ENCRYPTED CATEGORY KEY 1561
`
`SUBSCRIBER KEY GENERATION NUMBER
`157J
`
`KEYSTREAM
`
`PROCESS CONTROL
`
`159)
`
`158)
`
`DESCRAMBLER
`KEY
`DISTRIBUTION
`SYSTEM
`
`l
`
`DESCRAMBLED VIDEO 1601
`
`DESCRAMBLED AUDIO 1611_~
`
`- - - - - - -
`
`- -
`
`c . C'-) .
`~ a
`
`""C
`
`Cll
`~
`N w
`
`.... -"' 00
`
`0'\
`
`Cll
`:::r'
`('b
`('b
`f""'-
`UJ
`~
`00
`
`+;:..
`-..
`0\
`~ w
`-..
`' \0
`0
`-~
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 6
`
`

`

`U.S. Patent Sep. 23, 1986
`
`Sheet6 of8
`
`4,613,901
`
`56
`
`177
`
`193
`
`TRUNCATE
`
`56
`
`WORKING
`KEY
`
`190
`
`174
`
`TRUNCATE
`
`56
`
`CHANNEL
`KEY
`
`186
`
`175
`
`EXPAND
`
`64
`
`191
`
`171
`
`ENCRYPTED
`CHANNEL
`KEY
`
`154 64
`
`·ENCRYPTED .----.:...::16:...:..7..1....,
`CATEGORY
`CATEGORY
`KEY
`KEY
`156 64
`GENERATOR
`
`1---+-..lo..--~
`
`56
`
`SUBSCRIBER KEY
`
`182
`
`SUBSCRIBER KEY
`GENERATION NUMBER
`
`157
`
`32
`
`2
`
`SUBSCRIBER KEY
`SEED SELECTION
`
`56
`
`179
`
`163
`SUBSCRIBER
`KEY
`SEEDS
`
`FIG. 6
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 7
`
`

`

`SCRAMBLED
`TV
`152
`
`200
`BUFFER
`AMPLIFIER
`AND
`CLAM PER
`
`214
`
`201
`
`SYNC
`DETECTION
`AND
`CONTROL
`
`203
`
`204
`
`242
`
`DE MOD
`AND
`DEMUX
`
`227
`
`AUDIO
`
`PROCESSOR!•
`
`.243 1
`
`FIG 7
`
`DE SCRAMBLED
`AUDIO
`161
`
`~
`
`(I')
`(t)
`1=S
`DESCRAMBLED N
`w
`VIDEO
`
`I
`
`c .
`Cll .
`~ = f""t-
`·--I . ~ -1..0
`
`00
`0\
`
`CONTROL
`PROCESSOR
`
`1V FRAME COUNT
`
`ENCRYPTED CHANNEL KEY
`
`CATEGORY ADDRESS
`
`ENCRYPTED CATEGORY KEY
`
`156
`
`SUBSCRIBER KEY GENERATION NUMBER
`
`KEYSTREAM
`
`PROCESS CONTROL
`
`(I')
`t:r'
`
`-.....)
`
`(t) a
`~
`00
`
`.a;.
`-...
`0'\
`~ w
`-...
`\0
`0
`
`~
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 8
`
`

`

`U.S. Patent Sep. 23, 1986
`
`SheetS of8
`
`4,613,901
`
`SYNC AND TIMING
`
`243
`
`271
`
`275
`PARITY
`277
`Mc#>-M6
`E4>-E2, Cci>-C2,S
`
`259
`
`7
`
`277a
`
`279a
`
`15
`
`257
`
`MUX
`
`7
`
`7
`
`284
`
`266
`
`II
`
`FIG 8
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 9
`
`

`

`1
`
`4,613,901
`
`SIGNAL ENCRYPTION AND DISTRIBUTION
`SYSTEM FOR CONTROLLING SCRAMBLING
`AND SELECfiVE REMOTE DESCRAMBLING OF
`TELEVISION SIGNALS
`
`BACKGROUND OF THE INVENTION
`The present invention generally pertains to subscrip(cid:173)
`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- 15
`eluding 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(cid:173)
`thorized descrambling that is desired by the subscrip- 20
`tion television industry.
`
`SUMMARY OF THE INVENTION
`The present invention is characterized by a key signal
`encryption and distribution system for scrambling and 25
`selective, remote descrambling of television signals.
`The present invention utilizes advanced crypto(cid:173)
`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(cid:173)
`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 35
`decrypted unless all 72,057,590,000,000,000 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(cid:173)
`ministic cipher generator, the best one can hope for is to 40
`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- 45
`graphic algorithm that has been most thoroughly ana(cid:173)
`lyzed and tested under attack and which is now be(cid:173)
`lieved to provide an extremely high level of security. At
`least three levels of encryption algorithms are used in
`scrambling and descrambling the television signal in the so
`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(cid:173)
`scriber key signal that is unique to the descrambler.
`A control computer stores a list of the unique sub(cid:173)
`scriber key signals for the descramblers of the system.
`The control computer also stores a list defining a hierar(cid:173)
`chy of common category key signals corresponding to a
`hierarchy of address groups defmed on the basis of 60
`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(cid:173)
`archy list, a common category key signal corresponding 65
`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 subscnber
`
`10
`
`2
`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(cid:173)
`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(cid:173)
`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(cid:173)
`ization vector signal in accordance with a third encryp(cid:173)
`tion algorithm upon the third algorithm being keyed by
`the working key signal; and scrambles a television sig(cid:173)
`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(cid:173)
`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-
`30 vice is changed.
`Preferably the control computer stores a list defming
`a plurality of channel key signals respectively corre(cid:173)
`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(cid:173)
`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(cid:173)
`nel key signal.
`The scrambled television signal, the initialization
`vector signal, and the group of unique encrypted cate(cid:173)
`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 fust algo(cid:173)
`rithm upon the first algorithm being keyed by the
`55 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(cid:173)
`mon category key signal that is reproduced in the de-
`scrambler in relation to the reproduced common cate(cid:173)
`gory key signal (such as the selected channel key sig(cid:173)
`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 processing the initial(cid:173)
`ization vector signal in accordance with the third algo-
`
`APPLE EXHIBIT 1048
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`IPR2016-00754
`Page 10
`
`

`

`25
`
`3
`rithm upon the third algorithm being keyed by the
`working key signal that is reproduced in the descram(cid:173)
`bler; and descrambles the scrambled television signal,
`when the unique keystream is reproduced in the de(cid:173)
`scrambler, by descrambling the scrambled television 5
`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- 10
`mon category signal.
`Each descrambler includes a secure memory for stor(cid:173)
`ing information that is used for providing the unique
`subscriber key signal in the descrambler. The secure
`memory makes the system of the present invention 15
`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 20
`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(cid:173)
`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 30
`read by the microprocessor, a high level of security
`against disclosing the unit key signal to signal process(cid:173)
`ing methods of analysis is assured.
`In the preferred embodiment, a subscriber key gener(cid:173)
`ation number that is common to all of the subscribers' 35
`descramblers corresponding to selected address group
`is generated by the control computer and communi(cid:173)
`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- 40
`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- 45
`nal by processing the subscriber key generation signal in
`accordance 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 50
`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(cid:173)
`scriber key generation number.
`Although the present invention is described herein as 55
`being applicable to a subscription television system, it
`also is broadly applicable to other types of communica(cid:173)
`tions systems.
`Additional features of the present invention are de(cid:173)
`scribed in relation to the description of the preferred 60
`embodiment.
`
`BRIEF DESCRIPTION OF THE DRAWING
`FIG. 1 is a block diagram of a scrambling system
`according to the present invention.
`FIG. 2 is a block diagram of a preferred embodiment
`of the scrambler key distribution system included in the
`system of FIG. 1.
`
`65
`
`4,613,901
`
`4
`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(cid:173)
`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 10 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(cid:173)
`ing to a selected address group in the hierarchy of ad(cid:173)
`dress groups.
`From the stored subscriber key signal list, the control
`computer 12 generates a group of unique 56-bit sub(cid:173)
`scriber key signals on line 14 corresponding to the se(cid:173)
`lected address group.
`The control computer 12 further stores a list defming
`a plurality of channel key signals respectively corre(cid:173)
`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(cid:173)
`gory address signal on line 16 corresponding to the
`selected address group.
`The control computer 12 generates a 32-bit sub(cid:173)
`scriber key generation number on line 17 that is com(cid:173)
`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(cid:173)
`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(cid:173)
`ated on line 18 by the control computer 12 together
`with the respective unique subscriber key signals gener(cid:173)
`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 lines 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(cid:173)
`vided therefrom to the scrambler key distribution sys(cid:173)
`tem 11.
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 11
`
`

`

`4,613,901
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`25
`
`5
`The process control signals on lines 20 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(cid:173)
`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(cid:173)
`ments 25, 26, 27, 28 and 29 for expanding the signals 10
`respectively received from the control computer 12 on
`lines 19, 15, 16, 13 and 18 to 64 bits. Expansion is accom(cid:173)
`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 IS
`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(cid:173)
`panded to a 64-bit signal on line 31; the 16-bit category 20
`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(cid:173)
`panded to a 64-bit signal on line 33; and the 32-bit sub(cid:173)
`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(cid:173)
`lected channel key signal on line 31 with the category 30
`address signal on line 32 to provide a scrambled selected
`channel key signal on line 37. 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(cid:173)
`vide a scrambled common category key signal on line 35
`38.
`The encrypted category key signal generator 24 gen(cid:173)
`erates a group of unique 64-bit encrypted category key
`signals individually addressed to different selected sub(cid:173)
`scribers' descramblers by processing the scrambled 40
`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(cid:173)
`scriber key signals received on line 14 from the control
`computer 12. The group of encrypted category key 45
`signals are provided sequentially on line 39 to the
`scrambler signal processor 10 (FIGS. 1 and 3).
`The encrypted channel key signal generator 23 gen(cid:173)
`erates a 64-bit encrypted channel key signal by process(cid:173)
`ing the scrambled selected channel key signal on line 37 50
`in accordance with the DES encryption algorithm upon
`the DES algorithm being keyed by the generated com(cid:173)
`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 55
`10.
`The working key signal generator 22 generates a
`64-bit working key signal by processing the initializa(cid:173)
`tion vector signal on line 30 in accordance with the
`DES encryption algorithm upon the DES algorithm 60
`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(cid:173)
`plished by deleting the last eight bits from the 64-bit 65
`signal. In the preferred embodiment, a new working
`key is generated every four TV frames or at a 7.5 Hz
`rate.
`
`6
`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(cid:173)
`rithm upon the DES algorithm being keyed by the
`working key signal on line 43. The unique keystream is
`provided on line 44 to the scrambler signal processor
`10.
`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 47.
`Referring to FIG. 3, the scrambler signal processor
`10 includes a control processor 48, an audio processor
`49, a video amplifier SO, 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/first-out) queue 55, a line buffer control(cid:173)
`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 (D/ 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(cid:173)
`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 processor 49 in accordance with
`a different portion of each frame of the unique keys(cid:173)
`tream from line 44 that is provided to the audio proces(cid:173)
`sor on line 63.
`The video amplifier SO amplifies the video signal on
`line 45 and filters the same to remove any extraneous or
`harmonic signals. The amplified and ftltered video sig(cid:173)
`nal is provided on line 63 to the AID 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
`AID converter 52.
`The AID 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(cid:173)
`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 744 8-bit samples of active video informa(cid:173)
`tion. A first group includes four consecutive odd-num(cid:173)
`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(cid:173)
`secutive even-numbered lines from the same video field.
`One group of odd-numbered lines is stored in the mem(cid:173)
`ory 53 while the information from the previously-stored
`group of odd-numbered lines is retrieved from the mem(cid:173)
`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(cid:173)
`ory 53 while the information from the previously stored
`
`APPLE EXHIBIT 1048
`APPLE v. PMC
`IPR2016-00754
`Page 12
`
`

`

`4,613,901
`
`40
`
`7
`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 memory in a sequence dif(cid:173)
`ferent from that in which it was stored.
`The address counters 54 provide the respective ad(cid:173)
`dresses on line 67 to the memory 53 for storing and
`retrieving video information. These addresses are pro(cid:173)
`vided to the address counters 54 on line 68 via the ad- 10
`dress FIFO queue 55 and line 69 from the control pro(cid:173)
`cessor 48 in accordance with the unique keystream
`provided to the control processor 48 on line 44.
`The line buffer controller 56 provides clocking and
`control signals on lines 70 for synchronizing the opera- 15
`tions of the address FIFO queue 55, the address count(cid:173)
`ers 54 and the memory 53 in accordance with clocking
`and synchronization control signals provided