111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006993134 B 1
`
`(12) United States Patent
`Epstein
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,993,134 Bl
`Jan.31,2006
`
`(54) KEY EXCHANGE VIAA PORTABLE
`REMOTE CONTROL DEVICE
`
`(75)
`
`Inventor: Michael A. Epstein, Spring Valley, NY
`(US)
`
`(73) Assignee: Koninklijke Philips Electronics N.V.,
`Eindhoven (NL)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/370,488
`
`(22)
`
`Filed:
`
`Aug. 9, 1999
`
`(51)
`
`(52)
`
`(58)
`
`Int. Cl.
`H04L 9/00
`(2006.01)
`U.S. Cl. ........................ 380/262; 713/171; 705/66;
`380/283; 380/285; 455/410; 455/352; 455/88;
`348/14.05
`Field of Classification Search .................. 455/88,
`455/352, 410; 348/14.05; 713/171; 705/66;
`380/262, 283-285
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,905,279 A * 2/1990 Nishio ........................ 455!352
`
`5,028,919 A * 7/1991 Hidaka .................. 340/825.72
`5,371,794 A * 12/1994 Diffie et a!.
`.................. 380/21
`5,886,753 A * 3/1999 Shinyagaito ................ 348/734
`
`OTHER PUBLICATIONS
`
`Bruce Schneier: Applied Cryptography 2nd Edition, Oct.
`1995, John Wiley & Sons Pub., pp. 518-520.*
`
`* cited by examiner
`
`Primary Examiner-Emmanuel L. Moise
`Assistant Examiner-Paul E. Callahan
`
`(57)
`
`ABSTRACT
`
`The communications means that are commonly provided for
`the remote control of electronic components are utilized to
`effect an exchange of parameters to facilitate a crypto(cid:173)
`graphic key exchange. The bidirectional remote control
`transceivers, typically infrared transceivers, that are com(cid:173)
`monly used to communicate commands from the remote
`control device and to communicate feedback to the remote
`control device are configured to communicate parameters
`between a pair of consumer devices that are controllable by
`the remote control device. In a preferred embodiment of this
`invention the remote control device contains the control
`means to effect the transfer of these parameters between the
`consumer devices.
`
`8 Claims, 4 Drawing Sheets
`
`SET-TOP BOX
`am
`
`RC XCEIVER
`320
`
`DVD PLAYER
`330
`
`RCXCEIVER
`320
`
`1
`
`TELEVISION/
`DISPLAY DEVICE
`350
`RCXCEIVER
`320
`
`VCR
`360
`
`RC XCEIVER
`320
`
`RC XCEIVER
`320
`REMOTE
`CONTROL
`390
`
`Roku EX1026
`U.S. Patent No. 9,911,325
`
`

`

`U.S. Patent
`
`Jan.31,2006
`
`Sheet 1 of 4
`
`US 6,993,134 Bl
`
`110
`
`120
`
`130
`
`140
`
`131
`
`CONTENT
`MATERIAL
`M
`
`M
`
`150
`
`160
`
`GENERATE RANDOM
`NUMBER y
`
`115
`
`125
`
`135
`
`145
`
`165
`
`150'
`
`M
`
`CONTENT
`MATERIAL
`M
`
`FIG. 1
`PRIOR ART
`
`

`

`U.S. Patent
`
`Jan.31,2006
`
`Sheet 2 of 4
`
`US 6,993,134 Bl
`
`, •
`
`,41
`
`..... ,
`..
`""'
`"'
`......
`,
`;
`...
`,<
`"
`,."
`\
`'-262
`__ ," ,*'"'
`..
`"'
`..
`"'
`,
`"'
`,
`"'
`...
`, ,
`"'
`FIG. 2
`PRIOR ART
`
`SET-TOP BOX
`3l!l
`
`RC XCEIVER
`320
`
`DVD PlAYER
`330
`
`RCXCEIVER
`320
`
`TELEVISION/
`DISPlAY DEVICE
`350
`RCXCEIVER
`J2Q
`
`VCR
`300
`
`RC XCEIVER
`320
`
`RC XCEIVER
`320
`REMOTE
`CONTROL
`390
`FIG. 3
`
`

`

`U.S. Patent
`
`Jan.31,2006
`
`Sheet 3 of 4
`
`US 6,993,134 Bl
`
`411
`
`CONTROLLER
`~
`
`405
`
`APPLIANCE
`FUNCTIONS
`510
`
`CONTROLLER
`530
`
`DEVICE A
`400
`
`KEY
`PARAMETER
`GENERATOR
`540
`
`DEVICE B
`500
`
`/-501
`.... _______ _
`___________ :...-~-
`401-'
`
`~
`
`'
`
`"'-.L
`
`... --
`
`320
`
`DISPLAY
`DISPLAY
`~ 3.00
`REMOTE CONTROL
`DEVICE
`390
`FIG. 4
`
`

`

`U.S. Patent
`
`Jan.31,2006
`
`Sheet 4 of 4
`
`US 6,993,134 Bl
`
`DEVICE A
`~
`
`PREPARE FOR
`912 KEY EXCHANGE
`
`911
`~
`ALERT A
`
`REMOTE DEVICE
`390
`
`ESTABLISH
`NETWORK
`
`913
`~
`ALERTS
`
`GENERATE RANDOM
`922.._ _ _ __.
`NUMBERx
`
`931
`~
`g,n
`
`TRANSMIT
`g, n
`
`933
`~
`g,n
`
`930
`
`DEVICEB
`500
`
`PREPARE FOR
`KEY EXCHANGE
`
`914
`
`GENERATE RANDOM
`NUMBERy
`"--.......----- 924
`
`RECENEX
`
`COMPUTE KEY
`= vxmod n
`
`982
`
`COMPUTE KEY
`=xYmod n
`L . - - - . . . . 1 1 984
`
`FIG. 5
`
`

`

`US 6,993,134 Bl
`
`1
`KEY EXCHANGE VIAA PORTABLE
`REMOTE CONTROL DEVICE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`This invention relates to the field of consumer electronics,
`and in particular to encryption techniques for copy and
`display protection for copyright material.
`2. Description of Related Art
`Digital recordings have the unique property that copies of
`the recorded material have the same quality as the original.
`As such, the need for an effective copy protection scheme is
`particularly crucial for the protection of copyright material 15
`that is digitally recorded. A number of protection schemes
`have been developed or proposed that rely upon a secure link
`between electronic devices. These schemes typically rely
`upon the manufacturers of the electronic devices to comply
`with an agreed upon standard to make the mass production
`of protected material economically infeasible. For example,
`a set top box may communicate a received broadcast to a
`receiving device, such as a VCR or television, in an
`encrypted form that is only decryptable by the intended
`receiving device. In like manner, a playback device, such as 25
`a VCR or DVD, communicates the material in an encrypted
`form that is only decryptable by its intended receiving
`device, and so on.
`To effect this one-to-one encryption scheme, the proposed
`standards often call for the establishment of the encrypted 30
`link via a mutual key exchange. One such key exchange
`system is the "Diffie-Hellman" key-exchange algorithm,
`common in the art. FIG. 1 illustrates an example flow
`diagram for a key-exchange and subsequent encryption of
`content material using the Diffie-Hellman scheme. At 110, a 35
`first device, Device A, transmits a large prime n, and a
`number g that is primitive mod n, as a message 111 to a
`second device, Device B, that receives n and g, at 115. Each
`device, at 120 and 125, generate a large random number, x
`and y, respectively. At 130, Device A computes a number X 40
`that is equal to g" mod n; and, at 135, Device B computes a
`number Y that is equal to gY mod n. Device A communicates
`X to Device B, and Device B communicates Y to Device A,
`via messages 131, 136, respectively. Note that the determi(cid:173)
`nation of x from a knowledge of g and X, and y from a 45
`knowledge of g and Y, is computationally infeasible, and
`thus, an eavesdropper to the exchange of g, n, X, andY will
`not be able to determine x or y. Device A computes a key K
`that is equal to yx mod n, at 140, and Device B computes a
`key K' that is equal to xY mod n, at 145. Note that both K 50
`and K' are equal to g"Y mod n, and thus Device B knows
`Device A's key, and vice versa, while an eavesdropper to the
`exchange of g, n, X, and Y will not know the key, because
`the eavesdropper does not know x or y. This exchange of
`information from which to generate the knowledge of a 55
`corresponding key is termed a key exchange.
`After effecting the key exchange, Device A encrypts the
`content material M 150 and communicates the encrypted
`material Ek(M) to Device B, at 160, via communications
`path 161. Because Device B's key K' is identical to the key
`K that is used to encrypt the content material M 150, Device
`B uses key K' to decrypt the received encrypted material
`Ek(M) to create a decrypted copy 150' of the content material
`M 150, at 165. An eavesdropper to the communications path
`161, not having a knowledge of the key K, is unable to
`decrypt the encrypted material Ek(M), and thus unable to
`create a copy of the content material M 150.
`
`2
`Note that the above described key exchange, and virtually
`all known secure key exchanges, require a bidirectional
`transfer of information between the devices. Many con(cid:173)
`sumer electronic devices, however, are configured for a
`5 unidirectional transfer of content material. For example, as
`illustrated in FIG. 2, a conventional set-top box 210 or DVD
`player 230 includes a wide-bandwidth transmitter for trans(cid:173)
`mitting 211, 212, 231, 232 the content material to a VCR 260
`or display device 250, but rarely includes a receiver for
`10 receiving communications from the VCR or display device.
`In a device such as the VCR 260 that has bidirectional
`communications capabilities 251, 261, the key exchange can
`be effected by multiplexing the key exchange messages 111,
`131, 136 of FIG. 1 onto the same paths 251, 261 that are
`used to communicate content material. Note, however, that
`the adoption of this multiplexing scheme for key exchange
`requires that the receiving device 250 contain receiving
`equipment that is compatible with the transmission 261 of
`content material. Thus, a conventional DVD player 230 that
`transmits 232 wide-bandwidth content material to the VCR
`260 will be required to also contain a wide-bandwidth
`receiver to receive wide-bandwidth content-compatible
`transmissions 262 from the VCR to effect a key exchange,
`even though the DVD player will have no other practical use
`for this wide-bandwidth communications path 262. Note,
`also, that a switching means will be required at the VCR to
`redirect the wide-bandwidth output, from the conventional
`connection 261 to a display device 250, to the DVD player
`via this newly required communications path 262. Alterna(cid:173)
`tively, additional transmitters, receivers, and communica(cid:173)
`tions connectors can be added to each consumer component
`210, 220, 250, 260, etc. to effect the key exchange. Each of
`these options requires additional material and manufacturing
`costs to add the required communications and connection
`equipment.
`
`20
`
`BRIEF SUMMARY OF THE INVENTION
`
`It is an object of this invention to provide a method and
`system for effecting a cryptographic key exchange between
`consumer electronic components that utilizes communica(cid:173)
`tions devices and paths that are common to most consumer
`electronic components. It is a further object of this invention
`to provide an inexpensive system for effecting a crypto-
`graphic key exchange between consumer electronic compo(cid:173)
`nents. It is a further object of this invention to provide a
`method and system for effecting a cryptographic key
`exchange between consumer electronic components that is
`substantially independent of the physical location of the
`components.
`These objects and others are effected by utilizing the
`communications means that are commonly provided for the
`remote control of electronic components to effect a key
`exchange. As more sophisticated capabilities are provided
`for the remote control of equipment, most state of the art
`consumer electronic devices are being configured with bidi(cid:173)
`rectional infrared transceivers for receiving commands
`60 from, and providing feedback to, the remote control device.
`In accordance with this invention, these bidirectional remote
`control transceivers are configured to communicate the
`parameters required
`to effect
`the cryptographic key
`exchange between consumer devices. The principles pre-
`65 sented in this invention may also be used to transfer other
`parameters and information among consumer electronic
`devices. In a preferred embodiment of this invention a
`
`

`

`US 6,993,134 Bl
`
`3
`remote control device contains the control means to effect
`the transfer of these parameters between the consumer
`devices.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention is explained in further detail, and by way of
`example, with reference to the accompanying drawings
`wherein:
`FIG. 1 illustrates an example flow diagram of a prior art
`cryptographic key exchange technique.
`FIG. 2 illustrates an example block diagram of a prior art
`system of consumer electronic devices.
`FIG. 3 illustrates an example block diagram of a system
`of consumer electronic devices with bidirectional remote
`control capabilities in accordance with this invention.
`FIG. 4 illustrates an example block diagram of a pair of
`consumer electronic devices and a remote control device in
`accordance with this invention.
`FIG. 5 illustrates an example flow diagram of a key
`exchange via a remote control device in accordance with this
`invention.
`Throughout the drawings, same reference numerals indi(cid:173)
`cate similar or corresponding features or functions.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`With the increasing use of convenience features for home
`automation and integrated audio-visual systems, the tradi(cid:173)
`tional function of a remote control device has expanded to
`include feedback from the device being controlled. Copend(cid:173)
`ing U.S. patent application "REMOTE CONTROL PRO(cid:173)
`GRAM SELECTION BY GENRE", U.S. Ser. No. 09/282,
`319, filed Mar. 31, 1999 for Karen Travato, Dan Pelletier,
`Paul Rankin, and Jacquelyn Martino, for example, presents
`a remote control device that receives program information
`from the television, DVD or set-top box for display on the
`remote control device to facilitate a user selection among
`available programs, or to present information about a pro(cid:173)
`gram currently being viewed, and is incorporated by refer(cid:173)
`ence herein. Most state of the art consumer electronic
`devices contain bidirectional communications means, typi(cid:173)
`cally an infrared transceiver, for communicating with a
`remote control device. The conventional "universal" remote
`control device includes such a bidirectional transceiver that
`can be configured to receive infrared codes from sole(cid:173)
`appliance remote control devices to "learn" how to control
`each appliance.
`FIG. 3 illustrates a collection of consumer electronic
`devices that are controllable by a remote control device 390.
`Each consumer device, the set-top box 310, the DVD player
`330, the display device 350, and the VCR 360, contains a
`conventional remote control transceiver 320 for receiving
`commands from, and providing feedback to a corresponding
`conventional remote control transceiver 320 in the remote
`control device 390. In accordance with this invention, the
`remote control transceiver 320 in each device is also used to
`effect a cryptographic key exchange by communicating
`parameters to each other. Note that although this invention
`is presented in the context of transferring key-exchange
`parameters, any other parameters or information items may
`also be communicated among devices via the remote control
`transceivers 320 in the light of this disclosure.
`The communication of parameters between consumer
`electronic devices 310, 330, 350, and 360 can be effected via
`a direct communication between each pair of devices, but in
`
`5
`
`4
`a preferred embodiment, the remote control device 390
`effects a relay, or store-and-forward function, to facilitate the
`parameter exchange. Typically, remote control transceivers
`320 use line-of-sight communications means, such as infra-
`red transmissions. Often, consumer electronic devices are
`placed in close proximity to each other, with each remote
`control transceiver 320 oriented in the same direction,
`toward the expected location of a user of the remote control
`device 390. As such, adjacent devices are not within the line
`10 of sight of each other's remote control transceiver 320.
`Because each of the adjacent devices are, by intent, within
`the line of sight of the remote control device 390, the remote
`control device 390 is well suited to be a relay between the
`adjacent devices. Also, when the consumer devices are not
`15 adjacent to each other, they are often located in physically
`separate areas. For example, a home may be configured to
`allow a television in a bedroom to receive content material
`from a VCR that is located in a family room. By configuring
`the remote control device 390 as a store and forward relay
`20 system, the remote control device 390 can be configured to
`receive a parameter from a device in one room, then transmit
`the parameter to another device when it is brought into the
`proximity of the other device. It can then receive a parameter
`from the other device, and transmit it to the original device
`25 when it is brought into the proximity of original device.
`Copending U.S. patent application, "REMOTE CONTROL
`DEVICE WITH LOCATION DEPENDENT INTER(cid:173)
`FACE", U.S. Ser. No. 09/210,416, filed Dec. 11, 1998 for
`Joost Kemink and Yevgeniy Shteyn, presents a remote
`30 control device whose operation is dependent upon the physi(cid:173)
`callocation of the device, and is incorporated by reference
`herein. Note that the parameter exchange for a key exchange
`need only occur once between the devices; thereafter, the
`encrypted content material
`is communicated between
`35 devices in separate rooms via the aforementioned conven(cid:173)
`tional wide-bandwidth channels, using, for example, coaxial
`cable between the rooms.
`FIG. 4 illustrates an example block diagram of a pair of
`consumer electronic devices 400, 500 and a remote control
`40 device 390 in accordance with this invention. Each of the
`devices 400, 500, and 390 includes a remote control trans(cid:173)
`ceiver 320 that is illustrated as a transmitter 320A and a
`receiver 320B. The devices 400, 500 may be any pair of
`consumer devices that have a need to transfer parameters,
`45 such as the devices 310, 330, 350, 360 of FIG. 3. As noted
`above, an exchange of parameters via the consumer devices
`400 and 500 may be effected in accordance with this
`invention via direct communication paths 401, 501, but
`often such paths may not be physically practical to establish.
`50 In a preferred embodiment of this invention, the remote
`control device 390 facilitates the parameter transfer via a
`store-and-forward relay technique. The operation of the
`devices 400, 500, 390 to effect the parameter transfer is best
`explained with reference to the example flow diagram of
`55 FIG. 5. In the foregoing description, transmissions from
`each device 400, 500, and 390 are via the transmitter 390A
`within each device 400, 500, and 390, and receptions at each
`device 400, 500, and 390 are via the receiver 390B within
`each device 400, 500, and 390. The respective controllers
`60 430, 530, and 393 of the devices 400, 500, 390, effect the
`example flow of FIG. 5, respectively.
`At 910 of FIG. 5, the controller 393 of the remote control
`device 390 transmits an alert message 911, 913 to each
`device 400, 500, respectively, to establish the network of
`65 communications among the devices 400, 500, 390. Methods
`for communication among different devices are common in
`the art and traditionally used for commonly available "uni-
`
`

`

`US 6,993,134 Bl
`
`5
`
`5
`versal" remote controllers. In a preferred embodiment, the
`establishment of the network at 910 may be initiated via an
`entry on the keypad 398, or via the receipt of a request (not
`shown) from, for example, device A, signaling that it has
`content material to communicate to device B, and requesting
`that the remote device 390 facilitate the parameter transfer
`required to effect a key exchange between device A and
`device B.
`Upon receipt of the alert 911, 913 the controllers 430, 520
`of each device 400, 500 prepare for the key exchange, at
`912, 914, respectively. Illustrated in the example of FIG. 5
`is a key exchange based on the Diffie-Hellman key exchange
`technique. The application of the principles of this invention
`to other key exchange techniques, or other parameter
`exchange applications, will be evident to one of ordinary
`skill in the art in light of the principles presented herein.
`Each device 400, 500 generates a large random number x, y
`via their respective key parameter generators ( 440, 540 in
`FIG. 4). Techniques for generating or selecting random
`numbers, or pseudo-random numbers, are common in the 20
`art. To effect the Diffie-Hellman key exchange, the remote
`control device 390 transmits, at 930, a large prime n, and a
`number g that is primitive mod n, to each device 400, 500,
`via messages 931, 933, respectively. At 932, 934, each
`device computes the parameter X, Y that is to be transferred, 25
`based on the "secret" random numbers x, y, respectively. In
`the example Diffie-Hellman key exchange, X is equal to g"
`mod n, and Y is equal to gy mod n.
`Based upon an agreed upon convention, or protocol, one
`of the devices transmits its parameter first. In a preferred 30
`embodiment, the device having content material to send,
`device A 400 in the illustrated example, transmits its param(cid:173)
`eter X 941 to the remote device 390, at 942. As would be
`evident to one of ordinary skill in the art, any one of a variety
`of protocols may be employed to effect this transmission. 35
`For example, the remote device 390 may send a prompt to
`each device whenever it is ready to receive the parameter, or
`the device 400, 500 may repeatedly send the parameter until
`the remote device 390 sends an acknowledgment that it
`received the parameter, and so on. Because the encryption 40
`and subsequent decryption of the content material is depen(cid:173)
`dent upon an accurate communication of the parameters X,
`Y, error checking and error correction techniques, common
`in the art, are employed in a preferred embodiment. The
`parameter X 941 is received from the device A 400, at 940, 45
`and subsequently transmitted to device B 500, at 950.
`Device B receives the parameter X 941, at 954, and trans(cid:173)
`mits its parameter Y 963 to the remote control device 390,
`at 964. The remote control device 390 receives the param(cid:173)
`eter Y 963, at 960, and, within the locale of device A 400, 50
`transmits the parameter Y 963 to device A 400. Each device
`400, 500 subsequently computes a key that is equal to i(Y
`mod n by raising the received parameter Y, X to the power
`of the "secret" random number x, y, at 982, 984, respec(cid:173)
`tively.
`If the devices are in physically separate locales, the
`remote control device 390 transmits the alert 911, and
`parameters g, n 931 to device A 400 and receives the
`parameter X 941, at 940, and is then transported to the locale
`of device B 500. At the locale of device B 500, the control 60
`device 390 transmits the alert 913, the parameters g, n 933,
`and the parameter X 941, at 950.
`Returning to FIG. 4, having exchanged parameters X, Y,
`the key parameter generators 440, 540 provide the deter(cid:173)
`mined key K, K', each equal to ifY mod n, to their corre- 65
`sponding encryptor 420 and decryptor 520 devices, respec(cid:173)
`tively. Each of the devices 400, 500, is illustrated as having
`
`6
`an appliance function block 410, 510, respectively. These
`blocks 410, 510 represent the convention functions provided
`by each device, such as the receipt of content material by a
`set-top box, the recording and playback functions of a VCR,
`the display and tuning functions of a television, and so on.
`Note that, in conventional use, the appliance functions 410,
`510 are controllable by the remote control device 390, and
`feedback from the appliance functions 410, 510, or the
`controllers 430, 530, are provided to the remote control
`10 device 390, via the transmitters 320A and receivers 320B of
`each device 400, 500, 390. Feedback messages are display(cid:173)
`able on the display 395 of the remote control device 390, and
`may include messages and prompts that are applicable to the
`above described parameter exchange process or other related
`15 tasks.
`When the device A 400 has content material M 411 to
`communicate securely to device B 500, the material M 411
`is encrypted by the encryptor 420 to provide an encrypted
`material Ek(M) 421. The encrypted material Ek(M) 421 is
`subsequently communicated to device B 500, via a wide(cid:173)
`bandwidth communications channel 405. The decryptor 520
`decrypts the received encrypted material Ek(M)' 421' to
`produce a copy of the content material M' 411' that is
`processable by the appliance function 510, for example, to
`render a display of the content material M' 411' correspond(cid:173)
`ing to the original material M 411.
`The foregoing merely illustrates the principles of the
`invention. It will thus be appreciated that those skilled in the
`art will be able to devise various arrangements which,
`although not explicitly described or shown herein, embody
`the principles of the invention and are thus within its spirit
`and scope. For example, the control flows illustrated in FIG.
`5 may be effected automatically, or via a sequence of
`operations communicated via the keypad 398 of the remote
`control device 390 in FIG. 4. The particular configurations
`and sequences of the figures are presented for illustration
`purposes. The functions illustrated may be effected, for
`example, in alternative devices. For example, the parameters
`g and n may be provided by one of the devices 400, 500,
`rather than the remote device 390. In other systems, com(cid:173)
`mon in the art, one or more of the parameters may be
`embedded in the devices 400, 500, obviating the need for
`random number generators. If the parameters X and Y are
`embedded in the device, certificates verifying the authen(cid:173)
`ticity of these parameters may also be supplied. In like
`manner, either of the devices 400, 500 may be configured to
`control the parameter exchange, and the remote control may
`be configured as a relatively "unintelligent" relay device.
`For example, the messages from the transmitters 320A may
`include conventional communications packets having a des(cid:173)
`tination address, and the remote device 390 may be config(cid:173)
`ured to merely receive the packet and retransmit it to the
`device associated with the destination address. These and
`other system configuration and optimization features will be
`55 evident to one of ordinary skill in the art in view of this
`disclosure, and are included within the scope of the follow(cid:173)
`ing claims.
`
`I claim:
`1. A remote control device that is configured to facilitate
`control of a plurality of electronic devices, comprising:
`an input device that is configured to accept a user input
`and provides therefrom a control signal for control of a
`first device of the plurality of electronic devices;
`a receiver that is configured to receive a parameter from
`a second device of the plurality of electronic devices;
`a transmitter that is configured to:
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`communicate the parameter from the second device to
`the first device;
`communicate the control signal to the first device to effect
`the control of an appliance function of the first device;
`and
`a controller that effects the communication of the param(cid:173)
`eter and the other parameter,
`wherein
`the receiver is further configured to receive an other
`parameter from the first device, and
`the transmitter is further configured to communicate the
`other parameter from the first device to the second
`device, and
`wherein the controller effects the communication of the
`parameter and the other parameter to establish a cryp- 15
`tographic key exchange.
`2. The remote control device of claim 1, wherein the
`cryptographic key exchange corresponds to a Diffie-Hell(cid:173)
`man key exchange.
`3. An electronic device comprising:
`a transceiver that is structured to receive control com(cid:173)
`mands from a remote control device,
`an appliance apparatus that effects a processing of input
`information in dependence upon the control com(cid:173)
`mands,
`a parameter generator that produces a parameter for
`communication to an other device, and wherein,
`the transceiver is also structured to transmit the parameter,
`thereby effecting the communication of the parameter
`to the other device, wherein
`the transceiver is also structured to receive an other
`parameter that is communicated from the other device
`and wherein
`the parameter generator also produces
`a cryptographic key based on the other parameter that is 35
`communicated from the other device.
`4. The electronic device of claim 3, wherein the parameter
`generator produces the parameter and the cryptographic key
`in accordance with a Diffie-Hellman key exchange tech(cid:173)
`nique.
`5. A method for effecting a parameter exchange between
`a first device and a second device, the first device and the
`second device each having a transceiver that communicates
`with a remote control device to facilitate control of the first
`device and the second device via the remote control device, 45
`the method comprising:
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`30
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`40
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`US 6,993,134 Bl
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`5
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`10
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`transmitting a first parameter from the first device via a
`transmitter of the transceiver of the first device;
`receiving the first parameter at the second device via a
`receiver of the transceiver of the second device;
`receiving the first parameter at the remote control device;
`transmitting the first parameter to the second device from
`the remote control device;
`transmitting a second parameter from the second device
`via a transmitter of the transceiver of the second device;
`receiving the second parameter at the first device via a
`receiver of the transceiver of the first device; and
`receiving the second parameter at the remote control
`device; and
`transmitting the second parameter to the first device from
`the remote control device.
`6. A method for effecting a parameter exchange between
`a first device and a second device, the first device and the
`second device each having a transceiver that communicates
`with a remote control device to facilitate control of the first
`20 device and the second device via the remote control device,
`the method comprising:
`transmitting a first parameter from the first device via a
`transmitter of the transceiver of the first device;
`receiving the first parameter at the second device via a
`receiver of the transceiver of the second device;
`receiving the first parameter at the remote control device;
`transmitting the first parameter to the second device from
`the remote control device;
`transmitting a second parameter from the second device
`via a transmitter of the transceiver of the second device;
`receiving the second parameter at the first device via a
`receiver of the transceiver of the first device;
`generating a first cryptographic key at the first device
`based on the second parameter; and
`generating a second cryptographic key at the second
`device based on the first parameter,
`wherein the second cryptographic key is suitable for a
`decryption of material that is encrypted using the first
`cryptographic key.
`7. The method of claim 6, wherein the first cryptographic
`key and the second cryptographic key are equal.
`8. The method of claim 6, wherein the generating of the
`first and the second cryptographic keys is based on a
`Diffie-Hellman key-exchange technique.
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`* * * * *
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