WO1986007224A1 - Method and apparatus for scrambling and descrambling television signals - Google Patents
Method and apparatus for scrambling and descrambling television signals Download PDFInfo
- Publication number
- WO1986007224A1 WO1986007224A1 PCT/US1986/000801 US8600801W WO8607224A1 WO 1986007224 A1 WO1986007224 A1 WO 1986007224A1 US 8600801 W US8600801 W US 8600801W WO 8607224 A1 WO8607224 A1 WO 8607224A1
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- WO
- WIPO (PCT)
- Prior art keywords
- key
- encrypted
- code
- encryption key
- descrambling
- Prior art date
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
- H04L9/0822—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using key encryption key
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0891—Revocation or update of secret information, e.g. encryption key update or rekeying
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/14—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols using a plurality of keys or algorithms
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/234—Processing of video elementary streams, e.g. splicing of video streams, manipulating MPEG-4 scene graphs
- H04N21/2347—Processing of video elementary streams, e.g. splicing of video streams, manipulating MPEG-4 scene graphs involving video stream encryption
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
- H04N21/266—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel
- H04N21/26606—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/44—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream, rendering scenes according to MPEG-4 scene graphs
- H04N21/4405—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream, rendering scenes according to MPEG-4 scene graphs involving video stream decryption
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/16—Analogue secrecy systems; Analogue subscription systems
- H04N7/167—Systems rendering the television signal unintelligible and subsequently intelligible
- H04N7/1675—Providing digital key or authorisation information for generation or regeneration of the scrambling sequence
Definitions
- the present invention relates generally to the field of communication systems and, more particularly, is directed to a method and apparatus for scrambling and descrambling television signals in a subscription television system.
- the active line period includes one signal which simultaneously represents the instantaneous values of three independent color components.
- the method by which the three color components are coded into one signal is standardized throughout North America, Canada and Japan. This method is known as the NTSC standard.
- Alternative standards known as PAL and SECAM have been adopted in other countries but these standards have the same basic format as the NTSC standard, including a line blanking interval and an active line period in each scan line.
- analogue video signals which are particularly adapted for transmission by satellite and cable, and which lead to improved picture quality in comparison with existing standards, are presently being studied. Such signals are of particular importance to the subscription television field and are based on a time multiplex of the three independent color components during the active line periods of the scan line. Instead of coding the three components into one signal using the NTSC, PAL or SECAM - standard, the components are converted to digital form and sent sequentially using a time- compression technique.
- MAC Multiplexed Analogue Components
- Signals generated by a time compression technique also adhere to the same basic format as the NTSC, PAL and SECAM standards, including the presence of a line blanking interval and an active line period in each scan line.
- the audio portion of the signal may be converted to digital form and transmitted during the line blanking int erval as digi tal da ta.
- the line blanking interval is ofter referred to as the "data channel" and can include several multiplexed data signals.
- the color components, audio signals and any signals in the data channel can be collectively referred to as the intelligence portion of the television signal.
- scrambling a television signal selected parameters of the ana ⁇ logue video components of the signal are modified in accordance with pseudo-random scrambling codes.
- the codes can be signaled to the television receiver in the data channel of the signal and are used by a decoder at the receiver to descramble the video components for reconstruction to the appropriate format for viewing.
- the data channel may also be securely encrypted to further frustrate reception of the signal by unauthorized persons.
- Encryption and decryption are applied to digital data signals and scrambling and descrambling are applied to analogue signals. This distinction is drawn because of the fundamental difference between digital and analogue signals. Digital signals are defined at the bit level where each bit is independent of its neighboring bits. Any encoding, transformation or inversion of the data bits which make up the signal does not affect the signal's transmission characteristics at the bit level.
- an encrypted digital signal contains all of the information present in the original signal and may be precisely restored to the original signal by decryption.
- Analogue signals cannot be modified or changed without affecting their transmission characteristics. For example, changing the value of a point on the waveform of an ana ⁇ logue signal without reference to neighboring points on the waveform increases the bandwidth of the signal. Thus, the modified signal requires a wider bandwidth for accurate transmission. Therefore when scrambling an analogue signal, parameters must be selected which result in the least amount of change in transmission characteristics of the signal. Numerous methods may be used to scramble a television signal by modifying the analogue color components of the signal.
- Such methods include modifying the amplitude of the color components, modifying the time at which the color components are transmitted and modifying both the amplitude and transmission time of the color com ⁇ ponents.
- Each modification is, of course, done in accordance with a prescribed pattern which may be transmitted to the receiver in the data channel of the television signal.
- An example of scrambling a tel ⁇ evision signal by modifying the time at which the color components are transmitted is disclosed in commonly assigned U.S. Patent Appli ⁇ cation Serial No. 507,765 entitled “Encryption and Decryption (Scram ⁇ bling and Descrambling) of Video Signals" filed June 24, 1983. Said application is incorporated herein by reference.
- the color components could also be encrypted while being converted to digital form for time-compressed transmission, as for example in a MAC television signal.
- Such an encryption method is disclosed in commonly assigned U.S. Patent Application Serial No. 736 J01 entitled “Method and Apparatus for Creating Encrypted and Decrypted Television Signals” filed May 21, 1985. This application is also incorporated herein by reference.
- the audio component of the television signal can be scrambled in its analogue form or can be converted to digital form, encrypted and transmitted in the data channel.
- the bit configuration of the digital data signal to be encrypted is modified according to a pattern which is determined at the transmitter.
- the pattern generally is a member of a large class of similar patterns such that discovery of the pattern through exhaustive search Is extremely unlikely.
- a precise description of the pattern used for encryption is delivered to a decoder in desig ⁇ nated receivers which then is able to recover the original distribution.
- the description of the pattern is known in the art as the "encryption key” and the process of informing designated users of the encryption key, or more appropriately the “decryption key,” is known as "key distribution.”
- the decryption key is derived from the encryption key and permits the encrypted information to be returned to its original form.
- the decryption key i.e., the reverse of the encryption key
- the decryption key for decrypting the channel must be com mon to all users.
- Use of a common decryption key requires that means be provided to prevent circulation of the decryption key to those who are not subscribers to the system or to subscribers who are not presently in good standing.
- an object of the present invention to provide a method and apparatus for securely scrambling a television signal.
- ⁇ common decryption must be distributed in such a manner that unauthorized recipients cannot receive the key.
- One such way of providing this security is to change the decryption key at short intervals (say for exa m ple, every minute), thereby forci ng an unauthorized user of the service to maintain a permanent link with an authorized user so that he may continuously receive the upda t ed decryption key.
- a second way of fouling unauthorized reception of the decryption key is to perform a secondary encryption of the decryption key and to integrate the decryption key acquisition system at the receiver with data channel decryption in a single device which is dif ⁇ ficult to copy.
- the method and apparatus for securely scrambling a television signal in accordance with the present invention comprises a three-tier encryption technique.
- a distribution key is used to encrypt a session key.
- the distribution key is unique for each subscriber and is held constant for long periods of time.
- the session key is changed periodically, as for example, weekly or monthly.
- the encrypted session key is then transmitted in the digital data channel of the television signal.
- the session key is also used to encrypt a descramble code.
- the descramble code includes a plurality of keys which are used in the receiver to descramble or decrypt various signals in the receiver, such as the scrambled video components and/or audio signals.
- the descramble code is also changed periodically, e.g., four times per second in order to provide additional security.
- the encrypted descramble code is then transmitted in the data channel of the television signal.
- the encrypted session key is decrypted by a distribution key so that the session key can be used to dec : the encrypted descramble code.
- the descramble code may then be .ed to descramble or decrypt other signals in the receiver, such as the scram ⁇ bled video components and/or audio signals.
- a validation code is also transmitted in the data channel of the television signal.
- the validation code received by the receiver is compared to a locally derived validation code which is developed from the decrypted session key.
- the decrypted session key is permitted to decrypt the descram ble code.
- the decrypted descramble code may then be used to decrypt and/or descramble other signals in the receiver.
- Figures 1 and 2 are graphical representations of a line scanned television signal.
- Figure 3 is a block diagram of one embodiment of a system for encrypting the code used to descramble and/or decrypt the intelligence portion of a television signal in accordance with the present invention.
- Figure 4 is a block diagram of one embodiment of a system for decrypting the code used to descramble and/or decrypt the intelligence portion of a television signal in accordance with the present invention.
- Figures 5, 6 and 7 are block diagrams of other embodiments of a system for decrypting the code used to descramble and/or decrypt the intelligence portion of a television signal in accordance with the present invention.
- Figure 8 is a block diagram of one- example of a subscription television decoder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
- Figures 3 and 4 are block diagrams of one embodiment of a system for scrambling television signals in accordance with the present invention.
- Figure 3 illustrates encryption at the transmitter end and
- Figure 4 illustrates decryption at the receiver end.
- a session key 30 is encrypted in block 33 with a distribution key 32.
- the distribution key is unique for each subscriber and is held constant for long periods of time.
- the session key is changed at predetermined intervals, e.g., weekly or monthly.
- the encrypted session key is then transmitted in the digital data channel of the television signal.
- the session key is also used to encrypt a descrambling code 31.
- the descrambling code includes keys for descrambling and/or decrypting various signals in the receiver.
- These signals may include the scrambled video components of the tele ⁇ vision signal, scrambled or encrypted audio signals and/or other signals which may require descrambling or decryption at the receiver.
- the encrypted descrambling code is also transmitted in the digital data channel of the television signal.
- the descrambling code may also be regularly updated, e.g., four times per second, in order to provide fur ⁇ ther security.
- block 40 represents the received digital data channel of the television signal which includes the encrypted session key and the encrypted descrambling code as shown in Figure 3.
- the encrypted session key is provided to block 43 along with a distribution key 41.
- the distribution key is assigned to sub ⁇ scribers in return for a paid subscription to the system.
- the key is unique to each individual subscriber, or is part of a set of keys large enough to prevent key swapping.
- Distribution key 41 may be the same as or derived from distribution key 32 shown in Figure 3.
- the encrypted session key is transmitted in the data channel by the televi ⁇ sion transmitter individually for each distribution key 41 in use.
- Distribution key 41 is fixed for long periods of time and is maintained secret from the subscriber.
- One such way of maintaining the distribution key in confidence is to build it inside a custom inte ⁇ grated circuit as indicated by reference No. 42 which also executes session key decryption as shown in block 43.
- the digital bit pattern of the distribution key is also made long enough to prevent its dis ⁇ covery through exhaustive search.
- the encrypted session key is decrypted in block 43 by the distribution key and is supplied to block 44 along with the encrypted descrambling code from the data channel.
- the descrambling code is decrypted in block 44 by the now decrypted session key and is then available for descrambling or decrypting other signals such as the analogue color components of the television signal as shown in block 45, the audio portion of the televi ⁇ sion signal as shown in block 46 and any other signals in the receiver which may require descrambling or decryption as shown in block 47.
- the present invention provides three tiers of encryption and decryption before the scrambled or encrypted signal is returned to its original form.
- Figure 5 is a further embodiment of the present invention with respect to decryption at the receiver end. Similar reference numbers are used to identify corresponding elements shown in Fiugre 4.
- the audio portion of the television signal is encrypted and transmitted in the data channel.
- the audio and descramble code are decrypted in block 44 using the decrypted session key from block 43 as described above.
- FIG. 6 A further embodiment of the present invention with respect to decryption at the receiver end is shown , in Figure 6.
- only one encrypted session key is transmitted to all users. All users employ the same distribution key D but its derivation for each subscriber is unique.
- the distribution key D is derived from a fixed key K and a subscriber code C.
- Block 50 represents the received digital data channel of the television signal which includes the encrypted session key and the encrypted video descramble code.
- the encrypted session key is provided to block 54 where the fixed key K is maintained secret.
- the subscriber code C from block 51 is also unique to the subscriber and is entered manually by the subscriber.
- the distribution key D can be changed at infrequent intervals by updating the manual input code C.
- Distribution key D is derived from fixed key K and subscriber code C in block 52.
- the encrypted session key is thus decrypted in block 54 by the derived distribution key D and is supplied to block 55 along with the encrypted descrambling code from the data channel.
- the descrambling code is decrypted in block 55 by the now decrypted session key and is then available for descrambling or decrypting signals in the receiver as represented by blocks 56, 57 and 58.
- FIG. 7 A further embodiment of the present invention with respect to decryption at the receiver end is shown in Figure 7.
- the data channel of the signal includes the encrypted ses ⁇ sion key, a unique validation code based on the decoder's address or serial number and the encrypted descrambling code.
- the session key is provided to block 62 where it is decrypted by a distribution key from block 61.
- the decrypted encryption key is then provided to block 64 where a unique 32 bit internal validation code is derived based on the session key and the address or serial number of the decoder.
- the derived validation code is compared to the validation code transmitted in the data channel and if the two match, a logic signal is provided to AND gate 66.
- AND gate 66 allows the decrypted session keys from block 62 to pass through to block 67 only when the derived internal validation code matches the validation code transmitted in the data channel. The session key may then be used by block 67 to decrypt the descrambling code.
- every session is 30 seconds in duration and within this period, every decoder decrypts the session key for the next session.
- the session key is derived within a custom integrated circuit as indicated by reference number 62 in Figure 7 which is very difficult to copy.
- the session key currently being used to decrypt the video descrambling codes in the data channel is also employed to derive the internal validation code. Single-bit error correction is applied to the received validation codes which are 32-bits in length (sufficient to address up to 4 billion decoders).
- the session key is released from the custom IC only if an appropriate validation code has been received some time during the last 7 hours of operation on any particular television channel.
- the validation codes (with error correction bits) comprise a 39 bit word, these being transmitted in a 250 Kb/s channel. Twenty mil ⁇ lion receivers are thereby addressable within each 52 minute period. Over a period of 7 hours, each decoder will be validat ed on 8 separate occasions with a single-error corrected code. With a BER of 10-2, failure of validation at each attempt would occur with probability 0.044. Failure on all eight attempts would occur with a probability 1.4 x 10-11 (MTBF 100 million years).
- validation codes are that (unlike session keys) they can be received incorrectly for much of the time without affecting service to the customer. Therefore they do not require extensive error correction.
- the address cycle time is 26 minutes. If most decoders were operating at 10-3 BER, then 99.95% of the decoders would be validated within the normal transmission time of a typical TV program.
- the television receiver should automatically switch between commonly used channels to gather validation codes when in standby operation.
- standby operation is not a mandatory requirement provided that session counts (since the last validation) are stored (within the secure IC) in non- violatile memory, and that the receiver is operational for at least one continuous period of 52 minutes during each 7 hour period of use.
- the receiver can keep track of operational periods and e xtend the 7 hour limi t to an arbitrary maximum to ensure a predetermined probability of receiving a validation code.
- the receiver could issue messages (via teletext display) requesting a period of operation or standby mode when (according to its counters) only one hour of validation remains.
- the receiver need not turn off the service completely, i.e., stop descrambling the signal, but, instead, initiate a period of decreasing service, as for example, starting with several hours of monochrome reception.
- the function of the validation codes is to allow the receiver to 'form a view' concerning the validity of reception for each of the channels in use.
- the receiver should act intelligently to gather the necessary evidence for its decision, and take action only when sufficient evidence is at hand. In the embodiment shown in Figure 7, within 10 seconds of being switched on (or immediately if in standby mode) the security device has decrypted the session key for the next session.
- any device designed to deliver session keys, with or without validation, must make use of the distribution keys D (presumably acquired by breaking into one of the security devices). If pirate receivers are discovered which contain particular distribution keys, the corresponding session key encryptions may be excluded from the key distribution channel on condition that all other decoders are left with at least at one key (D) capable of decrypting session keys. This can be arranged by providing each decoder with four keys selected from the 3,000, no two decoders having the same set of four keys. There are 3.3 x 10---2 ways of selecting four differ ⁇ ent keys from 3,000.
- a scrambled MAC television signal first enters a multiplexer 300, which separates from it the luminance and chrominance signals (i.e., the color components), as well as the audio, synchronization, timing and any teletext information.
- the luminance signal is delivered to luminance store 302, a CCD line store, where it is decompressed, and then to low-pass filter 304, where it is filtered.
- the analog luminance signal then goes to output interface 306.
- the sampling signals necessary to decompress luminance are produced in timing generator 308 and supplied to luminance store 302 by two clock drivers 310.
- the chrominance signal from demultiplexer 300 is also decom ⁇ pressed in chrominance store 312, which is also a CCD line store. Separate outputs are provided for the two color difference signals, which are filtered in two low-pass filters 314 and then supplied to output interface 306. The necessary sampling signals are supplied to chrominance store 312 from timing generator 308 through three clock drivers 310.
- Signals not constituting luminance or chrominance are also separated from the MAC television signal by demultiplexer 300.
- These signals include audio, teletext and synchronization signals which are delivered to demultiplexer 316 through one of two low-pass filters 318; while the fixed-frequency ti mi ng infor mation is delivered to demultiplexer 316 through band-pass filter 320.
- Demultiplexer 316 separates these signals, supplying the audio to audio demultiplexer 322 and the synchronization and timing signals to clock and synchronization recovery circuit 324 and timing generator 308.
- Audio information from de m ulti plexer 316 is separated into four cha nnels i n a ud i o demultiplexer 322 and output by analog audio processor 326.
- Teletext information is sent to character generator 328 via clock and synchro ⁇ nization recovery circuitry 324.
- Decoder operations are under the con ⁇ trol of microprocessor 330, which communicates with clock and syn ⁇ chronization recovery circuit 324, teletext character generator 328, and RAM 332 over bidirectional buses 334, 336 and 338.
- Output interface 306 receives teletext characters from character generator 326, luminance from low-pass filter 304, chrominance from low-pass filters 314, and timing signals from timing generator 308. Its output is a standard NTSC color television signal for display on a tele ⁇ vision receiver.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US73759985A | 1985-05-24 | 1985-05-24 | |
US737,599 | 1985-05-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1986007224A1 true WO1986007224A1 (en) | 1986-12-04 |
Family
ID=24964519
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1986/000801 WO1986007224A1 (en) | 1985-05-24 | 1986-04-21 | Method and apparatus for scrambling and descrambling television signals |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0222818A1 (en) |
JP (1) | JPS62503066A (en) |
CN (1) | CN86103053A (en) |
AU (1) | AU5812086A (en) |
WO (1) | WO1986007224A1 (en) |
ZA (1) | ZA862839B (en) |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2241096A (en) * | 1990-02-14 | 1991-08-21 | Enfranchise Sixty Ltd | Controlling access to broadcast signals |
EP0809402A1 (en) * | 1990-02-01 | 1997-11-26 | Scientific-Atlanta, Inc. | External security module for a television signal decoder |
DE19726003A1 (en) * | 1997-06-19 | 1998-12-24 | Alsthom Cge Alcatel | Method for transmitting encrypted signals, and transmitting device and receiving device therefor |
EP0937348A1 (en) * | 1996-11-07 | 1999-08-25 | MCI Worldcom, Inc. | System and method for providing security in data communication systems |
WO2000059222A1 (en) * | 1999-03-30 | 2000-10-05 | Sony Electronics, Inc. | Method and apparatus for securing control words |
EP1418750A1 (en) | 2002-11-11 | 2004-05-12 | STMicroelectronics Limited | Security integrated circuit |
US7039614B1 (en) | 1999-11-09 | 2006-05-02 | Sony Corporation | Method for simulcrypting scrambled data to a plurality of conditional access devices |
US8098818B2 (en) | 2003-07-07 | 2012-01-17 | Qualcomm Incorporated | Secure registration for a multicast-broadcast-multimedia system (MBMS) |
US8121296B2 (en) | 2001-03-28 | 2012-02-21 | Qualcomm Incorporated | Method and apparatus for security in a data processing system |
US8713400B2 (en) | 2001-10-12 | 2014-04-29 | Qualcomm Incorporated | Method and system for reduction of decoding complexity in a communication system |
US8718279B2 (en) | 2003-07-08 | 2014-05-06 | Qualcomm Incorporated | Apparatus and method for a secure broadcast system |
US8971790B2 (en) | 2003-01-02 | 2015-03-03 | Qualcomm Incorporated | Method and apparatus for broadcast services in a communication system |
US8983065B2 (en) | 2001-10-09 | 2015-03-17 | Qualcomm Incorporated | Method and apparatus for security in a data processing system |
US9100457B2 (en) | 2001-03-28 | 2015-08-04 | Qualcomm Incorporated | Method and apparatus for transmission framing in a wireless communication system |
US9467287B2 (en) | 1997-04-23 | 2016-10-11 | Sony Corporation | Enciphering apparatus and method, deciphering apparatus and method as well as information processing apparatus and method |
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US4792972A (en) * | 1986-08-19 | 1988-12-20 | Scientific-Atlanta, Inc. | Remote programming of CATV channel authorization unit |
US4864615A (en) * | 1988-05-27 | 1989-09-05 | General Instrument Corporation | Reproduction of secure keys by using distributed key generation data |
US7069590B1 (en) * | 2000-02-17 | 2006-06-27 | Microsoft Corporation | System and method for protecting data streams in hardware components |
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US4531020A (en) * | 1982-07-23 | 1985-07-23 | Oak Industries Inc. | Multi-layer encryption system for the broadcast of encrypted information |
-
1986
- 1986-04-16 ZA ZA862839A patent/ZA862839B/en unknown
- 1986-04-21 JP JP61502563A patent/JPS62503066A/en active Pending
- 1986-04-21 WO PCT/US1986/000801 patent/WO1986007224A1/en not_active Application Discontinuation
- 1986-04-21 AU AU58120/86A patent/AU5812086A/en not_active Abandoned
- 1986-04-21 EP EP86902982A patent/EP0222818A1/en not_active Withdrawn
- 1986-05-03 CN CN198686103053A patent/CN86103053A/en active Pending
Patent Citations (3)
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US4388643A (en) * | 1981-04-06 | 1983-06-14 | Northern Telecom Limited | Method of controlling scrambling and unscrambling in a pay TV system |
US4484027A (en) * | 1981-11-19 | 1984-11-20 | Communications Satellite Corporation | Security system for SSTV encryption |
US4531020A (en) * | 1982-07-23 | 1985-07-23 | Oak Industries Inc. | Multi-layer encryption system for the broadcast of encrypted information |
Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0809402A1 (en) * | 1990-02-01 | 1997-11-26 | Scientific-Atlanta, Inc. | External security module for a television signal decoder |
GB2241096A (en) * | 1990-02-14 | 1991-08-21 | Enfranchise Sixty Ltd | Controlling access to broadcast signals |
WO1991012693A1 (en) * | 1990-02-14 | 1991-08-22 | Enfranchise Sixty Limited | Apparatus and method for controlling access to broadcast signals |
GB2241096B (en) * | 1990-02-14 | 1994-03-23 | Enfranchise Sixty Ltd | Apparatus and method for controlling access to broadcast signals |
EP0937348A1 (en) * | 1996-11-07 | 1999-08-25 | MCI Worldcom, Inc. | System and method for providing security in data communication systems |
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Also Published As
Publication number | Publication date |
---|---|
JPS62503066A (en) | 1987-12-03 |
ZA862839B (en) | 1986-12-30 |
EP0222818A1 (en) | 1987-05-27 |
AU5812086A (en) | 1986-12-24 |
CN86103053A (en) | 1986-11-19 |
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