CA1328501B - Security System for SSTV Encryption - Google Patents
Security System for SSTV EncryptionInfo
- Publication number
- CA1328501B CA1328501B CA613072A CA613072A CA1328501B CA 1328501 B CA1328501 B CA 1328501B CA 613072 A CA613072 A CA 613072A CA 613072 A CA613072 A CA 613072A CA 1328501 B CA1328501 B CA 1328501B
- Authority
- CA
- Canada
- Prior art keywords
- signal
- sequence
- key number
- signals
- program
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000004891 communication Methods 0.000 claims abstract description 24
- 230000005540 biological transmission Effects 0.000 claims abstract description 6
- 108010076504 Protein Sorting Signals Proteins 0.000 claims description 54
- 238000000034 method Methods 0.000 claims description 51
- 230000008054 signal transmission Effects 0.000 claims description 6
- 230000005236 sound signal Effects 0.000 description 7
- 238000011084 recovery Methods 0.000 description 3
- 230000000875 corresponding effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001702 transmitter Effects 0.000 description 2
- 241000429017 Pectis Species 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- 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
Abstract
ABSTRACT OF THE DISCLOSURE
In a secure communications system, a key number which is changed periodically, e.g. monthly, and a ran-dom number from a random number generator are combined and used as a seed to reset a Pn sequence generator, with the output of the generator being used to control encryption of transmission data in a signal processor.
The key is also provided to a first encipherer to en-cipher the random number for transmission with the en-crypted data. At the receiver, the key is provided in common to a decipherer for deciphering the random number and a Pn sequence generator which is periodically reset by the combination of the key and random number in the same manner as in the transmitter. The Pn sequence is then used to decrypt the information. User identifica-tion codes are stored in the transmitter and are used to encipher the key, with each employing its ID code to decipher the key. The user ID codes are known only to the system operator, so that not even a particular user can know the key.
In a secure communications system, a key number which is changed periodically, e.g. monthly, and a ran-dom number from a random number generator are combined and used as a seed to reset a Pn sequence generator, with the output of the generator being used to control encryption of transmission data in a signal processor.
The key is also provided to a first encipherer to en-cipher the random number for transmission with the en-crypted data. At the receiver, the key is provided in common to a decipherer for deciphering the random number and a Pn sequence generator which is periodically reset by the combination of the key and random number in the same manner as in the transmitter. The Pn sequence is then used to decrypt the information. User identifica-tion codes are stored in the transmitter and are used to encipher the key, with each employing its ID code to decipher the key. The user ID codes are known only to the system operator, so that not even a particular user can know the key.
Description
l32s~a~
The present invention is related to the confiden-tiality of television signal transmissions, and more particularly to the protection of TV signal trans-missions from unauthorized reception. The environmentin which the present invention may be widely applicable, and in the context of which the invention will be described herein, is that of subscriber television and TV program distribution.
lo Subscriber television systems are becoming increasingly widespread wherein TV signals are sent out via a cable network or over the air and are intended for reception and viewing by only those subscribers who have paid a monthly fee. With the increase in subscriber television systems has also come an increase in the number of people attempting to receive and display the premium television programs without payment. Thus, there is a need for more sophisticated security techniques for preventing such unauthorized reception.
Many existing subscriber television systems utilize, directly or indirectly, signals transmitted via satellite, and it is becoming quite common for non-paying individuals to receive and display the premium television programs via television receive on~y (TVR0) antennas, thus resulting in a substantial loss of revenue ~or the distributors of the subscrip-tion television programs. In addition, various direct satellite broadcast television systems are currently being proposed wherein subscription television programs will be broadcast directly via satellite to #
The present invention is related to the confiden-tiality of television signal transmissions, and more particularly to the protection of TV signal trans-missions from unauthorized reception. The environmentin which the present invention may be widely applicable, and in the context of which the invention will be described herein, is that of subscriber television and TV program distribution.
lo Subscriber television systems are becoming increasingly widespread wherein TV signals are sent out via a cable network or over the air and are intended for reception and viewing by only those subscribers who have paid a monthly fee. With the increase in subscriber television systems has also come an increase in the number of people attempting to receive and display the premium television programs without payment. Thus, there is a need for more sophisticated security techniques for preventing such unauthorized reception.
Many existing subscriber television systems utilize, directly or indirectly, signals transmitted via satellite, and it is becoming quite common for non-paying individuals to receive and display the premium television programs via television receive on~y (TVR0) antennas, thus resulting in a substantial loss of revenue ~or the distributors of the subscrip-tion television programs. In addition, various direct satellite broadcast television systems are currently being proposed wherein subscription television programs will be broadcast directly via satellite to #
2 1328~1 individual subscriber homes. These subscription satellite television (SsTV) systems will be quite vulnerable to unauthorized reception, and an effective security technique is therefore highly desirable.
The purpose of a security subsystem for an SSTV
system is to protect the distributor's business interest and, accordingly, the following objectives should be achieved:
(1) To prevent a non-subscriber from receiving intelligible video and audio signals by using a regular home television set;
(2) To prevent a delinquent subscriber from receiving intelligible video and audio signals by using the SSTV decoder;
The purpose of a security subsystem for an SSTV
system is to protect the distributor's business interest and, accordingly, the following objectives should be achieved:
(1) To prevent a non-subscriber from receiving intelligible video and audio signals by using a regular home television set;
(2) To prevent a delinquent subscriber from receiving intelligible video and audio signals by using the SSTV decoder;
(3) To prevent a legitimate subscriber from receiving intelligible video and audio signals of unsubscribed SSTV channels or programs;
(4) To discourage an average technician from building his own receiver capable of obtaining acceptable ~uality video and audio signals;
(5) To discourage a small unauthorized business concern from manufacturing and marketing devices which are capable of receiving and displaying acceptable ~uality video and audio signals from the SSTV channels; and (6) To allow a legitimate subscriber to receive and display high quality video and audio signals from the subscribed channels or programs.
It would also be highly desirable to achieve the above objectives at a reasonable cost.
A number of security systems for CATV exist, most of which involve the suppression or removal of the ., .. - ............................ :
. ' ` .
.
1328~1 horizontal sync pulses from the video signal before transmission, and the recovery of the sync pulses at the receive end. These techniques will prevent people without the sync recovery circuits from receiving and displaying 5 the programs and may therefore achieve objectives (l) and (6) above, but these security systems do not achieve objectives (2) and (3) and, since sync recovery circuits are relatively easily designed and manufactured, also do not satisfy objectives (4) and (5).
lo More sophisticated techniques may include additional intelligence in the subscriber's decoder box, including the capability of receiving commands from a control centre which are specifically addressed to an individual subscriber and are used to turn on or off some 15 or all of the channels. These more sophisticated security techniques may succeed in achieving objectives (1)-(3) and (6), but still do not satisfy objectives (4) and (5). For example, most of these techniques involve the checking of a password, and a particular channel is turned on only if the 20 password is matched. This could be relatively easily by-passed by modifying the subscriber's decoder box or building a separate box with all of the necessary features except the on/off switch. Further, subscribers may also be able to tamper with the decoder box to receive more 25 programs than are actually paid for.
It is an ob;ect of the present invention to provide a security subsystem for a subscription television system wherein at least some of the above-mentioned ob~ectives (1)-(6) are achieved.
Accordingly, one aspect of the present invention provides a communications system including a transmitter comprising: a program source for providing a program signal representing program information; and first generator means for generating a first sequence of signals 35 representing a first sequence of numbers; key number means for providing a key number signal representing a key number; encryption means responsive to at least said first sequence of signals for encrypting said program signal;
~ ' , ~' . .
1328~1 - 3a -enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; transmit means for transmitting said encrypted program signal and said enciphered first signal sequence; and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver;
and a receiver comprising: means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering said enciphered key number signal in accordance with said further signal; receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means response to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
Further aspects of the invention provide a transmitter, as defined above, for use in the stated communications system and a receiver, as defined above, for use in the stated communications system.
~, , , ~ , . , . ' -4 13285~1 When the system is in use it employs crypto-graphic scrambling and descrambling technizues which utilize a "key" which is changed on a regular basis and is sent only to paid subscribers, and even this "key" is sent in a different encrypted form to each subscriber so that delinquent subscribers cannnot learn the current key from others.
A record is kept of unique user ID codes corres-ponding to each subscriber, and in a transmitter according to the preferred embodiment of this inven-tion, the key is ciphered with each subscriber'sunique ID code prior to sending the key to that subscriber. A random number generator in the trans-mitter generates a new random nl~her at regular inter-vals, for example, every second, and this number is combined with the key, and the combined number is thenused as a seed to reset a PN seguence generator every second. This PN sequence generator will thus generate a PN sequence with a random seed in one-second seg-ments, and the segmented PN sequence is supplied to a signal processor where it is used to scramble theaudio and video program signals. The random number generator is also ciphered with the key and the en-ciphered random number is continually transmitted with the scrambled video signal.
At the receiver, the enciphered key, which has been sent either via satellite or mail, is deciphered in the receiver utilizing the particular subscriber's unique ID code, which ID code is internal to the receiver and is unknown to the subscriber. The de-ciphered key is then in turn used to decipher theenciphered random number received with the scrambled program signal. The deciphered key and random number are then combined as in the transmitter, and the , ..
: ' .
5 1328~01 combined signal is used to continually reset a PN
sequence generator identical to that in the trans-mitter so that a segmented PN sequence will be gener-ated in the receiver which is identical to that generated in the transmitter, and this segmented PN
sequence can then be used to descramble the received signal. The descrambled signal will then be supplied to the subscriber television set.
BRIEF DESCRIPTION OF 1~ DRAWING
lo The invention will be more clearly understood with reference to the following description in con-junction with the accompanying drawing wherein the single figure is a block diagram of the essential components of the SSTV security system embodying the present invention.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENT
The drawing illustrates a functional block dia-gram of the SSTV security system embodying this invention. The SSTV transmitter will typically in-clude or have access to a billing system computer 10 which will store subscribex information including a list of paid subscribers and their corresponding unique user ID codes. This information may typically be stored in a user data base 12 within the computer.
2s Also within the computer will be a register 14 or the like containing a key which will be changed on a regular basis, e.g. monthly. In preparation for sending this "key of the month" to each current sub-scriber, the key is enciphered in an encipherer 16 with the user ID code unique to that particular cur-rent subscriber, and the enciphered key is then sent to the subscriber.
The transmitter includes a pseudo-random number (PN) sequence generator 18 and a random number gener-ator 20. The random number generator 20 periodically generates a new random number, e.g. once every second, ..
6 1328~1 and the outputs of the random number generator 20 and key register 14 are combined and loaded into the PN
sequence generator 18 to periodically reset or "seed"
the PN sequence generator 18 in a manner well known in the art. Each seeding of the sequence generator 18 will begin a new segment of the PN sequence. The program signal from source 22 is supplied to a signal processor 24 where it is encrypted with the segmented PN seguence from generator 18. The encryption tech-0 nique used may be any one of a variety of well knowntechnigues and need not be discussed in detail herein.
The encrypted, or scrambled, signal is then provided to a transmitter 26 for transmission over link 100 to the various subscriber receivers.
The random number from generator 20 is enciphered with the key of the month in an encipherer 28, and the enciphered random number is transmitted with the scrambled video signal over the link 100.
At the receiver, a register 30 or the like internal to the subscriber TV receiver contains a subscriber-specific secret user ID code which is set prior to installation and is stored in the user data base 12 of the billing computer at the transmitter.
Thus, when the subscriber receiver receives the en-ciphered key or when the user receives the encipheredkey by mail and enters the enciphered key into the receiver, a decipherer 32 in the receiver deciphers the enciphered key with the secret user ID code specific to that particular subscriber, and the deciphered key is provided to a decipherer 34.
receiver 36 separates the scrambled signal from the enciphered random number received over link 100 and provides the enciphered random number to the de-cipherer 34 where it is deciphered with the key received from the decipherer 32. The deciphered 7 1328~1 random number and key are then combined and loaded into the PN sequence generator 38 to reset or "seed"
the sequence generator in the same manner as in the transmitter, to thereby result in the same segmented P~ sequence as was used for scrambling in the SSTV
transmitter signal processor 24. This segmented PN
sequence is then provided to signal processor 40 where it is used to descramble the received program signal.
The descr~hled signal is then provided to the lo subscriber television set 42.
The above-described security system provides a novel technique for generating and synchronizing a segmented pseudo-random number (PN) sequence, and a secure key distribution method. The segmented PN
sequence generated is used to control the video and audio signal processors that scramble and descramble the program signals. Since a different segmented PN
sequence will be generated by each distinct key, the scrambling sequence is different for each key, and by periodically changing the key the scrambling and descrambling sequences will change. Thus, it is not possible for anyone without exact knowledge of the current key to descramble the received program signal with or without a descrambling device.
For each given duration of time, a particular channel is scrambled by a PN se~uence that is generated by a randomly selected number and the key of the month. To prevent subscribers of different channels from exchanging the keys among themselves, it is essential that the key for a given channel distri-buted to each subscriber look different, and this accomplished by enciphering the key with each subscriber's unique user ID code. In this way, although a single key is provided by the register 14 at any one time, a different key is required by each subscriber. It is only when the subscriber-specific : .
`
It would also be highly desirable to achieve the above objectives at a reasonable cost.
A number of security systems for CATV exist, most of which involve the suppression or removal of the ., .. - ............................ :
. ' ` .
.
1328~1 horizontal sync pulses from the video signal before transmission, and the recovery of the sync pulses at the receive end. These techniques will prevent people without the sync recovery circuits from receiving and displaying 5 the programs and may therefore achieve objectives (l) and (6) above, but these security systems do not achieve objectives (2) and (3) and, since sync recovery circuits are relatively easily designed and manufactured, also do not satisfy objectives (4) and (5).
lo More sophisticated techniques may include additional intelligence in the subscriber's decoder box, including the capability of receiving commands from a control centre which are specifically addressed to an individual subscriber and are used to turn on or off some 15 or all of the channels. These more sophisticated security techniques may succeed in achieving objectives (1)-(3) and (6), but still do not satisfy objectives (4) and (5). For example, most of these techniques involve the checking of a password, and a particular channel is turned on only if the 20 password is matched. This could be relatively easily by-passed by modifying the subscriber's decoder box or building a separate box with all of the necessary features except the on/off switch. Further, subscribers may also be able to tamper with the decoder box to receive more 25 programs than are actually paid for.
It is an ob;ect of the present invention to provide a security subsystem for a subscription television system wherein at least some of the above-mentioned ob~ectives (1)-(6) are achieved.
Accordingly, one aspect of the present invention provides a communications system including a transmitter comprising: a program source for providing a program signal representing program information; and first generator means for generating a first sequence of signals 35 representing a first sequence of numbers; key number means for providing a key number signal representing a key number; encryption means responsive to at least said first sequence of signals for encrypting said program signal;
~ ' , ~' . .
1328~1 - 3a -enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; transmit means for transmitting said encrypted program signal and said enciphered first signal sequence; and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver;
and a receiver comprising: means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering said enciphered key number signal in accordance with said further signal; receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means response to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
Further aspects of the invention provide a transmitter, as defined above, for use in the stated communications system and a receiver, as defined above, for use in the stated communications system.
~, , , ~ , . , . ' -4 13285~1 When the system is in use it employs crypto-graphic scrambling and descrambling technizues which utilize a "key" which is changed on a regular basis and is sent only to paid subscribers, and even this "key" is sent in a different encrypted form to each subscriber so that delinquent subscribers cannnot learn the current key from others.
A record is kept of unique user ID codes corres-ponding to each subscriber, and in a transmitter according to the preferred embodiment of this inven-tion, the key is ciphered with each subscriber'sunique ID code prior to sending the key to that subscriber. A random number generator in the trans-mitter generates a new random nl~her at regular inter-vals, for example, every second, and this number is combined with the key, and the combined number is thenused as a seed to reset a PN seguence generator every second. This PN sequence generator will thus generate a PN sequence with a random seed in one-second seg-ments, and the segmented PN sequence is supplied to a signal processor where it is used to scramble theaudio and video program signals. The random number generator is also ciphered with the key and the en-ciphered random number is continually transmitted with the scrambled video signal.
At the receiver, the enciphered key, which has been sent either via satellite or mail, is deciphered in the receiver utilizing the particular subscriber's unique ID code, which ID code is internal to the receiver and is unknown to the subscriber. The de-ciphered key is then in turn used to decipher theenciphered random number received with the scrambled program signal. The deciphered key and random number are then combined as in the transmitter, and the , ..
: ' .
5 1328~01 combined signal is used to continually reset a PN
sequence generator identical to that in the trans-mitter so that a segmented PN sequence will be gener-ated in the receiver which is identical to that generated in the transmitter, and this segmented PN
sequence can then be used to descramble the received signal. The descrambled signal will then be supplied to the subscriber television set.
BRIEF DESCRIPTION OF 1~ DRAWING
lo The invention will be more clearly understood with reference to the following description in con-junction with the accompanying drawing wherein the single figure is a block diagram of the essential components of the SSTV security system embodying the present invention.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENT
The drawing illustrates a functional block dia-gram of the SSTV security system embodying this invention. The SSTV transmitter will typically in-clude or have access to a billing system computer 10 which will store subscribex information including a list of paid subscribers and their corresponding unique user ID codes. This information may typically be stored in a user data base 12 within the computer.
2s Also within the computer will be a register 14 or the like containing a key which will be changed on a regular basis, e.g. monthly. In preparation for sending this "key of the month" to each current sub-scriber, the key is enciphered in an encipherer 16 with the user ID code unique to that particular cur-rent subscriber, and the enciphered key is then sent to the subscriber.
The transmitter includes a pseudo-random number (PN) sequence generator 18 and a random number gener-ator 20. The random number generator 20 periodically generates a new random number, e.g. once every second, ..
6 1328~1 and the outputs of the random number generator 20 and key register 14 are combined and loaded into the PN
sequence generator 18 to periodically reset or "seed"
the PN sequence generator 18 in a manner well known in the art. Each seeding of the sequence generator 18 will begin a new segment of the PN sequence. The program signal from source 22 is supplied to a signal processor 24 where it is encrypted with the segmented PN seguence from generator 18. The encryption tech-0 nique used may be any one of a variety of well knowntechnigues and need not be discussed in detail herein.
The encrypted, or scrambled, signal is then provided to a transmitter 26 for transmission over link 100 to the various subscriber receivers.
The random number from generator 20 is enciphered with the key of the month in an encipherer 28, and the enciphered random number is transmitted with the scrambled video signal over the link 100.
At the receiver, a register 30 or the like internal to the subscriber TV receiver contains a subscriber-specific secret user ID code which is set prior to installation and is stored in the user data base 12 of the billing computer at the transmitter.
Thus, when the subscriber receiver receives the en-ciphered key or when the user receives the encipheredkey by mail and enters the enciphered key into the receiver, a decipherer 32 in the receiver deciphers the enciphered key with the secret user ID code specific to that particular subscriber, and the deciphered key is provided to a decipherer 34.
receiver 36 separates the scrambled signal from the enciphered random number received over link 100 and provides the enciphered random number to the de-cipherer 34 where it is deciphered with the key received from the decipherer 32. The deciphered 7 1328~1 random number and key are then combined and loaded into the PN sequence generator 38 to reset or "seed"
the sequence generator in the same manner as in the transmitter, to thereby result in the same segmented P~ sequence as was used for scrambling in the SSTV
transmitter signal processor 24. This segmented PN
sequence is then provided to signal processor 40 where it is used to descramble the received program signal.
The descr~hled signal is then provided to the lo subscriber television set 42.
The above-described security system provides a novel technique for generating and synchronizing a segmented pseudo-random number (PN) sequence, and a secure key distribution method. The segmented PN
sequence generated is used to control the video and audio signal processors that scramble and descramble the program signals. Since a different segmented PN
sequence will be generated by each distinct key, the scrambling sequence is different for each key, and by periodically changing the key the scrambling and descrambling sequences will change. Thus, it is not possible for anyone without exact knowledge of the current key to descramble the received program signal with or without a descrambling device.
For each given duration of time, a particular channel is scrambled by a PN se~uence that is generated by a randomly selected number and the key of the month. To prevent subscribers of different channels from exchanging the keys among themselves, it is essential that the key for a given channel distri-buted to each subscriber look different, and this accomplished by enciphering the key with each subscriber's unique user ID code. In this way, although a single key is provided by the register 14 at any one time, a different key is required by each subscriber. It is only when the subscriber-specific : .
`
8 13~8~1 key is entered into the receiver that the true key of the month contained in register 14 can be provided to the decipherer 34 and sequence generator 38, and the deciphering of this true key of the month in the 5 decipherer 32 is performed internally of the subscriber receiver and without the subscriber's knowledge.
An important feature of any security system is that a legitimate subscriber must be capable of 1o obtaining synchronization within a short period of time. In the system according to the present invention, the PN sequence used for scrambling and descrambling the signal in signal processors 24 and 40, re~pecti~ely, is separated into short segments each of which is seeded by the combination of the key of the month and a random number which changes, for example, once every second. Thus, assuming that a legitimate subscriber does have his appropriate key, the time required to acquire synchronization will be substantially equal to the duration of each random number so that synchronization can be acguired rapidly in case of loss of sync due to power outages, rainstorms, changing of channels, etc.
The individual components in the security system according to the present invention are known in the art and need not be described in detail herein since the internal details of these components do not constitute a part of the present invention. The encipherers used to encipher the key of the month and the random number can be two different encipherers, but for the sake of hardware simplicity at the receive side, and consequent cost savings in mass production of the subscriber receivers, it is preferable that the same encipherers be used. The encipherer may employ any enciphering method as long as it has a suffi-ciently high level of security.
. ,.......... . .. ~
An important feature of any security system is that a legitimate subscriber must be capable of 1o obtaining synchronization within a short period of time. In the system according to the present invention, the PN sequence used for scrambling and descrambling the signal in signal processors 24 and 40, re~pecti~ely, is separated into short segments each of which is seeded by the combination of the key of the month and a random number which changes, for example, once every second. Thus, assuming that a legitimate subscriber does have his appropriate key, the time required to acquire synchronization will be substantially equal to the duration of each random number so that synchronization can be acguired rapidly in case of loss of sync due to power outages, rainstorms, changing of channels, etc.
The individual components in the security system according to the present invention are known in the art and need not be described in detail herein since the internal details of these components do not constitute a part of the present invention. The encipherers used to encipher the key of the month and the random number can be two different encipherers, but for the sake of hardware simplicity at the receive side, and consequent cost savings in mass production of the subscriber receivers, it is preferable that the same encipherers be used. The encipherer may employ any enciphering method as long as it has a suffi-ciently high level of security.
. ,.......... . .. ~
- 9 1328~1 The PN sequence generator can be any general PN
sequence generator as long as it also has sufficient security strength, e.g. a properly selected non-linear feedback shift register may suffice.
The random number generator in the transmitter may be a well known thermal noise generator which generates "true" random numbers, or it may be a pseudo-random number generator similar to the sequence generator 18, implemented in a well known manner with lo digital electronics or computer software. Similarly, the technique for combining the key of the month and the random number generator to produce the "seed" for the PN sequence generators 18 and 38 is not critical, with the simplest technique being a bit-by-bit modulo-2 addition of the two numbers.
In general, each of the functional blocks in the drawing can be implemented with existing techniques, with system complexity and cost and security strength depending on the particular implementation of each of the functional blocks.
The transformation of the simple cipherer is specified by a variable which is different for each channel or special program, and is changed every month.
The user ID code 30 within each subscriber set may be a set of binary switches or a bit pattern programmed into a read-only memory in a sealed box to prevent the subscriber from seeing or changing the number.
The use of a simple cipherer in addition to the non-linear feedback shift-register may seem to increase the system complexity unnecesarily. However, since only a small amount of data, namely the "seed", need be handled each time, and since the statistical properties of the cipherer do not impact to the output of the PN sequence generator, the cipherer can be very , ~ ~ . .
132~
simple. One possible approach, for example, is a ROM
table of random bits with or without cipher feedback.
The use of this simple cipherer greatly simplifies the problem of cryptosynchronization and key distribution, and therefore reduces the overall system complexity.
Suita~le alternatives for the scrambling of the program signals include conventional scrambling techniques such as on-off switching, randomly invert-ing lines, fields or frames, and delaying horizontal lo lines or fields by certain randomly fixed steps. In any case, the technique used will require the genera-tion of a PN sequence which must be synchronized at both the transmit and receive sides.
sequence generator as long as it also has sufficient security strength, e.g. a properly selected non-linear feedback shift register may suffice.
The random number generator in the transmitter may be a well known thermal noise generator which generates "true" random numbers, or it may be a pseudo-random number generator similar to the sequence generator 18, implemented in a well known manner with lo digital electronics or computer software. Similarly, the technique for combining the key of the month and the random number generator to produce the "seed" for the PN sequence generators 18 and 38 is not critical, with the simplest technique being a bit-by-bit modulo-2 addition of the two numbers.
In general, each of the functional blocks in the drawing can be implemented with existing techniques, with system complexity and cost and security strength depending on the particular implementation of each of the functional blocks.
The transformation of the simple cipherer is specified by a variable which is different for each channel or special program, and is changed every month.
The user ID code 30 within each subscriber set may be a set of binary switches or a bit pattern programmed into a read-only memory in a sealed box to prevent the subscriber from seeing or changing the number.
The use of a simple cipherer in addition to the non-linear feedback shift-register may seem to increase the system complexity unnecesarily. However, since only a small amount of data, namely the "seed", need be handled each time, and since the statistical properties of the cipherer do not impact to the output of the PN sequence generator, the cipherer can be very , ~ ~ . .
132~
simple. One possible approach, for example, is a ROM
table of random bits with or without cipher feedback.
The use of this simple cipherer greatly simplifies the problem of cryptosynchronization and key distribution, and therefore reduces the overall system complexity.
Suita~le alternatives for the scrambling of the program signals include conventional scrambling techniques such as on-off switching, randomly invert-ing lines, fields or frames, and delaying horizontal lo lines or fields by certain randomly fixed steps. In any case, the technique used will require the genera-tion of a PN sequence which must be synchronized at both the transmit and receive sides.
Claims (44)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A transmitter for use in a communications system including a transmitter and a receiver, said transmitter comprising:
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence, transmit means for transmitting said encrypted program signal and said enciphered first signal sequence;
and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver.
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence, transmit means for transmitting said encrypted program signal and said enciphered first signal sequence;
and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver.
2. A receiver for receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers, said first sequence of signals being enciphered with a key number signal, said receiver comprising:
means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering an enciphered version of said key number signal in accordance with said further signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering an enciphered version of said key number signal in accordance with said further signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
3. A communications system including a transmitter comprising:
a program source for providing a program signal representing program information; and first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence;
transmit means for transmitting said encrypted program signal and said enciphered first signal sequence;
and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver; and a receiver comprising:
means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering said enciphered key number signal in accordance with said further signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
a program source for providing a program signal representing program information; and first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence;
transmit means for transmitting said encrypted program signal and said enciphered first signal sequence;
and means for enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver; and a receiver comprising:
means for providing said key number signal, said means for providing said key number signal comprising means for providing said further signal and means for deciphering said enciphered key number signal in accordance with said further signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
4. A communications system according to claim 3, wherein said encryption means includes a second generator means for generating a second sequence of signals representing a second sequence of numbers, said second generator means being periodically reset by a transmit reset signal comprising at least the output of said first generator means to thereby generate an output signal comprising a plurality of sequence segments each beginning with a transmit reset signal, said transmit signal processing means for encrypting said program signal in accordance with the output of said second generator means, and wherein said decryption means includes receiver sequence generating means for generating a sequence of signals representing said second sequence of numbers, said receiver sequence generating means being periodically reset by a receive reset signal comprising at least the output of said receive deciphering means to thereby generate said plurality of sequence segments, and receive signal processing means for decrypting said encrypted program signal in accordance with the output of said receiver sequence generating means.
5. A system according to claim 3 or 4, wherein said reset signals comprise a combination of said key number signal and said first sequence of signals.
6. A communications system as defined in claim 3, wherein said system includes a plurality of receivers for receiving the encrypted signal transmitted by said transmitter, each of said receivers having a corresponding unique identification number, and wherein said further signal comprises an identification number signal representing said unique identification number for transmission of said enciphered key number to each respective receiver.
7. A communications system as defined in claim 3 or 4, wherein said further signal is fixed during normal operation of said system.
8. A communications system as defined in claim 3, wherein said key number signal is periodically changed.
9. A communications system as defined in claim 8, wherein said key number signal changes at a rate slower than the signals of said first sequence of signals.
10. A communications system as defined in claim 4, wherein said second generator means is a non-linear pseudorandom sequence generator.
11. A communications system as defined in claim 10, wherein said first signal sequence represents a substantially random number sequence.
12. A transmitter for use in a communications system including a transmitter and a receiver, said transmitter comprising:
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal, said encryption means including a second generator means for generating a second sequence of signals representing a second sequence of numbers, said second generator means being periodically reset by a transmit reset signal comprising a combination of said key number signal and the output of said first generator means to thereby generate an output signal comprising a plurality of sequence segments each beginning with a transmit reset signal, and transmit signal processing means for encrypting said program signal in accordance with the output of said second generator means;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal, said encryption means including a second generator means for generating a second sequence of signals representing a second sequence of numbers, said second generator means being periodically reset by a transmit reset signal comprising a combination of said key number signal and the output of said first generator means to thereby generate an output signal comprising a plurality of sequence segments each beginning with a transmit reset signal, and transmit signal processing means for encrypting said program signal in accordance with the output of said second generator means;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
13. A receiver for receiving a program signal which has been encrypted in accordance with a second sequence of signals representing a second sequence of numbers, and a first sequence of signals representing a first sequence of numbers and enciphered with a key number signal, said receiver comprising:
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means for receiving and decrypting said encrypted program signal to obtain said program signal, said decryption means including receiver sequence generating means for generating a sequence of signals representing said second sequence of numbers, said receiver sequence generating means being periodically reset by a receive reset signal comprising a combination of said key number signal and the output of said receive deciphering means to thereby generate said plurality of sequence segments, and receive signal processing means for decrypting said encrypted program signal in accordance with the output of said receiver sequence generating means.
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means for receiving and decrypting said encrypted program signal to obtain said program signal, said decryption means including receiver sequence generating means for generating a sequence of signals representing said second sequence of numbers, said receiver sequence generating means being periodically reset by a receive reset signal comprising a combination of said key number signal and the output of said receive deciphering means to thereby generate said plurality of sequence segments, and receive signal processing means for decrypting said encrypted program signal in accordance with the output of said receiver sequence generating means.
14. A communications system including the transmitter of claim 12 and the receiver of claim 13.
15. A transmitter for use in a communications system including a transmitter and a receiver, said transmitter comprising:
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers common to all receivers receiving said program information;
key number means for providing a key number signal representing a key number common to all receivers receiving said program information;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers common to all receivers receiving said program information;
key number means for providing a key number signal representing a key number common to all receivers receiving said program information;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
16. A receiver for receiving a program signal which has been encrypted in accordance with at least a first sequence of signals common to all receivers receiving said program signal, said first sequence of signals being enciphered with a key number signal common to all receivers receiving said program signal, said receiver comprising:
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
17. A communications system including the transmitter of claim 15 and the receiver of claim 16.
18. A transmitter for use in a communications system including a transmitter and a receiver, said transmitter comprising:
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers changing at least several times per minute;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
a program source for providing a program signal representing program information;
first generator means for generating a first sequence of signals representing a first sequence of numbers changing at least several times per minute;
key number means for providing a key number signal representing a key number;
encryption means responsive to at least said first sequence of signals for encrypting said program signal;
enciphering means for enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmit means for transmitting said encrypted program signal and said enciphered first signal sequence.
19. A receiver for receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers changing at least several times per minute, said first sequence of signals being enciphered with a key number signal, said receiver comprising:
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
means for providing said key number signal;
receive deciphering means for receiving said enciphered first signal sequence and said key number, deciphering said first signal sequence in accordance with said key number and providing said deciphered first signal sequence as an output; and decryption means responsive to at least said output of said receive deciphering means for receiving and decrypting said encrypted program signal to obtain said program signal.
20. A communications system including the transmitter of claim 18 and the receiver of claim 19.
21. A transmitter according to claim 18, wherein the numbers in said first sequence of numbers change approximately once per second.
22. A receiver according to claim 19, wherein the numbers in said first sequence of numbers change approximately once per second.
23. A method of transmitting a secure signal from a transmitter to a receiver in a communications system, said method comprising the steps of:
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers;
providing a key number signal representing a key number;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence;
transmitting said encrypted program signal and said enciphered first signal sequence to said receiver; and enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver.
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers;
providing a key number signal representing a key number;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence;
transmitting said encrypted program signal and said enciphered first signal sequence to said receiver; and enciphering said key number signal in accordance with a further signal for communication of said further signal to said receiver.
24. A method of receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers, said first sequence of signals being enciphered with a key number signal, said receiving method comprising the steps of:
providing said key number signal by deciphering said enciphered key number signal in accordance with said further signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with at least said first signal sequence to obtain said program signal.
providing said key number signal by deciphering said enciphered key number signal in accordance with said further signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with at least said first signal sequence to obtain said program signal.
25. A method of providing security in a signal transmission system between a transmitter and a receiver, said method comprising the transmitting method of claim 23 and the receiving method of claim 24.
26. A method as defined in claim 25, wherein said step of encrypting said program signal in accordance with at least said first sequence of signals comprises the steps generating a second sequence of signals representing a second sequence of numbers, said second sequence of signals comprising a plurality of sequence segments each beginning with a transmit reset signal, said transmit reset signal comprising at least said first signal sequence, and encrypting said program signal in accordance with said second sequence of signals; and wherein said step of decrypting said encrypted program signal comprises the steps of generating a decryption sequence of signals representing said second sequence of numbers by periodically resetting a receiver sequence generator with a receive reset signal comprising at least the deciphered first signal sequence, and decrypting said encrypted program signal in accordance with said decryption sequence.
27. A method as defined in claim 25 or 26, wherein said transmit and receive reset signals each comprise a combination of said key number signal and said first sequence of signals.
28. A method as defined in claim 25, wherein said system includes a plurality of receivers for receiving the encrypted signal transmitted by said transmitter, each of said receivers having a corresponding unique identification number, and wherein said further signal comprises an identification number signal representing said unique identification number for transmission of said enciphered key number to each respective receiver.
29. A method as defined in claim 25 or 26, wherein said further signal is fixed during normal operation of said system.
30. A method as defined in claim 25, wherein said step of generating said key number signal comprises periodically changing said key number signal.
31. A method as defined in claim 30, wherein said key number signal changes at a rate slower than the signals of said first sequence of signals.
32. A method as defined in claim 25, wherein said second sequence of signals is a non-linear pseudorandom sequence.
33. A method as defined in claim 32, wherein said first signal sequence represents a substantially random number sequence.
34. A method of transmitting a secure signal, said method comprising the steps of:
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers;
providing a key number signal representing a key number;
generating a second sequence of signals representing a second sequence of numbers, said second sequence of signals comprising a plurality of sequence segments each beginning with a transmit reset signal, said transmit reset signal comprising a combination of said key number signal and said first sequence of signals;
encrypting said program signal in accordance with said second sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers;
providing a key number signal representing a key number;
generating a second sequence of signals representing a second sequence of numbers, said second sequence of signals comprising a plurality of sequence segments each beginning with a transmit reset signal, said transmit reset signal comprising a combination of said key number signal and said first sequence of signals;
encrypting said program signal in accordance with said second sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
35. A method of receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers, said first sequence of signals being enciphered with a key number signal, said receiving method comprising the steps of:
providing said key number signal:
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence;
generating a second sequence of signals representing a second sequence of numbers, said second sequence of signals comprising a plurality of sequence segments each beginning with a receive reset signal, said receive reset signal comprising a combination of said key number signal and said deciphered first sequence of signals; and decrypting said encrypted program signal in accordance with at least said deciphered first signal sequence to obtain said program signal.
providing said key number signal:
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence;
generating a second sequence of signals representing a second sequence of numbers, said second sequence of signals comprising a plurality of sequence segments each beginning with a receive reset signal, said receive reset signal comprising a combination of said key number signal and said deciphered first sequence of signals; and decrypting said encrypted program signal in accordance with at least said deciphered first signal sequence to obtain said program signal.
36. A method of communicating a secure signal between a transmitter and a receiver in a signal transmission system, comprising the signal transmitting method of claim 34 and the signal receiving method of claim 35.
37. A method of transmitting a secure signal, a comprising the steps of:
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers common to all receivers receiving said information;
providing a key number signal representing a key number common to all receivers receiving said information;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers common to all receivers receiving said information;
providing a key number signal representing a key number common to all receivers receiving said information;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
38. A method of receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers common to all receivers receiving said program signal, said first sequence of signals being enciphered with a key number signal representing a key number common to all receivers receiving said program signal, said receiving method comprising:
providing said key number signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with said first signal sequence to obtain said program signal.
providing said key number signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with said first signal sequence to obtain said program signal.
39. A method of communicating a secure signal from a transmitter to a receiver in a signal transmission system, comprising the transmitting method of claim 37 and the receiving method of claim 38.
40. A method of transmitting a secure signal, comprising the steps of:
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers changing at least several times per minute;
providing a key number signal representing a key number;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
providing a program signal representing information;
generating a first sequence of signals representing a first sequence of numbers changing at least several times per minute;
providing a key number signal representing a key number;
encrypting said program signal in accordance with at least said first sequence of signals;
enciphering said first sequence of signals with said key number signal to provide an enciphered first signal sequence; and transmitting said encrypted program signal and said enciphered first signal sequence to said receiver.
41. A method of receiving a program signal which has been encrypted in accordance with at least a first sequence of signals representing a first sequence of numbers changing at least several times per minute, said receiving method comprising the steps of:
providing said key number signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with said first signal sequence to obtain said program signal.
providing said key number signal;
deciphering said first signal sequence in accordance with said key number to obtain a deciphered first signal sequence; and decrypting said encrypted program signal in accordance with said first signal sequence to obtain said program signal.
42. A method of communicating a secure signal from a transmitter to a receiver in a signal transmission system, comprising the transmitting method of claim 40 and the receiving method of claim 41.
43. A method according to claim 40, wherein the numbers in said first sequence of numbers change approximately once per second.
44. A method according to claim 41, wherein the numbers in said first sequence of numbers change approximately once per second.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/322,833 US4484027A (en) | 1981-11-19 | 1981-11-19 | Security system for SSTV encryption |
| US322,833 | 1981-11-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA1328501E CA1328501E (en) | 1985-09-24 |
| CA1328501B true CA1328501B (en) | 1994-04-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA000415993A Expired CA1194212A (en) | 1981-11-19 | 1982-11-19 | Security system for sstv encryption |
| CA613072A Expired - Lifetime CA1328501B (en) | 1981-11-19 | 1982-11-19 | Security System for SSTV Encryption |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000415993A Expired CA1194212A (en) | 1981-11-19 | 1982-11-19 | Security system for sstv encryption |
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| US (1) | US4484027A (en) |
| EP (1) | EP0094423B1 (en) |
| JP (2) | JPS58501982A (en) |
| AT (1) | ATE56333T1 (en) |
| CA (2) | CA1194212A (en) |
| DE (1) | DE3280237D1 (en) |
| WO (1) | WO1983001881A1 (en) |
Families Citing this family (120)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4965825A (en) | 1981-11-03 | 1990-10-23 | The Personalized Mass Media Corporation | Signal processing apparatus and methods |
| USRE47642E1 (en) | 1981-11-03 | 2019-10-08 | Personalized Media Communications LLC | Signal processing apparatus and methods |
| US7831204B1 (en) | 1981-11-03 | 2010-11-09 | Personalized Media Communications, Llc | Signal processing apparatus and methods |
| USRE33189E (en) * | 1981-11-19 | 1990-03-27 | Communications Satellite Corporation | Security system for SSTV encryption |
| US4658292A (en) * | 1982-04-30 | 1987-04-14 | Nec Corporation | Enciphering key distribution system for subscription TV broadcast or catv system |
| EP0093525B1 (en) * | 1982-04-30 | 1985-10-02 | British Telecommunications | Broadcasting encrypted signals |
| US5500899A (en) * | 1982-05-20 | 1996-03-19 | The United States Of America As Represented By The Director, Nsa | Secure voice conferencing apparatus |
| US4531020A (en) * | 1982-07-23 | 1985-07-23 | Oak Industries Inc. | Multi-layer encryption system for the broadcast of encrypted information |
| US4811394A (en) * | 1982-07-28 | 1989-03-07 | Communications Satellite Corporation | Variable starting state scrambling circuit |
| US4757468A (en) * | 1982-09-22 | 1988-07-12 | Intel Corporation | Authenticated read-only memory |
| DE3371947D1 (en) * | 1982-12-20 | 1987-07-09 | Radiotechnique Sa | Generator of random number sequences |
| GB2140656A (en) * | 1983-05-13 | 1984-11-28 | Philips Electronic Associated | Television transmission system |
| US4613901A (en) * | 1983-05-27 | 1986-09-23 | M/A-Com Linkabit, Inc. | Signal encryption and distribution system for controlling scrambling and selective remote descrambling of television signals |
| EP0129299A3 (en) * | 1983-06-20 | 1986-03-19 | Philips Electronics Uk Limited | Secure television transmission system |
| GB2141905A (en) * | 1983-06-20 | 1985-01-03 | Philips Electronic Associated | Secure transmission system |
| WO1985000491A1 (en) * | 1983-06-30 | 1985-01-31 | Independent Broadcasting Authority | Encrypted broadcast television system |
| CA1213972A (en) * | 1983-07-13 | 1986-11-12 | Takashi Okada | Apparatus for scrambling a television signal |
| CA1219930A (en) * | 1983-07-21 | 1987-03-31 | Takashi Kamitake | Information transmission system |
| EP0151147B1 (en) * | 1983-07-22 | 1988-04-20 | Independent Broadcasting Authority | Security system for television signal encryption |
| US4682360A (en) * | 1983-12-22 | 1987-07-21 | Frederiksen Jeffrey E | Video transmission system |
| US4799258A (en) * | 1984-02-13 | 1989-01-17 | National Research Development Corporation | Apparatus and methods for granting access to computers |
| AU559311B2 (en) * | 1984-02-15 | 1987-03-05 | Matsushita Electric Industrial Co., Ltd. | Pay tv charge/time data display |
| US4819267A (en) * | 1984-02-22 | 1989-04-04 | Thumbscan, Inc. | Solid state key for controlling access to computer systems and to computer software and/or for secure communications |
| US4634808A (en) * | 1984-03-15 | 1987-01-06 | M/A-Com Government Systems, Inc. | Descrambler subscriber key production system utilizing key seeds stored in descrambler |
| JPS60210044A (en) * | 1984-04-03 | 1985-10-22 | Nec Corp | Transmitting and receiving device of error correction code |
| FR2563402B1 (en) * | 1984-04-19 | 1987-08-28 | Loire Electronique | ENCODING AND DECODING METHOD FOR A TOLL TELEVISION SYSTEM |
| US4712238A (en) * | 1984-06-08 | 1987-12-08 | M/A-Com Government Systems, Inc. | Selective-subscription descrambling |
| US4751732A (en) * | 1984-07-06 | 1988-06-14 | Kabushiki Kaisha Toshiba | Broadcasting system |
| JPS6120442A (en) * | 1984-07-09 | 1986-01-29 | Toshiba Corp | Chargeable broadcasting system |
| US4742544A (en) * | 1984-07-09 | 1988-05-03 | Kupnicki Richard A | Television transmission network with scrambling and descrambling |
| DE3428698A1 (en) * | 1984-08-03 | 1986-02-13 | Philips Patentverwaltung Gmbh, 2000 Hamburg | CIRCUIT ARRANGEMENT FOR A DEVICE WITH AN IMAGE AND / OR SOUND SIGNAL CHANNEL |
| US4747139A (en) * | 1984-08-27 | 1988-05-24 | Taaffe James L | Software security method and systems |
| US4829569A (en) * | 1984-09-21 | 1989-05-09 | Scientific-Atlanta, Inc. | Communication of individual messages to subscribers in a subscription television system |
| US4885775A (en) * | 1984-09-21 | 1989-12-05 | Scientific-Atlanta, Inc. | Information display scheme for subscribers of a subscription television system |
| US4696034A (en) * | 1984-10-12 | 1987-09-22 | Signal Security Technologies | High security pay television system |
| US4908834A (en) * | 1984-10-12 | 1990-03-13 | Wiedemer John D | High security pay television system |
| US4905280A (en) * | 1984-10-12 | 1990-02-27 | Wiedemer John D | High security videotext and videogame system |
| US4907273A (en) * | 1984-10-12 | 1990-03-06 | Wiedemer John D | High security pay television system |
| US4887296A (en) * | 1984-10-26 | 1989-12-12 | Ricoh Co., Ltd. | Cryptographic system for direct broadcast satellite system |
| JPS61108272A (en) * | 1984-11-01 | 1986-05-26 | Toshiba Corp | Chargeable broadcast system |
| US5036537A (en) * | 1984-11-19 | 1991-07-30 | General Instrument Corp. | Geographic black-out method for direct broadcast satellite system |
| SE8406489L (en) * | 1984-12-19 | 1986-06-20 | Nordspace Ab | television reception |
| US4709266A (en) * | 1985-01-14 | 1987-11-24 | Oak Industries Inc. | Satellite scrambling communication network using geographically separated uplinks |
| US4694491A (en) * | 1985-03-11 | 1987-09-15 | General Instrument Corp. | Cryptographic system using interchangeable key blocks and selectable key fragments |
| US4803725A (en) * | 1985-03-11 | 1989-02-07 | General Instrument Corp. | Cryptographic system using interchangeable key blocks and selectable key fragments |
| DE3518462A1 (en) * | 1985-05-23 | 1986-11-27 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | ENCRYPTED MESSAGE TRANSMISSION SYSTEM |
| ZA862839B (en) * | 1985-05-24 | 1986-12-30 | Scientific Atlanta | Method and apparatus for scrambling and descrambling television signals |
| US4802217A (en) * | 1985-06-07 | 1989-01-31 | Siemens Corporate Research & Support, Inc. | Method and apparatus for securing access to a computer facility |
| GB2183378A (en) * | 1985-11-25 | 1987-06-03 | Philips Electronic Associated | Receiving scrambled signals |
| EP0253885A4 (en) * | 1985-12-26 | 1991-03-20 | Gordian Systems | Solid state key for controlling access to computer systems and to computer software and/or for secure communications |
| US4688250A (en) * | 1986-01-29 | 1987-08-18 | Rca Corporation | Apparatus and method for effecting a key change via a cryptographically protected link |
| US4890321A (en) * | 1986-07-08 | 1989-12-26 | Scientific Atlanta, Inc. | Communications format for a subscription television system permitting transmission of individual text messages to subscribers |
| US5261070A (en) * | 1986-07-24 | 1993-11-09 | Meiji Milk Product Co., Ltd. | Method and apparatus for forming unique user identification data at remote terminal for secure transmission of data from host terminal |
| US4792972A (en) * | 1986-08-19 | 1988-12-20 | Scientific-Atlanta, Inc. | Remote programming of CATV channel authorization unit |
| US4893339A (en) * | 1986-09-03 | 1990-01-09 | Motorola, Inc. | Secure communication system |
| US4827514A (en) * | 1986-09-03 | 1989-05-02 | Motorola, Inc. | Method and apparatus to detect and recover a pseudo-random sequence |
| US4797672A (en) * | 1986-09-04 | 1989-01-10 | Octel Communications Corp. | Voice network security system |
| US4805216A (en) * | 1987-01-08 | 1989-02-14 | Compfax Corporation | Method and apparatus for continuously acknowledged link encrypting |
| US4870682A (en) * | 1987-02-25 | 1989-09-26 | Household Data Services (Hds) | Television scrambling system |
| US4807286A (en) * | 1987-04-22 | 1989-02-21 | Wiedemer John D | High security pay television system |
| IL83549A (en) * | 1987-08-16 | 1992-08-18 | Yossi Matias | Video scrambling apparatus and method based on space filling curves |
| FR2631193B1 (en) * | 1988-05-06 | 1994-09-16 | Europ Rech Electr Lab | METHOD FOR SCRAMBLING AND SCALING-UP OF COMPOSITE VIDEO SIGNALS, AND IMPLEMENTING DEVICE |
| IT1217755B (en) * | 1988-06-01 | 1990-03-30 | Sits Soc It Telecom Siemens | ENCRYPTION AND DECIFRATION DEVICE FOR HIGH SPEED TRANSMISSION SYSTEMS, |
| US5208856A (en) * | 1988-12-23 | 1993-05-04 | Laboratoire Europeen De Recherches Electroniques Avancees | Scrambling and unscrambling method for composite video signals and implementing device |
| FR2643529B1 (en) * | 1989-02-22 | 1991-06-07 | Kudelski Sa Fabr Enregistr Nag | PAID TELEVISION SYSTEM USING A MEMORY CARD ASSOCIATED WITH A DECODER |
| GB2231755B (en) * | 1989-04-21 | 1993-10-06 | Pioneer Electronic Corp | Method for scrambling a television signal and method and apparatus for descrambling a scrambled television signal |
| US5113440A (en) * | 1989-07-21 | 1992-05-12 | Oci Communcations, Inc. | Universal decoder |
| US5029207A (en) * | 1990-02-01 | 1991-07-02 | Scientific-Atlanta, Inc. | External security module for a television signal decoder |
| US5237610A (en) * | 1990-02-01 | 1993-08-17 | Scientific-Atlanta, Inc. | Independent external security module for a digitally upgradeable television signal decoder |
| US5235643A (en) * | 1991-05-21 | 1993-08-10 | Anderson Steven E | Satellite receiver retuning system |
| JP2622049B2 (en) * | 1991-05-24 | 1997-06-18 | 松下電器産業株式会社 | Cable broadcasting system |
| US5208853A (en) * | 1991-09-09 | 1993-05-04 | Motorola, Inc. | Method and apparatus for usage protection of data files using split key and unique variable |
| US5230020A (en) * | 1991-10-16 | 1993-07-20 | Motorola, Inc. | Algorithm independent cryptographic key management |
| US5179591A (en) * | 1991-10-16 | 1993-01-12 | Motorola, Inc. | Method for algorithm independent cryptographic key management |
| US5272752A (en) * | 1992-03-16 | 1993-12-21 | Scientific-Atlanta, Inc. | Authorization code lockout mechanism for preventing unauthorized reception of transmitted data |
| JP3010930B2 (en) * | 1992-09-24 | 2000-02-21 | 松下電器産業株式会社 | Recording and playback device |
| JPH06266670A (en) * | 1993-03-11 | 1994-09-22 | Fujitsu Ltd | Ciphering virtual terminal initialization device |
| DE69433257T2 (en) * | 1993-07-20 | 2009-09-10 | Canon K.K. | Method and communication system using an encryption device |
| BR9408552A (en) * | 1994-03-18 | 1997-08-19 | Thomson Consumer Electronics | Apparatus for processing digital signals in a digital video signal processing system including signals containing encrypted information |
| FI97184C (en) * | 1994-11-07 | 1996-10-25 | Nokia Telecommunications Oy | Method and apparatus for performing subscriber-specific editing and remodeling in a subscriber network |
| US5555308A (en) * | 1994-11-10 | 1996-09-10 | Angelika R. Levien | Encryption of signals to insure viewership of commercials |
| FR2730372A1 (en) * | 1995-02-08 | 1996-08-09 | Philips Electronics Nv | PAY TELEVISION METHOD |
| JP3294739B2 (en) * | 1995-03-30 | 2002-06-24 | 三洋電機株式会社 | Method for scrambling or descrambling FM multiplex broadcasting |
| US5608723A (en) * | 1995-04-26 | 1997-03-04 | Interval Research Corporation | Methods and systems for secure wireless communication within a predetermined boundary |
| US5774549A (en) * | 1995-12-04 | 1998-06-30 | Sun Microsystems, Inc. | Method and apparatus that processes a video signal to generate a random number generator seed |
| US6289314B1 (en) * | 1996-09-18 | 2001-09-11 | Matsushita Electric Industrial Co., Ltd. | Pay information providing system for descrambling information from plural sources and rescrambling the information before sending to a terminal or terminals |
| JPH10301492A (en) | 1997-04-23 | 1998-11-13 | Sony Corp | Enciphering device and method therefor, decoding device and method therefor, and information processing device and method therefor |
| WO1999004530A1 (en) * | 1997-07-15 | 1999-01-28 | V-One Corporation | File encryption with key recovery |
| US6510228B2 (en) | 1997-09-22 | 2003-01-21 | Qualcomm, Incorporated | Method and apparatus for generating encryption stream ciphers |
| US6252958B1 (en) * | 1997-09-22 | 2001-06-26 | Qualcomm Incorporated | Method and apparatus for generating encryption stream ciphers |
| IL123554A (en) | 1998-03-04 | 2003-01-12 | Nds Ltd | Key delivery in a secure broadcasting system |
| TW412909B (en) * | 1998-05-07 | 2000-11-21 | Kudelski Sa | Mechanism of matching between a receiver and a security module |
| US6560338B1 (en) | 1998-08-28 | 2003-05-06 | Qualcomm Incorporated | Limiting delays associated with the generation of encryption stream ciphers |
| US6490357B1 (en) * | 1998-08-28 | 2002-12-03 | Qualcomm Incorporated | Method and apparatus for generating encryption stream ciphers |
| JP2003506919A (en) * | 1999-08-03 | 2003-02-18 | ポリコム・インコーポレイテッド | System and method for secure data transfer in a wireless communication system |
| US7170996B1 (en) * | 1999-10-18 | 2007-01-30 | Qualcomm Incorporated | Random number generation for encrypting cellular communications |
| WO2001041357A1 (en) * | 1999-12-03 | 2001-06-07 | Cipheractive Communication Security Ltd. | Encryption of partitioned data blocks utilizing public key methods and random numbers |
| AU2001256645A1 (en) | 2000-05-22 | 2001-12-03 | Nds Limited | Dynamically shifting control word |
| US6772434B1 (en) * | 2000-05-24 | 2004-08-03 | The Directv Group, Inc. | Device and method for the integrated presentation of a secondary service as a part of a primary service |
| WO2002048837A2 (en) * | 2000-12-15 | 2002-06-20 | Polycom, Inc. | System and method for device co-location discrimination |
| US9100457B2 (en) | 2001-03-28 | 2015-08-04 | Qualcomm Incorporated | Method and apparatus for transmission framing in a wireless communication system |
| TW566024B (en) † | 2001-07-30 | 2003-12-11 | Nagravision Sa | Method to create a virtual private network through a public network |
| US7352868B2 (en) | 2001-10-09 | 2008-04-01 | Philip Hawkes | Method and apparatus for security in a data processing system |
| US7649829B2 (en) | 2001-10-12 | 2010-01-19 | Qualcomm Incorporated | Method and system for reduction of decoding complexity in a communication system |
| US20030112978A1 (en) * | 2001-12-17 | 2003-06-19 | Jeffrey Rodman | System and method for secured data transmission within a wireless communication system |
| US7477743B2 (en) * | 2002-02-07 | 2009-01-13 | Nokia Corporation | Hybrid network encrypt/decrypt scheme |
| US7599655B2 (en) | 2003-01-02 | 2009-10-06 | Qualcomm Incorporated | Method and apparatus for broadcast services in a communication system |
| US7346160B2 (en) * | 2003-04-23 | 2008-03-18 | Michaelsen David L | Randomization-based encryption apparatus and method |
| US7925013B1 (en) | 2003-06-30 | 2011-04-12 | Conexant Systems, Inc. | System for data encryption and decryption of digital data entering and leaving memory |
| US8718279B2 (en) | 2003-07-08 | 2014-05-06 | Qualcomm Incorporated | Apparatus and method for a secure broadcast system |
| US8229108B2 (en) * | 2003-08-15 | 2012-07-24 | Broadcom Corporation | Pseudo-random number generation based on periodic sampling of one or more linear feedback shift registers |
| US7308100B2 (en) * | 2003-08-18 | 2007-12-11 | Qualcomm Incorporated | Method and apparatus for time-based charging for broadcast-multicast services (BCMCS) in a wireless communication system |
| US8724803B2 (en) | 2003-09-02 | 2014-05-13 | Qualcomm Incorporated | Method and apparatus for providing authenticated challenges for broadcast-multicast communications in a communication system |
| KR100617671B1 (en) * | 2003-12-22 | 2006-08-28 | 삼성전자주식회사 | High-speed wireless lan system |
| US20060126841A1 (en) * | 2004-12-14 | 2006-06-15 | Tata Consultancy Services Ltd. | Method and apparatus for a security system for wireless networks |
| US20090210695A1 (en) * | 2005-01-06 | 2009-08-20 | Amir Shahindoust | System and method for securely communicating electronic documents to an associated document processing device |
| US7502466B2 (en) * | 2005-01-06 | 2009-03-10 | Toshiba Corporation | System and method for secure communication of electronic documents |
| US7406120B1 (en) * | 2005-04-01 | 2008-07-29 | Bae Systems Information And Electronic Systems Integration Inc. | Transmission channel impulse response estimation using fast algorithms |
| JP2008270870A (en) * | 2007-04-16 | 2008-11-06 | Sony Corp | Communications system, communications apparatus and method, and computer program |
| JP2009188751A (en) * | 2008-02-06 | 2009-08-20 | Fujitsu Ltd | Encryption and decryption method, transmission device, and reception device in radio communication system |
Family Cites Families (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6906145A (en) * | 1968-05-15 | 1969-11-18 | ||
| US3649915A (en) * | 1970-06-22 | 1972-03-14 | Bell Telephone Labor Inc | Digital data scrambler-descrambler apparatus for improved error performance |
| US3801732A (en) * | 1971-11-22 | 1974-04-02 | J Reeves | Method and apparatus for scrambled television |
| US3914534A (en) * | 1973-10-29 | 1975-10-21 | Magnavox Co | Methods and apparatus for scrambling and unscrambling premium television channels |
| US3911216A (en) * | 1973-12-17 | 1975-10-07 | Honeywell Inf Systems | Nonlinear code generator and decoder for transmitting data securely |
| JPS5831762B2 (en) * | 1974-08-21 | 1983-07-08 | 横河電機株式会社 | Random Shingo Hatsusei Cairo |
| US4115662A (en) * | 1975-06-06 | 1978-09-19 | Etablissement Public Dit Telediffusion De France | One way data transmission system |
| FR2313825A1 (en) * | 1975-06-06 | 1976-12-31 | Telediffusion Fse | DATA DISSEMINATION SYSTEM |
| US4081832A (en) * | 1976-06-08 | 1978-03-28 | Pay Television Corporation | Pay television system, method and apparatus |
| US4115807A (en) * | 1976-07-19 | 1978-09-19 | Pires H George | Telephone billing apparatus for a subscription television system |
| US4163254A (en) * | 1977-02-14 | 1979-07-31 | Block Robert S | Method and system for subscription television billing and access |
| US4200770A (en) * | 1977-09-06 | 1980-04-29 | Stanford University | Cryptographic apparatus and method |
| US4310720A (en) * | 1978-03-31 | 1982-01-12 | Pitney Bowes Inc. | Computer accessing system |
| FR2448824A1 (en) * | 1979-02-06 | 1980-09-05 | Telediffusion Fse | VIDEOTEX SYSTEM PROVIDED WITH INFORMATION ACCESS CONTROL MEANS |
| FR2448825A1 (en) * | 1979-02-06 | 1980-09-05 | Telediffusion Fse | SYSTEM FOR TRANSMITTING INFORMATION BETWEEN A TRANSMISSION CENTER AND RECEIVING STATIONS, WHICH IS PROVIDED WITH A MEANS OF CONTROLLING ACCESS TO THE INFORMATION TRANSMITTED |
| US4365110A (en) * | 1979-06-05 | 1982-12-21 | Communications Satellite Corporation | Multiple-destinational cryptosystem for broadcast networks |
| FR2459595A1 (en) * | 1979-06-15 | 1981-01-09 | Telediffusion Fse | ACCESS CONTROL TELEVISION SYSTEM USING A VARIABLE ELECTRONIC KEY |
| JPS5612185A (en) * | 1979-07-11 | 1981-02-06 | Clarion Co Ltd | Chargeable television system of independent synchronizing type on radio system |
| JPS5639685A (en) * | 1979-09-07 | 1981-04-15 | Clarion Co Ltd | Decoding system |
| US4292650A (en) * | 1979-10-29 | 1981-09-29 | Zenith Radio Corporation | Stv Subscriber address system |
| JPS5843743B2 (en) * | 1979-12-25 | 1983-09-28 | 富士通株式会社 | Encryption method |
| JPS6035865B2 (en) * | 1979-12-27 | 1985-08-16 | 株式会社東芝 | Data transmission method |
| US4388643A (en) * | 1981-04-06 | 1983-06-14 | Northern Telecom Limited | Method of controlling scrambling and unscrambling in a pay TV system |
-
1981
- 1981-11-19 US US06/322,833 patent/US4484027A/en not_active Ceased
-
1982
- 1982-11-19 DE DE8383900222T patent/DE3280237D1/en not_active Expired - Fee Related
- 1982-11-19 WO PCT/US1982/001631 patent/WO1983001881A1/en active IP Right Grant
- 1982-11-19 CA CA000415993A patent/CA1194212A/en not_active Expired
- 1982-11-19 AT AT83900222T patent/ATE56333T1/en not_active IP Right Cessation
- 1982-11-19 JP JP83500335A patent/JPS58501982A/en active Pending
- 1982-11-19 EP EP83900222A patent/EP0094423B1/en not_active Expired - Lifetime
- 1982-11-19 CA CA613072A patent/CA1328501B/en not_active Expired - Lifetime
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1992
- 1992-11-19 JP JP4332267A patent/JPH06125554A/en active Pending
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|---|---|
| ATE56333T1 (en) | 1990-09-15 |
| JPH06125554A (en) | 1994-05-06 |
| WO1983001881A1 (en) | 1983-05-26 |
| CA1194212A (en) | 1985-09-24 |
| EP0094423A4 (en) | 1986-11-27 |
| US4484027A (en) | 1984-11-20 |
| DE3280237D1 (en) | 1990-10-11 |
| CA1328501E (en) | 1985-09-24 |
| JPS58501982A (en) | 1983-11-17 |
| EP0094423A1 (en) | 1983-11-23 |
| EP0094423B1 (en) | 1990-09-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| NARE | Reissued | ||
| MKLC | Lapsed (correction) | ||
| MKEC | Expiry (correction) | ||
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20021119 |