Enciphering key distribution system for subscription TV broadcast or catv system

• US 4,658,292 A
• Filed: 04/27/1983
• Issued: 04/14/1987
• Est. Priority Date: 04/30/1982
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Okamoto, Eiji, Nakamura, Katsuhiro
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Koltak, Melissa L.
• Application Number:
  US06/489,243
• Time in Patent Office: 1,448 Days
• Field of Search: 178/22.13, 178/22.14, 178/22.15, 178/22.16, 178/22.08, 178/22.09, 178/22.18, 178/22.19, 358/114, 358/122, 358/123, 358/124
• US Class Current: 380/239
• CPC Class Codes: H04L 2209/601 Broadcast encryption
• CPC Class Codes: H04L 9/0819 Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) network architectures or network communication protocols for key distribution in a packet data network H04L63/062
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

An enciphering key distribution system comprises a transmitter having an address generator for generating the addresses of those subscribers to which a first enciphered TV signal is to be distributed. An enciphering generator generates a second enciphering, in response to the individual addresses, on a one-to-one correspondence with the individual subscribers. A multiplier produces a product which is associated with all the subscribers. An adder adds the first enciphered signal to the product. The system also comprises a receiver having a divider for dividing the signal transmitted from the transmitter by one of the second encipherings on a basis which is assigned to the particular subscriber or receiver.

Claims

1. An enciphering key signal distribution system comprising:

transmitter means having first enciphering key signal generator means for generating a first key enciphering signal which is used for enciphering a TV signal, address generating means for generating addresses of subscribers, second enciphering key signal generator means for generating second enciphering key signals in response to said addresses, said second enciphering key signals being assigned on a one-to-one correspondence with said subscribers, multiplier means for producing a product of the second key signals associated with all of said subscribers, and adder means responsive to a signal supplied from said address generating means which is indicative of the last address of said subscribers for adding said first key signal to said product of said second key signals;

means for transmitting a signal responsive to the output of said adder means; and

receiver means having a divider means for dividing the signal transmitted from said transmitter means by one of said second enciphering key signals which is assigned to identify the particular subscriber who is receiving the signal.

3. The enciphering key distribution system as claimed in claim 1, in which said second enciphering keys comprise prime numbers.

4. The enciphering key distribution system as claimed in claim 1, in which said first and second enciphering keys comprise polynominal coefficients.

2. An enciphering key signal transmitter comprising:

address generator means for generating addresses of subscribers to which a first enciphering key signal for enciphering a TV signal is to be distributed;

enciphering key signal generator means for generating second enciphering key signals in response to said addresses, said second enciphering key signals being assigned on a one-to-one correspondence with said subscribers;

multiplier means for producing a product of said second key signals associated with all said subscribers; and

adder means for adding said first key signal to said product of second key signal.

5. An enciphering key receiver comprising:

demodulator means for demodulating a signal transmitted from a transmitter;

means for separating said demodulated signal into a key signal including a first key and a control signal;

register means for sequentially receiving said key signal bit by bit;

means for storing a second key assigned to said receiver;

subtractor means for producing a difference between an output of said register means and said second key supplied from a key storage means;

a selector for selecting said difference when the difference is nonnegative and selecting said second key when the difference is negative; and

means for picking up an output of said selector as said first key in response to said control signal.

6. A process for enabling the distribution of subscription television signals, said process comprising the steps of:

(a) transmitting TV signals from a station having the addresses of all subscribers stored therein;

(b) generating enciphered key signals corresponding to individually associated subscriber addreses on a one-for-one basis;

(c) producing a product of all of said enciphered key signals;

(d) generating a key signal for enciphering said TV signals;

(e) adding the key signals generated in steps (c) and (d);

(f) transmitting the signal combined in step (e) along with said television signals; and

(g) receiving and dividing the signal transmitted in step (f) by the key signal which individually corresponds to the individual subscriber who is receiving the signal.

7. The process of claim 6 wherein each of said key signal of step (b) which corresponds with individual subscriber addresses is a prime number.

8. The process of claim 6 wherein said key signal representing all subscribers is a signal selected by a random number of generator.

9. The process of claim 7 wherein said key signal representing all subscribers is a signal selected by a random number of generator and the added step of enciphering said television signals responsive to said random number selected by said generator.

10. The process of claim 9 wherein said transmission of step (f) includes the added step of transmitting said signals by satellite directly to said subscriber.