Key distribution method and system in secure broadcast communication
First Claim
1. A key distribution system in which a sender and a plurality of receivers use individual key information generated beforehand by a key generator to share a common key information for performing a secure broadcast communication, wherein(i) the key generator side is provided with:
- means for generating confidential information of a receiver in association with a subset inclusive of at least two elements of a first finite set S1 on the basis of a space determined by a subset inclusive of at least two elements of a second finite set S2; and
means for distributing said confidential information to the receiver,(ii) the sender side is provided with;
means for generating key distribution data corresponding to each element of said first finite set S1; and
communication means for making the multi-address transmission of said key distribution data,and (iii) the receiver side is provided with;
storage means for storing said confidential information beforehand; and
means for calculating common key information K between the sender and the receiver from the stored confidential information for each receiver and the key distribution data.
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Accused Products
Abstract
A key distribution method and system are disclosed in which a sender and receivers share a common key information for performing a secure broadcast communication. By use of a center side apparatus, a center generates key information of a receiver in association with a subset inclusive of two or more elements of a proper finite set S1 on the basis of a space determined by a subset inclusive of two or more elements of another finite set S2. A sender side apparatus, a sender makes the multi-address transmission of key distribution data W inclusive of data generated corresponding to each element of the finite set S1 and data generated corresponding to a set of plural receivers through a communication network. By use of a receiver side apparatus, a receiver generates common key information between the sender and the receiver from the key distribution data W and the key information of the receiver.
49 Citations
42 Claims
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1. A key distribution system in which a sender and a plurality of receivers use individual key information generated beforehand by a key generator to share a common key information for performing a secure broadcast communication, wherein
(i) the key generator side is provided with: -
means for generating confidential information of a receiver in association with a subset inclusive of at least two elements of a first finite set S1 on the basis of a space determined by a subset inclusive of at least two elements of a second finite set S2; and means for distributing said confidential information to the receiver, (ii) the sender side is provided with; means for generating key distribution data corresponding to each element of said first finite set S1; and communication means for making the multi-address transmission of said key distribution data, and (iii) the receiver side is provided with; storage means for storing said confidential information beforehand; and means for calculating common key information K between the sender and the receiver from the stored confidential information for each receiver and the key distribution data. - View Dependent Claims (5, 6, 9, 10)
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2. A key distribution system in a limited secure broadcast communication in which a broadcasting station as a sender communicates with only receivers limited beforehand from among a plurality of receivers, wherein
(i) the sender side is provided with: -
means for generating confidential information of a receiver in association with a subset inclusive of at least two elements of a finite set S; means for distributing said confidential information to the receiver; means for generating key distribution data corresponding to each element of said finite set S; communication means for making the multi-address transmission of said key distribution data; means for generating individual information for each receiver to be transmitted to only said limited receivers; and communication means for transmitting said individual information for each limited receiver x, and (ii) the receiver x side is provided with; means for storing said confidential information; and means for calculating common key information K between the sender side and the receiver from said confidential information sx for each receiver distributed by said sender side, said key distribution data and said individual information. - View Dependent Claims (3, 4, 7, 8, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A key distribution method in which a sender and a plurality of receivers use individual key information generated beforehand by a key generator to share a common key information for performing a secure broadcast communication, wherein
(i) the key generator side is provided with the steps of: -
generating confidential information of a receiver in association with a subset inclusive of at least two elements of a first finite set SI on the basis of a space determined by a subset inclusive of at least two elements of a second finite set S2; and distributing said confidential information to the receiver, (ii) the sender side is provided with; generating key distribution data corresponding to each element of said first finite set S1; and making the multi-address transmission of said key distribution data, and (iii) the receiver side is provided with the steps of; storing said confidential information beforehand; and calculating common key information K between the sender and the receiver from the stored confidential information for each receiver and the key distribution data. - View Dependent Claims (26, 27, 30, 31)
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31. A key distribution method according to claim 26, wherein said key generator side is further provided with a step of selecting the key information s.sub.σ
- .sbsb.x of the receiver x to satisfy so that ##EQU111## is satisfied.
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23. A key distribution method for sharing common key information in a limited secure broadcast communication in which a broadcasting station as a sender communicates wits only receivers limited from among a plurality of receivers, wherein
(i) the sender side is provided with the steps of: -
generating confidential information of a receiver in association with a subset inclusive of at least two elements of a finite set S; distributing said confidential information to the receiver; generating key distribution data corresponding to each element of said finite set S; making the multi-address transmission of said key distribution data; generating individual information for each receiver to be transmitted to only said limited receivers; and transmitting said individual information for each limited receiver x, and (ii) the receiver x side is provided with; a step of calculating common key information K between the sender side and the receiver from said confidential information sx for each receiver distributed by said sender side, said key distribution data and said individual information. - View Dependent Claims (24, 25, 28, 29, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification