Combination-based broadcast encryption method
First Claim
1. A broadcast encryption method comprising:
- generating, by a server, a base group of unique base values, each of the base values generated from a unique combination of integers among a plurality of different integers having values greater than 1, and assigning a first base value among the unique base values to a first user and a second base value among the unique base values to a second user;
generating first secret information and second secret information for the first user and the second user through calculations with key value information allocated to a corresponding user by using the first base value and the second base value as a base, respectively, and sending the secret information to the first user and the second user;
generating an inverse-base parameter value through calculations with an integer used to produce the base group and key value information of the first user and the second user, and sending the produced inverse-base parameter value and key value information to the first user and the second user; and
deriving a first group key and a second group key based on the key value information and the first secret information and the second secret information, respectively, encrypting a session key with the derived first group key and second group key and sending the encrypted session key encrypted with the derived first group key and the encrypted session key encrypted with the derived second group key to the first user and the second user, respectively.
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Accused Products
Abstract
A combination-based broadcast encryption method includes: assigning by a server a base group of different combinations to each user; producing and sending secret information for each user by using as a base the base group allocated to each user; producing and sending an inverse-base parameter value through calculations with integers used to produce the base group and key value information of one or more privileged users; and deriving a group key by using the key value information of the privileged users, encrypting a session key by using the derived group key, and sending the encrypted session key to each user. Accordingly, each user is assigned a different base through a combination, thereby having security against collusion attacks.
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Citations
50 Claims
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1. A broadcast encryption method comprising:
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generating, by a server, a base group of unique base values, each of the base values generated from a unique combination of integers among a plurality of different integers having values greater than 1, and assigning a first base value among the unique base values to a first user and a second base value among the unique base values to a second user; generating first secret information and second secret information for the first user and the second user through calculations with key value information allocated to a corresponding user by using the first base value and the second base value as a base, respectively, and sending the secret information to the first user and the second user; generating an inverse-base parameter value through calculations with an integer used to produce the base group and key value information of the first user and the second user, and sending the produced inverse-base parameter value and key value information to the first user and the second user; and deriving a first group key and a second group key based on the key value information and the first secret information and the second secret information, respectively, encrypting a session key with the derived first group key and second group key and sending the encrypted session key encrypted with the derived first group key and the encrypted session key encrypted with the derived second group key to the first user and the second user, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A broadcast encryption method comprising:
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grouping, by a server, into a first group of users and a second group of users that receive a broadcast message, and assigning a first key value to a first user of the first group and a first user of the second group and second key value to a second user of the first group and a second user of the second group; generating a base group of unique base values for the first group and the second group, each of the base values generated from a unique combination of integers among a plurality of different integers having values greater than 1, and assigning a first base value among the unique base values to the first user of the first group and the first user of the second group and a second base value among the unique base values to the second user of the second group; generating first secret information for the first user of the first group and the first user of the second group and second secret information for the second user of the first group and the first user of the second group through calculations with key value information allocated to a corresponding user by using the first base value and the second base value as a base, and sending the secret information to the first user of the first group, the first user of the second group, the second user of the first group, and the second user of the second group; generating a first inverse-base parameter value through calculations with a first integer used to produce the first base group, a second inverse-base parameter value through calculations with a second integer used to produce the second base group, first key value information of the first user of the first group and the first user of the second group, and second key value information of the second user of the first group and the second user of the second group, sending the first inverse-base parameter value and the first key information to the first user of the first group and the first user of the second group, and sending the second inverse-base parameter value and the second key value information to the second user of the first group and the second user of the second group; and deriving a first group key based on the first key value information and the first secret information and the second group key based on the second key value information and the second secret information, encrypting a first session key with the first group key and a second session key with the second group key, sending the first session key to the first user of the first group and the first user of the second group, and sending the second session key to the second user of the first group and the second user of the second group. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A broadcast encryption method comprising:
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receiving by a first user first secret information generated for the first user through calculations with first key value information allocated to the first user and receiving by a second user second secret information generated for the second user through calculations with second key value information allocated to the second user; receiving by the first user an inverse-base parameter value and the first key value information, and receiving by the second user the inverse-base parameter value and the second key value information; generating a first group key and a second group key by using the first secret information and second secret information, respectively; and decrypting, by a processor of the first user and the second user, a session key received from the server by using the first group key and the second group key, respectively, wherein the first secret information and the second secret information are generated from a base group of unique base values, each of the base values of the base group generated from a unique combination of integers among a plurality of different integers having values greater than 1, that includes a first base value assigned to the first user and a second base value assigned to the second user, and wherein the inverse-base parameter value is generated through calculations with integers used to generate the base group and the key value information of the first user and the second user. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. A broadcast encryption method comprising:
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receiving by first of a first group of users and a first user of a second group of users from a server first secret information generated for the first user of the first group and the first user of the second group through calculations with first key value information, and receiving by a second user of the first group of users and a second user of the second group of users from the server second secret information generated for the second user of the first group and the second user of the second group through calculations with second key value information; receiving by the first user of the first group and the first user of the second group from the server a first inverse-base parameter value and the first key value information, and receiving by the second user of the first group and the second user of the second group a second inverse-base parameter value and the second key value information; generating a first group key and a second group key for each group based on the first secret information and second secret information, respectively; and decrypting, by a processor of the first user of the first group and the first user of the second group, a first session key received from the server based on the first group key, and decrypting by a processor of the second user of the second group and the second user of the second group, a second session key received from the server based on the second group key, wherein a first key value is assigned to the first user of the first group and the first user of the second group and a second key value is assigned to the second user of the first group and the second user of the second group, wherein the first secret information and the second secret information are generated from a base group of unique base values, each of the base values of the base group are generated for each group from unique combinations of integers among a plurality of different integers having values greater than 1, that includes a first base value assigned to the first user of the first group and the second user of the first group and a second base value assigned to the first user of the second group and the second user of the second group, and wherein the inverse-base parameter value is generated through calculations with the integers used to generate the base group and the first and second key value information. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. A broadcast encryption method comprising:
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generating, by a server, a first base value as a first product of a first prime integer and a common prime integer and a second base value as a product of a second prime integer and the common prime integer; allocating a first random integer to a first user and allocating a second random integer to a second user; generating first secret key information of the first user from the first base value exponentially modified by the first random integer and generating second secret key information of the second user from the second base value exponentially modified by the second random value; transmitting the first secret key information to the first user and transmitting the second secret key information to the second user; generating a first inverse-base parameter from the first base value and the first random integer and generating a second inverse-base parameter from the second base value and the second random integer; transmitting the first inverse-base parameter to the first user and transmitting the second inverse-base parameter to the second user; encrypting a session key based on the first secret key information and encrypting the session key based on the second secret key information; and transmitting the encrypted session key to the first user and the second user.
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50. A broadcast encryption method comprising:
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generating, by a server, secret key information Kij of n users of a group L of the n users; and transmitting, by the server, the secret key information Kij to the n users for calculating a group key value by eliminating a base group from the secret information Kij, wherein Kij≡
(Oσij(1) . . . Oσij(d) O)zxi y (mod N),wherein Oσ ij (1), . . . , Oσij (d) is the base group produced from a combination of different prime integers, O is a prime integers different from the different prime integers, σ
ij is an index of O, xi is a random number that identifies the group L, z is a random integer, yj is a distinct prime integer among the different integers, N is an RSA composite, d is a positive integer satisfying
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Specification