# US 8,752,126 B2 · Method for enhancing the security of the multicast or broadcast system

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- Number: US 8,752,126 B2
- Document ID: US8752126B2
- Status: Granted
- Kind: B2
- Application number: 13/059,547
- Filed: 2009-08-20
- Published: 2011-11-24
- Granted: 2014-06-10
- Earliest claimed: 2008-08-21
- Assignees: China Iwncomm Co., Ltd.
- Applicants: Liaojun Pang; Jun Cao; Manxia Tie
- Inventors: Liaojun Pang; Jun Cao; Manxia Tie
- Web page: https://patentgrep.com/patent/US8752126B2

## CPC

- H04L 9/085: {Secret sharing or secret splitting, e.g. threshold schemes}
- H04L 9/3073: {involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing}
- H04L 63/062: {for key distribution, e.g. centrally by trusted party (cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819)}
- H04W 12/041: Key generation or derivation
- H04W 12/0433: Key management protocols
- H04L 2209/601: Broadcast encryption
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A method for enhancing the security of the multicast or broadcast system comprises the following steps: after having established the system parameter, the base station receives the register request message transmitted by the terminal, and the register request message carries the device identity information of the terminal; the base station registers the terminal according to the register request message and transmits the authorization key to the terminal after successful registration. By the base station establishing the specific system parameter, generating and awarding the corresponding terminal's key based on the parameter, the embodiment of the present invention can construct a secure network system of multicast or broadcast effectively and solve the security problem of the multicast or broadcast from the base station to the terminal in the network system.

## Claims

### Claim 1

A method for enhancing security of a broadcast or multicast system, wherein, after defining by a base station system parameters of the broadcast/multicast system, the method comprises:
receiving by the base station a registration request message from a mobile terminal, the registration request message contains device identity information of the mobile terminal; and
registering by the base station the mobile terminal according to the registration request message and transmitting by the base station an authorized key to the mobile terminal upon successful registration,
wherein, the method further comprises: receiving by the mobile terminal a broadcast/multicast encryption text transmitted from the base station, wherein, the mobile terminal decrypts the broadcast/multicast encryption text with the authorized key,
wherein, an operation of defining by a base station system parameters of the broadcast/multicast system comprises: defining two q-order cyclic groups of (G1, +) and (G2, ·), wherein, q is a prime number, G1 is irreversible in Diffie-Hellman calculation, and P is a generator of G1; defining e representing bilinear transformation on G1 and G2; and defining h(·) representing a unidirectional hash function,
wherein, an operation of registering by the base station the mobile terminal according to the registration request message comprises: verifying, by the base station, physical information of the mobile terminal, and when the mobile terminal complies with the registration request message, selecting by the base station randomly a number n−1 of different elements from Z*q, wherein, n is an integer larger than or equal to 2, and selecting from G1 and publishing two elements Q1 and Q2; constructing randomly an (n−1)-order secret polynomial f(x)εZp[x]; calculating QK from QK=f(0)PεG1 and Vi from Vi=f(vi)P(i=0, 1, . . . , n−2) according to a constructed polynomial, wherein, i ranges from 0 to n−2; and extracting the device identity information IDx from the registration request message, and calculating Vx from Vx=f(IDx)(Q1+Q2) according to the device identity information IDx.

### Claim 2 (depends on 1)

The method of claim 1, wherein, an operation of transmitting by the base station an authorized key to the mobile terminal upon successful registration comprises:
transmitting the Vx to the mobile terminal.

### Claim 3 (depends on 2)

The method of claim 2, wherein, an operation of receiving by the mobile terminal a broadcast/multicast encryption text transmitted from the base station comprises:
acquiring by the base station a broadcast/multicast plain text M, where the broadcast/multicast plain text MεG2, and encrypting the broadcast/multicast plain text M by the base station to obtain the broadcast/multicast encryption text and then transmitting by the base station the broadcast/multicast encryption text to the mobile terminal.

### Claim 4 (depends on 3)

The method of claim 3, wherein an operation of encrypting the broadcast/multicast plain text M by the base station comprises:
selecting by the base station randomly an element from the group Z*q and performing the following calculation:
C=(P*,Q*1,U,V*0, . . . V*n-2)=(rP,rQ1,e(QK,Q2)r(T∥M∥h(T∥M)),rV0, . . . rVn-2), wherein,
C represents the broadcast/multicast encryption text of the broadcast/multicast plain text, and T represents a current time of the broadcast/multicast system.

### Claim 5 (depends on 4)

The method of claim 4, wherein an operation of decrypting by the mobile terminal the broadcast/multicast encryption text C with the authorized key comprises:
constructing by the mobile terminal a set Γ by using system parameter e and the device identity information IDx: Γ={e0, e1, . . . , en-1}={v0, . . . , vn-2, IDx};
calculating by the mobile terminal σei,Γ from
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calculating, from
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T∥M∥h(T∥M) according to the σei,Γ; and
comparing calculated h(T∥M) with h(T∥M) transmitted from the base station, and if they are consistent, then determining that M is the broadcast/multicast plain text.

### Claim 6 (depends on 5)

The method of claim 5, further comprising: determining by the mobile terminal based on the time T whether M is a replay message.