# US 8,787,574 B2 · Multicast key negotiation method suitable for group calling system and a system thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,574 B2 - Document ID: US8787574B2 - Status: Granted - Kind: B2 - Application number: 13/637,375 - Filed: 2010-05-12 - Published: 2013-01-17 - Granted: 2014-07-22 - Earliest claimed: 2010-05-12 - Assignees: China Iwncomm Co., Ltd. - Applicants: Yanan Hu; Jun Cao; Manxia Tie; Zhenhai Huang - Inventors: Yanan Hu; Jun Cao; Manxia Tie; Zhenhai Huang - Web page: https://patentgrep.com/patent/US8787574B2 ## CPC - H04L 12/189: {in combination with wireless systems (selective distribution or broadcast in wireless communication networks H04W4/06)} - H04L 63/065: {for group communications (cryptographic mechanisms or cryptographic arrangements for key management involving conference or group key H04L9/0833)} - H04W 12/041: Key generation or derivation - H04W 12/0431: Key distribution or pre-distribution; Key agreement - H04W 12/0433: Key management protocols - H04W 12/106: Packet or message integrity - 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 The present invention discloses a multicast key negotiation method suitable for group calling system and a system thereof. The method includes that: a user terminal (UT) negotiates about a unicast key with a base station (BS), derives an information encryption key and an integrity verifying key according to the unicast key, and registers a service group identifier that the UT belongs to at the BS; the BS notifies the UT the multicast key of the service group that the UT needs to apply, constructs a multicast key notification packet, and sends it to the UT; after receiving the multicast key notification packet sent by the BS, the UT obtains the multicast key of the service group that the UT needs to apply by decrypting a service group key application list, constructs a multicast key confirmation packet, and sends it to the BS; the BS confirms that the multicast key of the UT service group is built successfully according to the multicast key confirmation packet sent by the UT. ## Claims ### Claim 1 A multicast key negotiation method suitable for a group call system, comprising: a) negotiating a unicast key between a UT and a BS, deriving an information encryption key and an integrity check key from the unicast key, and registering by the UT to the BS identifiers of service groups to which the UT pertains; b) notifying, by the BS, the UT of multicast keys of service groups to be applied by the UT, constructing a multicast key notification message which comprises a service group key application list and a message integrity check value, and sending the multicast key notification message to the UT, wherein the service group key application list, which is a ciphertext obtained by encryption using the information encryption key, comprises identifiers and the multicast keys of the service groups to be applied by the UT; c) decrypting, by the UT, the service group key application list on receiving the multicast key notification message sent by the BS to obtain the multicast keys of the service groups to be applied by the UT, constructing a multicast key confirmation message which comprises a service group key response list and the message integrity check value, and sending the multicast key confirmation message to the BS, wherein the service group key response list, which is a ciphertext obtained by encryption using the information encryption key, comprises the identifiers of the service groups which have been applied; and d) confirming, by the BS, that the multicast keys of the service groups for the UT have been established successfully upon the multicast key confirmation message sent by the UT. ### Claim 2 (depends on 1) The multicast key negotiation method suitable for a group call system according to claim 1, wherein: a multicast key of the service group is generated by the BS if the multicast key of the service group to be applied by the UT is applied for a first time in a network; or a multicast key of the service group in a first time application is forwarded by the BS if the multicast key of the service group to be applied by the UT has been applied in a network. ### Claim 3 (depends on 2) The multicast key negotiation method suitable for a group call system according to claim 2, further comprising: encrypting, by the BS, a multicast data frame by using an old multicast key of the service group and sending the multicast data frame, in a process of updating a multicast key of the service group, and enabling, by the BS, a new multicast key of the service group for encrypting and sending of the multicast data frame, upon completion of the multicast key negotiation of the service group for all the UTs associated with the BS. ### Claim 4 (depends on 1) The multicast key negotiation method suitable for a group call system according to claim 1, further comprising: verifying, by the UT, the message integrity check value of the multicast key notification message by using the derived integrity check key, before a process of decrypting the service group key application list; discarding the multicast key notification message if the message integrity check value is incorrect; and performing the step of decrypting the service group key application list if the message integrity check value is correct, wherein the decrypting the service group key application list and acquiring the multicast keys of the service groups to be applied by the UT comprises: obtaining the identifiers of the service groups to be applied by the UT from the service group key application list; and obtaining the multicast keys of the service groups to be applied by the UT if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 5 (depends on 4) The multicast key negotiation method suitable for a group call system according to claim 4, wherein the confirming by the BS the multicast keys of service groups for the UT have been established successfully upon the multicast key confirmation message sent by the UT comprises: verifying, by the BS, the message integrity check value of the multicast key confirmation message by using the derived integrity check key on receiving the multicast key confirmation message sent by the UT; discarding the multicast key confirmation message if the message integrity check value is incorrect; decrypting, by the BS, the service group key response list to obtain the identifiers of the service groups from the service group key response list if the message integrity check value is correct; and confirming that the multicast keys of the service groups for the UT have been established successfully, if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 6 (depends on 5) The multicast key negotiation method suitable for a group call system according to claim 5, wherein the multicast key notification message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index. ### Claim 7 (depends on 6) The multicast key negotiation method suitable for a group call system according to claim 6, wherein the multicast key confirmation message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index. ### Claim 8 A multicast key negotiation system suitable for a group call system, comprising a UT and a BS, wherein the UT and the BS negotiate a unicast key and derive an information encryption key from the unicast key; the BS sends a multicast key notification message to the UT; and the UT receives the multicast key notification message and then decrypts a service group key application list from the multicast key notification message to obtain the multicast keys of the service groups, constructs a multicast key confirmation message, and sends the multicast key confirmation message to the BS, wherein the service group key application list, which is a ciphertext obtained by encryption using the information encryption key, comprises identifiers and the multicast keys of the service groups to be applied by the UT. ### Claim 9 (depends on 2) The multicast key negotiation method suitable for a group call system according to claim 2, further comprising: verifying, by the UT, the message integrity check value of the multicast key notification message by using the derived integrity check key, before a process of decrypting the service group key application list; discarding the multicast key notification message if the message integrity check value is incorrect; and performing the step of decrypting the service group key application list if the message integrity check value is correct; wherein the decrypting the service group key application list and acquiring the multicast keys of the service groups to be applied by the UT comprises: obtaining the identifiers of the service groups to be applied by the UT from the service group key application list; and obtaining the multicast keys of the service groups to be applied by the UT if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 10 (depends on 9) The multicast key negotiation method suitable for a group call system according to claim 9, wherein the confirming by the BS the multicast keys of service groups for the UT have been established successfully upon the multicast key confirmation message sent by the UT comprises: verifying, by the BS, the message integrity check value of the multicast key confirmation message by using the derived integrity check key on receiving the multicast key confirmation message sent by the UT; discarding the multicast key confirmation message if the message integrity check value is incorrect; decrypting, by the BS, the service group key response list to obtain the identifiers of the service groups from the service group key response list if the message integrity check value is correct; and confirming that the multicast keys of the service groups for the UT have been established successfully, if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 11 (depends on 10) The multicast key negotiation method suitable for a group call system according to claim 10, wherein the multicast key notification message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index. ### Claim 12 (depends on 11) The multicast key negotiation method suitable for a group call system according to claim 11, wherein the multicast key confirmation message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index. ### Claim 13 (depends on 3) The multicast key negotiation method suitable for a group call system according to claim 3, further comprising: verifying, by the UT, the message integrity check value of the multicast key notification message by using the derived integrity check key, before the process of decrypting the service group key application list; discarding the multicast key notification message if the message integrity check value is incorrect; and performing the step of decrypting the service group key application list if the message integrity check value is correct, wherein the decrypting the service group key application list and acquiring the multicast keys of the service groups to be applied by the UT comprises: obtaining the identifiers of the service groups to be applied by the UT from the service group key application list; and obtaining the multicast keys of the service groups to be applied by the UT if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 14 (depends on 13) The multicast key negotiation method suitable for a group call system according to claim 13, wherein the confirming by the BS the multicast keys of service groups for the UT have been established successfully upon the multicast key confirmation message sent by the UT comprises: verifying, by the BS, the message integrity check value of the multicast key confirmation message by using the derived integrity check key on receiving the multicast key confirmation message sent by the UT; discarding the multicast key confirmation message if the message integrity check value is incorrect; decrypting, by the BS, the service group key response list to obtain the identifiers of the service groups from the service group key response list if the message integrity check value is correct; and confirming that the multicast keys of the service groups for the UT have been established successfully, if the identifiers of the service groups to be applied by the UT are identical to the identifiers of the service groups to which the UT pertains, registered by the UT with the BS. ### Claim 15 (depends on 14) The multicast key negotiation method suitable for a group call system according to claim 14, wherein the multicast key notification message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index. ### Claim 16 (depends on 15) The multicast key negotiation method suitable for a group call system according to claim 15, wherein the multicast key confirmation message further comprises a message interactive mechanism identifier, a present message identifier, a multicast key security association, a BS identifier, a UT identifier and a unicast key index.