Handshake procedure
The invention discloses a solution for establishing by a handshake procedure a group temporal key for group communication. The group temporal key is established by a group procedure and is a group-specific temporal key.
1 . A method for establishing, by a handshake procedure, a group temporal key for group communication, the method comprising:
providing a handshake initiator with a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members;
generating a group temporal key identifier;
generating an initiator random number;
creating an initiating message comprising the group identifier, the group key identifier, the group temporal key identifier, and the initiator random number;
sending the initiating message to other group members;
receiving a response message from at least one group member, the response message comprising a random number of the sender of the response message;
determining, whether response messages have been received from a predetermined set of group members; and
calculating the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers, when a response message have been received from the predetermined set of group members.
2 . The method according to claim 1 , wherein when determining that response messages have not been received from the predetermined set of group members, the method further comprises one of the following steps:
reinitiating the handshake procedure, and
aborting the handshake procedure.
3 . The method according to claim 1 , wherein using in the group temporal key calculation random numbers of all the group members belonging to the predetermined set of group members.
4 . The method according to claim 1 , wherein the predetermined set of group members comprises all the group members.
5 . The method according to claim 1 , wherein the predetermined set of group members comprises a subgroup of all the group members.
6 . The method according to claim 1 , further comprising:
reinitiating the handshake procedure, when detecting a group member from which a response message was not received.
7 . The method according to claim 1 , further comprising:
sending a message comprising random numbers used in calculating the group temporal key to the group.
8 . The method according to claim 1 , further comprising:
sending a message comprising random numbers used in calculating the group temporal key and sender information of the received random numbers to the group.
9 . The method according to claim 1 , further comprising:
sending a message comprising random numbers used in calculating the group temporal key, the group key identifier and the group identifier to at least one group member from which a response message was not received.
10 . The method according to claim 9 , further comprising:
indicating in the message whether the order of the initiator random number and the random numbers used in calculating the group temporal key is significant.
11 . The method according to claim 1 , wherein the group key identifier and the group identifier are comprised in a single identifier.
12 . The method according to claim 1 , wherein the handshake procedure is performed in the data link layer.
13 . The method according to claim 1 , wherein the handshake procedure is performed above the data link layer, and wherein the method further comprises:
transporting the calculated group temporal key to the data link layer.
14 . A method for establishing, by a handshake procedure, a group temporal key for group communication, the method comprising;
providing a handshake responder with a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members;
receiving an initiating message from a handshake initiator, the initiating message comprising the group identifier, a group temporal key identifier, and an initiator random number;
receiving a response message from at least one group member, the message comprising a random number of the sender of the message;
determining, whether response messages have been received from a predetermined set of group members; and
calculating the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers in the at least one received response message, when a response message has been received from the predetermined set of group members.
15 . The method according to claim 14 , further comprising:
generating a responder random number;
creating a response message that comprises at least the responder random number; and
sending the response message to other members of the group.
16 . The method according to claim 14 , wherein when determining that response messages have not been received from the predetermined set of group members, the method further comprises:
aborting the handshake procedure.
17 . The method according to claim 14 , wherein using in the group temporal key calculation random numbers of all the group members belonging to the predetermined set of group members.
18 . The method according to claim 14 , wherein the predetermined set of group members comprises all the group members.
19 . The method according to claim 14 , wherein the predetermined set of group members comprises a subgroup of all the group members.
20 . The method according to claim 14 , further comprising:
receiving, from the handshake initiator, a key calculation message comprising random numbers used by the handshake initiator in calculating the group temporal key;
checking, whether the handshake responder has received the same random numbers as comprised in the key message;
using in calculating the group temporal key the random numbers comprised in the key message, when the result of the checking is affirmative; and
aborting the handshake procedure, when the result of the checking is negative.
21 . The method according to claim 14 , further comprising:
receiving, from the handshake initiator, a key calculation message comprising random numbers used in calculating the group temporal key and corresponding sender information of the random numbers;
checking, whether the handshake responder has received the same random numbers from the same senders as comprised in the key message;
using in calculating the group temporal key the random numbers comprised in the key message, when the result of the checking is affirmative; and
aborting the handshake procedure, when the result of the checking is negative.
22 . The method according to claim 14 , wherein the group key identifier and the group identifier are comprised in a single identifier.
23 . The method according to claim 14 , wherein the handshake procedure is performed in the data link layer.
24 . The method according to claim 14 , wherein the handshake procedure is performed above the data link layer, and wherein the method further comprises:
transporting the calculated group temporal key to the data link layer.
25 . A method for establishing, by a handshake procedure, a group temporal key for group communication, the method comprising;
providing a group member with a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members;
receiving, from a handshake initiator, a key calculation message comprising a group temporal key identifier, a group identifier and random numbers of those group members which were used in calculating the group temporal key; and
calculating the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, the group identifier, and the received random numbers.
26 . The method according to claim 25 , further comprising:
indicating in the key calculation message whether the order of the random numbers in calculating the group temporal key is significant.
27 . A device for establishing, by a handshake procedure, a group temporal key for group communication, the device comprising:
a transceiver configured to communicate with other group members over a wired or wireless connection; and
a handshake unit comprising a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members, wherein the handshake unit is configured to:
generate a group temporal key identifier;
generate an initiator random number;
create an initiating message comprising the group identifier, the group key identifier, the group temporal key identifier, and the initiator random number;
send the initiating message to other group members;
receive a response message from at least one group member, the response message comprising a random number of the sender of the response message;
determine, whether response messages have been received from a predetermined set of group members; and
calculate the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers, when a response message have been received from the predetermined set of group members.
28 . A device for establishing, by a handshake procedure, a group temporal key for group communication, the device comprising;
a transceiver configured to communicate with other group members over a wired or wireless connection; and
a handshake unit comprising a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members, wherein the handshake unit is configured to:
receive an initiating message from a handshake initiator, the initiating message comprising the group identifier, a group temporal key identifier, and an initiator random number;
receive a response message from at least one group member, the message comprising a random number of the sender of the message;
determine, whether response messages have been received from a predetermined set of group members; and
calculate the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers in the at least one received response message, when a response message has been received from the predetermined set of group members
29 . A device for establishing, by a handshake procedure, a group temporal key for group communication, the device comprising;
a transceiver configured to communicate with other group members over a wired or wireless connection; and
a handshake unit comprising a shared group key, a group key identifier and a group identifier, the group identifier identifying the group members, wherein the group comprises at least three members, wherein the handshake unit is configured to:
receive, from a handshake initiator, a key calculation message comprising a group temporal key identifier, a group identifier and random numbers of those group members which were used in calculating the group temporal key; and
calculate the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, the group identifier, and the received random numbers.
30 . A computer program for establishing, by a handshake procedure, a group temporal key for group communication, the group comprising at least three members, embodied on a computer-readable medium, the computer program configured to perform the following when executed on a data-processing device:
generating a group temporal key identifier;
generating an initiator random number;
creating an initiating message comprising a group identifier, a group key identifier, a group temporal key identifier, and the initiator random number;
sending the initiating message to other group members;
receiving a response message from at least one group member, the response message comprising a random number of the sender of the response message;
determining, whether response messages have been received from a predetermined set of group members; and
calculating the group temporal key with at least a key derivation function, a shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers, when a response message have been received from the predetermined set of group members.
31 . A computer program for establishing, by a handshake procedure, a group temporal key for group communication, the group comprising at least three members, embodied on a computer-readable medium, the computer program configured to perform the following when executed on a data-processing device:
receiving an initiating message from a handshake initiator, the initiating message comprising a group identifier, a group temporal key identifier, and an initiator random number;
receiving a response message from at least one group member, the message comprising a random number of the sender of the message;
determining, whether response messages have been received from a predetermined set of group members; and
calculating the group temporal key with at least a key derivation function, a shared group key identified by the group key identifier, and at least one random number from a set of the initiator random number and the received random numbers in the at least one received response message, when a response message has been received from the predetermined set of group members
32 . A computer program for establishing, by a handshake procedure, a group temporal key for group communication, the group comprising at least three members, embodied on a computer-readable medium, the computer program configured to perform the following when executed on a data-processing device:
receiving, from a handshake initiator, a key calculation message comprising a group temporal key identifier, a group identifier and random numbers of those group members which were used in calculating the group temporal key; and
calculating the group temporal key with at least a key derivation function, the shared group key identified by the group key identifier, the group identifier, and the received random numbers.