System and method for security association between communication devices within a wireless home network
Embodiments of the application describe a method and system for discovering and authenticating communication devices and establishing a secure communication link within a wireless home network without requiring a secure channel. According to an embodiment, communication devices exchange public keys using multiple messages each including at least a portion of the public key of the sending device. The devices authenticate the receipt of the public key and establish a shared master key. The shared master key is used to further derive a session key for securing the application data between the communicating devices for a current session.
1. A wireless home network comprising:
a plurality of hardware devices configured to communicate with each other within the wireless network, wherein each one of the plurality of devices is configured to:
initiate a secure communication link with at least one other device within the wireless home network without requiring a secure channel;
exchange public keys with the at least one other device using a first plurality of messages, wherein each of the first plurality of messages includes at least a portion of a public key of message sending device, wherein exchanging public keys between the first and second devices further comprises:
sending a first message of the first plurality of messages from the first device to the second device, wherein the first message includes a first portion of the public key of the first device;
receiving at the first device an acknowledgment of receipt of the first message from the second device;
sending a second message of the first plurality of messages from the second device to the first device in response to the first message received from the first device, wherein the second message includes a first portion of the public key of the second device;
receiving at the second device an acknowledgment of receipt of the second message from the first device
sending a third message of the first plurality of messages from the first device to the second device only after the corresponding acknowledgment for the first message is received by the first device, wherein the third message includes a second portion of the public key of the first device;
receiving at the first device an acknowledgment of receipt of the third message from the second device;
sending a fourth message of the first plurality of messages from the second device to the first device only after the corresponding acknowledgment for the second message is received by the second device in response to the third message received from the first device, wherein the fourth message includes a second portion of the public key of the second device;
receiving at the second device an acknowledgment of receipt of the fourth message from the first device;
verify correct reception of the public keys; and
generate a shared symmetric master key for the secure communication link using the public key, the private key and a random number.
2. A wireless network according to claim 1 , wherein each one of the first plurality of messages includes a sequence number, and the plurality of devices are further configured to:
send messages to the other devices in an order of the sequence numbers.
3. A wireless network according to claim 2 , wherein each one of the plurality of wireless devices is further configured to:
issue an error warning and terminate the secure link establishment process if the device receives a message that is out-of-order of the sequence number.
4. A wireless network according to claim 1 , wherein each one of the plurality of devices is configured to:
setup a time window for the exchange of public keys; and
indicate the initiation of the secure communication link, wherein devices exchanges their public keys within the time window.
5. A communication device configured to:
establish a secure communication link with at least one other device in a wireless home network without requiring a secure channel;
exchange public keys with the other device using a first plurality of messages, wherein each of the first plurality of messages includes at least a portion of a public key of message sending device, wherein exchanging public keys between the first and second devices further comprises:
sending a first message of the first plurality of messages from the first device to the second device, wherein the first message includes a first portion of the public key of the first device;
receiving at the first device an acknowledgment of receipt of the first message from the second device;
sending a second message of the first plurality of messages from the second device to the first device in response to the first message received from the first device, wherein the second message includes a first portion of the public key of the second device;
receiving at the second device an acknowledgment of receipt of the second message from the first device
sending a third message of the first plurality of messages from the first device to the second device only after the corresponding acknowledgment for the first message is received by the first device, wherein the third message includes a second portion of the public key of the first device;
receiving at the first device an acknowledgment of receipt of the third message from the second device;
sending a fourth message of the first plurality of messages from the second device to the first device only after the corresponding acknowledgment for the second message is received by the second device in response to the third message received from the first device, wherein the fourth message includes a second portion of the public key of the second device;
receiving at the second device an acknowledgment of receipt of the fourth message from the first device;
verify correct reception of the public keys; and
generate a shared symmetric master key for the secure communication link using the public key, the private key and a random number.
6. A communication device according to claim 5 , wherein each one of the first plurality of messages includes a sequence number, the communication device is configured to
send messages to the other device in an order of the sequence numbers; and
the communication device does not send a message including a portion of the corresponding public key to the other device if the communication device receives a message that is out-of-order of the sequence number.
7. A communication device according to claim 6 , further configured to:
issue an error warning, and
terminate the secure link establishment process if a message that is out-of-order of sequence is received.
8. A communication device according to claim 5 , further configured to:
setup a time window for the exchange of the public keys; and
indicate the initiation of the secure communication link, wherein the communication device and the other device exchange their public keys within the time window.
9. A communication device according to claim 5 , wherein the communication device establishes the shared symmetric master key with the other device based on their respective public keys and private keys and information exchanged in verifying the correct reception of their respective public keys.
10. A communication device according to claim 5 , further configured to:
use the shared symmetric master key to derive a shared session key for one or more application sessions on the secure communication link with the other device, wherein the session key is used to secure application data exchanged between the communication device and the other.