Root Node Key Reuse for Wireless Mesh Network Security
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Solution Overview
Problem
In wireless mesh networks, the frequent joining and leaving of nodes lead to an increase in the number of device keys, resulting in a larger Media Key Block (MKB) size, which increases processing load due to the combination of device keys, making it inefficient to manage and distribute new group keys securely.
Innovation Solution
Implement a system where the root node assigns device keys belonging to fewer groups by reassigning existing device keys when nodes rejoin, rather than generating new ones, to maintain a smaller MKB size and reduce processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If new device keys are assigned to nodes that rejoin the wireless mesh network, then security is maintained, but the number of device keys increases, resulting in larger MKB size and increased processing load
Solution Approach 1:
The patent recovers and reuses device keys from nodes that have left the network. When a node rejoins, instead of assigning a new device key, the system retrieves the previously assigned key from storage and reassigns it, thereby preventing key proliferation and keeping MKB size manageable while maintaining security
Solution Approach 2:
The patent makes device keys universal by allowing the same device key to be reassigned to different nodes at different times. A device key is no longer tied to a specific node permanently but can serve multiple nodes sequentially, reducing the total number of unique keys needed in the system
2Reliability
If new device keys are assigned to nodes that rejoin the wireless mesh network, then security is maintained, but processing load increases due to the combination of device keys
Solution Approach 1:
The system recovers previously used device keys from storage and reassigns them to rejoining nodes, avoiding the need to generate and process new keys. This recovery mechanism significantly reduces the computational burden of key management and MKB generation while preserving security through the use of cryptographically strong keys
Solution Approach 2:
The patent changes the parameter of device key assignment from 'unique per node instance' to 'reusable across node instances'. By changing this assignment parameter, the system reduces the total number of keys that need to be combined in MKB generation, thereby reducing processing load while maintaining the security properties of the keys
3Adaptability or versatility
If the number of device keys is increased to accommodate frequent node joining and leaving, then node mobility is supported, but MKB size increases, making key management inefficient
Solution Approach 1:
The patent implements a key recovery mechanism that stores device keys of nodes that have left the network. When nodes join and leave frequently, the system recovers previously assigned keys rather than generating new ones, thereby supporting high node mobility while preventing the accumulation of excessive keys that would degrade key management efficiency
Solution Approach 2:
The patent creates copies of device keys for storage in the root node's database. Instead of creating new unique keys for each node instance, the system creates and stores copies of keys that can be retrieved and reassigned, enabling efficient support for node mobility without proportionally increasing the total number of keys in the system
Data Source
AI summary
A wireless mesh network includes a plurality of nodes to which a device key is assigned. The device key belongs to one of a plurality of groups. In a root node, a correspondence relationship between the nodes and the device key thereof, and a correspondence relationship between past join nodes and a device key thereof, are stored. When a new node in the wireless mesh network is detected as a past join node, the device key assigned to the past join node is assigned to the new node again. When the new node is not the past join node, a new device key is assigned to the new node. A cipher text is generated by encrypting a message using device keys assigned to the nodes and the new node. If the number of groups to which the device keys belong is fewer, a size of the cipher text is smaller.