Group-Wide Key Counter for Secure Real-Time Control
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Solution Overview
Problem
Conventional communication protocols and electrical/electronic (E/E) architectures face challenges in processing power, overhead, and time required for generating shared keys needed for secure and authentic communications across networks, particularly in real-time control systems.
Innovation Solution
The implementation of a group-wide key counter system, where each node stores the latest key counter value in non-volatile memory and transmits this value in each secured message, allowing nodes to synchronize and agree on session keys without the need for separate key agreement messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional key agreement protocols are used, then secure communications are established, but communication overhead and processing time increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-distributing key material (pre-shared keys or seed keys) to nodes before they need to communicate securely. This eliminates the need for time-consuming key agreement protocols during actual communication, as nodes can immediately use the pre-shared keys. The key material is prepared and distributed in advance through secure channels or embedded in nodes during manufacturing.
Solution Approach 2:
The patent extracts the key agreement function from the data communication protocol by separating key management into a distinct preliminary process. Instead of embedding key agreement within every data transmission, the system extracts key material distribution as a separate preliminary action that occurs once during system initialization or key rotation, thereby eliminating repeated key agreement overhead during normal operations.
2Reliability
If dedicated key agreement messages are transmitted, then key synchronization is achieved, but network bandwidth is consumed and latency increases
Solution Approach 1:
The patent merges the key synchronization function with the existing data communication protocol by incorporating key material or key derivatives directly into data messages. Instead of sending separate dedicated key agreement messages, the system embeds key information within the normal data stream, allowing key synchronization to occur implicitly during regular communication without adding separate protocol layers or message types.
Solution Approach 2:
The patent applies universality by designing data messages to serve multiple functions: carrying both operational data and key synchronization information. The same message structure used for regular data communication also facilitates key distribution and synchronization, eliminating the need for specialized key agreement messages and reducing overall protocol complexity.
3Reliability
If frequent key rotation is performed, then security is improved, but processing overhead and time required for key generation increase
Solution Approach 1:
The patent applies preliminary action by pre-computing and pre-distributing multiple key material sets before they are needed. During key rotation events, nodes can quickly switch between pre-prepared key material without performing time-consuming key generation operations. The system prepares key material in advance and stores it in non-volatile memory, enabling rapid key switching during operations.
Solution Approach 2:
The patent uses copying by creating multiple copies of key material (pre-shared keys or seed keys) that can be quickly switched between nodes during key rotation. Instead of generating new keys from scratch during rotation, the system copies and switches between pre-computed key material copies, significantly reducing processing time and overhead during frequent key rotation events.
Data Source
AI summary
The described techniques address issues to achieve key agreement without the need to exchange separate key agreement messages and, consequently, meets the stringent starting time requirements for real-time control systems. This is achieved using a group-wide key counter, with each node storing the latest value of this counter that was observed via the last received secured message. This counter value increases monotonically, and nodes maintain synchronization by transmitting this counter value (or a representation of the counter value) in each secured message.