Key Sharing via Distributed Configuration Servers
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Solution Overview
Problem
Key agreement protocols in cryptographic systems, such as those used in resource-restrained devices like IoT and RFID tags, face security vulnerabilities due to reliance on a single trusted third party, which can be compromised, leading to a single point of failure and reduced trust requirements.
Innovation Solution
A cryptographic system utilizing multiple configuration servers to generate and distribute local key material to network devices, allowing each device to combine key materials from multiple servers for secure key derivation, eliminating the single point of failure and reducing trust requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single trusted third party is used to generate and distribute key material to network devices, then key distribution is simplified and devices can easily derive shared keys, but the system creates a single point of failure where compromise of the trusted third party leads to complete system security breakdown
Solution Approach 1:
The patent divides the key material generation function into multiple independent configuration servers instead of relying on a single trusted third party. Each server holds a portion of the key material, and network devices receive key material from multiple servers to combine into their final keys. This segmentation eliminates the single point of failure while maintaining operational simplicity.
Solution Approach 2:
The patent introduces configuration servers as intermediaries between the trusted third party and network devices. These servers act as mediators that distribute key material without having full knowledge of the final keys, thereby reducing the trust requirements for each individual server while maintaining the overall key distribution mechanism.
2Device complexity
If key material is stored centrally in a trusted third party, then key management is centralized and simplified, but the trusted third party becomes a single point of failure and requires very high trust levels
Solution Approach 1:
The patent segments the centralized key material storage into multiple distributed configuration servers. Each server stores only a portion of the key material, so that compromise of one server does not expose the complete key material. This reduces the trust requirements for each individual server while maintaining simplified key management through the coordinated operation of multiple servers.
Solution Approach 2:
The patent creates an asymmetric trust model where configuration servers require lower trust levels since they only hold partial key material, while the combined system maintains high security. This asymmetry allows the key management structure to remain relatively simple while significantly reducing the security risks associated with centralized storage.
3Reliability
If Diffie-Hellman key agreement is used between parties without shared secrets, then secure key agreement is achieved without pre-shared keys, but resource-heavy mathematical operations are required making it unsuitable for low-resource devices
Solution Approach 1:
The patent performs key material generation and distribution in advance through configuration servers before the actual key agreement is needed. Network devices receive their key material beforehand, so that during the actual communication, they only need to perform simple local computations to derive shared keys, avoiding the resource-heavy operations of traditional Diffie-Hellman while maintaining security.
Data Source
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AI summary
A cryptographic system is provided comprising multiple configuration servers (200, 201, 202) arranged to configure multiple network devices (300, 350, 360) for key sharing. Each configuration server comprising a computation unit (220) arranged to compute local key material for the network device from root key material specific to the configuration server and the network device identity number of the network device that is being configured. At least two configuration servers of the multiple configuration servers provide computed local key material to said network device. The network devices are configured to determine a shared key with any one of multiple network devices. A network device comprises a shared key unit (330) arranged to derive a shared key from another network device's identity number and at least two of the multiple local key materials of the network device.