AMI Device Key Generation via ECDH and Extraction
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Solution Overview
Problem
Advanced metering infrastructure (AMI) devices are vulnerable to compromise during installation and setup, as conventional solutions expose AMI keys to potential threats through field programming tools and interfaces.
Innovation Solution
A system utilizing Elliptic-curve Diffie-Hellman (ECDH) based key agreement, where a client computing device generates a first key agreement key pair and loads the public key into an AMI device. The AMI device then generates a second key agreement key pair, performs key agreement to determine a MasterSecret, and uses this to generate security keys, storing them while deleting the MasterSecret.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional field programming tools are used to install and maintain AMI devices, then ease of operation is improved, but security is worsened due to potential compromise of AMI keys
Solution Approach 1:
The patent extracts the AMI device private key from the field programming tool environment entirely. The key is generated and stored only within the AMI device itself, removing it from exposure to potentially compromised external tools. This extraction eliminates the security vulnerability while maintaining the tool's ability to program and maintain the device through other non-key-sensitive operations.
Solution Approach 2:
The patent introduces a public key as an intermediary between the field programming tool and the AMI device private key. The tool can only access and manipulate public keys, which do not contain the sensitive private key material. This intermediary layer allows the tool to perform its functions without direct exposure to the private key, thus maintaining ease of operation while improving security.
2Ease of manufacture
If AMI keys are exposed through field programming tools and interfaces, then ease of manufacture and installation is improved, but reliability is worsened due to potential compromise
Solution Approach 1:
The patent segments the cryptographic key material into two distinct parts: a private key stored securely within the AMI device and a public key exposed to external tools. This segmentation allows the manufacturing and installation process to proceed with ease using the public key, while the private key remains protected within the device, maintaining both ease of manufacture and security reliability.
Solution Approach 2:
The patent extracts the sensitive private key from the field programming tool and confines it strictly within the AMI device. The tool is designed to operate without accessing the private key, using only the public key for necessary operations. This extraction maintains installation ease while eliminating the reliability issue of key exposure.
3Device complexity
If private keys are stored in field programming tools, then device complexity is reduced, but security is worsened due to exposure risks
Solution Approach 1:
The patent extracts the private key from the field programming tool and stores it exclusively within the AMI device. This increases the device's internal complexity slightly but eliminates the tool's security vulnerability. The overall system security is improved because the key is no longer exposed in the external tool environment.
Solution Approach 2:
The patent uses the public key as an intermediary that allows the field programming tool to function without containing or accessing the private key. This intermediary approach maintains relatively simple tool design while eliminating the security risk of private key exposure in the tool.
Data Source
AI summary
A system includes at least one processor to receive a second public key, a first random number, and a second random number, and store the second public key, the first random number, and the second random number in an installation record, perform key agreement with a first private key and the second public key to determine a MasterSecret, perform key expansion with the MasterSecret, the first random number, and the second random number to generate a client authentication key, a server authentication key, a client encryption key, and a server encryption key, and store the client authentication key, the server authentication key, the client encryption key, and the server encryption key and delete the MasterSecret.