Dynamic Password Management for Cable Modems Using Public Key Encryption
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Solution Overview
Problem
Existing CPE systems face challenges in providing scalable, dynamic, and secure password management for cable modems, as they often rely on centralized key distribution and symmetric key systems, which can lead to security exposure and inefficiencies in large-scale deployments.
Innovation Solution
A password system where each cable modem generates a random password, encrypts it with a public key, and stores it in a Management Information Base, allowing for periodic renewal and quick recovery without relying on centralized key management or symmetric key distribution, ensuring unique and secure access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If centralized key distribution is used, then password management is simplified, but security exposure increases and scalability is limited
Solution Approach 1:
The patent divides the centralized key distribution system into distributed segments where each cable modem generates and stores its own unique password in a local Management Information Base (MIB). This eliminates the single point of failure in centralized key management while maintaining operational simplicity through automated password generation and storage.
Solution Approach 2:
The patent introduces a public key infrastructure as an intermediary between the cable system operator and individual modems. Each modem receives a public key from the operator, uses it to encrypt its password, and stores the encrypted password locally. This intermediary mechanism enables secure distributed key management without requiring direct trust between all system components.
2Device complexity
If symmetric key distribution is used, then key management is simpler, but system scalability and security are compromised
Solution Approach 1:
The patent replaces symmetric key distribution with asymmetric key cryptography. Instead of using shared secret keys that require complex distribution and revocation mechanisms, the system uses public key infrastructure where each modem has a unique public/private key pair. The public key is distributed to modems, and passwords are encrypted using these public keys, eliminating the need for symmetric key management while enabling scalable deployment.
3Ease of operation
If fixed passwords are used, then device operation is simpler, but security and adaptability deteriorate
Solution Approach 1:
The patent implements dynamic password management where passwords are not fixed but are periodically regenerated and changed. The system automatically generates new passwords, encrypts them using the modem's public key, and updates the Management Information Base. This dynamic approach maintains operational simplicity through automated management while significantly improving security by preventing long-term exposure of static credentials.
4Ease of operation
If centralized password storage is used, then password management is easier, but recovery time and security exposure increase
Solution Approach 1:
The patent implements self-service password storage where each cable modem independently stores its own encrypted password in a local Management Information Base. The modem uses its private key to decrypt and manage its password without requiring centralized intervention. This self-service approach enables rapid password recovery and regeneration locally, significantly reducing recovery time while limiting security exposure to individual modems rather than a centralized system.
Data Source
AI summary
A password scheme is provided that can be used for security of cable modems in a cable network. In the system, the password is unique to each modem, the password is not fixed for the life of the device, is not shared across cable systems, is easily recoverable after a compromise, and is changed periodically based on some type of configuration. In the system each modem creates its own random password. Then the modem encrypts the password using a public key provided by the cable system and stores the encrypted password in a Management Information Base (MIB) operated by the cable system. The MIB operator decrypts the encrypted password corresponding to the public key and recovers the password. The cable operator uses the password to log in remotely to the modem. If a compromise or change of the public key or password occurs, the password is regenerated using the same procedure.