Secure Configuration Distribution via SIP Public Key Encryption
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Solution Overview
Problem
Cable MSOs face challenges in securely distributing configuration files to user devices without conforming to the PacketCable security specifications, often due to equipment costs or integration difficulties, necessitating an alternative method for authenticating and initializing user devices over SIP sessions.
Innovation Solution
A system and method for securely distributing configuration files using a session initiation protocol (SIP) that employs public/private key pairs, where a user device's public key is used to encrypt a session key, which is then used to encrypt configuration information, creating a composite file sent to the device for decryption using its private key, facilitating secure initialization without relying on PacketCable-specified security procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PacketCable-specified security procedures (Kerberized Key Management, SNMPv3) are used to securely distribute configuration files, then security and reliability are improved, but device complexity and implementation cost increase
Solution Approach 1:
The patent extracts the essential security function (secure key distribution) from the complex PacketCable protocol suite. Instead of implementing the full Kerberized Key Management and SNMPv3 stack, the invention uses a simplified approach where the CMTS generates a configuration file encrypted with the device's public key, eliminating the need for complex mutual authentication protocols while maintaining security.
Solution Approach 2:
The patent uses disposable cryptographic keys generated specifically for each device provisioning event. The CMTS generates a configuration file encrypted with the device's public key, and the session key is transmitted within this encrypted file. This approach replaces expensive, long-term key management infrastructure with simple, event-specific cryptographic operations that are computationally inexpensive and easy to implement.
2Adaptability or versatility
If existing telephony equipment is integrated with network equipment for secure provisioning, then service functionality is improved, but integration difficulty and implementation complexity increase
Solution Approach 1:
The patent makes the CMTS multi-functional by enabling it to perform both data service provisioning and telephony service provisioning through a unified mechanism. The same CMTS that provides DOCSIS data services also generates and transmits encrypted configuration files for SIP-based telephony devices, eliminating the need for separate secure provisioning infrastructure and simplifying integration between network and telephony equipment.
Solution Approach 2:
The patent uses the configuration file itself as an intermediary carrier that bridges the network infrastructure and the telephony device. The configuration file contains the session key encrypted with the device's public key and is transmitted through the network to the device, serving as a universal intermediary that works across different equipment vendors and implementations without requiring direct integration between telephony and network equipment.
3Reliability
If public key encryption is used to encrypt session keys and configuration information, then security is improved, but computational overhead and processing time increase
Solution Approach 1:
The patent segments the cryptographic operations into two distinct phases: (1) Asymmetric encryption using public/private key pairs to securely transmit the session key, and (2) Symmetric encryption using the session key to encrypt the configuration information. This segmentation allows the computationally intensive asymmetric encryption to be used only once for key exchange, while the faster symmetric encryption handles the bulk data encryption, minimizing overall processing time while maintaining security.
Data Source
AI summary
An MTA certificate containing a public key is provided to a provisioning server, typically via an MIB. The provisioning server retrieves configuration information associated with the MTA. A symmetric session key is randomly generated and used to encrypt the configuration information. The public key is used to encrypt the symmetric key. The encrypted session key is combined with the encrypted configuration information into a composite file, and the composite file is distributed to the device that contains the MTA.The MTA device decrypts the session key using its private key that corresponds to the public key and the decrypted session key is used to decrypt the configuration information. The decrypted configuration information is used to complete initialization of the MTA device.