Network Device Key Management for Lawful Intercept
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Solution Overview
Problem
Traditional public key infrastructure systems are vulnerable to attacks on the root of trust, allowing attackers to compromise the entire system and preventing legitimate law enforcement from intercepting and reading encrypted messages, which is necessary for legal proceedings.
Innovation Solution
A network node utilizing an identity-based key predistribution scheme with separate trusted third parties for confidentiality and integrity, allowing lawful intercept authorities to access key material for confidentiality while preventing message tampering and ensuring non-repudiation through separate message authentication codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single root of trust is used to sign certificates, then the system is simple to manage, but the entire system is compromised if the root key is hacked
Solution Approach 1:
The patent divides the single root of trust into multiple trusted third parties (TTPs), each holding a portion of the key material. This segmentation ensures that no single TTP has complete control, and the system remains secure even if one TTP is compromised. The key material is split such that a threshold number of TTPs are required to reconstruct the full key, providing both simplified management (multiple independent TTPs) and enhanced security (no single point of failure).
2Ease of operation
If the root of trust provides access to private keys for lawful intercept, then law enforcement can read encrypted messages, but the private keys can be used to spoof messages without control
Solution Approach 1:
The patent segments the cryptographic functions by assigning different TTPs different roles: one TTP holds key material for confidentiality (enabling lawful intercept) while another TTP holds key material for integrity (enabling message verification). This segmentation allows law enforcement to read messages through the confidentiality TTP without compromising message authenticity, as the integrity TTP maintains separate control over verification capabilities.
Solution Approach 2:
Different portions of the key material have different local qualities or functions: one portion enables decryption (confidentiality) while another portion enables authentication (integrity). The lawful intercept authority receives only the confidentiality portion, which allows reading but not spoofing messages, as the integrity portion remains with the integrity TTP and cannot be obtained by the intercept authority.
3Ease of operation
If private key material is deposited with the root of trust, then lawful intercept is enabled, but the value of intercepted messages for legal proceedings is reduced due to susceptibility to fraudulent activities
Solution Approach 1:
The patent segments the key material so that the lawful intercept authority receives only the confidentiality portion needed for reading messages, while the integrity portion remains with the integrity TTP. This ensures that intercepted messages maintain their evidentiary value because the separate integrity key material prevents fraudulent activities, as the intercept authority cannot generate valid authentication codes without the integrity portion.
Data Source
AI summary
A first network node (100; 200) is configured to, —compute a first shared key (245) to protect confidentiality from the first identity of the second network node and the local key material to protect confidentiality of the first network node, —compute a second shared key (246) to protect integrity from the second identity of the second network node and the local key material to protect integrity of the first network node, —encrypt a message using the first shared key, and —compute a first message authentication code over the message using the second shared key.