Lawful Interception Key Generation Signature Verification
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Solution Overview
Problem
The existing MIKEY-IBAKE key generation protocol for lawful interception in IMS media security is vulnerable to subversive users modifying their kernels to prevent lawful interception, and the lack of secure timestamp signaling complicates the process, especially with the rise of open-source operating systems and counterfeiting issues with International Mobile Station Equipment Identity (IMEI) identifiers.
Innovation Solution
A method is introduced that involves generating and verifying signatures using private keys, nonces, and identifiers like IMEI, along with security parameters that associate user identities with public keys, ensuring that timestamps and key components are securely signaled and verified during the key generation process, using either signature or MAC tag mechanisms to protect the integrity of communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MIKEY-IBAKE key generation is used, then key exchange between UEs is simple, but lawful interception cannot be prevented by subversive users modifying kernels
Solution Approach 1:
The patent applies preliminary action by pre-distributing master keys to UEs through secure channels before communication begins. These master keys are embedded in the UE devices during manufacturing or provisioning, enabling lawful interception capability to be established in advance without requiring complex runtime key management or trust verification mechanisms.
Solution Approach 2:
The patent introduces an intermediary element in the form of a trusted third party (such as a key distribution center or certification authority) that facilitates the secure distribution of master keys to UEs. This intermediary ensures that subversive users cannot arbitrarily modify their kernels to prevent interception, as the master keys are protected and distributed through controlled channels.
2Ease of operation
If timestamps are signaled in SIP, then key generation can proceed, but subversive users can send arbitrary timestamps to prevent lawful interception
Solution Approach 1:
The patent applies preliminary anti-action by implementing signature verification mechanisms that prevent subversive users from sending arbitrary timestamps. Before the timestamp is accepted for key generation, it must be signed by the UE using its master key, and the receiving party verifies this signature. This preliminary verification counteracts the potential harm of timestamp manipulation.
Solution Approach 2:
The patent implements feedback through signature verification, where the receiving party checks the digital signature on the timestamp before proceeding with key generation. If the signature is invalid or missing, the process is aborted, providing immediate feedback that prevents the use of arbitrary timestamps while maintaining ease of operation for legitimate users.
3Ease of operation
If IMEI identifiers are used, then device identification is straightforward, but counterfeiting issues compromise security
Solution Approach 1:
The patent replaces the physical IMEI identifier with a cryptographic copy or surrogate - specifically, a digital signature or public key that serves as the device's authentic identifier. Instead of relying on the IMEI which can be counterfeited, the system uses cryptographic credentials that are computationally infeasible to replicate, thereby maintaining ease of identification while ensuring authenticity.
Solution Approach 2:
The patent substitutes the mechanical/physical identifier system (IMEI) with a cryptographic system. Rather than relying on hardware-based identification that can be copied or counterfeited, the system uses mathematical principles of cryptography to provide unforgeable device identification through digital signatures and public key infrastructure.
4Reliability
If master keys are distributed to UEs, then lawful interception is enabled, but security risks increase from key compromise
Solution Approach 1:
The patent applies segmentation by dividing the cryptographic system into multiple components: master keys for identity establishment, ephemeral keys for session-specific encryption, and derived keys for actual communication. This segmentation ensures that compromise of one key does not compromise the entire system, as each key serves a specific purpose and has a limited scope of validity.
Solution Approach 2:
The patent implements discarding and recovering by using ephemeral keys that are generated for each session and then discarded after use. The master keys are recovered or protected in secure storage, while the temporary session keys are eliminated after completing their cryptographic function, minimizing the window of opportunity for key compromise.
Data Source
AI summary
A method is presented for secure communication, the method including generating a signature using a private key, a nonce, and at least one of an identifier and a key component; and transmitting the signature, the nonce, a security parameter, and the at least one of the identifier and the key component, wherein the security parameter associates a user identity with a public key, the public key being associated with the private key.