Cellular Voice Communication Intermediation via Cross-Generation Key Switching

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Solution Overview

Problem

Existing methods for intercepting cellular voice communication using interrogation devices face challenges in switching mobile communication terminals back to their original communication standard after breaking encryption, as users may notice performance degradation, and networks may reset encryption keys, making continuous monitoring difficult.

Innovation Solution

A system and method that involves capturing a mobile terminal, switching it to a lower-generation standard, obtaining encryption keys, deriving higher-generation keys, and maintaining connection to the lower-generation network for encryption and decryption, allowing seamless communication with the original network using both sets of keys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal is switched to a lower-generation standard to break encryption, then the encryption can be compromised, but the user may notice performance degradation

Engineering Contradiction:

Improveencryption compromiseVSAvoiduser performance perception

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically switches the terminal between different communication standards (e.g., from 5G to 4G) based on the encryption requirements. The processor controls the terminal to switch to a lower-generation standard when encryption compromise is needed, and switches back to the original standard when normal operation is required, making the system adaptable to different operational needs

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the communication standard parameter from the original higher-generation standard (Nth generation) to a lower-generation standard (Mth generation where M < N). This parameter change enables the use of weaker encryption algorithms that can be compromised, while the system can revert the parameter change when normal secure operation is needed

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the terminal is switched to a lower-generation standard, then encryption can be broken, but the network may reset encryption keys making continuous monitoring difficult

Engineering Contradiction:

Improveencryption compromiseVSAvoidcontinuous monitoring capability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The system performs preliminary actions by obtaining lower-generation encryption keys before the network can reset them. The processor causes the terminal to switch to the lower-generation standard, obtains the encryption keys at this vulnerable moment, and then switches back to the original standard. This preliminary key acquisition ensures continuous monitoring capability without being affected by subsequent network key resets

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains continuous monitoring capability by seamlessly switching the terminal between communication standards. The useful action of monitoring voice communication continues uninterrupted as the processor obtains keys from the lower-generation network and uses them to decrypt communication, then switches back to the original standard without breaking the monitoring continuity

Inventive Principle:

Principle #20Continuity of useful action

3Speed

If the terminal is switched to a higher-generation standard, then communication performance is improved, but the original encryption keys cannot be obtained

Engineering Contradiction:

Improvecommunication performanceVSAvoidencryption key accessibility

Core Design Contradiction:

SpeedVSLoss of information

Solution Approach 1:

Instead of trying to obtain high-generation encryption keys directly (which is difficult or impossible), the system inverts the approach by switching to a lower-generation standard where encryption keys are weaker and more obtainable. The processor causes the terminal to switch from the Nth-generation standard to an Mth-generation standard (M < N), obtains the encryption keys at this lower level, and then switches back to the original standard. This inversion enables key acquisition while maintaining the ability to communicate at the original high-performance standard

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12381862B2System and method for intermediating cellular voice communication

Publication Date: 2025.08.05 COGNYTE TECH ISRAEL LTD

AI summary

A system including a transceiver, a modem, and a processor. The processor is configured to cause the transceiver to imitate a base transceiver station (BTS) such that a mobile communication terminal disconnects from an Nth-generation mobile communication network, which uses an Nth-generation communication standard, and connects to the transceiver. The processor is further configured to cause the terminal to switch to the Pth-generation communication standard, and to cause the modem to impersonate the terminal with respect to an Mth-generation mobile communication network. The processor is further configured to intermediate voice communication between the terminal and the Mth-generation mobile communication network exchanged between the modem and the Mth-generation mobile communication network.