Key Derivation for Handover Security in LTE
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Solution Overview
Problem
Existing handover techniques in wireless communication systems, such as those used in LTE/UTRAN, face security vulnerabilities due to the repetition of keystreams during processes like handover and NAS service requests, which can lead to security breaches.
Innovation Solution
A method is introduced to derive different key values for handover from a GERAN/UTRAN system to an E-UTRAN system using distinct input values for the key derivation function, ensuring that the same key is not reused across different processes, thereby preventing keystream repetition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same key derivation function and input values are used for both handover and NAS service request processes, then the key derivation process is simple and efficient, but keystream repetition occurs leading to security vulnerabilities
Solution Approach 1:
The patent applies local quality by using different input values (S1 for handover, S2 for NAS service request) in the key derivation function for different processes. This ensures that while the overall key derivation mechanism remains consistent, each specific process receives customized input parameters, preventing keystream repetition and improving security without fundamentally changing the derivation approach.
2Reliability
If different input values are used for handover and NAS service request key derivation, then keystream repetition is prevented improving security, but the complexity of key management increases
Solution Approach 1:
The patent applies universality by using a single key derivation function KDF that handles both handover and NAS service request processes. The function remains universal and multi-functional, accepting different input values (S1 or S2) based on the process type. This approach prevents keystream repetition through varied inputs while maintaining a unified, simple key derivation framework that does not increase overall system complexity.
3Productivity
If the UL NAS COUNT value is used as input to KDF for handover, then the same key is derived for both handover and subsequent NAS requests, but this causes security breaches due to keystream repeat
Solution Approach 1:
The patent applies segmentation by dividing the input string S into distinct components: S1 for handover processes and S2 for NAS service request processes. Each segment (S1 or S2) contains specific parameters relevant to its process type (e.g., handover indicator, NAS COUNT). This segmentation ensures that different processes use different input segments, preventing keystream repetition and eliminating security breaches while maintaining efficient key derivation.
Data Source
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AI summary
Systems, methods and apparatus for facilitating handover security are provided. In some embodiments, the method can include deriving a key value for handover from a GERAN/UTRAN system to an E-UTRAN system using a first input value. The method can also include deriving a key value for a connection establishment using a second input value, wherein the first input value is different from the second input value and is different from input values derived subsequent to the second input value, and wherein the first input value, the second input value and the input values derived subsequent to the second input value are configured to be input to a same key derivation function configured to output a key for use between a network entity and user equipment.