Key Agreement Using Key Derivation Functions
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Solution Overview
Problem
Wireless communication systems face challenges in maintaining long-term security due to the difficulty in modifying or replacing security algorithms in embedded UICC devices, and the need for agility in security primitives to keep pace with advancing computational capabilities.
Innovation Solution
Implementing key agreement protocols using key derivation functions (KDFs) and message authentication code (MAC) functions within existing standards, such as UMTS systems, to derive session keys for confidentiality and data integrity, allowing for greater flexibility in security primitives and ease of computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If security algorithms are embedded in UICC devices, then long-term security is maintained, but the ability to modify or replace algorithms is lost
Solution Approach 1:
The patent segments the security architecture into two parts: long-term secret keys stored in the embedded UICC (providing stable security), and algorithmic functions implemented in the software-based SE (providing flexibility). This segmentation allows the system to maintain both long-term security through hardware-protected keys and adaptability through software-updatable algorithms.
Solution Approach 2:
The patent introduces a dual-architecture intermediary system where the UICC and SE work together. The UICC provides hardware-secured key storage while the SE provides flexible algorithm execution. This intermediary architecture resolves the contradiction by distributing different security functions to appropriate components.
2Reliability
If security primitives are updated to keep pace with computational advances, then security is maintained, but system complexity increases
Solution Approach 1:
The patent implements dynamic security by allowing the SE to update cryptographic algorithms and parameters remotely without hardware changes. This enables the system to adapt to computational advances by dynamically updating software-based security primitives while keeping the overall architecture simple and manageable.
Solution Approach 2:
The patent enables parameter changes in security algorithms through software updates in the SE. Key lengths, algorithm types, and other security parameters can be modified by updating the SE firmware, allowing the system to respond to computational advances without increasing hardware complexity.
3Adaptability or versatility
If key agreement protocols are implemented with flexibility, then security agility is improved, but computational overhead increases
Solution Approach 1:
The patent performs preliminary key derivation and authentication operations using the hardware-secured UICC before SE-based operations. This preliminary action in hardware reduces the computational burden on the SE, enabling security agility without excessive energy consumption in the mobile device.
Solution Approach 2:
The patent replaces computationally intensive cryptographic operations with hardware-accelerated operations in the UICC where possible. This substitution moves heavy computational lifting to dedicated hardware security modules, reducing energy consumption in the mobile device while maintaining security flexibility.
Data Source
AI summary
Methods, systems, and computer programs for performing key agreement operations in a communication system are described. In some aspects, a wireless network operator accesses a secret key associated with a mobile device. A key derivation function (KDF) is evaluated based on the secret key to produce a key derivation key, and the KDF is evaluated based on the key derivation key to produce an output value. A session key and a challenge value are obtained based on the output value. In some aspects, the mobile device receives the challenge value and accesses a secret key. A KDF is evaluated based on the secret key to produce a key derivation key, and the KDF is evaluated based on the key derivation key to produce an output value. A response value and a session key are obtained based on the output value. The response value is transmitted to the wireless network operator.