Ephemeral Key Management for Subscriber Identity Privacy
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Solution Overview
Problem
Existing wireless communication systems do not adequately protect subscriber identities from snooping and eavesdropping, as globally unique subscription permanent identifiers (SUPIs) are often transmitted in clear, readable formats, making them vulnerable to passive and active attacks.
Innovation Solution
The use of one-time ephemeral asymmetric keys generated by user equipment (UE) and network-provided keys to encrypt SUPIs into subscription concealed identifiers (SUCIs), which are then validated and updated as network public keys change, ensuring secure authentication and privacy protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If SUPI is transmitted in clear readable format for network authentication, then network authentication is simplified, but subscriber identity becomes vulnerable to snooping and eavesdropping
Solution Approach 1:
The patent applies preliminary action by pre-generating multiple SUCIs and their corresponding ephemeral public keys before network authentication. The UE stores these pre-computed credentials and uses them during authentication, eliminating the need to compute encryption keys in real-time while maintaining security. This resolves the contradiction by preparing security credentials in advance, making both authentication efficient and identity protection effective.
2Object-affected harmful factors
If one-time ephemeral keys are generated and stored in advance for encryption, then identity protection is enhanced, but device memory requirements and key management complexity increase
Solution Approach 1:
The patent segments the key management system by separating long-term private keys from ephemeral key pairs. The LOPK (Long-term Operator Public Key) is stored securely in the UE, while multiple ephemeral key pairs are generated and stored temporarily. This segmentation allows the system to maintain strong security through separate key hierarchies while managing complexity through organized key storage and validation mechanisms.
Solution Approach 2:
The patent implements disposable ephemeral key pairs that are generated, used once for authentication, and then discarded. Each ephemeral key pair serves a single purpose and is never reused, eliminating the need for complex long-term key management. This approach enhances security by ensuring that even if one ephemeral key is compromised, other keys remain valid, while keeping key management relatively simple through automated generation and disposal.
3Reliability
If network public keys are updated over time to maintain security, then forward security is improved, but previously generated SUCIs become invalid requiring regeneration
Solution Approach 1:
The patent implements dynamic key management where the network can update LOPKs over time, and the UE adapts by validating received LOPKs against stored references. When LOPK updates occur, the system dynamically regenerates SUCIs using the new public key, ensuring forward security. This dynamic adaptation maintains authentication efficiency through automated validation and regeneration processes while ensuring that old keys cannot compromise future security.
Solution Approach 2:
The patent incorporates feedback mechanisms where the network provides LOPK updates to the UE, and the UE validates these updates against previously stored keys. The system uses this feedback to determine whether LOPK changes have occurred and accordingly regenerates SUCIs only when necessary. This feedback-driven approach maintains forward security while minimizing unnecessary regeneration and preserving authentication efficiency.
4Productivity
If multiple ephemeral key pairs are generated and stored for future use, then authentication readiness is improved, but security risk from key compromise increases
Solution Approach 1:
The patent uses disposable ephemeral key pairs that are pre-generated and stored for quick authentication, but designed to be used only once. Each key pair is inexpensive to generate and can be rapidly created if compromised. The system stores multiple such keys for authentication readiness, but their single-use nature ensures that compromise of one key does not affect others, resolving the contradiction between readiness and security risk.
Data Source
AI summary
Techniques to protect subscriber identity in messages communicated between a user equipment (UE) and a cellular wireless network entity by using multiple ephemeral asymmetric keys are disclosed. The UE determines multiple ephemeral UE public and secret key pairs, while the cellular wireless network entity provides a network public key to the UE. The network public key may be updated over time. Multiple encryption keys based on the multiple ephemeral UE secret keys and the public network key are derived and used to encrypt a subscription permanent identifier (SUPI) to generate multiple subscription concealed identifiers (SUCIs). Each SUCI is used only once for messages communicated to a cellular wireless network and discarded after use. New SUCI are generated when the network public key is updated.