SUCI Padding Scheme to Reduce 5G Subscription Identifier Leakage

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Solution Overview

Problem

Existing 5G wireless communication networks face privacy issues due to the potential leakage of sensitive information through subscription concealed identifiers (SUCI), which can be exploited by attackers to track or identify users, despite encryption mechanisms designed to conceal SUPIs.

Innovation Solution

The solution involves generating a padded identifier by inserting a padding bitstring in the SUPI field and encrypting it to create a concealed padded identifier, which is then transmitted, and the network node decrypts this identifier to recover the original content while reducing the correlation between SUPI and SUCI lengths, thereby minimizing information leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If SUPI is transmitted over-the-air without padding, then identification functionality is achieved, but user privacy is compromised due to information leakage through SUCI length

Engineering Contradiction:

Improveinformation leakageVSAvoididentifier processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by padding the SUPI identifier before encryption to prevent information leakage. The padding is performed in advance on the identifier field before the SUCI generation process, ensuring that the length correlation between SUPI and SUCI is broken from the outset, thereby preventing attackers from inferring SUPI length or content from observed SUCI lengths.

Inventive Principle:

Principle #10Preliminary action

2Loss of information

If padding is inserted in SUPI field, then information leakage is reduced, but processing complexity increases

Engineering Contradiction:

Improvesensitive information leakageVSAvoididentifier processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the length parameter of the identifier through padding. By changing the SUPI length parameter before encryption, the direct correlation between SUPI length and SUCI length is altered, making it difficult for attackers to determine original identifier characteristics from the encrypted form, thus reducing information leakage.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If SUCI length correlates with SUPI length, then decryption accuracy is improved, but user tracking becomes easier

Engineering Contradiction:

Improveidentifier recovery accuracyVSAvoiduser tracking

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces padding as an intermediary element between the original SUPI and the encrypted SUCI. This intermediary padding layer decouples the length correlation between SUPI and SUCI, preventing attackers from using SUCI length as a tracking mechanism while still allowing authorized decryption through knowledge of the padding scheme.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12604181B2Subscription concealed identifier privacy

Publication Date: 2026.04.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A user equipment (“UE”) in a wireless communication network can generate a padded identifier by inserting a padding bitstring in a field of an identifier associated with the UE. The UE can further encrypt the padded identifier to generate a concealed padded identifier. The UE can further transmit the concealed padded identifier to a network node operating in the wireless communication network.