Hash-Based Identity Management for Constrained IoT Devices

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Solution Overview

Problem

Constrained devices in 3GPP networks face challenges in managing identities, particularly when changing ownership, as they lack easily removable or exchangeable secure storage components, leading to security vulnerabilities and operational complexities.

Innovation Solution

A method involving a hash function is applied to the device's public key to generate a new identity, with an incrementing generation counter, allowing secure identity management and verification, ensuring only authorized changes and maintaining security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If certificates or RPKs are stored in a trusted execution environment with no user access, then device identity security is improved, but change of ownership becomes problematic

Engineering Contradiction:
Improvedevice identity securityVSAvoidchange of ownership
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The identity management system is segmented into multiple components: the immutable trusted execution environment containing the asymmetric key pair, and the mutable hash-based identity values that can be regenerated. This segmentation allows the security-critical private key to remain protected while the identity representation can be changed through hash regeneration, enabling ownership transfer without compromising security.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the parameter representation of the identity from the static private key to dynamic hash values. By applying hash functions to the public key or device identifier, the system generates identity values that can be regenerated or reassigned without modifying the underlying secure credentials, thus enabling flexible ownership changes while maintaining security.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the device owner is given access to the secure storage where certificate and asymmetric key pair are held, then change of ownership is addressed, but the device becomes vulnerable to attacks on identity and misconfigurations

Engineering Contradiction:
Improvechange of ownershipVSAvoidattacks on identity and misconfigurations
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system extracts the identity representation from the secure storage contents. Instead of giving users access to the actual certificate and key pair in secure storage, the system provides access to hash-based identity values that are derived from these credentials. Users can request identity changes without ever accessing the private key, thus enabling ownership transfer while preventing direct attacks on the security credentials.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Hash functions serve as an intermediary between the secure credentials and the identity representation. The hash-based identity acts as a mediator that allows ownership changes to be managed without exposing the actual security credentials. This intermediary layer enables flexible identity management while maintaining the integrity and security of the underlying asymmetric key pair.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If hash of device public key is used as device identity, then verification capability is improved, but identity length increases

Engineering Contradiction:
Improveverification capabilityVSAvoididentity length
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The system applies hash functions to transform the device public key into a fixed-length identity value. This parameter transformation maintains the verification capability (since the hash is derived from the public key) while converting the variable-length public key into a standardized, manageable length suitable for storage and transmission.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3259928B1Establishing and managing identities for constrained devices
Publication Date: 2023.07.26 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3259928B1 patent drawingFigure 1
  • EP3259928B1 patent drawingFigure 2
  • EP3259928B1 patent drawingFigure 3

AI summary

A method (100) for establishing a new identity for a constrained device is disclosed, wherein the device has an existing identity and is associated with an asymmetric key pair comprising a device public key and a device private key. The method comprises applying a hash function to the existing identity (106) and setting the resulting value as the new identity for the constrained device (108), wherein the existing identity comprises at least a first generation hash value of a hash chain formed by applying the hash function to the device public key. Also disclosed is a method (200) for managing an identity of a constrained device, the device being associated with an asymmetric key pair comprising a device public key and a device private key. The method comprises maintaining a record of the device public key (202), receiving an identity from the device (204), sequentially applying a hash function to the device public key to generate a hash chain of the device public key (206),and identifying a hash value in the hash chain matching the identity received from the device (208).