US: Out-of-Battery and Offline Proximity capability for Digital Car Key Holder

[turbosree]

Description

As a digital car key holder (e.g., a user with a phone having an EU Wallet containing a QEAA -driving eligibility & vehicle authorization), I want to be able to unlock, start, and securely share access to the vehicle even when my phone has low or no battery, so that I can continue my journey or manage access without being stranded (seamless journey) or dependent on network connectivity or requiring expensive security hardware -because mobility is a fundamental right, even during emergencies or disruptions.

User Story

User: A vehicle user in Europe
Goal: The goal is to extend the non-functional requirements for EAAs & QEAAs -such as those supporting automotive digital credentials -by incorporating reliability, resilience, and digital safety as core design attributes. This ensures that systems remain trustworthy and operational during emergencies, power loss, or network disruptions. The objective includes defining availability targets, fault management strategies, and recovery mechanisms to guarantee continuous access, rapid restoration, and public confidence in digital mobility infrastructure.
Reason: Designing for graceful degradation is crucial when a digital car key holder runs out of battery (e.g., a user with a phone having an EU Wallet containing a QEAA -driving eligibility & vehicle authorization), ensuring the EU Wallet remains reliable and accessible even in low-power or offline conditions -because mobility is a fundamental right.

Acceptance Criteria

The following scenarios shall be covered.

Scenario 1: Out-of-Battery vehicle access

Description:
The digital car key holder’s phone battery is critically low or fully depleted. The user must be able to operate the vehicle or temporarily share access with another authorized person, even when one or both devices are in this low-power or out-of-battery state. The user must still be able to unlock and start the vehicle using offline, local proximity capability, without requiring network connectivity or expensive security hardware. Access should remain secure, privacy-preserving, and reliable.

Scenario 2: Offline proximity capability (e.g., Credential presentation and sharing)

Description:
The user needs to temporarily share vehicle access with another authorized person while one of the device or both devices are offline. The system must support secure wallet-to-wallet exchange of credentials locally, maintaining privacy and ensuring that access is granted only to authorized parties.

Scenario 3: Emergency and crisis access

Description:
During an emergency or network disruption (e.g., disaster scenario), the user must be able to access the vehicle and essential mobility services. The system should provide graceful degradation, preserving critical functionality and ensuring public trust in the resilience and reliability of digital mobility infrastructure.

Scenario 4: Rapid recovery after outage

Description:
After a temporary outage or low-power situation, the system must rapidly restore full digital key functionality once the phone regains sufficient power or local connectivity. Users should experience seamless continuity without manual intervention.

Priority

Level: Medium

Estimates

Effort: 8 - 13 story points
Rationale: High complexity due to security, offline protocols, and resilience requirements.

Technical Notes and Constraints

Notes:
Device limitations: Works on standard phones, low-power and offline proximity support required universally; citizen services should not require expensive security hardware as a prerequisite.
Graceful degradation: Unlock/start must work with low or no battery; fast recovery after outage.

Dependencies

Related Stories and Tasks: This section extends the user story and Wallet-to-Wallet interaction content previously included in ARF Release v2.6.0.
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