This thesis explores the synchronization of Self-Sovereign Identity (SSI) credentials within Software-Defined Vehicles (SDVs) and their verification through Vehicle Signal Specification (VSS) triggers. The rising complexity in digital identity management for vehicle users, particularly in shared mobility and car-sharing scenarios, necessitates a streamlined approach to credential synchronization across multiple vehicles and devices. The study investigates how SSI credentials can be securely synchronized across SDV platforms and external services, focusing on building the foundation for safe and secure identity management leading to enhanced user experience. To address this challenge, a prototype that integrates SSI principles with the VSS framework is designed and implemented. The methodology includes interviews with industry experts and the development of a prototype based on real-world mobility use cases. The synchronization process involves comparing locally stored credentials with cloud-stored data, followed by the re-issuance of credentials if discrepancies are found. The system verifies credentials through real-time VSS triggers, ensuring seamless interaction between vehicles and external services, such as rental or charging stations. Key findings reveal that the prototype successfully synchronizes and verifies SSI credentials within the SDV ecosystem. Using VSS as a trigger for verification proves to be an effective method for automating and securing identity management tasks. However, potential improvements, such as the inclusion of Two-Factor Authentication (2FA) and more robust revocation mechanisms, are identified as necessary for future scalability and security. The results contribute to advancing SSI adoption in the mobility industry, particularly in developing standardized solutions for digital identity management across different vehicle platforms. Future work can focus on defining a standard for the credential verification process and ensuring broad interoperability within the automotive ecosystem, possibly via VSS.