Description:

Digital Identity Wallets rely on strong cryptographic protection to bind credentials to a legitimate wallet instance. In the European Digital Identity (EUDI) Wallet ecosystem, this protection is closely connected to what is called Wallet Secure Cryptographic Device (WSCD), where cryptographic keys used for Personal Identification Data (PID) and other sensitive credentials must be protected at an appropriate high assurance or security level. The EUDI Wallet Architecture and Reference Framework (ARF) allows different WSCD architectures, including remote architectures commonly implemented through remote Hardware Security Modules (HSMs) hosted by the wallet provider or a trusted backend service. In such cases, the provider remains responsible for ensuring that the overall architecture meets Level of Assurance High where required, and that proper user authentication, secure key management, and access control mechanisms are in place so that only legitimate wallet instances can use the protected cryptographic assets.

Compared to purely local wallet architectures, where cryptographic keys must be protected by secure hardware on the user device, remote HSM architectures can support inclusiveness and scalability by providing high-assurance key protection through certified backend infrastructure, especially when user devices cannot provide secure hardware capable of supporting that level of assurance. However, they also introduce new security and privacy questions. Moving cryptographic operations from user devices to a backend changes the trust boundaries of the wallet architecture and may create risks related to centralized key control, backend compromise, observability of user activity, metadata leakage, insider abuse, and availability. This makes it necessary to assess remote HSM architectures not only in terms of technical security, but also against ARF principles related to security, privacy such as privacy by design, data minimization, selective disclosure, user control, transparency, and security by design.

Building on this, this project aims to define a structured set of security and privacy requirements for remote HSM-based European Digital Identity Wallet architectures, starting from the ARF high-level requirements, and relevant EUDI Wallet security assumptions. It will then compare how selected national solutions for which sufficient information is available, with a focus on Germany, Italy, and the Netherlands, address these requirements in their design.

The final outcome of the project will be a comparative security and privacy analysis of remote HSM architectures for European Digital Identity Wallets, including a requirements catalogue, a country-by-country evaluation matrix, and a reusable threat model applicable to the analyzed architectures.