Following a Recommendation by the European Commission, from the end of 2023 each EU Member State will gradually offer the European Digital Identity (EUDI) wallet to their citizens, residents, and businesses. This mobile-based wallet will serve to manage access to verified sensitive personal information and to identify and authenticate the wallet's owner when interacting with financial services, medical institutions, government agencies, and other third-party services. Due to the high value of information and authentication capabilities provided by EUDI wallets, they are highly attractive targets for threat actors. This article explores secure development strategies for an EUDI wallet app. While being specific to the EUDI wallet, the methodology is equally applicable to the development of any IT asset.