Senior Software Engineer – Digital Identity, Applied Cryptography

This is a fully remote position, open to applicants in Germany.

📋 Description

• Assume technical responsibility for the continuous development of the complete SecureID stack — encompassing the mobile application, PKI backend, and platform integrations.

• Enhance the secure exchange of cryptographic materials and operations with operating systems: CryptoTokenKit token extensions and Keychain integration on iOS; Android KeyChain provider and Samsung Knox UCM/eSE integration on Android — allowing third-party applications (email, browsers, VPN) to utilize SecureID certificates without exposing key materials outside secure hardware.

• Assist in the BSI approval process: preparation for audits and hardening in accordance with BSI TR-03161 and TR-02102-1, ensuring crypto compliance, conducting threat modeling, providing support during penetration tests, and liaising with assessment bodies.

• Design and implement new functionalities (e.g., credential lifecycle management, external IdP integrations, smart-lock integrations).

• Advance the Windows login path (Credential Provider, CNG Key Storage Provider bridge) as part of various platform features.

• Oversee build, signing, and release processes while enhancing test coverage; produce technical documentation and collaborate with partners and pilot customers.

⛳️ Requirements

• Multiple years of professional experience in mobile and/or system-level software development (e.g., Swift/iOS, Kotlin/Android, C#/.NET, C++).

• Strong understanding of public-key cryptography and PKI: X.509 certificates, ECDSA, certificate chains, challenge–response schemes.

• Experience with platform-level cryptographic APIs and hardware key stores: Apple Keychain Services / Secure Enclave, Android Keystore/KeyChain — preferably with CryptoTokenKit extensions or Samsung Knox UCM.

• Practical experience with BSI approval or certification processes (e.g., TR-03161, TR-02102, or Common Criteria) — having actively participated in such processes.

• Openness to working across a diverse stack: Flutter/Dart, Python, React, Windows internals — while you don't need to master all areas, you should possess a willingness to engage with various components.

• Independent and structured work style; familiarity with Git, CI/CD, and thorough documentation practices.

• Proficiency in both German and English, spoken and written.

🏝️ Benefits

• Engaging work: Play a role in developing a technically advanced security product from the secure element to system integration — with deep technical engagement instead of routine CRUD tasks.

• Influence: You will have a significant impact on architectural and technological choices, benefiting from short communication lines within a small team.

• Premium equipment: Access to the latest MacBooks or Windows Surfaces, iPhone or Pixel, along with an unlimited mobile plan — usable for personal purposes as well.

• Modern software stack: Utilize tools such as ChatGPT, Claude, Personio, HubSpot.

• Additional perks: Corporate credit card with an expense tool, along with an Edenred City card (€50 per month).

• Flexible working conditions: Enjoy 30 vacation days and trust-based working hours ("Come as you are").

• Work locations: Option to work remotely as well as from modern offices in Münster, Cologne, and Leverkusen.

• Professional development: Opportunities for certifications, leadership, and soft-skill training, along with access to platforms like LinkedIn Learning and Udemy.