Senior Software Engineer Startup Jobs in Wisconsin

We are looking for a Cryptography Software Engineer to join our team to help design and implement the next generation of secure Embedded Software implementations of Classic & Post Quantum Cryptography.

We have been established since 2018, so you would be directly working with the founders and inventors of this deep tech startup. The technology is already a couple of years in the making, its feasibility having been established, funding secured, and it has a clear path to market. This is a great opportunity for career progression and to get a head start in a rapidly expanding segment of the semiconductor industry (Post-Quantum Cryptography and RISC-V).

Our platform IP components come together as a RISC-V MCU based Sub-system with advanced (post-quantum) cryptography algorithm support and security features.

As a Senior Software Engineer at PQShield, you will be designing and developing secure solutions, helping to develop software solutions working seamlessly through the entire software development life cycle. You will assist with the development of PQShield's core software cryptography libraries. Responsibilities include developing internal tools to support the build, test and security analysis of PQShield's software products.

• Design, implement, and test classical and post-quantum cryptographic primitives with a strong emphasis on functional correctness, interoperability, and optimized performance across software environments.
• Develop and integrate cryptographic solutions on hardware platforms, including FPGA and hardware cryptographic coprocessors, with a focus on acceleration and secure implementation on ARM and RISC-V architectures.
• Harden cryptographic implementations against side-channel analysis (SCA), fault injection attacks (FIA), and other physical or logical threats through constant-time design and other countermeasures.
• Ensuring integration with cryptographic system and application API’s, for example: GlobalPlatform, ARM Platform Security Architecture, Linux Kernel drivers
• Collaborate with cryptographers, security engineers, and cross-functional teams—including hardware, verification, and platform security—to review, validate, and harden cryptographic implementations.
• Contribute to performance benchmarking and optimization across multiple platforms.
• Contribute to design and code review meetings to improve cryptographic software quality, architecture, and development processes.
• Perform and support security-focused code reviews, including static and dynamic analysis, and apply formal methods such as model checking where applicable.
• Maintain and enhance existing cryptographic software, ensuring robustness, security, and performance across supported platforms.
• Support compliance with relevant security standards (e.g., FIPS, ISO/IEC, NIST PQC).
• Participate in threat modeling and risk assessments related to cryptographic software.

• Master’s or PhD degree in computer science, mathematics, or a related field, with a strong background in cryptography or computer security.
• Proficiency in C and Assembly, with a focus on resource-constrained, bare-metal environments. Experience with Rust is nice to have.
• Familiarity with classical and post-quantum cryptographic algorithms, including NIST PQC candidates, and a solid understanding of NIST and FIPS publications and compliance requirements.
• Excellent problem-solving and debugging skills.

• Experience with secure coding practices and countermeasures against implementation attacks.
• Solid understanding of side-channel attacks (timing, power, EM), fault attacks, and corresponding mitigation strategies.
• Hands‑on experience with or working knowledge of security certification frameworks such as FIPS 140‑3, SESIP, PSA Certified, or Common Criteria.
• Ability to read and implement specifications from cryptographic research papers.
• 2+ years of professional experience in cryptographic software engineering is preferred; however, we assess seniority primarily based on your depth of knowledge, hands‑on experience, and problem‑solving skills rather than just years worked.

• Unparalleled opportunities to learn and accelerated career development.
• A collaborative, team environment with people who truly love what they do.
• Competitive salary and share option scheme.
• Flexible and hybrid working, and a working from home budget.
• Private health insurance for yourself and your family.
• 25 days annual leave (plus bank holidays and two wellness weeks).
• 50% gym membership discount.
• The chance to work with a spirited, smart, and friendly team!

PQShield is an Equal Employment Opportunity employer. We’re passionate about talent and proud to foster an inclusive environment; all applicants will be considered regardless of their gender identity, ethnicity, sexual orientation, disability, and age.