Cryptographer Engineer - Defense & Security - Le Plessis Robinson

CS, a subsidiary of the Sopra Steria group, is a leading technology player in the design, integration, and operation of critical systems. Present in 7 countries with over 2,600 passionate employees, we are involved in the core issues of sovereignty, security, and performance, in strategic sectors such as defense, space, energy, industry, transport, aeronautics, and cybersecurity.

Our difference? Unique expertise in real-time systems, sovereign and sustainable solutions, and a strong culture of innovation, with 15% of our revenue invested in R&D. We support our clients in the success of their most complex programs, from air traffic control to anti-drone systems, including nuclear systems and satellite control centers.

By joining CS, you become part of a human-centric and innovative company.

• We deliver more than just systems; we build trust.
• We go beyond expressed needs; we prepare for tomorrow's challenges.
• More than just experts, we shape innovation.

Protecting territories, anticipating threats.

Our Defense & Security Business Unit is at the heart of national sovereignty issues. With over 800 employees across the country, it designs critical systems for the army and civil aviation. Our teams work on high-value-added projects: tactical data links, anti-drone systems, maritime surveillance, simulation and training, and air safety. Thanks to our expertise and our involvement in international programs, we actively contribute to the security of territories.

Joining this Business Unit means contributing to the protection of citizens within a committed collective.

As part of strengthening our cybersecurity activities, we are looking for an engineer/academic capable of combining technical expertise with the ability to support clients in their transformation towards post-quantum cryptography (PQC). This position places support for the post-quantum transition at the core of its missions. It combines cryptographic expertise, analytical skills, and strategic support, in a context aligned with ANSSI recommendations and international standards.

Your missions:

• Support clients in their transition to post-quantum cryptography (PQC).
• Conduct maturity assessments and map cryptographic uses, dependencies, and risks.
• Define migration strategies and roadmaps, integrating crypto-agility and hybrid approaches.
• Lead awareness, training, and decision-making support workshops for clients.
• Contribute technically to the integration, testing, PoC, validation, and evaluation of cryptographic solutions.
• Maintain active watch on NIST, IETF, ETSI, and ANSSI standards and recommendations.
• Disseminate PQC and crypto-agility best practices internally and with clients.

Technical Environment:

• Cryptography: AES, RSA, ECC, SHA, MAC, signatures, and encryption.
• PQC & Crypto-agility: KEM, PQC signatures, hybridization, and NIST standards.
• Security & Protocols: TLS/HTTPS, PKI/X.509, HSM, PKCS#11.
• Development & Systems: C/C++, Python, Linux, OpenSSL, and cryptographic libraries.
• Standards & Compliance: ANSSI, NIST, IETF, and ETSI recommendations.

A graduate of an engineering school specializing in cryptography and PQC, you have a strong grasp of the fundamentals of cryptography, PKI/secure protocols, and post-quantum mechanisms. You are also comfortable with standards and recommendations (NIST/IETF work and ANSSI recommendations related to the PQC transition).

You have recognized experience in these areas, possess a strong analytical mindset, rigor, and synthesis skills, with a structured approach to complex problems.

Then, your profile interests us!

Join a company where people, innovation, and impact meet.
At CS, we offer:

• An enriching employee experience, driven by a work environment designed to foster flexibility, autonomy, and daily well-being.

• A comprehensive onboarding program designed to welcome every talent from day one and an Academy to develop your skills, enrich your expertise, and build professional paths that suit you.

• A strong societal commitment: over 3,000 associations supported, an active disability policy, an inclusive culture, a responsible digital initiative, and partnerships like Elles bougent to inspire future female talent.

…and many other benefits to discover by joining us!

Our uniqueness? The unique blend of technological expertise, critical projects, and human commitment. As an innovative and responsible company, we build an ethical, inclusive, and future-oriented environment. Open to all talents, we believe that diversity is a strength.

THE NEXT STEPS:

If your profile matches, you will be invited to an interview with an operational manager to discuss your skills and your vision of the role. You will then meet Dylan, the recruitment manager, for a discussion about your background, your aspirations, and our company culture.
Finally, because we value transparency and respect, we commit to providing you with personalized feedback by phone, regardless of the outcome of the process.

#CS #PQC #Cryptography

As an inclusive and committed employer, our company works daily to combat all forms of discrimination and promote a respectful work environment. Therefore, committed to gender balance and diversity, we encourage all applications and all profiles.

https://www.soprasteria.fr/nous-connaitre/nos-engagements