Senior Cryptography Engineer - C and FPGA

CryptoNext Security is seeking a Senior Cryptography Engineer to own a strategic project: porting our post-quantum cryptographic library across multiple platforms, with a focus on hardware/software FPGA accelerators. You will work at the intersection of cryptography, low-level C engineering, and embedded/hardware design, contributing to the Quantum Safe Library (C-QSL) that helps enterprises migrate to post-quantum cybersecurity.

What you'll do

• Design and implement efficient C code for post-quantum cryptographic algorithms (NIST-selected or recommended by EU agencies), balancing performance, portability and security
• Port and optimize the CryptoNext Quantum Safe Library (C-QSL) across multiple platforms and architectures, with emphasis on hardware/software FPGA accelerators
• Contribute to hardware/software co-design: specify and prototype cryptographic accelerators, evaluate trade-offs between software and FPGA-based implementations
• Adapt implementations for constrained and embedded environments such as IoT, Cortex-M, and embedded Linux
• Define and run test and validation strategies (functional, performance, security) across all target platforms
• Support security certification processes (CSPN, Common Criteria, FIPS) for the ported implementations
• Document your work through technical reports and, where relevant, scientific papers
• Collaborate closely with the R&D team and cross-functional teams to solve complex technical challenges
• Depending on your profile and the product roadmap, work on side-channel countermeasures and collaborate on library integration with communication protocols and cryptographic objects (TLS, IPsec, PKCS#11, X.509) in post-quantum or hybrid mode

What you bring

• 5+ years of senior-level experience in cryptography engineering, gained in a software company or cybersecurity department (ideally with international teams or clients)
• Engineering degree or Master's in computer science, mathematics or a related field
• Solid foundations in algorithmics and algebra, with the ability to translate mathematical constructs into efficient, correct implementations
• Strong programming skills in C; comfort working close to the hardware and optimizing for performance and security
• Experience with embedded development and hardware debugging tools (GCC, GDB, QEMU, JTAG) and practical experience with source code management and continuous integration using GitLab CI
• Good French and English communication skills, both oral and written

Nice to have

• PhD in cryptography or a related discipline
• Experience with public-key cryptography, symmetric-key cryptography, hash functions, and cryptographic protocols/frameworks such as OpenSSL
• Embedded software development, hardware/software co-design, or FPGA implementation experience
• Exposure to FPGA development using Intel (Altera) or AMD (Xilinx) devices, including familiarity with associated EDA tools (Quartus Prime, Vivado)

What we offer

• Ownership of a strategic, high-impact technical challenge at the heart of the product roadmap
• Full-time position based in Paris
• Competitive salary commensurate with experience

About CryptoNext Security

CryptoNext Security is a Paris-based start-up founded in 2019, building on more than 20 years of academic research in post-quantum cryptography (PQC). Named among Gartner's 5 reference leaders in post-quantum cryptography and a member of Campus Cyber, Hexatrust and Systematic, CryptoNext develops the Quantum Safe Remediation Suite, including the world-reference Quantum Safe Library (C-QSL) covering NIST algorithms, to help enterprises migrate to post-quantum cybersecurity.