Senior Cryptography Engineer

IonQ is a leading provider of quantum‑computing platforms and services, delivering integrated solutions for computing, networking, sensing and security to customers such as AWS and AstraZeneca. The senior position is located on‑site in Geneva, Switzerland, and is part of ID Quantique, IonQ's division that secures governments, telecom networks and financial institutions with quantum‑safe communications. The engineer will create and sustain software implementations of cutting‑edge post‑quantum algorithms, including reference and bit‑accurate models for ML‑KEM, ML‑DSA and SLH‑DSA/LMS. Work will involve writing constant‑time code in C, C++ or Rust as well as Python, constructing test‑vector generators and NIST ACVP tooling, and supporting hardware and firmware teams by breaking algorithms into hardware‑friendly components such as Keccak, NTT and polynomial arithmetic. Collaboration with senior cryptographers and assistance to RTL engineers are also key parts of the daily routine. Candidates must hold a Master's degree in cryptography, mathematics, computer science or a closely related discipline, with a PhD considered a plus. They need at least five years of hands‑on experience building cryptographic or security‑critical software using C/C++ or Rust, and a solid grasp of contemporary cryptographic building blocks. The role requires fluency in English; additional proficiency in French or German is beneficial but not mandatory. The position offers the chance to deepen expertise in post‑quantum cryptography while contributing to real‑world products that demand rigorous correctness and security. Working in Geneva provides a multicultural environment and close interaction with a global team of experts. IonQ promotes flexible work arrangements, continuous learning opportunities, and a career development framework within its rapidly expanding quantum‑technology group. What the role asks for: - Master's degree in Cryptography, Mathematics, Computer Science or related field - At least five years developing cryptographic or security‑critical software in C/C++ or Rust - Deep knowledge of modern cryptographic primitives - Fluent English proficiency - Experience with post‑quantum lattice‑ or hash‑based schemes (nice‑to‑have) - Familiarity with NIST test‑vector formats or CAVP/ACVP (nice‑to‑have) - French or German language skills (nice‑to‑have)