Job Title: Senior Cryptographic Protocol Engineer Office Location: 7303 Warden Ave. Markham, ON Employment Type: Full‑time Application Email: [email protected] We are building a novel secure data-encryption protocol around key material generated by our Quantum Key Distribution infrastructure — not another AES wrapper, but a new cryptographic construction designed specifically around what QKD-derived keys make possible. We need someone who can take that specification from idea to a production-grade, battle-tested Rust implementation running between geographically distributed nodes. About the Role

The successful candidate will work closely with our technical team to translate a defined cryptographic protocol into a robust, secure, and production-quality implementation. Rust will be the primary implementation language, but this is a systems and network-security role rather than a conventional application-development position. The ideal candidate has strong experience across cryptography, secure networking, systems programming, distributed systems, and security-sensitive software development. You do not need to be a QKD expert.

Our team will provide the necessary background on QKD, the existing infrastructure, and how shared key material is made available between nodes. Your job is to understand the protocol specification, design its software architecture, implement it securely, and integrate it with the surrounding communications infrastructure. Responsibilities

Implement a novel cryptographic protocol based on a defined protocol specification. Design and develop the core implementation primarily in Rust . Design secure interfaces between the cryptographic protocol and the underlying QKD key-management infrastructure. Develop mechanisms for securely consuming, managing, rotating,



and tracking shared key material between communicating nodes. Design and implement protocol state machines, session management, key lifecycle management, and error handling. Integrate the protocol with existing networking and application infrastructure. Implement protections against protocol-level attacks — replay, message manipulation, key reuse, state confusion, and related threats. Develop comprehensive unit, integration, interoperability, performance, and security tests. Analyze protocol behavior under failure conditions: lost messages, node restarts, key exhaustion, synchronization problems, network interruptions. Document protocol implementation, interfaces, assumptions, security-sensitive design decisions, and operational procedures. Participate in security reviews alongside cryptography and QKD specialists. Profile and optimize for performance, latency, memory usage, concurrency, and productive key consumption. Troubleshoot systems and networking issues across geographically distributed nodes. Travel between project sites and QKD/network infrastructure located in different cities as required. Programming Languages

Required

Rust — systems, networking, or security-sensitive software C/C++ — systems programming, integration with existing libraries Python — automation, testing, tooling, crypto prototyping Bash / Linux shell scripting Preferred





Go Java or C# — for integration with existing infrastructure Rust FFI and integration between Rust and C/C++ libraries Cryptography & Security

Required

Strong understanding of applied cryptography and cryptographic protocols, and experience implementing security-sensitive software, with a solid grasp of: Symmetric cryptography Key management and key lifecycle Key derivation and key separation Authentication and integrity Randomness and entropy Nonces, initialization vectors, and counters Replay protection Secure session establishment Protocol state machines Plus a working understanding of threat modeling, secure software design, and the ability to identify security risks in protocol implementations. Preferred

Experience with cryptographic protocol design or implementation Experience reviewing cryptographic implementations Experience with cryptographic libraries and APIs Experience with HSMs, secure enclaves, or other key-protection technologies Familiarity with formal methods, protocol verification, or cryptographic security analysis Familiarity with post-quantum cryptography Experience with QKD or quantum communications Systems & Computer Engineering

Strong understanding of Linux operating systems Experience with processes, threads, concurrency, synchronization, and memory management Experience developing multithreaded and asynchronous software Strong understanding of computer networking and networking stacks Experience with performance profiling, debugging, and optimization Understanding of hardware/software interfaces Experience troubleshooting systems at both software and OS levels Networking & Distributed Systems

Strong understanding of TCP/IP and UDP networking Experience with IPv4/IPv

📌 Senior Cryptographic Protocol Engineer (Toronto)
🏢 SuperQubit
📍 Toronto