Senior Cryptographic Protocol Engineer

SuperQubit is building a novel secure data-encryption protocol around key material generated by quantum key distribution infrastructure. You will translate a defined cryptographic protocol specification into a production-grade, battle-tested Rust implementation running between geographically distributed nodes. This is a systems and network-security role combining cryptography, secure networking, systems programming, distributed systems, and security-sensitive software development.

What you'll do

• 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 including 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 including lost messages, node restarts, key exhaustion, synchronization problems, and 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 efficient 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

What you bring

• A Bachelor's or Master's degree in Computer Science, Computer Engineering, Electrical Engineering, Cybersecurity, Mathematics, or a related field
• 5+ years of professional software engineering experience, with significant work in systems, networking, cybersecurity, or cryptographic software
• Demonstrated professional experience with Rust in systems, networking, or security-sensitive software
• Proficiency in C/C++ for systems programming and library integration
• Proficiency in Python for automation, testing, tooling, and crypto prototyping
• Proficiency in Bash and Linux shell scripting
• Strong understanding of applied cryptography and cryptographic protocols, including symmetric cryptography, key management and lifecycle, key derivation and separation, authentication and integrity, randomness and entropy, nonces and initialization vectors, replay protection, secure session establishment, and protocol state machines
• Experience implementing security-sensitive software with a working understanding of threat modeling, secure software design, and the ability to identify security risks in protocol implementations
• Strong understanding of Linux operating systems, processes, threads, concurrency, synchronization, and memory management
• Experience developing multithreaded and asynchronous software
• Experience with performance profiling, debugging, and optimization
• Understanding of hardware/software interfaces and experience troubleshooting systems at both software and OS levels
• Strong understanding of TCP/IP and UDP networking, IPv4/IPv6, Ethernet, sockets, routing, and network troubleshooting
• Experience designing or implementing network protocols
• Experience with distributed systems and inter-node communication
• Understanding of network latency, reliability, synchronization, and failure recovery
• Experience with secure network communications
• Experience using Wireshark, tcpdump, and standard Linux networking tools
• Strong experience with Git and modern software development workflows
• Experience with automated unit, integration, and system testing
• Experience with CI/CD
• Experience with Docker and containerized environments
• Familiarity with static analysis, dependency management, and vulnerability scanning
• Experience with debugging and profiling tools
• Familiarity with observability, logging, monitoring, and system diagnostics
• Experience working in Linux-based development and production environments
• Strong understanding of software architecture and maintainable code design
• Experience documenting protocol specifications, message formats, state machines, key-management procedures, error conditions, and security assumptions
• Exceptional attention to detail, particularly with security-sensitive code
• Strong analytical and problem-solving abilities
• Comfort reasoning about complex protocols and distributed systems
• Canadian citizen or permanent resident, required for project/security clearance
• Based in Toronto, Ontario, or willing to relocate
• Willing to travel between project sites in Canada

Nice to have

• Experience with Go
• Experience with Java or C# for integration with existing infrastructure
• Rust FFI and integration between Rust and C/C++ libraries
• 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
• Familiarity with TLS, QUIC, IPsec, WireGuard, or the Noise Protocol Framework

What we offer

• On-site position based in Toronto, Ontario
• Relocation support available
• Travel budget for work between Canadian project sites

About SuperQubit

SuperQubit is building secure, innovative technologies for the quantum era, focused on shaping the future of cybersecurity.