Job Title: Senior Cryptographic Protocol EngineerOffice Location: 7303 Warden Ave. Markham, ONEmployment Type: Full-timeApplication Email: [email protected] are building a novel secure data-encryption protocol around key material generated by our Quantum Key Distribution infrastructure - not another AES wrapper, but a current 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 RoleThe 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.ResponsibilitiesImplement 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 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.Programming LanguagesRequiredRust - systems, networking, or security-sensitive softwareC/C++ - systems programming, integration with existing librariesPython - automation, testing, tooling, crypto prototypingBash / Linux shell scriptingPreferredGoJava or C# - for integration with existing infrastructureRust FFI and integration between Rust and C/C++ librariesCryptography & SecurityRequiredStrong understanding of applied cryptography and cryptographic protocols, and experience implementing security-sensitive software,



with a solid grasp of:Symmetric cryptographyKey management and key lifecycleKey derivation and key separationAuthentication and integrityRandomness and entropyNonces, initialization vectors, and countersReplay protectionSecure session establishmentProtocol state machinesPlus a working understanding of threat modeling, secure software design, and the ability to identify security risks in protocol implementations.PreferredExperience with cryptographic protocol design or implementationExperience reviewing cryptographic implementationsExperience with cryptographic libraries and APIsExperience with HSMs, secure enclaves, or other key-protection technologiesFamiliarity with formal methods, protocol verification, or cryptographic security analysisFamiliarity with post-quantum cryptographyExperience with QKD or quantum communicationsSystems & Computer EngineeringStrong understanding of Linux operating systemsExperience with processes, threads, concurrency, synchronization, and memory managementExperience developing multithreaded and asynchronous softwareStrong understanding of computer networking and networking stacksExperience with performance profiling, debugging, and optimizationUnderstanding of hardware/software interfacesExperience troubleshooting systems at both software and OS levelsNetworking & Distributed SystemsStrong understanding of TCP/IP and UDP networkingExperience with IPv4/IPv6, Ethernet, sockets, routing, and network troubleshootingExperience designing or implementing network protocolsExperience with distributed systems and inter-node communicationUnderstanding of network latency, reliability, synchronization, and failure recoveryExperience with secure network communicationsFamiliarity with TLS, QUIC, IPsec, WireGuard, or the Noise Protocol Framework is an assetExperience using Wireshark, tcpdump, and standard Linux networking toolsSoftware Engineering & DevOpsStrong experience with Git and modern software development workflowsExperience with automated unit, integration, and system testingExperience with CI/CDExperience with Docker and containerized environmentsFamiliarity with static analysis, dependency management, and vulnerability scanningExperience with debugging and profiling toolsFamiliarity with observability, logging, monitoring, and system diagnosticsExperience working in Linux-based development and production environmentsStrong understanding of software architecture and maintainable code designProtocol DocumentationExperience documenting protocol specifications, message formats, state machines, key-management procedures, error conditions, and security assumptions.You should be comfortable converting complex technical and cryptographic concepts into clear engineering documentation that can be implemented, tested, reviewed, and independently understood by other engineers.QKD ExperienceQKD expertise is not a requirementThe QKD infrastructure and its key-management mechanisms are already available. The selected engineer will work with our team to understand how shared key material is generated and made available between nodes, how keys are identified and retrieved, key availability and consumption constraints, key lifecycle and rotation requirements, the interfaces/APIs exposed by the QKD infrastructure,



and its operational constraints.Your responsibility is to build the cryptographic protocol on top of this key-management capability — not to develop the QKD system itself.On‐Site & Travel RequirementsThis is an on‐site position based in Toronto, Ontario. The project includes geographically distributed QKD and network nodes located in different cities, so the successful candidate must be comfortable traveling between project sites to support development, testing, deployment, integration, and troubleshooting.Based in Toronto, or willing to relocateWilling to travel between project sites in CanadaComfortable in data centers, network facilities, and labsAble to troubleshoot on‐site, across software and networking layersValid driver's licence, if required for site travelAble to satisfy applicable site‐access and security requirementsCanadian citizen or permanent resident - required for project/security clearancePersonal QualitiesExceptional attention to detail, particularly with security-sensitive codeStrong analytical and problem‐solving abilitiesEnjoys reasoning about complex protocols and distributed systemsComfortable challenging assumptions and identifying potential security weaknessesWorks independently and takes ownership of technical problemsCommunicates complex technical concepts clearly, in writing and in personCollaborates well with cryptographers, QKD engineers, network engineers, and software developersComfortable working with novel technology where established patterns may not existPragmatic - balances security, performance, reliability, and engineering complexityStrong sense of responsibility when working with cryptographic keys and security-critical infrastructureEducation & ExperienceBachelor's or Master's degree in Computer Science, Computer Engineering, Electrical Engineering, Cybersecurity, Mathematics, or a related field5+ years of professional software engineering experience, with significant work in systems, networking, cybersecurity, or cryptographic softwareDemonstrated professional experience with RustDemonstrated experience implementing or working with secure protocols or security-sensitive systemsEquivalent combinations of education, professional experience, and demonstrated technical expertise may be consideredWhat Success Looks LikeIn this role, you will take a novel cryptographic protocol from specification to a secure, tested, interoperable implementation. You'll be expected to think beyond simply implementing cryptographic operations - the implementation must correctly handle the complete protocol lifecycle: key acquisition, key usage, session state, message processing, failures, concurrency, synchronization, and secure recovery.The end result should be a robust, well‐engineered implementation capable of reliably operating between geographically distributed nodes connected through the QKD infrastructure.Important Security ExpectationBecause this project involves a novel cryptographic protocol, we distinguish between implementing a protocol and establishing that the underlying cryptographic construction is secure. You will be expected to identify implementation- and protocol-level security risks and participate in security reviews. Independent cryptographic review of the underlying construction may also be performed by cryptography specialists.SuperQubit is committed to building secure, innovative technologies for the quantum era. We welcome applicants who are passionate about shaping the future of cybersecurity.

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