Senior Cryptographic Protocol Engineer

SuperQubit Inc.; Toronto; On-site; CAD 120,000 - 170,000; Full time

Job summary

SuperQubit Inc. seeks a Senior Cryptographic Protocol Engineer to transform protocol specifications into a production-grade Rust implementation that securely manages key material across distributed nodes. You will work closely with cryptographers and QKD specialists in a security-focused environment.

The role emphasizes systems programming, cryptography, secure networking, and performance optimization. On-site work in Toronto with travel to project sites is required; strong background in Rust,

Qualifications

• Strong understanding of applied cryptography and cryptographic protocols.
• Experience building security-sensitive software with robust threat modeling.
• Proven ability to design and implement secure, scalable systems.

Responsibilities

• Implement a novel cryptographic protocol per a defined spec.
• Design core Rust-based implementation and secure interfaces with QKD infrastructure.
• Develop testing, performance, and security validation across distributed nodes.
• Travel between project sites as required.

Skills

Rust

Cryptography

Distributed systems

Networking

Security

Education

Bachelor's or Master's in CS/CE/EE/Cybersecurity/Math

Tools

C/C++

Python

Bash

Docker

Job description

Job Title: Senior Cryptographic Protocol Engineer
Office Location:7303 Warden Ave. Markham, ON
Employment Type:Full‑time
Application Email:[e-mail]

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 inRust.
• 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 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/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
• Familiarity with TLS, QUIC, IPsec, WireGuard, or the Noise Protocol Framework is an asset
• Experience using Wireshark, tcpdump, and standard Linux networking tools

Software Engineering & DevOps

• 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

Protocol Documentation

Experience 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 Experience

QKD expertise is not a requirement

The 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 Requirements

This is anon-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 relocate
• Willing to travel between project sites in Canada
• Comfortable in data centers, network facilities, and labs
• Able to troubleshoot on-site, across software and networking layers
• Valid driver's licence, if required for site travel
• Able to satisfy applicable site-access and security requirements
• Canadian citizen or permanent resident— required for project/security clearance

Personal Qualities

• Exceptional attention to detail, particularly with security-sensitive code
• Strong analytical and problem-solving abilities
• Enjoys reasoning about complex protocols and distributed systems
• Comfortable challenging assumptions and identifying potential security weaknesses
• Works independently and takes ownership of technical problems
• Communicates complex technical concepts clearly, in writing and in person
• Collaborates well with cryptographers, QKD engineers, network engineers, and software developers
• Comfortable working with novel technology where established patterns may not exist
• Pragmatic — balances security, performance, reliability, and engineering complexity
• Strong sense of responsibility when working with cryptographic keys and security-critical infrastructure

Education & Experience

• Bachelor's or Master's degree in Computer Science, Computer Engineering, Electrical Engineering, Cybersecurity, Mathematics, or a related field
• 5+ yearsof professional software engineering experience, with significant work in systems, networking, cybersecurity, or cryptographic software
• Demonstrated professional experience with Rust
• Demonstrated experience implementing or working with secure protocols or security-sensitive systems
• Equivalent combinations of education, professional experience, and demonstrated technical expertise may be considered

What Success Looks Like

In 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 Expectation

Because 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.

How to Apply

Send your resume, GitHub or relevant open-source contributions, and a short note on a systems or cryptography project you're proud of to [e-mail].

SuperQubit is committed to building secure, innovative technologies for the quantum era. We welcome applicants who are passionate about shaping the future of cybersecurity.