C developer Jobs in Markham, ON

Our client, is seeking a high-caliber Lead Software Engineer to head the development of their core cryptographic engine.

This engine is a high-performance, cross-platform C/C++ library that delivers mission-critical data encryption, tokenization, key management, HSM integration, and payment-terminal security for Tier-1 banks, major retailers, and healthcare organizations worldwide. The product compiles and ships across a vast matrix of operating systems—including Linux, Windows, macOS, AIX, Solaris, HPE NonStop, and IBM z/OS.

This is a technical leadership role requiring deep systems-level C/C++ development. You will be a hands-on "player-coach"—writing substantial production code, establishing engineering best practices, driving architectural design reviews, and acting as a senior escalation authority for complex cross-platform and mainframe-integrated defects.

Position Type: 6-Month Contract

Location: Hybrid / Office-Based (On-site presence required at the Richmond Hill, ON office location)



Advantages
High-Impact Cryptographic Ownership: Take technical ownership of an elite, enterprise-grade security system used globally by major financial infrastructures.

Extreme Platform Breadth: Work across an ultra-rare matrix of computing platforms, including POS terminals, Linux/Windows cloud instances, HPE NonStop, and legacy IBM mainframes.

Modern Toolchain Transition: Drive cutting-edge mainframe modernization work, utilizing modern VS Code-based developer toolchains to interface with legacy architectures.

Strategic Future Focus: Pioneer the organization's security roadmap for post-quantum cryptographic algorithm readiness (ML-KEM, ML-DSA) and FIPS 140 compliance.



Responsibilities
Technical Leadership & Architecture
Engineering Culture: Set coding standards, comprehensive testing strategies, and a rigorous peer code-review culture across the global engineering squad.

End-to-End Feature Design: Lead product features from original requirement mapping through strict API design, implementation, and multi-platform qualification testing.

Build Optimization: Manage the cross-platform compilation and packaging strategy utilizing CMake, GitLab CI, Jenkins pipelines, artifact promotion, and secure code signing.

DevSecOps Ingestion: Embed automated static analysis, security vulnerability scanning, and dependency management tools directly into the unified CI pipeline.

Technical Escalation: Serve as the final escalation authority for customer defects involving cryptographic correctness, hardware security module (HSM) integrations, and platform authorization frameworks.

Hands-on Full-Stack & Core Systems Engineering
Cryptographic Engineering: Implement and refine complex symmetric/asymmetric ciphers, format-preserving encryption (FPE), key wrapping algorithms, message authentication codes, and TLS configurations in C and C++.

Multi-Language Interop Bindings: Own the Java SDK layer—managing both pure-Java modules and components that interface with the native C library through cross-language runtime boundaries (JNI interop).

Mainframe Engineering (IBM z/OS Core): Partner with the team's mainframe specialists to build, maintain, and support the product's IBM z/OS port. Write portable code across the IBM xLC/C++ compiler, HLASM assembly interfaces, and COBOL callable boundaries via JCL build configurations and SMP/E installation packages.

Systems Consulting: Engage directly with client-side z/OS Systems Programmers to troubleshoot runtime issues, TLS hygiene, and SAF/RACF/ACF2 authentication security integrations.



Qualifications
Essential Criteria ("What Excellent Looks Like")
Expert C/C++ Systems Development: 8+ years of professional experience writing highly portable, maintainable C/C++ source code across disparate compilers, architectures, and platforms, with deep knowledge of avoiding undefined behaviors.

Operating System Depth: Deep foundational understanding of OS memory management, dynamic linking, shared-library design, multi-threading models, and process isolation across at least two platforms (e.g., Linux, Windows, AIX).

Applied Cryptography & Standards: Hands-on experience implementing public-key cryptography, symmetric ciphers, key management structures, and custom TLS/SSL configurations.

Native Interoperability Boundaries: Proven experience owning native interoperation boundaries in production, managing strict memory ownership and error-propagation boundaries between cross-language bindings.

Build Systems & Pipelines: Demonstrated mastery maintaining CMake configurations across multi-compiler environments, combined with direct ownership of designing multi-stage CI/CD delivery pipelines.

Java Mastery: Robust production-quality Java experience with the ability to diagnose JVM runtime and interop integration failures.

Highly Preferred Technical Assets
C# / .NET Profile: Strong background in .NET Standard library design, native interop wrappers, and NuGet packaging.

HSM Integrations: Direct, referenceable experience deploying PKCS#11 or Hardware Security Module SDKs (e.g., Thales Luna, nCipher nShield, Atalla).

Post-Quantum Cryptography (PQC): Familiarity with the NIST PQC standards trajectory and upcoming algorithm frameworks (ML-KEM, ML-DSA, SLH-DSA).

Payment Domain Knowledge: Practical familiarity with banking standards such as ISO 8583, EMV, PCI-DSS P2PE, and terminal-to-host key exchange mechanisms.

IBM z/OS Environment Familiarity: Prior experience or strong architectural familiarity with JCL, HLASM, xLC/C++, SMP/E packaging, TSO/ISPF, and the z/Architecture 31-bit/64-bit addressing models. (A strong systems C/C++ programmer with a passionate interest in non-POSIX environments will be considered).

HPE NonStop Infrastructure: Experience or interest in the Guardian/OSS shell, TAL/pTAL programming, and C cross-compilation configurations.



Summary
If you are a premier Systems Engineer who thrives on low-level memory allocation, deep cryptographic mathematics, and cross-platform architecture compilation from Linux to the Mainframe, this Richmond Hill mandate offers a phenomenal technical stage. Bring your C/C++ expertise, multi-language interop skills, and technical leadership to an elite data security squad today!



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