Principal Applied Cryptography Engineer (Rust) : Protocol Security & PQC

Principal Cryptography Engineer (Rust) — Post-Quantum & Zero-Knowledge

Senior / Principal Level | Global Remote | Part-Time Contract

About Hashmark Labs

Hashmark Labs is a senior-led engineering consultancy building advanced systems across blockchain infrastructure, cryptography, AI and FinTech for international clients.

We are seeking an exceptional Applied Cryptography Engineer with deep expertise in Rust, post-quantum cryptography and zero-knowledge systems.

This is a hands-on engineering opportunity focused on building, securing and validating cryptographic infrastructure for production environments. We are looking for someone who can translate research and specifications into secure, performant Rust implementations—not simply integrate existing libraries.

What You'll Work On

Post-Quantum Cryptography: Implement and integrate quantum-resistant signatures and key-establishment mechanisms, including ML-KEM, ML-DSA and related schemes, with hybrid migration and interoperability considerations.

Zero-Knowledge Systems: Develop and optimize proof-verification components, evaluate SNARK/STARK architectures and benchmark cryptographic performance.

Cryptographic Protocols & Security: Engineer secure signature schemes, identity and key-management systems, cryptographic interfaces and protection against side-channel vulnerabilities.

Security Testing & Verification: Perform threat modeling, test-vector validation, fuzzing, differential testing, security reviews and cryptographic benchmarking.

Production Rust Engineering: Build secure, reusable cryptographic components with automated testing, CI integration, performance optimization and cross-platform compatibility.

Required Expertise

Advanced Rust proficiency: Ownership, lifetimes, traits/generics, secure memory handling, low-level systems engineering and performance optimization.

Applied cryptography expertise: Demonstrated implementation of cryptographic algorithms from specifications, standards or research papers, validated against reference test vectors.

Cryptographic systems depth: Strong experience in at least one of PQC, elliptic-curve cryptography, signature schemes, threshold cryptography or ZK proving/verification.

Security engineering: Understanding of constant-time implementations, nonce misuse, signature malleability, side-channel risks, fuzzing and cryptographic correctness.

Verifiable Rust contributions: Public Rust cryptography implementations, open-source contributions, crates, or published research with accompanying Rust code.

Preferred Qualifications

Published research in cryptography, a PhD in Cryptography or closely related research-level expertise.

Contributions to RustCrypto, dalek, arkworks, halo2, Plonky2/3, RISC Zero, SP1, zkcrypto or comparable projects.

Experience with cryptographic security audits, formal methods, zero-knowledge infrastructure or post-quantum protocol implementations.

Engagement & Compensation

Location: Remote Worldwide

Engagement: Part-Time Contract

Working Arrangement: Flexible hours, with deliverables and collaboration expectations agreed for the engagement.

Compensation: Negotiable based on prior experience, demonstrated cryptographic expertise and engagement scope.

International payment arrangements, including USDC or INR where applicable, may be discussed.

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