Principal Security Engineer

About

Dfns is the leading Wallets-as-a-Service (WaaS) platform, helping fintechs, institutions, and enterprises simplify digital asset management and securely onboard users onchain.

Its API-first wallet platform unifies transaction management, workflow governance, key deployment, and third-party integrations into one secure operating system for blockchains. Built on advanced security and cryptography, Dfns is trusted by over 200 financial institutions and applications—including ABN AMRO, Broadridge, Fidelity, Zodia Custody, Banca Sella, Stripe, Moonpay, Circle, IBM, Deblock, and Gemini—and secures over $3 billion in monthly transactions.

Founded in 2020, Dfns has raised $30 million from global investors such as White Star Capital, Motive Partners, Bpifrance, Coinbase, Wintermute, and Susquehanna. Originally incubated by Techstars and Station F in Paris, Dfns now operates globally with teams across the US, Europe, the Middle East, and Asia.

Job Description

Join a stellar team of leaders and experts in blockchain technology, cryptography, infrastructure, and security to build the backbone of blockchain wallet infrastructure for the next financial era. We’re hiring a Principal Security Engineer to lead security design and development across our platform. Reporting to the CISO, you’ll set the strategy to protect our systems, fix vulnerabilities, and keep client wallets safe. Your work will span the full security lifecycle: architecture reviews, threat modeling, penetration testing, incident response, and secure software practices. You’ll work closely with engineering, infrastructure, and product teams to make security part of every layer of the stack, while ensuring compliance with industry standards. Beyond defense, you’ll design new security features, test ideas to improve resilience, and share your knowledge with the wider community through articles or conferences.

Preferred Experience

Responsibilities

  • Lead security architecture, setting priorities and ensuring secure, reliable delivery.

  • Drive threat modeling, vulnerability management, and pentesting (internal and external).

  • Conduct and oversee security reviews (code, design, architecture, and dynamic testing).

  • Design and implement defense-in-depth security controls.

  • Build frameworks for automated security testing and SSDLC enforcement.

  • Mentor engineers on secure coding, incident response, and best practices.

  • Manage bug bounty, security releases, and coordinate with external researchers.

  • Monitor and respond to emerging threats, including supply chain risks.

  • Represent the company in client discussions, audits, and at security conferences.

Requirements

  • 10+ years of experience in security engineering, with leadership in fintech or blockchain.

  • Strong expertise in application security, smart contract security, and cryptography.

  • Deep understanding of pentesting, static/dynamic testing, vulnerability management.

  • Hands-on with secure networking, cloud security (AWS), and software supply chains.

  • Familiar with industry standards and frameworks (ISO 27001, NIST, CIS, SOC 2, etc.).

  • Strong knowledge of network and web protocols, applied cryptography, and PKI.

  • Experience integrating security into CI/CD pipelines and observability systems.

  • Proficient in TypeScript and Rust (or similar languages) with secure coding expertise.

  • Clear communicator who can explain complex security concepts to both technical and business stakeholders.

Recruitment Process

Process

  • Intro call with Co-CEO (30 min)

  • Personality and cognitive tests (45 min)

  • Coding test in a language of your choice

  • Focus interview with the hiring panel (120 min)

    • Threat model exercice
    • Infrastructure security
    • Culture fit check

  • Final interview with CISO (30 min)

  • Reference calls and background checks

Terms

  • Title: Principal Security Engineer

  • Salary: $220,000–300,000 per year (full-time)

  • Equity: 150–300 stock options vested over 4 years

  • Benefits: Healthcare, 401K, and travel expenses

  • Location: US or EU (remote-first, office optional)

  • Equipment: MacBook Pro + essentials

Additional Information

  • Contract Type: Full-Time
  • Location: Paris, New York
  • Experience: > 10 years
  • Possible full remote
  • Salary: between 220000$ and 300000$ / year
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