Web3 Principal Cryptographer

Job at Dfns


Paris, Île-de-France, France

Full time



Dfns is a cybersecurity company that builds custody SaaS protocol for web3 apps. Think of it as a developer tool that provides a secure cloud for crypto. Our mission is to bring serenity to DeFi by eliminating new blockchain risks and making crypto transactions easier, faster, more affordable, and compliant with existing regulations.

From fintechs to large banks to e-commerce sites, Dfns gives financial institutions and businesses the freedom to own and transfer crypto on a battle-designed security infrastructure. Our API is designed to offer best-in-class developer experience allowing any platform to deploy custodial wallets in a matter of days, with streamlined feature delivery and frequent security upgrades.

Founded in 2020 in Paris, Dfns is a startup incubated at Station F (awarded Future 40), accelerated by Techstars and recognized DeepTech by the French Ministry of Economy. Our company is fully remote with offices in Paris, Amsterdam, New York, London, Stockholm, Sofia, and other cities.

Job Description

You will contribute to one of the most ambitious technology projects in crypto today: building a trustless custody infrastructure for the trillion-dollar digital asset industry.

You will join an amazing team of leaders (CTO, Chief Scientist, CISO) and experts (Software Engineers, R&D Engineers, Security Engineers) in a highly challenging and collaborative environment.

We are looking for a Principal Cryptographer to explore different research tracks such as algorithms, asymmetric cryptography, threshold cryptography, PQC, crypto-agility, off-chain transfers, signatures and other types of tools to encrypt sensitive data and protect it from hackers, misuse, and cybercrime.

As a Principal Cryptographer, you will be laser-focused on finding ways to protect blockchain keys from being intercepted, decrypted, copied, altered, or deleted by unauthorized actors. You will need a deep understanding of cryptography, namely MPC, ZKP, and all related algorithms. You will also develop and apply various mathematical models to help find and thwart potential systems threats.


Your primary goal will be to research state-of-the-art cryptography to enhance our products with security systems, primitives, techniques, and algorithms, and make them safer, faster, more efficient, and more affordable.

Example of a primary metric would be Publication Per Year.

Your day-to-day projects will involve:

  • Acting as a powerhouse of ideas on all cryptographic and research issues.
  • Identifying weaknesses and designing robust security systems to negate new risks.
  • Testing in-practice cryptographic theorems according to product security requirements.
  • Identifying and securing weaknesses in new and existing cryptographic systems.
  • Working closely with Chief Scientist to implement the R&D roadmap.
  • Working closely with R&D engineers to iterate and specify the implementation of new, patent-pending crypto-primitives and protocols.
  • Researching public key cryptography with ECDSA, EDdsa, Schnorr, or other NIST-approved ciphers.
  • Leveraging private and public key cryptography to make our product as compatible and interoperable as possible with any blockchain.
  • Developing and managing our company's proprietary encryption technology, including its code, software, and third-party product adoption.
  • Prototyping new security solutions with advanced programming encryption techniques.
  • Training staff that handles cryptography and helping them develop more secure systems.
  • Working closely with the security research team to detect mathematical vulnerabilities in our proprietary crypto-systems and utilized open-source libraries.
  • Analyzing security protocols, researching weaknesses, reporting possible threats or mathematical issues, and finding ways to counter them.
  • Authoring and updating internal and external documentation, such as White Papers.
  • Facilitating cross-team communication and know-how exchange between team members.
  • Handling communications with independent vulnerability researchers and designing appropriate mitigation strategies for reported vulnerabilities.
  • Keeping abreast of the latest developments in crypto, DeFi and blockchain to feed the company's strategic orientations.
  • Continually researching current and emerging technologies and propose changes.


  • 8+ years experience as a Principal Cryptographer or similar role.
  • 3+ years proven work experience in blockchain and DeFi.
  • Extremely strong mathematical knowledge and skillset.
  • Experience with public key cryptography, such as ECDSA and EDdsa.
  • Engineering expert capabilities of challenging the reasoning of other engineers.
  • Thorough understanding of the latest security principles, techniques, and protocols.
  • Having published >1 article in well-known, international scientific reviews.
  • Having been granted a PhD in cryptography and/or computer science.
  • Experience working with secure, fault-tolerant, and resilient systems.
  • Founding-spirited with grit and guts to pursue complex worldwide ambitions.
  • Excellent analytical and problem-solving skills.
  • Excellent written and verbal communication skills.
  • Humble, respectful, and very professional to others.
  • Able to decide even in ambiguous, unstable situations.
  • Appetite for Cybersecurity, Fintech, Blockchain and/or Crypto industries.
  • [Bonus] In-depth understanding of coding languages, namely Rust, Go and/or Typescript.
  • [Bonus] Proven track record working on developer tools and/or cybersecurity software.
  • [Bonus] Hands-on experience and willingness to contribute to open source projects.
  • [Bonus] Extensive knowledge about the crypto custody industry and its use cases.


  • Title: Principal Cryptographer
  • Salary: €100-250K / year (avg base range).
  • Equity: 0.2-0.4% (≈ €5.2-10.4M in case of €2B exit).
  • Location: Hybrid. You can either work in our offices, from home, or remote.
  • Paid time off: No less than 30 days per year, plus national holidays.
  • Employee benefits: Healthcare, life insurance, retirement plan, sponsored transportation, gym cards, food, Apple devices and home office equipment, tuition fee assistance, team retreats, and more.

Company: Dfns

Website: http://www.dfns.co/

Skills: rustdefiblockchaincrypto

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