Security Auditor

Common Prefix is seeking a full-time Security Auditor.

Common Prefix is a blockchain research & development company. Blockchain technologies enable large-scale economic coordination through shared, programmable ledgers. Our mission is to solve the foundational scientific and engineering challenges standing in the way of mainstream adoption, particularly around interoperability, scalability, and usability.

We combine formal scientific research with production-grade engineering. Our team publishes in top-tier peer-reviewed venues and builds open-source infrastructure used across major blockchain ecosystems. We have contributed to advanced systems including Axelar, XRPL, Sui, and Flashbots, and are trusted partners to protocols building critical infrastructure.

Description

This is a full-time position for a Security Auditor with a strong background in blockchain systems, smart contracts, and cryptographic protocols.

You will work on security reviews and audits of production blockchain protocols and implementations used by our partners. You will reason about protocol security using adversarial models, cryptographic assumptions, and formal arguments, and connect these analyses to concrete implementations. Your work will directly impact the safety of systems securing and moving real economic value. This role combines protocol-level reasoning, cryptographic analysis, and rigorous security review, together with clear written and verbal communication.

You will join a team of security researchers, cryptographers, and engineers performing protocol-level and cryptographic audits, often in close collaboration with clients. The role involves both independent technical work and direct interaction with partners to explain findings, risks, and recommended mitigations.

Responsibilities

In this role, you will work across the following areas:

• Blockchain and cryptographic protocol security audits
  • Perform security audits of blockchain systems, including cryptographic constructions, consensus mechanisms, and smart contract logic
  • Review implementations for correctness, soundness, and adherence to specifications
  • Identify vulnerabilities arising from protocol design, cryptographic misuse, or implementation errors
  • Assess threat models and identify attack surfaces
  • Produce clear, actionable audit reports with concrete recommendations
  • Stay current with developments in blockchain systems, cryptography, and security research
• Collaboration and communication
  • Work closely with internal researchers and engineers to validate findings and assumptions
  • Communicate audit results to partners, both in writing and in technical discussions
  • Explain security issues and trade-offs to both technical and non-technical stakeholders
  • After onboarding, take ownership of audits or workstreams to ensure timely and high-quality delivery
• Technical growth and knowledge sharing
  • Engage with internal research discussions, lectures, and paper reviews as relevant
  • Share practical engineering insights with researchers to keep analyses grounded in real systems
  • Contribute to internal security tooling, methodologies, or documentation over time

Requirements

The requirements for this position are:

• Adversarial mindset and strong fundamentals in computer science and systems security
• Ability to reason about protocol security using cryptographic assumptions, threat models, and formal or semi-formal arguments
• Experience auditing, reviewing, or building blockchain protocols or smart contracts
• Familiarity with one or more blockchain ecosystems (e.g. Ethereum, Cosmos, Bitcoin, Sui)
• Proficiency in at least one relevant language (e.g. Solidity, Rust, Go)
• Familiarity with high-quality technical sources such as EIPs
• Hands-on experience with smart contract design patterns and best practices for blockchain security
• Strong attention to detail and structured analytical thinking
• Ability to work independently and collaboratively
• Professional proficiency in spoken and written English

The following skills are appreciated but not required:

• Formal education in computer science, mathematics, or a related field
• Background in cryptography or distributed systems theory
• Prior experience performing professional security audits
• Experience with Layer 2s, rollups, and DeFi protocols
• Participation in CTFs, bug bounty programs, or security competitions
• Open-source security research or tooling contributions

What we offer

• Base compensation ranges from $76,000 to $171,000 per year before tax, depending on experience and scope of responsibility, and is not adjusted by location
• Equity grants and performance-based bonuses in addition to base compensation
• Unlimited vacations (typically ~30 days per year including public holidays), with appropriate planning
• Fully remote work, or the option to work from our offices in Athens, Greece
• Optional work travel to conferences and partner locations 2–3 times per year
• Direct involvement in high-impact audits of real-world blockchain systems
• Collaboration with experienced researchers and engineers in cryptography and distributed systems
• Significant open-source and research-facing work
• A small, senior team that values rigor, clarity, and responsible security work
• A collaborative, low-ego culture with a strong emphasis on correctness and trust