Rust Senior Engineer - Cryptographer

The Team

Founded in 2020, Synonym is preparing for the post‑Bitcoin economy by designing and developing an ecosystem of products and protocols that includes Pubky, Bitkit, Blocktank and now Atomicity. Synonym empowers individuals to take control and ownership of their digital lives. We are committed to the principles of digital autonomy, privacy, and open‑source technology.

Synonym is an entirely remote team working to bring new integrated products to open source protocols and cutting‑edge peer‑to‑peer technology.

We are seeking a Senior Rust Engineer with a strong cryptography background to join our team and contribute to the implementation of Atomicity
, our open protocol for peer‑to‑peer mutual credit issuance, settlement, and routing of trusted payments.

Atomicity is currently in the research and design phase. It combines several Synonym primitives (Pkarr for key‑based identity, Pubky Core for the semantic social graph) with an Offset‑like mutual credit model. The goal is to enable web‑of‑trust based credit channels where users can issue, transfer, route, and settle debts in any denomination, with Bitcoin as the underlying settlement rails.

This position is for an engineer who is equally comfortable reading a cryptography paper, writing a clean Rust implementation of it, and reasoning about how it composes with the rest of the system.

• Contract type: Full‑time
• Location: Remote only
• Salary: Based on experience, be prepared to communicate your requirements

• Cryptographic Design: Design and document the cryptographic primitives behind Atomicity, including credit note formats, signature schemes, hash chains, commitment schemes, and key binding to Pkarr identities.
• Design & Development: Architect, develop, and maintain robust Rust‑based solutions for our core products and protocols.
• Integration: Work with the rest of the Atomicity team to wire the cryptographic layer into the routing, settlement, and identity components, and with the wider Synonym stack (Pubky Core, Bitkit, Paykit).
• Innovation: Stay informed about emerging libraries, and industry trends; proactively suggest and implement improvements or new approaches.
• Security & Reliability: Work closely to protect user data and maintain system integrity.

• Specifications: Comfortable reading RFCs and academic papers, and writing precise, implementable specifications.
• Problem‑Solving Mindset: Ability to break down complex challenges into manageable tasks and deliver scalable solutions.
• Expertise in Rust: Proven experience building production‑grade applications or systems in Rust.
• Systems Programming: Comfortable working with low‑level systems, concurrency, and performance optimization.
• Collaboration: Strong communication skills and the ability to work effectively in a fully remote team setting.
• AI‑Assisted Engineering: Comfortable using LLM‑based coding tools in daily workflow. Ability to critically evaluate AI‑generated code for correctness, security, and performance.

• Server Protection: Experience building secure systems, protecting servers from potential threats, and designing robust access controls.
• Decentralized / P2P Systems: Exposure to peer‑to‑peer architectures and protocols.
• Blockchain / Bitcoin: Experience with Bitcoin or other blockchain technologies.
• Security Auditing: Prior experience auditing cryptographic code or coordinating external audits.

• Impactful Work: Play a key role in shaping next‑generation technologies that empower individuals and communities.
• Growth & Ownership: Enjoy the flexibility to define your role, innovate, and lead initiatives.
• Cutting‑Edge Environment: Collaborate with a forward‑thinking, decentralized team working on Bitcoin and peer‑to‑peer ecosystems.
• Remote Culture: Work from anywhere with flexible hours. We prioritize productivity and well‑being.
• Time Off: 28 vacation days per year.