Cryptography and Systems Researcher

Char Network is a proof-of-stake application coordination protocol built on Bitcoin. By anchoring data into Bitcoin through cryptographic proofs and economic guarantees, Char powers the next generation of Bitcoin layer twos and applications. We’re a small, sharp, and adventurous team led by Bitcoin developer Jeremy Rubin, pushing the limits of what Bitcoin can be. Our work blends deep protocol expertise with a hacker’s creativity to unlock new capabilities for Bitcoin at scale. We keep things collaborative, fast-moving, and fun—where every contribution counts and every voice matters. Joining Char means working at the frontier of Bitcoin R&D and infrastructure.

### What You’ll Do - Design and analyze cryptographic schemes: BLS proof-of-stake commitments, signature aggregation protocols, hash-based accumulator designs, and zero-knowledge proof systems for Bitcoin anchoring. - Formalize consensus protocols for protocol security: fork-free properties, Byzantine fault tolerance guarantees, and commitment finality, with rigorous threat modeling and adversarial analysis. - Develop and validate cryptographic implementations: work with the protocol team to guide BLS Purify integration, verify protocol specifications against implementation, and conduct security reviews. - Build simulations and prototypes in Rust or C++ to validate cryptographic protocol designs under adversarial conditions: analyze safety/liveness properties and attack resilience. - Conduct formal cryptographic security analysis: threat modeling, game-theoretic attack analysis, and stress-testing through simulation and fuzzing to identify vulnerabilities before shipping.

### What We’re Looking For #### Must-Haves - Deep expertise in applied cryptography: signature schemes, commitment schemes, zero-knowledge proofs, or cryptographic protocol design. - Expert-level understanding of distributed systems theory: BFT consensus, fork-free protocols, Byzantine fault tolerance, and formal safety/liveness analysis. - Strong programming skills in Rust or C++ (or equivalent systems languages). - Experience designing, analyzing, or breaking adversarial cryptographic protocols or consensus systems. - Ability to move between theory and practice: formal reasoning, mathematical modeling, and implementation. - Exceptional communication skills—you can explain complex cryptographic ideas clearly to both researchers and engineers. #### Nice-to-Haves - PhD or equivalent research experience in cryptography, distributed systems, or a related field. - Prior contributions to Bitcoin, Ethereum, or other consensus-critical software. - Experience with formal verification, model checking, or advanced testing frameworks. - Published papers, technical reports, or BIPs in cryptography or distributed systems. - Understanding of Bitcoin primitives: taproot, timelocks, covenant designs, transaction scripting. - Experience with game-theoretic analysis or mechanism design (helpful for understanding protocol incentives). - Strong open-source collaboration background.

Char Network is a proof-of-stake application coordination protocol built on Bitcoin that enables rollups and applications to coordinate outcomes on Bitcoin without changing Bitcoin's rules. It uses attestation chains and bonded consensus to serve as a Layer 2 solution for Bitcoin, improving security and functionality for BitVM ecosystems.