Software Engineer - Wallets

• • Design secure, scalable systems for custody, key management, transaction signing, authorization, and recovery
• • Design flexible signing infrastructure supporting MPC, HSMs, secure enclaves, TEEs, and emerging cryptographic approaches
• • Build and evolve wallet systems across EOAs, smart contract wallets, account abstraction, ERC-4337, embedded wallets, and multichain infrastructure
• • Define boundaries between cryptography and wallet orchestration, including keys, signing authority, transaction policies, permissions, and authorization
• • Architect key management systems covering key generation, distributed key generation, storage, rotation, backup, recovery, and hardware-backed isolation
• • Build highly available signing and transaction infrastructure controlling high-value customer assets while maintaining developer-friendly APIs
• • Set technical direction for wallet security, including threat modeling, policy engines, secrets management, account recovery, authentication, and programmable authorization
• • Make build-versus-buy decisions across cryptography, custody, wallet, and security infrastructure
• • Ensure the architecture evolves alongside new blockchain standards and cryptographic techniques
• • Collaborate within Rain’s open, flat Engineering organization and influence the product roadmap and company vision

• Deep expertise in one or more areas of wallet, custody, cryptography, or security infrastructure
• Strong distributed systems and architecture fundamentals
• Experience designing or building production wallet, custody, signing, or key management systems, particularly infrastructure securing high-value assets
• Strong knowledge of applied cryptography, including MPC, threshold cryptography, threshold signatures, distributed key generation, ECDSA, EdDSA, or secure multiparty computation
• Experience with HSMs, secure enclaves, TEEs, confidential computing, hardware-backed key isolation, or other security-critical infrastructure
• Strong understanding of wallet and blockchain account architecture, including EOAs, smart contract wallets, account abstraction, ERC-4337, transaction orchestration, and multichain systems
• Experience designing authentication, authorization, policy, permissions, recovery, or secrets-management systems where security and correctness are critical
• Track record of making architectural decisions in complex distributed systems and evaluating security, reliability, developer experience, and extensibility tradeoffs
• Ability to form strong technical opinions, communicate tradeoffs clearly, and own architecture from first principles through production
• Able to work in a hybrid role and come into a NYC office 3 days a week
• Legally authorized to work in the United States for any employer without restrictions
• Four-year university graduation/degree information requested in the application form
• Experience in fintech, payments, crypto, stablecoins, or blockchain requested in the application form, Demonstrates deep expertise in wallet architecture, custody, and cryptography, with a strong focus on designing secure and scalable systems for high-value asset management. Proficient in applied cryptography and distributed systems, ensuring robust security and developer-friendly infrastructure., * Applied Cryptography
• Key Management Systems
• Distributed Systems
• Security Infrastructure, * Cryptography
• MPC
• Threshold Cryptography
• ECDSA
• EdDSA
• Key Generation
• Transaction Signing
• Authorization
• Account Abstraction
• Multichain Systems

Soft Skills

• Technical Communication
• Decision-Making
• Collaboration, * Fintech
• Payments
• Crypto
• Stablecoins
• Blockchain, * HSMs
• Secure Enclaves
• TEEs
• Confidential Computing