Hardware Wallet Firmware Developer

Summary

Join Blockstream, a leading Bitcoin technology company, as an Embedded C Developer to build and maintain firmware for a Bitcoin hardware wallet. You will work on a security-critical embedded platform, integrating cryptographic functionality with low-level drivers and secure communication interfaces. Responsibilities include developing, testing, and maintaining firmware using C on embedded systems, working with low-level hardware interfaces, implementing secure communication protocols and key management, and collaborating with the testing team. You will participate in design and security reviews and ensure compatibility of dependencies. Close collaboration with Bitcoin protocol engineers is also required to ensure accurate and secure implementation of core functionality. This role demands significant experience in C development, embedded systems, and embedded communication protocols.

Requirements

• 5+ years of C development experience, including direct interaction with memory and registers
• 5+ years of experience on embedded systems (bare metal or RTOS)
• Strong understanding of embedded communication protocols (I2C, SPI, Serial)
• Experience writing or debugging BLE integrations
• Experience developing and testing over serial and BLE interfaces across desktop and mobile platforms
• Experience with low level/embedded GUI development
• Experience with multithreading/thread safety/locking

Responsibilities

• Develop, test, and maintain firmware for a Bitcoin hardware wallet using C on embedded systems
• Work with low-level hardware interfaces: I2C, SPI, UART/Serial, DMA, and BLE, USB Host/Guest
• Implement and optimize secure communication protocols and key management
• As applicable, develop for and collaborate with the testing team to ensure the device works reliably over BLE and USB serial on Windows, macOS, Linux, Android, and iOS
• Participate in design and security reviews of firmware components
• Keep dependencies and submodules up to date and compatible
• Work closely with Bitcoin protocol engineers to ensure accurate, secure implementation of core functionality

Preferred Qualifications

• Experience with esp-idf on the ESP32 series platform
• Experience in Bitcoin protocol development or applications
• Familiarity with Liquid/Elements sidechains
• Security background: familiarity with cryptography (DH, symmetric/asymmetric encryption, digital signatures, etc), HSMs, secure key storage, and threat models
• Experience working with DMA-driven data pipelines
• Contributions to Bitcoin Core, Elements, or similar open-source projects