Hardware Wallet Firmware Developer

Blockstream was founded in 2014 by Dr. Adam Back and a group of fellow cryptographers and engineers passionate about Bitcoin and its potential to change the future of finance. Focusing on building fundamental Bitcoin infrastructure, Blockstream quickly grew into one of the leading technology power houses of the industry.

At Blockstream, we’re building solutions on Bitcoin that will disrupt the existing financial system. We imagine a world where individuals and businesses can easily access a global, permissionless system to secure their money, use it every day, and invest it or put it to work. In pursuit of our expansive vision, we’ve built a full stack of innovative products on top of the Bitcoin protocol, from layer-2 projects like Liquid and Core Lightning, to end-user software and hardware wallets like Green and Jade. Our brand stands for innovation in the Bitcoin community, and we’re growing our team to accelerate the future. 

We are seeking an experienced Embedded C Developer to help build and maintain the firmware for a Bitcoin hardware wallet. You’ll work on a security-critical embedded platform, integrating cryptographic functionality with low-level drivers and secure communication interfaces.

What You’ll Be Doing (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.

What We Look For In You (Required Qualifications):

• 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

Nice To Haves (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.