Senior C++ Engineer, Key Management

The KMS team sits at the very heart of Fireblocks’ platform and is a pivotal team in the company.

The team is responsible for the cryptographic backbone of the platform that secures customers’ most sensitive secrets. Every transaction signing flow. Every cosigner interaction. Every key generation ceremony. Every backup and recovery mechanism. If it touches a private key - it touches this team.

The team performs mission-critical engineering at high scale, working on systems where failure is not an option, security is existential, performance matters and correctness is everything. The work is deep, challenging, and intellectually demanding - blending modern C++ systems programming with distributed backend architecture and applied cryptography.

You’ll collaborate with backend engineers, infrastructure teams and security and cryptography researchers to ship production-grade highly secure digital signing systems, balancing cryptographic rigor, performance constraints, and distributed reliability in a domain where small mistakes have massive consequences. This includes:

• →Architecting, designing and implementing distributed backend services responsible for key generation, storage and lifecycle management
• →Developing high-assurance signing protocols and signing flows (utilizing MPC or external signing devices)
• →Building easy to use, secure backup and disaster recovery mechanisms for cryptographic material
• →Hardening systems against adversarial conditions and real-world attack vectors
• →Optimizing performance-critical components that execute complex operations
• →Providing visible value to customers by constant product optimisation
• →Winning new customers with industry leading flexible deployments

• 5+ years of strong C++ experience in production systems
• 3+ years of experience in any other high-level programming language
• Experience working inside an Agile R&D organization that delivers value fast
• Experience building large-scale backend or distributed systems (SaaS experience strongly preferred)
• Hands-on experience working with AI tools and the ability to effectively prompt, integrate, and build workflows around AI assistants
• Critical AI judgment: the ability to challenge, validate, and override AI-generated output especially in security-sensitive or correctness-critical contexts
• Experience working with SQL DBs
• Experience working with cloud and backend technologies (e.g. Docker, K8S, AWS, Azure, DataDog, Prometheus)
• Deep understanding of concurrency, memory management, system design, and performance optimization
• Experience working on mission-critical or high-reliability platforms
• A strong security engineering mindset
• Proven capability to understand and take part in novel research: either in industry or by having any scientific academic degrees  

• Familiarity with the blockchain ecosystem
• Familiarity with product components hosted on-premise 
• Experience integrating with HSMs or Trusted Execution Environments (confidential computing) 
• Background in either highly security-sensitive environments, Kernel development or cyber-security