Summary At Apple, privacy and security aren't features - they're foundational principles. As a Senior Security Software Engineer on our iCloud Security team within Apple Services Engineering (ASE), you'll be part of a small, elite group of engineers building and protecting the infrastructure that hundreds of millions of people trust with their most personal data every single day. If you have a passion for systems‑level security software and want your work to matter at a scale very few engineers ever experience, we'd love to talk. Description This isn't security work on the margins. You'll be working deep in the stack - interfacing directly with low-level Linux kernel primitives, designing security architecture that operates at global scale, and making critical technical decisions that shape how iCloud protects its users worldwide. You're part of a highly skilled team within Apple Services Engineering that provides foundational security infrastructure underpinning consumer‑facing iCloud applications and services. The performance and correctness of the systems we build are paramount. We work directly with low-level Linux kernel interfaces, leveraging asynchronous I/O and multithreaded architecture to build high‑throughput, low‑latency secure services. In this role, you will not only execute on technical deliverables but serve as a key contributor to the architectural and strategic decisions that define the team's direction. Responsibilities Architect, develop, and own security‑critical systems software underpinning iCloud services used by hundreds of millions of users worldwide Design and implement token‑based authentication and authorization systems with a focus on correctness, performance, and resilience Work directly with low‑level Linux kernel interfaces using asynchronous I/O and multithreaded design patterns to build high‑throughput secure services Lead security design reviews and drive a culture of security excellence across Apple Services Engineering Partner with cross‑functional teams across Apple to identify security risks and deliver solutions that raise the bar for the entire platform Drive key technical and architectural decisions that influence the team's long‑term strategic direction Minimum Qualifications BS in Computer Science and/or equivalent experience 10+ years of industry experience in systems software engineering Deep proficiency in C and/or C++ – writing systems‑level code, not just calling libraries Strong networking fundamentals including TCP/IP, TLS, and protocol design Demonstrated expertise with Unix/Linux internals and operating system concepts Solid understanding of software security primitives including cryptography, authentication protocols, and secure coding practices Familiarity with distributed systems design principles and token‑based architecture Strong written and verbal communication skills with the ability to convey complex security concepts to diverse audiences Preferred Qualifications Hands‑on experience designing or implementing token‑based authentication systems such as OAuth, JWT, macaroons, or proprietary token frameworks Experience with modern security technologies including HSMs, PKI, secrets management, or secure enclaves Familiarity with additional systems languages including Go, Rust, Swift, or Java Background in cloud services security, identity and access management (IAM), or internet‑scale security infrastructure Experience building and operating security systems at large‑scale production environments Apple is an equal opportunity employer that is committed to inclusion and diversity. Apple provides reasonable accommodations to applicants with disabilities. Apple is a drug‑free workplace. #J-18808-Ljbffr