Hi, I'm
Jonathan Lo [he • him]
Software Engineer
Security
I build cryptographic infrastructure at Apple — PKI systems, X.509 certificate pipelines, and the encryption and signing services that protect sensitive data across Apple's platforms.
// about
What I focus on
Cryptography & PKI
From X.509 certificate issuance at scale to encryption and signing primitives, I work across the full lifecycle of cryptographic services Apple's platforms depend on.
Key Management
Designing secure key derivation and lifecycle systems — including hardware-backed storage with the Secure Enclave — so keys are generated, used, and retired safely.
Post-Quantum Readiness
Evaluating NIST post-quantum standards like ML-KEM for integration into existing cryptographic stacks, before quantum threats become practical.
Misuse-Resistant APIs
Security should be the path of least resistance. I design interfaces that make the right thing easy and the wrong thing hard — for services and developer-facing SDKs alike.
// experience
Places I've Worked
// skills
Technologies & tools
Languages
Cryptography
Identity & Auth
Platforms
Frameworks
Tools & Infrastructure
// projects
Areas of focus
Certificate Infrastructure at Scale
Part of the team behind Apple's PKI systems — including the pipeline that issues hundreds of thousands of SSL/TLS X.509 certificates every week, spanning lifecycle management, validation, and backend reliability.
Encryption & Signing Services
Contributed to the cryptographic services layer responsible for encryption and signing operations protecting sensitive data across Apple. Focus on correctness, auditability, and misuse-resistant abstractions.
Secure Key Management
Design and implementation of key derivation and lifecycle primitives, including hardware-backed storage integrated with the Secure Enclave for tamper-resistant guarantees on Apple devices.
Post-Quantum Readiness
Evaluating NIST post-quantum algorithms — including ML-KEM — for integration into Apple's cryptographic stack, with a focus on performance, migration strategies, and hybrid transition paths.
// education & certifications
Background
// contact
Get in touch
Interested in cryptography, security engineering, or open source? I'm always happy to connect.
// you found something