Senior Certificate Authority Architect

Job Overview

We are seeking a Senior Certificate Authority Architect to help define the systems, protocols, and security architecture behind Cloudflare's new public Certificate Authority for the Internet.

Mission

Define and guide the end-to-end architecture of Cloudflare's public Certificate Authority: a high-assurance, highly available system capable of issuing conventional publicly trusted certificates at Cloudflare scale while supporting Merkle Tree Certificates (MTCs) and the evolution toward a post-quantum Web PKI.

Key Responsibilities

• Define and maintain the end-to-end technical architecture of Cloudflare's public CA across certificate issuance, key management, transparency, revocation, renewal, and relying-party integration.
• Design root and intermediate CA trust hierarchies, signing systems, HSM integration, key ceremonies, key rotation, backup, recovery, migration, and key-compromise response.
• Architect secure, resilient, and highly available issuance services capable of operating at Internet scale and across multiple geographic and failure domains.
• Design certificate lifecycle systems around ACME, domain and IP validation, CAA, Certificate Transparency, pre-issuance linting, revocation, renewal, and large-scale certificate replacement.
• Integrate Cloudflare's MTC infrastructure, including CA logs, landmarks, cosigning or mirroring, and interactions with relying parties.
• Develop practical architectures for coexistence and migration between classical X.509 certificates and post-quantum authentication mechanisms.
• Define trust boundaries, security properties, and threat models covering key compromise, unauthorized issuance, software supply-chain compromise, operator error, malicious insiders, infrastructure failure, split views, and cryptographic migration.
• Design systems that make CA behavior observable and independently verifiable through transparency mechanisms, reproducible builds, cryptographic attestations, public operational telemetry, tamper-evident evidence, and audit controls.
• Design failure containment and recovery mechanisms that support safe certificate replacement, revocation, key rotation, and incident response without creating avoidable Internet availability failures.
• Translate CA/Browser Forum requirements, browser and operating-system root-program policies, audit criteria, and certification requirements into concrete technical and operational controls.
• Review protocols, architecture, and implementations with an adversarial mindset, identifying assumptions and failure modes that do not hold at Internet scale.
• Work closely with Cloudflare's cryptography, TLS, security, networking, infrastructure, compliance, product, and operations teams.
• Provide architectural direction, design review, and technical mentorship to engineers implementing and operating the CA platform.
• Represent Cloudflare in relevant standards and industry work, collaborating with browser vendors, root programs, researchers, auditors, CA operators, and the wider Web PKI community.

Requirements

• Substantial experience designing or operating security-critical systems, with deep expertise in at least one of: public Certificate Authorities, Web PKI, applied cryptography, TLS and Internet security protocols, Certificate Transparency, hardware-backed key management, or large-scale distributed security systems.
• Strong knowledge of certificate trust chains, issuance and validation, revocation, key lifecycle management, and the security and availability implications of CA design decisions.
• Experience defining system trust boundaries, threat models, security invariants, and failure-handling strategies.
• Ability to reason about systems in which a subtle architectural or operational mistake can affect a significant fraction of the Internet.
• Experience leading architecture across multiple engineering teams without relying solely on organizational authority.
• Strong written and verbal communication, including the ability to explain cryptographic and architectural tradeoffs to engineers, auditors, standards participants, and senior stakeholders.
• Comfort operating with substantial autonomy in an evolving technical and policy environment.

What Makes Cloudflare Special?

• Project Galileo: Since 2014, we've equipped more than 2,400 journalism and civil society organizations in 111 countries with powerful tools to defend themselves against attacks that would otherwise censor their work.
• Athenian Project: In 2017, we created the Athenian Project to ensure that state and local governments have the highest level of protection and reliability for free, so that their constituents have access to election information and voter registration.
• 1.1.1.1: We released 1.1.1.1 to help fix the foundation of the Internet by building a faster, more secure and privacy-centric public DNS resolver.

Benefits

• Competitive salary
• Opportunities for professional growth and development
• Collaborative and dynamic work environment
• Flexible work arrangements, including hybrid and remote work options
• Access to cutting-edge technologies and tools
• Recognition and rewards for outstanding performance