Staff Security Engineer - Calix Cloud

The Calix platform enables Communication Service Providers (CSPs) of all sizes to transform and future-proof their businesses. Through real-time data, automation, and actionable insights delivered via Calix One — our cloud-first, AI-powered platform — CSPs can simplify operations, collapse cost, and accelerate innovation. Calix One brings together the automation of everything and the experience of one, empowering customers to deliver differentiated subscriber experiences while driving acquisition, loyalty, and revenue growth. This is the Calix mission: to enable CSPs of all sizes to simplify, innovate, and grow, strengthening both their businesses and the communities they serve.

We’re at the forefront of a once in a generational change in the broadband industry. Join us as we innovate, help our customers reach their potential, and connect underserved communities with unrivaled digital experiences.

Calix is where passionate innovators come together with a shared mission: to reimagine broadband experiences and empower communities like never before. As a true pioneer in broadband technology, we ignite transformation by equipping service providers of all sizes with an unrivaled platform, state-of-the-art cloud technologies, and AI-driven solutions that redefine what’s possible. Every tool and breakthrough we offer is designed to simplify operations and unlock extraordinary subscriber experiences through innovation.

We’re looking for a Staff Security Engineer to define and strengthen the trust architecture connecting our devices, customers, and cloud platform. In this highly influential, hands-on role, you’ll serve as a senior technical authority across device identity, PKI, cloud and workload identity, secure device-to-cloud communications, and embedded security. You’ll partner across device, network, mobile, and cloud engineering teams to design resilient security architecture, pressure-test it through threat modeling and offensive testing, and drive solutions from design through production.

What you'll do

• Design and run our PKI on GCP: offline root, HSM-backed issuing CAs in Certificate Authority Service, certificate profiles, and key ceremonies.
• Define device identity: unique keys in a secure element or TPM, factory provisioning, field enrollment (for example EST), rotation, revocation, and a tested plan for CA key compromise.
• Architect workforce, workload and customer identity: SSO and Workforce Identity Federation, Workload Identity Federation instead of service account keys, and OAuth 2.0 and OIDC flows for apps and devices.
• Secure the path from device to cloud: mutual TLS, per-device authorization, and protection against replay, cloned devices and fleet-wide denial of service.
• Own security of the ingestion layer on GCP (self-operated MQTT brokers and gateways on GKE feeding Pub/Sub, Dataflow and BigQuery), since Cloud IoT Core was retired in 2023.
• Secure remote commands and over-the-air updates so a compromised cloud account cannot push malicious firmware to the fleet.
• Set on-device requirements: secure boot, signed and rollback-protected firmware, encrypted storage, locked debug ports, and a hardened OS image.
• Test devices hands-on: firmware analysis, hardware and local-interface attacks (Bluetooth, Wi-Fi, USB, serial), and protocol fuzzing; secure the companion mobile apps.
• Govern the firmware supply chain: SBOMs, vulnerability management, signing-key custody, and manufacturer and silicon-vendor assessments.
• Build threat models for the full device, app, gateway and cloud system (STRIDE, attack trees, MITRE ATT&CK), and run pentests, red-team and purple-team exercises.
• Set GCP guardrails: organization policy, VPC Service Controls, IAM, Cloud KMS, GKE hardening, Binary Authorization, and secure CI/CD and data pipelines (BigQuery, Dataflow, Datastream, Kafka).
• Map controls to ISO 27001, SOC 2, NIST CSF, CIS Controls, ETSI EN 303 645, NIST IR 8259, GSMA baseline controls and FCC CPNI rules.
• Be the escalation point for hard security decisions and incidents, mentor senior engineers, and brief executives.

Required qualifications

• BS or MS in computer science, information security or cryptography, or equivalent experience.
• 10+ years in security engineering, with deep ownership of at least two of: PKI, identity and access, device security, or cloud security architecture.
• PKI depth: X.509 profiles, CA hierarchy design, HSM and key management, certificate lifecycle automation, revocation at scale, and protocols such as EST, SCEP and ACME. Experience with GCP Certificate Authority Service or a comparable managed CA.
• Identity depth: OAuth 2.0, OIDC, SAML, SSO and federation; running or integrating an enterprise IdP; designing token and session security for apps and devices.
• Strong GCP security experience: IAM, Workload Identity Federation, Cloud KMS, VPC Service Controls, GKE and container security, Security Command Center, and securing data pipelines (BigQuery, Dataflow, Datastream, Kafka).
• Applied knowledge of secure device-to-cloud communication: mutual TLS, MQTT and gRPC security, broker and gateway hardening, and OTA update integrity.
• Hands-on device and embedded security skills: secure boot, TPM or secure element use, firmware analysis, hardware debug interfaces, and mobile app security on Android and iOS.
• Hands-on offensive skills and the ability to threat-model a full device-to-cloud system; you write tooling in Python, Go or similar.
• Experience with CI/CD and DevSecOps security, and with ISO 27001, SOC 2, NIST CSF and CIS Controls.
• A record of influencing architecture across multiple teams, with clear writing and briefing skills.

Why Join Us?

• Be part of a team driving AI innovation in telecom and cloud solutions.
• Opportunity to work on cutting-edge projects impacting millions of users.
• Collaborative culture with continuous learning and growth.
• Competitive Benefits and Vacation package.

#LI-Remote

The base pay range for this position varies based on the geographic location. More information about the pay range specific to candidate location and other factors will be shared during the recruitment process. Individual pay is determined based on location of residence and multiple factors, including job-related knowledge, skills and experience.

San Francisco Bay Area:

156,400 - 265,700 USD Annual136,000 - 231,000 USD Annual