Senior/Staff Security Engineer

About Sandbar

About
We’re looking for a senior or staff backend engineer with deep security expertise to help build Stream, a new conversational interface. Stream is a self extension that people use to expand their own thinking. We believe thoughts belong only to you and must be private.

You’ll own the backend systems that make that privacy real: how user data is encrypted, how keys are managed, how services and people authenticate to our infrastructure, and how we detect and respond to problems. You’ll define security at Sandbar, working inside a small backend team on a live production service rather than in a separate security function.

Responsibilities

• Design and ship end-to-end encryption for user data, including key management and keeping search and background processing working on encrypted data
• Build confidential-computing infrastructure so sensitive processing is isolated and verifiable, including attestation and reproducible builds
• Own identity and secrets across the stack: short-lived workload credentials, least-privilege service identities, environment isolation, and auditable privileged access
• Own supply chain and CI/CD security
• Build the detection and response loop: audit logging, alerting, runbooks, and post-incident reviews that end in engineering changes rather than documents
• Drive vendor and data-handling security: AI provider data agreements, third-party integration and OAuth scope review, and data retention and deletion
• Lead compliance work (e.g. SOC 2) from the engineering side, with controls enforced by systems and evidence produced automatically
• Carry a share of the core backend: build product features on the real-time Python services you secure, and review the team’s changes with a security eye
• Set direction on secure engineering practice through design reviews, threat models, and clear, minimal guidance that engineers actually follow

Qualifications

• 7+ years building and operating backend systems, with meaningful time as the engineer accountable for security on a production service
• Strong Python and comfort owning a live, real-time service end to end
• Hands-on applied cryptography: envelope encryption, authenticated encryption, key hierarchies, and the practical mistakes that break otherwise-correct designs
• Deep cloud security experience on AWS and/or GCP: IAM, workload identity federation, KMS, secrets management, audit logging
• Experience leading incident response on a production service, from containment through follow-up hardening
• Experience with confidential computing or attestation (e.g. Nitro Enclaves, SEV-SNP, TDX, App Attest) strongly preferred
• Comfortable with document stores and their access-control models
• Able to make tradeoffs explicitly and ship: you know the difference between a control that gates a launch and one that can follow
• Communicate precisely with engineers, founders, auditors, and vendors

Nice to have

• iOS security primitives (Secure Enclave, Keychain)
• Bluetooth LE device security, firmware signing, or secure pairing
• Experience with retrieval systems or LLM infrastructure and their data-flow controls
• SOC 2 or ISO 27001 audit experience from the engineering side