About SandbarSandbar is an interface company in New York City. We aim to augment individuals so we can each think, act, and move more freely. Our team has built SW, ML, and HW products across Meta, CTRL-labs, Google, Apple, Fitbit, Peloton, and Equinox.Our first product, Stream, is a self extension—a private voice ring and conversational interface. Stream has been featured in WSJ, Bloomberg, & Wired, and begins shipping in Summer '26.Join us in creating technology that extends human thinking. AboutWe’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.ResponsibilitiesDesign and ship end-to-end encryption for user data, including key management and keeping search and background processing working on encrypted dataBuild confidential-computing infrastructure so sensitive processing is isolated and verifiable, including attestation and reproducible buildsOwn identity and secrets across the stack: short-lived workload credentials, least-privilege service identities, environment isolation, and auditable privileged accessOwn supply chain and CI/CD securityBuild the detection and response loop: audit logging, alerting, runbooks, and post-incident reviews that end in engineering changes rather than documentsDrive vendor and data-handling security: AI provider data agreements, third-party integration and OAuth scope review, and data retention and deletionLead compliance work (e.g. SOC 2) from the engineering side, with controls enforced by systems and evidence produced automaticallyCarry 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 eyeSet direction on secure engineering practice through design reviews, threat models, and clear, minimal guidance that engineers actually followQualifications7+ years building and operating backend systems, with meaningful time as the engineer accountable for security on a production serviceStrong Python and comfort owning a live, real-time service end to endHands-on applied cryptography: envelope encryption, authenticated encryption, key hierarchies, and the practical mistakes that break otherwise-correct designsDeep cloud security experience on AWS and/or GCP: IAM, workload identity federation, KMS, secrets management, audit loggingExperience leading incident response on a production service, from containment through follow-up hardeningExperience with confidential computing or attestation (e.g. Nitro Enclaves, SEV-SNP, TDX, App Attest) strongly preferredComfortable with document stores and their access-control modelsAble to make tradeoffs explicitly and ship: you know the difference between a control that gates a launch and one that can followCommunicate precisely with engineers, founders, auditors, and vendorsNice to haveiOS security primitives (Secure Enclave, Keychain)Bluetooth LE device security, firmware signing, or secure pairingExperience with retrieval systems or LLM infrastructure and their data-flow controlsSOC 2 or ISO 27001 audit experience from the engineering sideFTE BenefitsHealth, vision, and dental benefitsCompany-sponsored 401(k)Unlimited PTO and sick timeEarly stage equity