{"id":1573817,"url":"https://alion.io/job/threema-protocol-stack-engineer-80-100","title":"Protocol Stack Engineer (80–100%)","company":{"id":454542,"name":"Threema","domain":"threema.com","url":"https://alion.io/company/threema-2","size_band":"51-200","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Schema","truth_index":null},"role":"Industrial Engineering","role_family":"Industrial Engineering","seniority":"senior","employment_type":"full_time","work_mode":"remote","remote_scope":"stated_countries","remote_scope_basis":"board_field","remote_working_hours":null,"hiring_geo_confidence":"structured","locations":[],"countries":[],"hiring_countries":["CH"],"hiring_countries_total":1,"salary":null,"salary_estimate":{"min_usd":85000,"max_usd":190000,"period":"year","method":"global_role_cell_scaled_by_country","sample_n":3947},"experience_years_min":6,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Rust","optional":false},{"name":"Linux","optional":true},{"name":"Signal Protocol","optional":true}],"status":"live","first_seen_at":"2026-09-28T20:07:30Z","employer_posted_date":"2026-09-30","last_verified_at":"2026-10-01T22:37:26Z","board_verified":true,"closed_at":null,"days_open":3,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":3},"description":"Threema is the world’s best-selling secure messenger for both private users and businesses. Since 2012, we have been working tirelessly to ensure that our users can communicate freely without worrying about their privacy. Our growing user base includes millions of private customers and thousands of businesses and organizations from all over the world.\nWe are growing and looking for a new team member to join as a\nProtocol Stack Engineer (80-100%)\nYour Role\nThe protocols underneath all of this are what we’re hiring for. You will design, implement, and maintain the cryptographic protocols that carry every Threema message, including Ibex, our forward-secrecy protocol. Your work will be read by our own engineers and also by outside researchers, auditors, and curious users. We expect it to hold up to that.\nWhat You Will Do\nDesign new protocol features and extensions, such as multi-device sync, group messaging, and calls, and write the specifications for them\n\nImplement protocol logic in Rust and review implementations across our Android, iOS, desktop, and web clients\n\nModel threats and reason through edge cases like message reordering, device loss, malicious servers, and compromised keys\n\nWork with external security researchers and auditors, respond to findings, and ship fixes\n\nKeep backward compatibility for a large installed base while moving the protocol forward\n\nMentor other engineers and help set standards for how we write and review security-critical code\n\nWhat you bring\nAt least six years of software engineering, with several years working on network or cryptographic protocols\n\nA solid grasp of applied cryptography: you know how authenticated encryption, key exchange, forward secrecy, and post-compromise security work, and where implementations usually go wrong\n\nExperience in reading and writing protocol specifications precise enough for someone else to implement from\n\nStrong skills in at least one systems language; Rust is a plus\n\nCare about the details: in this job, a missing length check is a vulnerability\n\nNice to Have\nExperience with formal analysis tools such as Tamarin, ProVerif, or TLA+\n\nFamiliarity with the Signal protocol, MLS, or the Noise framework\n\nPublished research, CVEs, audit reports, or open-source contributions in security\n\nBackground in mobile platforms and their constraints, such as push delivery, background limits, and battery use\n\nExperience with AI Tools:\nYou’re familiar with current frontier AI models and use them as a productivity multiplier in design work as well as in coding, for example, to review specification drafts, survey recent literature, or poke holes in a protocol design\n\nWhatever tools you use, the outcome is yours; AI can draft and suggest, but the person accountable for a protocol that holds is you\n\nSoft Skills:\nStrong sense of responsibility, precise way of working\n\nYou can write a protocol specification that someone else can implement, and explain trade-offs to people who are not protocol specialists\n\nPragmatic judgment about when a design is good enough to ship and when it is not\n\nWillingness to have your own designs picked apart, and to pick apart other people’s with care\n\nGood written and spoken German and English (at least B2)\n\nWe are also happy to accept applications from people who meet many but not all of these criteria.\nWhat We Offer\nA young, motivated team with straightforward communication\n\nFlexible working hours, option to work from home up to two days per week\n\nOption to work from anywhere for two weeks per year\n\nOption to take unpaid leave\n\nYou can choose your own hardware (macOS or Linux)\n\nPublic transportation discount or parking space (electric car charging available)\n\nFree use of fitness room, including a fitness trainer once a month\n\nProfessional massage once a month\n\nInternal German or English courses\n\nA great coffee machine ;-)\n\nRegular company events and aperitifs\n\nThe good feeling of contributing to the effective protection of the privacy of millions of people\n\nPlace of work: Pfäffikon SZ (Greater Zurich Area)\nStart date: Immediately or by agreement\nHave we sparked your interest?\nWe believe that diverse teams build better products. We welcome and encourage applications from people of all backgrounds, and perspectives. Your unique experience is an asset, and we’d love to hear from you.\nApplications sent via email cannot be considered. Please use the official “Apply” button below so we don’t accidentally miss your resume in our crowded inboxes.\nFor agencies: we are filling this role directly and do not accept unsolicited candidate profiles.","description_format":"text","description_chars":4587,"description_truncated":false,"requirements":{"experience_years_min":6,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":null,"security_clearance":false,"languages":[{"language":"German","level":"Upper-Intermediate (B2)","optional":true},{"language":"English","level":"Upper-Intermediate (B2)","optional":true}]},"benefits":["Company events","Flexible schedule"],"hiring_locations":[{"name":"Switzerland","iso":"CH","kind":"country"}],"hiring_excludes":[],"relocation_offered":false,"industries":["Cybersecurity","Exhibitions","Security Compliance"],"lifecycle":[{"event":"open","at":"2026-10-01T09:06:13Z"}],"liveness":{"score":86,"band":"hot","label":"Hiring now","p_open":1,"p_active":0.86,"p_room":1,"age_days":3,"expected_fill_days":38,"reasons":["conf:3","win:early"],"computed_at":"2026-10-02T01:52:16Z"},"pay":null,"html_url":"https://alion.io/job/threema-protocol-stack-engineer-80-100","json_url":"https://alion.io/job/threema-protocol-stack-engineer-80-100.json","meta":{"generated_at":"2026-10-02T01:52:16Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","usage":{"tier":"crawler","counted_by":"address","units_charged":1,"used_today":2419,"day_limit":5000,"remaining_today":2581,"minute_limit":60,"resets_at":"2026-10-03T00:00:00Z"}}}