About OSHI — Swiss-Engineered Privacy for Everyone

OSHI is a free, open-source encrypted messenger developed in Switzerland and designed from the ground up to provide the most comprehensive privacy protection available in any communication application. In a world where digital surveillance has become pervasive and personal data has become the most traded commodity, OSHI exists to give individuals back control over their communications.

Our Mission

OSHI was created with a single, unwavering mission: to build a communication tool that makes truly private messaging accessible to everyone, regardless of their technical expertise, financial resources, or geographic location. Privacy is not a luxury. It is a fundamental human right recognized by the Universal Declaration of Human Rights (Article 12), the European Convention on Human Rights (Article 8), and the constitutions of democratic nations worldwide.

We believe that the current landscape of messaging applications has fundamentally failed users. Even applications that claim to offer end-to-end encryption still collect metadata, require phone numbers for registration, store messages on central servers, and cooperate with surveillance requests. OSHI is built to need as little of that as possible. We require no phone number and no account. Messages sent over the local mesh involve no server whatsoever. When a message has to travel further, it goes through a relay we run ourselves, which can see the sender and recipient public keys, the timestamp and the message size, but never the contents. We would rather state that plainly than claim we collect nothing.

The Swiss Privacy Advantage

Switzerland has a centuries-long tradition of protecting individual privacy and neutrality. Swiss privacy law is among the strictest in the world, providing protections that go significantly beyond even the European Union GDPR. The Swiss Federal Act on Data Protection (FADP), revised in 2023, establishes rigorous requirements for data processing and grants individuals extensive rights over their personal information.

Being developed in Switzerland means OSHI benefits from this legal framework and cultural commitment to privacy. Switzerland is not part of the European Union and is not a member of the Five Eyes, Nine Eyes, or Fourteen Eyes intelligence-sharing alliances. This independence from multinational surveillance agreements provides an additional layer of protection for OSHI users and development practices.

Switzerland is also home to CERN (where the World Wide Web was invented), ETH Zurich (one of the world-leading technical universities), and a thriving ecosystem of privacy-focused technology companies. This environment of technical excellence and privacy commitment is the foundation on which OSHI is built.

Open Source Philosophy

OSHI is fully open source under the MIT license. Every line of code that runs on your device is publicly available for inspection, audit, and contribution on GitHub. This is not a marketing decision; it is a fundamental architectural principle.

We believe that security through obscurity is no security at all. Any encryption system, privacy feature, or security mechanism that relies on keeping its implementation secret is inherently fragile. True security comes from implementations that remain secure even when every detail of their operation is publicly known. This is the Kerckhoffs principle, established in 1883 and still the foundation of modern cryptography.

By making OSHI open source, we invite the global security research community to examine our code, identify vulnerabilities, and verify that our privacy claims are technically accurate. You do not need to trust our promises; you can verify our implementation directly.

Preparing for Quantum Attack

On iOS 26 and macOS 26, and only when both people in a conversation run a build that supports it, OSHI negotiates X-Wing — ML-KEM-768 combined with X25519 — for its key exchange. This is worth stating precisely rather than loudly: the app's deployment target is iOS 17.5, so devices below iOS 26 continue to use the classical X25519 exchange, and the upgrade is negotiated per conversation under a hybrid-when-available policy.

The threat this addresses is harvest-now-decrypt-later. An adversary with the means to record encrypted traffic does not need to break it today. They can store it indefinitely and decrypt it years from now, once a quantum computer capable of defeating elliptic-curve cryptography exists. Under that model, a conversation you have this evening is only as safe as the key exchange that protected it, judged against machines that have not been built yet.

Our implementation is hybrid and never post-quantum alone. The session secret depends on both the ML-KEM-768 and the X25519 components, which means a future cryptanalytic break of ML-KEM cannot leave a session weaker than plain X25519 would have been. Where the hybrid exchange cannot be completed, it fails closed rather than silently degrading to something weaker. The code is in OSHI/PostQuantumKEM.swift and is open to inspection like the rest of the app.

Vision for the Future

OSHI is more than a messaging application. It is a statement that private communication is possible, practical, and necessary. Our vision extends beyond individual privacy to encompass the broader goal of ensuring that free, uncensored communication remains available to everyone on the planet, regardless of the political environment they live in.

We are continuously developing new privacy features, expanding platform support, and strengthening our security architecture. Every feature we build follows the same principles: maximum privacy, minimum trust requirements, and zero compromises on user data protection.

The future we are building is one where sending a private message is as natural and reliable as sending a letter in a sealed envelope, regardless of whether you have internet access, whether your government approves of your communication, or whether any particular server or network is operational. OSHI mesh networking, its optional disguised relay transport, and multiple delivery paths are steps toward that future.