OSHI Guides — Privacy & Encryption, Explained
Welcome to the OSHI privacy & cryptography guides — plain-English explainers of the technologies that make secure, private, censorship-resistant messaging possible. Each guide defines a concept clearly, explains how it actually works, and shows where it fits in a real encrypted messenger.
These pages are educational first. We describe each technology on its own terms, then include a short, honest note on how OSHI uses it. You do not need OSHI to learn from them — but if privacy matters to you, OSHI is a free, open-source, Swiss messenger built on exactly these ideas.
Encryption & protocols
End-to-End Encryption
What E2EE means, how it differs from encryption in transit, and why only the sender and recipient can read the message.
ProtocolThe Signal Protocol
The open cryptographic protocol behind modern secure messaging: X3DH key agreement plus the Double Ratchet.
AlgorithmThe Double Ratchet
How a DH ratchet and a symmetric-key ratchet combine to give forward secrecy and post-compromise security.
CipherAES-256
The 256-bit Advanced Encryption Standard, GCM authenticated encryption, and why it is trusted worldwide.
PropertyPerfect Forward Secrecy
Why a stolen long-term key should never unlock your past conversations.
Privacy & metadata
What Is Metadata?
The data about your messages — who, when, how often — and why it can reveal as much as the content.
PrivacyAnonymous Messaging
What anonymity really requires, from no phone number to metadata resistance and network anonymity.
CovertSteganography
Hiding the existence of a message, not just its contents — and how it differs from encryption.
Networks & transport
Mesh Networking
How devices relay for each other to form a resilient, infrastructure-free network.
NetworkBluetooth Mesh
Messaging over Bluetooth Low Energy when there is no Wi-Fi, no cell service, and no internet.
AnonymityWhat Is Tor?
Onion routing: how layered encryption across volunteer relays hides who is talking to whom.
StorageWhat Is IPFS?
Content-addressed storage where a file's address is a hash of the file itself.
Frequently Asked Questions
What are these OSHI guides?
They are free, educational explainers of the encryption, privacy, and networking technologies used in secure messaging. Each guide defines the concept, explains how it works, and honestly notes how OSHI applies it.
Do I need to install OSHI to read them?
No. The guides are written to be useful on their own. OSHI is a free, open-source, Swiss encrypted messenger for iOS and Android that you can optionally install.
Is OSHI really open source?
Yes. OSHI is released under the MIT license and its source code is public on GitHub, so anyone can audit how it implements the technologies described here.
Private messaging, by design
OSHI is a free, open-source, Swiss encrypted messenger. No phone number, no ads, no tracking.