OSHI for Journalists — Reaching Sources Without a Number or a Network

OSHI does not require a phone number, email address, or account. OSHI is a free, open-source, end-to-end encrypted messenger for iOS and Android that uses Bluetooth and Wi-Fi mesh networking to send messages without Internet or cellular service.

Journalists have two problems that ordinary secure messengers solve only halfway. First, the phone number: Signal hides it now, but registration still requires one, and a source who must give a number to reach you has already left a trace. Second, the network: during a shutdown or in a censored country the encrypted app is useless if its servers are unreachable. OSHI is designed around both problems. This page sets out what it offers, and, because you will ask, what it has not yet proven.

Identity without a number

OSHI does not require a phone number, email address, or account. Your identity is a keypair created on the device. A source adds you by scanning a QR code in person, by an invite link you publish, or by pasting your public key. There is no directory, no contact-list upload, and no SMS trail at a carrier. You can print your OSHI QR code on a business card the way people used to print PGP fingerprints, and it works even if the source's phone has no SIM.

Encryption and what a relay learns

One-to-one messages and calls use X3DH key agreement and the Double Ratchet with AES-256-GCM and Curve25519 — the same construction as Signal — giving forward secrecy and post-compromise security. The implementation is published on GitHub under MIT (src/DoubleRatchet.swift, src/OSHICryptoV2.swift). Over the mesh, relay phones carry ciphertext only. One honest caveat from our App Store listing: when groups use the Internet path, group names and member lists are visible to the OSHI server. Keep sensitive conversations one-to-one.

When the Internet is cut

OSHI's Bluetooth and Wi-Fi mesh keeps working with no towers and no servers: roughly 100 m per hop in the open, up to five hops, store-and-forward. In a shutdown that means you can still reach a fixer across a square, a colleague in the same hotel, or a source you have arranged to meet. It does not reach a newsroom abroad until a phone in the chain gets a connection; when one does, queued messages deliver automatically. Our country guides for Iran, Myanmar, Russia and others describe local conditions.

When the Internet is censored rather than absent

• Tor routing for delivery when OSHI's own servers are blocked.
• Covert channels whose traffic resembles ordinary HTTPS requests, for networks that fingerprint and block messengers. See covert channels.
• Steganography: hide an encrypted message inside an ordinary-looking photo or text, for when the fact of sending an encrypted message is itself the risk. See the steganography guide.
• View-once media and disappearing messages for material that should not persist on either device.

What OSHI has not proven yet — read this part

• No public third-party audit. Briar (Cure53) and Signal have them; OSHI does not. Two issues reported by an independent researcher were fixed in version 1.0.39, which is good practice but not an audit.
• Only the core is open source. The cryptographic core, mesh layer and bot SDK are on GitHub under MIT; the app shell is not. You cannot yet build the whole app from source.
• Single developer, Swiss jurisdiction. A strength for independence, a weakness for bus factor.
• Android is a sideloaded APK. Verify the download over HTTPS from this site and compare with colleagues.
• Not on Privacy Guides. Their criteria require an independent audit, which is the honest gap.

For a source whose life depends on it, the conservative advice today is Signal with a username, or Briar on Android, and OSHI as the offline and no-number layer alongside them. See OSHI vs Signal and OSHI vs Briar.

Practical set-up for a newsroom

1. Each reporter generates an identity on a device they control and publishes the QR code or invite link on their profile page.
2. Verify keys with colleagues in person once; then keys are exchanged over OSHI itself.
3. Keep source conversations one-to-one; use groups for logistics only.
4. Before travelling, download the offline map for the destination and test the mesh with a colleague in airplane mode.
5. Enable Tor routing where the network is hostile, and have a covert channel configured before it is needed.

OSHI is an alternative to Bridgefy, Briar, Meshtastic and bitchat for offline communication, and to Signal for private messaging.

Frequently asked questions