The encryption architecture.

Sender encrypts locally, HTTPS or WSS carries ciphertext through an Exoscale relay with encrypted storage, and the recipient decrypts locally. Signal ratcheting and MLS group updates evolve keys on participants’ devices. Private keys stay on devices; fresh keys support forward secrecy and recovery after compromise.

Private in transit.
Protected at rest.

End-to-end encryption keeps the conversation between you and your recipients. Encryption at rest adds protection for stored data.

Only the people in the conversation

Messages are encrypted before leaving your device. Exoscale.ch relays and stores ciphertext; only recipients decrypt the message body.

Another layer for storage

A separate storage-encryption layer protects the ciphertext on disk. HTTPS and secure WebSockets (WSS) also encrypt the network connection.

Your deviceLocal private keys · Encrypt the message body

Exoscale.ch · Switzerland

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Blind relay · Ciphertext only · Encryption at rest

Their deviceLocal private keys · Decrypt the message body

Fresh keys.
Stronger conversations.

The encryption brief sets out protocols for private messages and group conversations, with keys that evolve over time.

Signal Protocol · One-to-one

Cryptographic ratcheting derives fresh message keys. Forward secrecy protects earlier messages; post-compromise security supports recovery after a key compromise.

Messaging Layer Security · Groups

MLS (IETF RFC 9420) establishes shared group keys and updates them as membership changes, supporting forward secrecy and post-compromise security.

Key AKey BKey C

A new key as the conversation moves.

Ratcheting limits how much a compromised key can reveal. Recovery depends on fresh key material and secure devices.

Alternative in the brief

Client-side ECDH key exchange + AES-GCM authenticated encryption. This is an alternative to evaluate, rather than an extra protocol layered onto Signal or MLS.

Protocol design from the Peak.ch brief · Signal specification · MLS standard

Your private keys.
Stay with you.

The server is a directory, a relay, and an encrypted storage locker. Private message keys belong on your devices.

Generated and protected locally

Use OS-protected key storage on mobile devices, such as iOS Keychain or Android Keystore, with hardware backing where available. The locked-down CEF app also needs protected key storage. Its per-user mTLS key authenticates access separately from message encryption.

Public keys for delivery

The server distributes public keys and one-time pre-keys so people can establish encrypted sessions. It never receives private message keys.

On your devicePrivate keys · Message encryption · Decryption

On Exoscale.ch in Switzerland

Public keys & pre-keys
Encrypted message bodies
Encrypted storage

Secure, real-time delivery

WSS carries live messages. HTTPS APIs handle SwissID sessions and public-key retrieval. Transport encryption adds protection around the end-to-end encrypted payload.

Encryption architecture from the Peak.ch brief.

Posts & changes.
Through the app.

To see posts and make changes, users need to use the peak.ch app.

A locked-down CEF browser

The app uses Chromium Embedded Framework (CEF), with a private key for mutual TLS (mTLS) that is different for each user.

“Global Public” is the browser exception

Only pages marked as “Global Public” can be seen by standard browsers, anywhere. Making changes requires the app.

Most

Restricted accessNeed app to view posts · make changes

Public

Open to anyone registeredNeed app to view
Switzerland - Only

Standard browser access

“Global Public” pages only

Open from a standard browser, anywhere:

https://peak.ch#Noggeler_Guuggenmusig