Security deep dive
How Cloak protects your data
Cloak doesn't just promise privacy. We engineer it into every layer. From the cryptographic protocols to local key storage, here is exactly how your data stays yours.
Private content and public sharing
Ordinary chats, calls, and private uploads use end-to-end encryption. Public uploads are a separate path for shareable media such as memes and reels, served through a public CDN without end-to-end encryption. Both file paths use HTTPS uploads; attachments are not limited to WebTransport streams.
X25519 · AES-256-GCM · ENCRYPTED BACKUPS · PUBLIC AND PRIVATE UPLOADS
The encryption architecture
How the encryption works
Modern Public Key Cryptography
STANDARD HPKE KEY SHARING
Cloak uses HPKE with X25519, HKDF-SHA256, and AES-256-GCM to protect conversation-key sharing. Public keys and encrypted key material pass through our servers. Private keys are generated and used on your device, with encrypted recovery backups stored by the service.
AES-256-GCM Message Encryption
AUTHENTICATED ENCRYPTION, PER-MESSAGE RANDOMNESS
Ordinary chat message bodies are encrypted on your device with AES-256-GCM and a fresh random initialization vector (IV). Authentication tags let clients detect altered ciphertext. Incoming webhooks and server-hosted flow bots use a separate, service-readable content path.
Client-Side Content Encryption
PRIVATE CONTENT IS ENCRYPTED BEFORE UPLOAD
Ordinary message bodies, private uploads, and call media are encrypted on your device. Public CDN uploads are deliberately shareable and are not end-to-end encrypted. Account and routing metadata, submitted reports, webhook/flow-bot content, and temporary Discord import archives are accessible to the service.
Per-Conversation Keys
UNIQUE KEYS FOR EVERY DM AND EVERY SERVER
Each direct message conversation and server has its own key material. Server key cycling changes the keys used for subsequent messages; it cannot erase keys or plaintext a former member already retained. Private threads and restricted channels rely on server-enforced delivery permissions within the shared server-key boundary.
Secret Key Recovery
YOU HOLD THE MASTER KEY, NOT US
Account setup generates a random 32-character recovery secret, separate from your login password. The service stores encrypted identity and conversation-key backups, including encrypted recovery-secret material, rather than plaintext recovery keys. Keep the secret safe or link from an existing device. Losing both the secret and all devices holding your keys makes encrypted history unrecoverable; a password reset cannot restore it.
Encrypted Voice & Video
END-TO-END ENCRYPTED CALLS, FRAME BY FRAME
Voice, video, and screen-sharing media use end-to-end encryption on participating devices. Browser clients use WebRTC media transforms, with native media encryption support on mobile. Call infrastructure relays encrypted media and processes the signaling and routing metadata needed to connect participants.
Account security
Your account, locked down too
Encryption protects the content; these protect the account it belongs to. Even moderation respects the design: AutoMod works on rate signals like message bursts and mention storms, never on message content.
Two-factor authentication
TOTP two-factor with backup codes. Sensitive actions like ownership transfer require a fresh re-authentication.
Device management
See every device signed into your account, revoke any one of them, or sign out everything else in one tap.
QR device linking
Add a new device by scanning a QR code. Your keys are handed off in a sealed envelope only the new device can open.
Blocking and local key removal
Blocking someone severs the friendship and removes locally held conversation keys. It cannot erase content or keys the other person has already saved.
Spec sheet
Technical specifications
The cryptographic primitives and transport protocols powering Cloak's security.
- Key Exchange
- HPKE: X25519, HKDF-SHA256, AES-256-GCM
- Message Cipher
- AES-256-GCM with per-message random IV
- Key Storage
- Platform local storage and encrypted server backups
- Transport
- WebTransport (QUIC/TLS 1.3), WSS, HTTPS, WebRTC
- Media Encryption
- WebRTC E2EE, browser and native implementations
- Identity Backup
- Encrypted using a separate user-held recovery secret
Cryptography and its limits
Standard primitives, explicit boundaries
Cloak uses standard cryptographic primitives in its own messaging design. It does not implement the Signal Double Ratchet and does not provide per-message forward secrecy. Standard primitives do not by themselves establish that an entire application is secure.
Initial identity trust uses trust on first use; clients pin the identity key they first receive. Server permissions control delivery to private threads and restricted channels, which are not separate cryptographic boundaries. See our Privacy Policy for the data the service can access and the recovery process.
OPEN STANDARDS · X25519 · AES-256-GCM
Your server. Your keys. Your conversation.
Download Cloak, create your account in the app, and bring your community somewhere it can speak freely.
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