Sending Messages

Messages are encrypted client-side and sent as opaque binary blobs. The server never sees plaintext. 

const { messageId } = await client.sendMessage(
  'alice-user-id',
  'Hey Alice, this is end-to-end encrypted!'
);
console.log('Sent:', messageId);

Parameters

  • toUserId, string, Recipient's stable user ID (must match their JWT subject)
  • plaintextMessage, string, Message content; encrypted by the SDK

Returns Promise<{ messageId: string }>

Encryption flow

  • 1. Fetch recipient's public key from your key directory (cached after first call)
  • 2. Derive shared secret via X25519 ECDH → HKDF-SHA256 → AES-256 key
  • 3. Encrypt with AES-256-GCM (96-bit nonce, AAD = messageId+senderId+recipientId+timestamp)
  • 4. Serialize into a protobuf Envelope with opaque encryptedPayload bytes
  • 5. Send as a binary WebSocket frame to DropOnAir