Implemented websocket (client <-> server) traffic encryption & compression.

src/common/event.nim

@@ -3,26 +3,66 @@ when defined(server):
 when defined(client): 
     import whisky
 
-import times, json
-import ./[types, utils, serialize]
+import times, json, zippy
+import ./[types, utils, serialize, crypto]
 
-proc sendEvent*(ws: WebSocket, event: Event) = 
+proc sendEvent*(ws: WebSocket, event: Event, key: Key = default(Key)) = 
     var packer = Packer.init() 
 
+    let iv = generateBytes(Iv)
+
+    var 
+        data = string.toBytes($event.data)
+
     packer.add(cast[uint8](event.eventType))
     packer.add(cast[uint32](event.timestamp))
-    packer.addDataWithLengthPrefix(string.toBytes($event.data))
-    let data = packer.pack() 
+    
+    if event.eventType != CLIENT_KEY_EXCHANGE and event.eventType != CLIENT_HEARTBEAT: 
+        # Compress data
+        let compressed = compress(data, BestCompression, dfGzip)
+        
+        # Encrypt data
+        let (encData, gmac) = encrypt(key, iv, compressed)
+        
+        packer.addData(iv)      # 12 bytes IV
+        packer.addData(gmac)    # 16 bytes Authentication Tag
+        packer.addDataWithLengthPrefix(encData)
+    else: 
+        packer.addDataWithLengthPrefix(data)
+    
+    let body = packer.pack()
 
-    ws.send(Bytes.toString(data), BinaryMessage)
+    ws.send(Bytes.toString(body), BinaryMessage)
+
+proc recvEvent*(message: Message, key: Key = default(Key)): Event = 
 
-proc recvEvent*(message: Message): Event = 
     var unpacker = Unpacker.init(message.data)
+    let 
+        eventType = cast[EventType](unpacker.getUint8()) 
+        timestamp = cast[int64](unpacker.getUint32())
+    var data: string
+
+    if eventType != CLIENT_KEY_EXCHANGE and eventType != CLIENT_HEARTBEAT: 
+    
+        let 
+            iv = unpacker.getByteArray(Iv)
+            gmac = unpacker.getByteArray(AuthenticationTag)
+            encData = string.toBytes(unpacker.getDataWithLengthPrefix())
+    
+        # Decrypt data
+        let (decData, tag) = decrypt(key, iv, encData)
+        if tag != gmac: 
+            raise newException(CatchableError, "Invalid authentication tag.")
+
+        # Decompress data
+        data = Bytes.toString(uncompress(decData, dfGzip))
+    else: 
+        data = unpacker.getDataWithLengthPrefix()
 
     return Event(
-        eventType: cast[EventType](unpacker.getUint8()),
-        timestamp: cast[int64](unpacker.getUint32()),
-        data: parseJson(unpacker.getDataWithLengthPrefix())
+        eventType: eventType,
+        timestamp: timestamp,
+        data: parseJson(data)
     )
 
 proc sendHeartbeat*(ws: WebSocket) =