diff --git a/lib/STP/index.js b/lib/STP/index.js
index 01eba90..e6362ca 100644
--- a/lib/STP/index.js
+++ b/lib/STP/index.js
@@ -55,11 +55,15 @@ class Server extends EventEmitter {
 
 class STPSocket extends EventEmitter {
 	tcpSocket;
-	readyState = 0;
 	buffer = '';
 	externalKey;
 	identity;
 
+	CONNECTING = Symbol('connecting');
+	EXCHANGE = Symbol('exchange');
+	SECURED = Symbol('secured');
+	readyState = this.CONNECTING;
+
 	get loopback() {
 		return this.identity.publicKey ===
 			this.externalKey.exportKey('pkcs8-public-pem');
@@ -112,24 +116,21 @@ class STPSocket extends EventEmitter {
 	}
 
 	processMessage(obj) {
-		switch(obj.cmd) {
-			case 'KEY': {
-				if(this.readyState === 0) {
-					this.externalKey = new NodeRSA();
-					this.externalKey.importKey(obj.data.key, 'pkcs8-public-pem');
-					this.tcpSocket.write(new AckPacket().toBuffer());
-					this.readyState = 1;
-				}
-				break;
-			}
-			case 'ACK': {
-				if(this.readyState === 1) {
-					this.readyState = 2;
-					this.emit('ready');
-				}
-				break;
-			}
+
+		if(this.readyState === this.CONNECTING && obj.cmd === 'KEY') {
+			this.externalKey = new NodeRSA();
+			this.externalKey.importKey(obj.data.key, 'pkcs8-public-pem');
+			this.tcpSocket.write(new AckPacket().toBuffer());
+			this.readyState = this.EXCHANGE;
+			return;
 		}
+
+		if(this.readyState === this.EXCHANGE && obj.cmd === 'ACK') {
+			this.readyState = this.SECURED;
+			this.emit('ready');
+			return;
+		}
+
 	}
 
 	handshake() {