Since the Register API call now requires the client's access token in order to validate his Minecraft login, it is now being provided.

src/main/java/eu/crushedpixel/replaymod/api/ApiClient.java

@@ -36,11 +36,14 @@ public class ApiClient {
         return auth;
     }
 
-    public AuthKey register(String username, String mail, String password) throws IOException, ApiException {
+    public AuthKey register(String username, String mail, String password, String uuid, String accessToken)
+            throws IOException, ApiException {
         QueryBuilder builder = new QueryBuilder(ReplayModApiMethods.register);
         builder.put("username", username);
         builder.put("email", mail);
         builder.put("password", password);
+        builder.put("uuid", uuid);
+        builder.put("accesstoken", accessToken);
         AuthKey auth = invokeAndReturn(builder, AuthKey.class);
         return auth;
     }

src/main/java/eu/crushedpixel/replaymod/gui/online/GuiRegister.java

@@ -197,6 +197,7 @@ public class GuiRegister extends GuiScreen {
                         } catch(ApiException ae) {
                             message = ae.getLocalizedMessage();
                         } catch(Exception e) {
+                            e.printStackTrace();
                             message = I18n.format("replaymod.gui.login.connectionerror");
                         }
                     }

src/main/java/eu/crushedpixel/replaymod/online/authentication/AuthenticationHandler.java

@@ -5,6 +5,7 @@ import eu.crushedpixel.replaymod.api.ApiClient;
 import eu.crushedpixel.replaymod.api.ApiException;
 import eu.crushedpixel.replaymod.api.replay.holders.AuthConfirmation;
 import eu.crushedpixel.replaymod.api.replay.holders.AuthKey;
+import net.minecraft.client.Minecraft;
 import net.minecraftforge.common.config.Property;
 
 import java.io.IOException;
@@ -33,8 +34,12 @@ public class AuthenticationHandler {
         return apiClient.hasDonated(uuid);
     }
 
+    private static Minecraft mc = Minecraft.getMinecraft();
+
     public static void register(String usrname, String mail, String password) throws IOException, ApiException {
-        AuthKey auth = apiClient.register(usrname, mail, password);
+        AuthKey auth = apiClient.register(usrname, mail, password,
+                mc.getSession().getProfile().getId().toString(),
+                Minecraft.getMinecraft().getSession().getToken());
         username = usrname;
         authkey = auth.getAuthkey();
         saveAuthkey(authkey);

src/main/resources/assets/replaymod/lang/en_US.lang

@@ -23,7 +23,8 @@ replaymod.api.usernameexists=This username is already taken
 replaymod.api.mailexists=This Email address is already linked to an account
 replaymod.api.invalidmail=Invalid Email Address
 replaymod.api.nopermissions=You don't have permission to do this
-
+replaymod.api.authfailed=Authentication to the Minecraft Session Servers failed
+replaymod.api.mcuserexists=A ReplayMod account is already associated with this Minecraft account
 
 #All of the chat messages
 replaymod.chat.recordingstarted=Recording started