diff --git a/Minecraft.Client/AuthScreen.cpp b/Minecraft.Client/AuthScreen.cpp
new file mode 100644
index 00000000..706d454b
--- /dev/null
+++ b/Minecraft.Client/AuthScreen.cpp
@@ -0,0 +1,101 @@
+#include "stdafx.h"
+#include "AuthScreen.h"
+#include "Minecraft.h"
+#include "User.h"
+#include <fstream>
+
+static constexpr auto PROFILES_FILE = L"auth_profiles.dat";
+
+vector<AuthProfile> AuthProfileManager::profiles;
+int AuthProfileManager::selectedProfile = -1;
+
+void AuthProfileManager::load()
+{
+	profiles.clear();
+	std::ifstream file(PROFILES_FILE, std::ios::binary);
+	if (!file) return;
+
+	uint32_t count = 0;
+	file.read(reinterpret_cast<char *>(&count), sizeof(count));
+
+	for (uint32_t i = 0; i < count && file.good(); i++)
+	{
+		AuthProfile p;
+		uint8_t type;
+		file.read(reinterpret_cast<char *>(&type), sizeof(type));
+		p.type = static_cast<AuthProfile::Type>(type);
+
+		auto readWstr = [&file]() -> wstring {
+			uint16_t len = 0;
+			file.read(reinterpret_cast<char *>(&len), sizeof(len));
+			wstring s(len, L'\0');
+			file.read(reinterpret_cast<char *>(s.data()), len * sizeof(wchar_t));
+			return s;
+		};
+
+		p.uid = readWstr();
+		p.username = readWstr();
+		p.token = readWstr();
+		profiles.push_back(std::move(p));
+	}
+
+	if (!profiles.empty())
+		selectedProfile = 0;
+}
+
+void AuthProfileManager::save()
+{
+	std::ofstream file(PROFILES_FILE, std::ios::binary | std::ios::trunc);
+	if (!file) return;
+
+	uint32_t count = static_cast<uint32_t>(profiles.size());
+	file.write(reinterpret_cast<const char *>(&count), sizeof(count));
+
+	auto writeWstr = [&file](const wstring &s) {
+		uint16_t len = static_cast<uint16_t>(s.length());
+		file.write(reinterpret_cast<const char *>(&len), sizeof(len));
+		file.write(reinterpret_cast<const char *>(s.data()), len * sizeof(wchar_t));
+	};
+
+	for (const auto &p : profiles)
+	{
+		uint8_t type = static_cast<uint8_t>(p.type);
+		file.write(reinterpret_cast<const char *>(&type), sizeof(type));
+		writeWstr(p.uid);
+		writeWstr(p.username);
+		writeWstr(p.token);
+	}
+}
+
+void AuthProfileManager::addProfile(AuthProfile::Type type, const wstring &username)
+{
+	profiles.push_back({type, L"offline_" + username, username, {}});
+	selectedProfile = static_cast<int>(profiles.size()) - 1;
+	save();
+}
+
+void AuthProfileManager::removeSelectedProfile()
+{
+	if (selectedProfile < 0 || selectedProfile >= static_cast<int>(profiles.size()))
+		return;
+
+	profiles.erase(profiles.begin() + selectedProfile);
+	if (selectedProfile >= static_cast<int>(profiles.size()))
+		selectedProfile = static_cast<int>(profiles.size()) - 1;
+	save();
+}
+
+bool AuthProfileManager::applySelectedProfile()
+{
+	if (selectedProfile < 0 || selectedProfile >= static_cast<int>(profiles.size()))
+		return false;
+
+	const auto &p = profiles[selectedProfile];
+	auto *mc = Minecraft::GetInstance();
+
+	if (mc->user)
+		delete mc->user;
+
+	mc->user = new User(p.username, p.token);
+	return true;
+}
diff --git a/Minecraft.Client/AuthScreen.h b/Minecraft.Client/AuthScreen.h
new file mode 100644
index 00000000..f31f294a
--- /dev/null
+++ b/Minecraft.Client/AuthScreen.h
@@ -0,0 +1,30 @@
+#pragma once
+using namespace std;
+
+struct AuthProfile
+{
+	enum Type : uint8_t { MICROSOFT, ELYBY, OFFLINE };
+
+	Type type;
+	wstring uid;
+	wstring username;
+	wstring token;
+};
+
+class AuthProfileManager
+{
+private:
+	static vector<AuthProfile> profiles;
+	static int selectedProfile;
+
+public:
+	static void load();
+	static void save();
+	static void addProfile(AuthProfile::Type type, const wstring &username);
+	static void removeSelectedProfile();
+	static bool applySelectedProfile();
+
+	static const vector<AuthProfile> &getProfiles() { return profiles; }
+	static int getSelectedIndex() { return selectedProfile; }
+	static void setSelectedIndex(int idx) { selectedProfile = idx; }
+};
diff --git a/Minecraft.Client/ClientConnection.cpp b/Minecraft.Client/ClientConnection.cpp
index a80af5d2..bdace064 100644
--- a/Minecraft.Client/ClientConnection.cpp
+++ b/Minecraft.Client/ClientConnection.cpp
@@ -54,6 +54,8 @@
 #include "PS3/Network/SonyVoiceChat.h"
 #endif
 #include "DLCTexturePack.h"
+#include "..\Minecraft.World\HandshakeManager.h"
+#include "..\Minecraft.World\AuthModule.h"
 
 #ifdef _WINDOWS64
 #include "Xbox\Network\NetworkPlayerXbox.h"
@@ -140,6 +142,9 @@ ClientConnection::ClientConnection(Minecraft *minecraft, Socket *socket, int iUs
 	}
 
 	deferredEntityLinkPackets = vector<DeferredEntityLinkPacket>();
+
+	handshakeManager = nullptr;
+	authComplete = false;
 }
 
 bool ClientConnection::isPrimaryConnection() const
@@ -202,6 +207,7 @@ ClientConnection::~ClientConnection()
 	delete connection;
 	delete random;
 	delete savedDataStorage;
+	delete handshakeManager;
 }
 
 void ClientConnection::tick()
@@ -4129,3 +4135,34 @@ ClientConnection::DeferredEntityLinkPacket::DeferredEntityLinkPacket(shared_ptr<
 	m_recievedTick = GetTickCount();
 	m_packet = packet;
 }
+
+void ClientConnection::beginAuth()
+{
+	handshakeManager = new HandshakeManager(false);
+	handshakeManager->registerModule(new MojangAuthModule());
+	handshakeManager->registerModule(new ElyByAuthModule());
+	handshakeManager->registerModule(new KeypairOfflineAuthModule());
+	handshakeManager->registerModule(new OfflineAuthModule());
+
+	auto initial = handshakeManager->createInitialPacket();
+	if (initial) send(initial);
+}
+
+void ClientConnection::handleAuth(const shared_ptr<AuthPacket> &packet)
+{
+	if (done || authComplete) return;
+	if (!handshakeManager) return;
+
+	auto response = handshakeManager->handlePacket(packet);
+	if (response) send(response);
+
+	if (handshakeManager->isComplete())
+	{
+		authComplete = true;
+	}
+	else if (handshakeManager->isFailed())
+	{
+		done = true;
+		message = L"Auth handshake failed";
+	}
+}
diff --git a/Minecraft.Client/ClientConnection.h b/Minecraft.Client/ClientConnection.h
index 3448496d..69ed2805 100644
--- a/Minecraft.Client/ClientConnection.h
+++ b/Minecraft.Client/ClientConnection.h
@@ -6,6 +6,7 @@ class MultiPlayerLevel;
 class SavedDataStorage;
 class Socket;
 class MultiplayerLocalPlayer;
+class HandshakeManager;
 
 class ClientConnection : public PacketListener
 {
@@ -179,4 +180,10 @@ private:
 	static const int MAX_ENTITY_LINK_DEFERRAL_INTERVAL = 1000;
 
 	void checkDeferredEntityLinkPackets(int newEntityId);
+
+public:
+	HandshakeManager *handshakeManager;
+	bool authComplete;
+	void beginAuth();
+	virtual void handleAuth(const shared_ptr<AuthPacket> &packet);
 };
\ No newline at end of file
diff --git a/Minecraft.Client/Common/UI/UIController.cpp b/Minecraft.Client/Common/UI/UIController.cpp
index b12ea5e7..bf81472c 100644
--- a/Minecraft.Client/Common/UI/UIController.cpp
+++ b/Minecraft.Client/Common/UI/UIController.cpp
@@ -2948,7 +2948,7 @@ C4JStorage::EMessageResult UIController::RequestMessageBox(UINT uiTitle, UINT ui
 														   int( *Func)(LPVOID,int,const C4JStorage::EMessageResult),LPVOID lpParam, WCHAR *pwchFormatString,DWORD dwFocusButton, bool bIsError)
 
 {
-	MessageBoxInfo param;
+	MessageBoxInfo param = {};
 	param.uiTitle = uiTitle;
 	param.uiText = uiText;
 	param.uiOptionA = uiOptionA;
diff --git a/Minecraft.Client/Common/UI/UIScene_MainMenu.cpp b/Minecraft.Client/Common/UI/UIScene_MainMenu.cpp
index 93f1edf1..f9dbc6eb 100644
--- a/Minecraft.Client/Common/UI/UIScene_MainMenu.cpp
+++ b/Minecraft.Client/Common/UI/UIScene_MainMenu.cpp
@@ -4,6 +4,7 @@
 #include "..\..\..\Minecraft.World\Random.h"
 #include "..\..\User.h"
 #include "..\..\MinecraftServer.h"
+#include "..\..\AuthScreen.h"
 #include "UI.h"
 #include "UIScene_MainMenu.h"
 #ifdef __ORBIS__
@@ -46,12 +47,12 @@ UIScene_MainMenu::UIScene_MainMenu(int iPad, void *initData, UILayer *parentLaye
 	if(ProfileManager.IsFullVersion())
 	{
 		m_bTrialVersion=false;
-		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].init(IDS_DOWNLOADABLECONTENT,eControl_UnlockOrDLC);
+		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].init(L"Auth",eControl_UnlockOrDLC);
 	}
 	else
 	{
 		m_bTrialVersion=true;
-		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].init(IDS_UNLOCK_FULL_GAME,eControl_UnlockOrDLC);
+		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].init(L"Auth",eControl_UnlockOrDLC);
 	}
 
 #ifndef _DURANGO
@@ -181,8 +182,8 @@ void UIScene_MainMenu::handleGainFocus(bool navBack)
 		
 	if(navBack && ProfileManager.IsFullVersion())
 	{
-		// Replace the Unlock Full Game with Downloadable Content
-		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].setLabel(IDS_DOWNLOADABLECONTENT);
+		// once again replacing the shop with auth. not a bad thing.
+		m_buttons[static_cast<int>(eControl_UnlockOrDLC)].setLabel(L"Auth");
 	}
 
 #if TO_BE_IMPLEMENTED
@@ -357,7 +358,7 @@ void UIScene_MainMenu::handlePress(F64 controlId, F64 childId)
 		ui.PlayUISFX(eSFX_Press);
 
 		m_eAction=eAction_RunUnlockOrDLC;
-		signInReturnedFunc = &UIScene_MainMenu::UnlockFullGame_SignInReturned;
+		RunAction(primaryPad);
 		break;
 	case eControl_Exit:
 		//CD - Added for audio
@@ -438,8 +439,11 @@ void UIScene_MainMenu::RunAction(int iPad)
 		RunHelpAndOptions(iPad);
 		break;
 	case eAction_RunUnlockOrDLC:
-		RunUnlockOrDLC(iPad);
+	{
+		AuthProfileManager::load();
+		ShowAuthMenu(iPad, this);
 		break;
+	}
 #ifdef _DURANGO
 	case eAction_RunXboxHelp:
 		// 4J: Launch the dummy xbox help application.
@@ -450,6 +454,161 @@ void UIScene_MainMenu::RunAction(int iPad)
 	}
 }
 
+static int s_authPad = 0;
+
+static const wchar_t *BuildAuthProfileText()
+{
+	static wstring text;
+	const auto &profiles = AuthProfileManager::getProfiles();
+	int sel = AuthProfileManager::getSelectedIndex();
+	if (profiles.empty())
+	{
+		text = L"No profiles - press Add to create one";
+	}
+	else
+	{
+		text.clear();
+		for (int i = 0; i < static_cast<int>(profiles.size()); i++)
+		{
+			const auto &p = profiles[i];
+			const wchar_t *type = (p.type == AuthProfile::MICROSOFT) ? L"[MS]"
+				: (p.type == AuthProfile::ELYBY) ? L"[Ely]" : L"[Off]";
+			if (i > 0) text += L"\n";
+			text += (i == sel) ? L"> " : L"  ";
+			text += wstring(type) + L" " + p.username;
+		}
+	}
+	return text.c_str();
+}
+
+void UIScene_MainMenu::ShowAuthMenu(int iPad, void *pClass)
+{
+	s_authPad = iPad;
+
+	static const wchar_t *authOptions[] = { L"Next", L"Use", L"Add", L"Back" };
+	MessageBoxInfo param = {};
+	param.uiOptionC = 4;
+	param.dwPad = iPad;
+	param.Func = &UIScene_MainMenu::AuthMenuReturned;
+	param.lpParam = pClass;
+	param.rawTitle = L"Authentication";
+	param.rawText = BuildAuthProfileText();
+	param.rawOptions = authOptions;
+	ui.NavigateToScene(iPad, eUIScene_MessageBox, &param, eUILayer_Alert, eUIGroup_Fullscreen);
+	UIScene *scene = ui.FindScene(eUIScene_MessageBox);
+	if (scene)
+		static_cast<UIScene_MessageBox *>(scene)->setKeepOpen(true);
+}
+
+void UIScene_MainMenu::ShowAuthAddMenu(int iPad, void *pClass)
+{
+	static const wchar_t *addOptions[] = { L"Microsoft Auth", L"Ely.by Auth", L"Add Offline User", L"Back" };
+	MessageBoxInfo param = {};
+	param.uiOptionC = 4;
+	param.dwPad = iPad;
+	param.Func = &UIScene_MainMenu::AuthAddMenuReturned;
+	param.lpParam = pClass;
+	param.rawTitle = L"Add Profile";
+	param.rawText = L"Select an auth type";
+	param.rawOptions = addOptions;
+	ui.NavigateToScene(iPad, eUIScene_MessageBox, &param, eUILayer_Alert, eUIGroup_Fullscreen);
+}
+
+int UIScene_MainMenu::AuthMenuReturned(LPVOID lpParam, int iPad, const C4JStorage::EMessageResult result)
+{
+	const auto &profiles = AuthProfileManager::getProfiles();
+	switch (result)
+	{
+	case C4JStorage::EMessage_ResultAccept:
+	{
+		if (!profiles.empty())
+		{
+			int next = (AuthProfileManager::getSelectedIndex() + 1) % static_cast<int>(profiles.size());
+			AuthProfileManager::setSelectedIndex(next);
+		}
+		if (auto *scene = ui.FindScene(eUIScene_MessageBox))
+			static_cast<UIScene_MessageBox *>(scene)->updateContent(BuildAuthProfileText());
+		return 0;
+	}
+	case C4JStorage::EMessage_ResultDecline:
+	{
+		ui.NavigateBack(iPad);
+		AuthProfileManager::applySelectedProfile();
+		break;
+	}
+	case C4JStorage::EMessage_ResultThirdOption:
+	{
+		ui.NavigateBack(iPad);
+		ShowAuthAddMenu(iPad, lpParam);
+		break;
+	}
+	default:
+	{
+		ui.NavigateBack(iPad);
+		break;
+	}
+	}
+	return 0;
+}
+
+int UIScene_MainMenu::AuthAddMenuReturned(LPVOID lpParam, int iPad, const C4JStorage::EMessageResult result)
+{
+	switch (result)
+	{
+	case C4JStorage::EMessage_ResultAccept:
+		AuthProfileManager::addProfile(AuthProfile::MICROSOFT, L"Player");
+		ShowAuthMenu(iPad, lpParam);
+		break;
+	case C4JStorage::EMessage_ResultDecline:
+		AuthProfileManager::addProfile(AuthProfile::ELYBY, L"Player");
+		ShowAuthMenu(iPad, lpParam);
+		break;
+	case C4JStorage::EMessage_ResultThirdOption:
+	{
+#ifdef _WINDOWS64
+		UIKeyboardInitData kbData;
+		kbData.title = L"Enter Username";
+		kbData.defaultText = L"Player";
+		kbData.maxChars = 16;
+		kbData.callback = &UIScene_MainMenu::AuthKeyboardReturned;
+		kbData.lpParam = lpParam;
+		kbData.pcMode = g_KBMInput.IsKBMActive();
+		ui.NavigateToScene(iPad, eUIScene_Keyboard, &kbData);
+#else
+		InputManager.RequestKeyboard(L"Enter Username", L"Player", (DWORD)0, 16, &UIScene_MainMenu::AuthKeyboardReturned, lpParam, C_4JInput::EKeyboardMode_Default);
+#endif
+		break;
+	}
+	default:
+		ShowAuthMenu(iPad, lpParam);
+		break;
+	}
+	return 0;
+}
+
+int UIScene_MainMenu::AuthKeyboardReturned(LPVOID lpParam, const bool bRes)
+{
+	if (bRes)
+	{
+		uint16_t ui16Text[128];
+		ZeroMemory(ui16Text, 128 * sizeof(uint16_t));
+#ifdef _WINDOWS64
+		Win64_GetKeyboardText(ui16Text, 128);
+#else
+		InputManager.GetText(ui16Text);
+#endif
+		if (ui16Text[0] != 0)
+		{
+			wchar_t wName[128] = {};
+			for (int k = 0; k < 127 && ui16Text[k]; k++)
+				wName[k] = static_cast<wchar_t>(ui16Text[k]);
+			AuthProfileManager::addProfile(AuthProfile::OFFLINE, wName);
+		}
+	}
+	ShowAuthMenu(s_authPad, lpParam);
+	return 0;
+}
+
 void UIScene_MainMenu::customDraw(IggyCustomDrawCallbackRegion *region)
 {
 	if(wcscmp((wchar_t *)region->name,L"Splash")==0)
@@ -1946,7 +2105,7 @@ void UIScene_MainMenu::tick()
 		if(ProfileManager.IsFullVersion())
 		{
 			m_bTrialVersion=false;
-			m_buttons[(int)eControl_UnlockOrDLC].init(app.GetString(IDS_DOWNLOADABLECONTENT),eControl_UnlockOrDLC);
+			m_buttons[(int)eControl_UnlockOrDLC].init(L"Auth",eControl_UnlockOrDLC);
 		}
 	}
 #endif
diff --git a/Minecraft.Client/Common/UI/UIScene_MainMenu.h b/Minecraft.Client/Common/UI/UIScene_MainMenu.h
index 2b49a44b..4a059cce 100644
--- a/Minecraft.Client/Common/UI/UIScene_MainMenu.h
+++ b/Minecraft.Client/Common/UI/UIScene_MainMenu.h
@@ -144,7 +144,13 @@ private:
 	void RunHelpAndOptions(int iPad);
 
 	void RunAction(int iPad);
-	
+
+	static void ShowAuthMenu(int iPad, void *pClass);
+	static void ShowAuthAddMenu(int iPad, void *pClass);
+	static int AuthMenuReturned(void *pParam, int iPad, C4JStorage::EMessageResult result);
+	static int AuthAddMenuReturned(void *pParam, int iPad, C4JStorage::EMessageResult result);
+	static int AuthKeyboardReturned(LPVOID lpParam, const bool bRes);
+
 	static void LoadTrial();
 
 #ifdef _XBOX_ONE
diff --git a/Minecraft.Client/Common/UI/UIScene_MessageBox.cpp b/Minecraft.Client/Common/UI/UIScene_MessageBox.cpp
index 7a0749d4..9767b83b 100644
--- a/Minecraft.Client/Common/UI/UIScene_MessageBox.cpp
+++ b/Minecraft.Client/Common/UI/UIScene_MessageBox.cpp
@@ -23,28 +23,29 @@ UIScene_MessageBox::UIScene_MessageBox(int iPad, void *initData, UILayer *parent
 	int buttonIndex = 0;
 	if(param->uiOptionC > 3)
 	{
-		m_buttonButtons[eControl_Button0].init(app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
+		m_buttonButtons[eControl_Button0].init(param->rawOptions ? param->rawOptions[buttonIndex] : app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
 		++buttonIndex;
 	}
 	if(param->uiOptionC > 2)
 	{
-		m_buttonButtons[eControl_Button1].init(app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
+		m_buttonButtons[eControl_Button1].init(param->rawOptions ? param->rawOptions[buttonIndex] : app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
 		++buttonIndex;
 	}
 	if(param->uiOptionC > 1)
 	{
-	m_buttonButtons[eControl_Button2].init(app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
+	m_buttonButtons[eControl_Button2].init(param->rawOptions ? param->rawOptions[buttonIndex] : app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
 		++buttonIndex;
 	}
-	m_buttonButtons[eControl_Button3].init(app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
+	m_buttonButtons[eControl_Button3].init(param->rawOptions ? param->rawOptions[buttonIndex] : app.GetString(param->uiOptionA[buttonIndex]),buttonIndex);
 
-	m_labelTitle.init(app.GetString(param->uiTitle));
-	m_labelContent.init(app.GetString(param->uiText));
+	m_labelTitle.init(param->rawTitle ? param->rawTitle : app.GetString(param->uiTitle));
+	m_labelContent.init(param->rawText ? param->rawText : app.GetString(param->uiText));
 
 	out = IggyPlayerCallMethodRS ( getMovie() , &result, IggyPlayerRootPath( getMovie() ), m_funcAutoResize , 0 , nullptr );
 
 	m_Func = param->Func;
 	m_lpParam = param->lpParam;
+	m_keepOpen = false;
 
 	parentLayer->addComponent(iPad,eUIComponent_MenuBackground);
 
@@ -99,7 +100,7 @@ void UIScene_MessageBox::handleInput(int iPad, int key, bool repeat, bool presse
 	case ACTION_MENU_CANCEL:
 		if(pressed)
 		{
-			navigateBack();
+			if(!m_keepOpen) navigateBack();
 			if(m_Func) m_Func(m_lpParam, iPad, C4JStorage::EMessage_Cancelled);
 		}
 		break;
@@ -136,10 +137,15 @@ void UIScene_MessageBox::handlePress(F64 controlId, F64 childId)
 		break;
 	}
 
-	navigateBack();
+	if(!m_keepOpen) navigateBack();
 	if(m_Func) m_Func(m_lpParam, m_iPad, result);
 }
 
+void UIScene_MessageBox::updateContent(const wchar_t *text)
+{
+	m_labelContent.init(text);
+}
+
 bool UIScene_MessageBox::hasFocus(int iPad)
 {
 	// 4J-JEV: Fix for PS4 #5204 - [TRC][R4033] The application can be locked up by second user logging out of the system. 
diff --git a/Minecraft.Client/Common/UI/UIScene_MessageBox.h b/Minecraft.Client/Common/UI/UIScene_MessageBox.h
index c10f6ab8..213a825d 100644
--- a/Minecraft.Client/Common/UI/UIScene_MessageBox.h
+++ b/Minecraft.Client/Common/UI/UIScene_MessageBox.h
@@ -18,6 +18,7 @@ private:
 	int( *m_Func)(LPVOID,int,const C4JStorage::EMessageResult);
 	LPVOID m_lpParam;
 	int m_buttonCount;
+	bool m_keepOpen;
 
 	UIControl_Button m_buttonButtons[eControl_COUNT];
 	UIControl_Label m_labelTitle, m_labelContent;
@@ -57,4 +58,8 @@ public:
 
 protected:
 	void handlePress(F64 controlId, F64 childId);
+
+public:
+	void updateContent(const wchar_t *text);
+	void setKeepOpen(bool keep) { m_keepOpen = keep; }
 };
\ No newline at end of file
diff --git a/Minecraft.Client/Common/UI/UIStructs.h b/Minecraft.Client/Common/UI/UIStructs.h
index 99c3d7bd..28fcbcd1 100644
--- a/Minecraft.Client/Common/UI/UIStructs.h
+++ b/Minecraft.Client/Common/UI/UIStructs.h
@@ -485,6 +485,9 @@ typedef struct _MessageBoxInfo
 	//C4JStringTable *pStringTable; // 4J Stu - We don't need this for our internal message boxes
 	WCHAR *pwchFormatString;
 	DWORD dwFocusButton;
+	const wchar_t *rawTitle;
+	const wchar_t *rawText;
+	const wchar_t **rawOptions;
 } MessageBoxInfo;
 
 typedef struct _DLCOffersParam
diff --git a/Minecraft.Client/ConnectScreen.cpp b/Minecraft.Client/ConnectScreen.cpp
index 18d50a52..0a19291d 100644
--- a/Minecraft.Client/ConnectScreen.cpp
+++ b/Minecraft.Client/ConnectScreen.cpp
@@ -11,13 +11,14 @@
 ConnectScreen::ConnectScreen(Minecraft *minecraft, const wstring& ip, int port)
 {
 	aborted = false;
+	preLoginSent = false;
 //    System.out.println("Connecting to " + ip + ", " + port);
     minecraft->setLevel(nullptr);
 #if 1
 	// 4J - removed from separate thread, but need to investigate what we actually need here
     connection = new ClientConnection(minecraft, ip, port);
     if (aborted) return;
-    connection->send(std::make_shared<PreLoginPacket>(minecraft->user->name));
+    connection->beginAuth();
 #else
 
     new Thread() {
@@ -47,6 +48,11 @@ void ConnectScreen::tick()
 {
     if (connection != nullptr)
 	{
+		if (!preLoginSent && connection->authComplete)
+		{
+			preLoginSent = true;
+			connection->send(std::make_shared<PreLoginPacket>(minecraft->user->name));
+		}
         connection->tick();
     }
 }
diff --git a/Minecraft.Client/ConnectScreen.h b/Minecraft.Client/ConnectScreen.h
index 07e65cbb..76424a07 100644
--- a/Minecraft.Client/ConnectScreen.h
+++ b/Minecraft.Client/ConnectScreen.h
@@ -10,6 +10,7 @@ class ConnectScreen : public Screen
 private:
 	ClientConnection *connection;
     bool aborted;
+	bool preLoginSent;
 public:
 	ConnectScreen(Minecraft *minecraft, const wstring& ip, int port);
     virtual void tick();
diff --git a/Minecraft.Client/PendingConnection.cpp b/Minecraft.Client/PendingConnection.cpp
index f24086c1..c10edb90 100644
--- a/Minecraft.Client/PendingConnection.cpp
+++ b/Minecraft.Client/PendingConnection.cpp
@@ -14,6 +14,8 @@
 #include "..\Minecraft.World\net.minecraft.world.item.h"
 #include "..\Minecraft.World\SharedConstants.h"
 #include "Settings.h"
+#include "..\Minecraft.World\HandshakeManager.h"
+#include "..\Minecraft.World\AuthModule.h"
 #if defined(_WINDOWS64) && defined(MINECRAFT_SERVER_BUILD)
 #include "..\Minecraft.Server\ServerLogManager.h"
 #include "..\Minecraft.Server\Access\Access.h"
@@ -59,10 +61,14 @@ PendingConnection::PendingConnection(MinecraftServer *server, Socket *socket, co
 	this->server = server;
 	connection = new Connection(socket, id, this);
 	connection->fakeLag = FAKE_LAG;
+
+	handshakeManager = nullptr;
+	authComplete = false;
 }
 
 PendingConnection::~PendingConnection()
 {
+	delete handshakeManager;
 	delete connection;
 }
 
@@ -98,6 +104,13 @@ void PendingConnection::disconnect(DisconnectPacket::eDisconnectReason reason)
 
 void PendingConnection::handlePreLogin(shared_ptr<PreLoginPacket> packet)
 {
+	if (handshakeManager && !authComplete)
+	{
+		app.DebugPrintf("PendingConnection: PreLogin received before auth complete, disconnecting\n");
+		disconnect(DisconnectPacket::eDisconnect_Closed);
+		return;
+	}
+
 	if (packet->m_netcodeVersion != MINECRAFT_NET_VERSION)
 	{
 		app.DebugPrintf("Netcode version is %d not equal to %d\n", packet->m_netcodeVersion, MINECRAFT_NET_VERSION);
@@ -394,3 +407,33 @@ bool PendingConnection::isDisconnected()
 {
 	return done;
 }
+
+void PendingConnection::initAuth()
+{
+	handshakeManager = new HandshakeManager(true);
+	handshakeManager->registerModule(new MojangAuthModule());
+	handshakeManager->registerModule(new ElyByAuthModule());
+	handshakeManager->registerModule(new KeypairOfflineAuthModule());
+	handshakeManager->registerModule(new OfflineAuthModule());
+}
+
+void PendingConnection::handleAuth(const shared_ptr<AuthPacket> &packet)
+{
+	if (done || authComplete) return;
+
+	if (!handshakeManager)
+		initAuth();
+
+	auto response = handshakeManager->handlePacket(packet);
+	if (response) send(response);
+
+	if (handshakeManager->isComplete())
+	{
+		authComplete = true;
+		name = std::move(handshakeManager->finalUsername);
+	}
+	else if (handshakeManager->isFailed())
+	{
+		disconnect(DisconnectPacket::eDisconnect_Closed);
+	}
+}
diff --git a/Minecraft.Client/PendingConnection.h b/Minecraft.Client/PendingConnection.h
index e8a493b0..53724896 100644
--- a/Minecraft.Client/PendingConnection.h
+++ b/Minecraft.Client/PendingConnection.h
@@ -5,6 +5,7 @@ class Socket;
 class LoginPacket;
 class Connection;
 class Random;
+class HandshakeManager;
 using namespace std;
 
 class PendingConnection : public PacketListener
@@ -43,6 +44,10 @@ public:
 	wstring getName();
 	virtual bool isServerPacketListener();
 	virtual bool isDisconnected();
+	HandshakeManager *handshakeManager;
+	bool authComplete;
+	void initAuth();
+	virtual void handleAuth(const shared_ptr<AuthPacket> &packet);
 
 private:
 	void sendPreLoginResponse();
diff --git a/Minecraft.Client/cmake/sources/Common.cmake b/Minecraft.Client/cmake/sources/Common.cmake
index 3936a9c3..de727931 100644
--- a/Minecraft.Client/cmake/sources/Common.cmake
+++ b/Minecraft.Client/cmake/sources/Common.cmake
@@ -969,6 +969,8 @@ set(_MINECRAFT_CLIENT_COMMON_NET_MINECRAFT_CLIENT_SKINS
 source_group("net/minecraft/client/skins" FILES ${_MINECRAFT_CLIENT_COMMON_NET_MINECRAFT_CLIENT_SKINS})
 
 set(_MINECRAFT_CLIENT_COMMON_NET_MINECRAFT_CLIENT_TITLE
+  "${CMAKE_CURRENT_SOURCE_DIR}/AuthScreen.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/AuthScreen.h"
   "${CMAKE_CURRENT_SOURCE_DIR}/TitleScreen.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TitleScreen.h"
 )
diff --git a/Minecraft.Server/cmake/sources/Common.cmake b/Minecraft.Server/cmake/sources/Common.cmake
index 06aa0bfe..0d6f382b 100644
--- a/Minecraft.Server/cmake/sources/Common.cmake
+++ b/Minecraft.Server/cmake/sources/Common.cmake
@@ -5,6 +5,7 @@ set(_MINECRAFT_SERVER_COMMON_ROOT
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/AllowAllCuller.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/ArchiveFile.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/ArrowRenderer.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/AuthScreen.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/BatModel.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/BatRenderer.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../Minecraft.Client/BeaconRenderer.cpp"
diff --git a/Minecraft.World/AuthModule.cpp b/Minecraft.World/AuthModule.cpp
index 0d5ffb0f..35bd3e85 100644
--- a/Minecraft.World/AuthModule.cpp
+++ b/Minecraft.World/AuthModule.cpp
@@ -50,8 +50,6 @@ vector<wstring> MojangAuthModule::supportedVariations()
 	return {L"java", L"bedrock"};
 }
 
-// --- KeypairOfflineAuthModule ---
-
 const wchar_t *KeypairOfflineAuthModule::schemeName() { return L"mcconsoles:keypair_offline"; }
 
 vector<wstring> KeypairOfflineAuthModule::supportedVariations()
diff --git a/Minecraft.World/AuthPackets.cpp b/Minecraft.World/AuthPackets.cpp
index 4bd2bb95..4490b264 100644
--- a/Minecraft.World/AuthPackets.cpp
+++ b/Minecraft.World/AuthPackets.cpp
@@ -26,10 +26,10 @@ void AuthPacket::write(DataOutputStream *dos)
 {
 	dos->writeByte(static_cast<byte>(stage));
 	dos->writeShort(static_cast<short>(fields.size()));
-	for (const auto &field : fields)
+	for (const auto &[key, value] : fields)
 	{
-		writeUtf(field.first, dos);
-		writeUtf(field.second, dos);
+		writeUtf(key, dos);
+		writeUtf(value, dos);
 	}
 }
 
@@ -41,7 +41,7 @@ void AuthPacket::handle(PacketListener *listener)
 int AuthPacket::getEstimatedSize()
 {
 	int size = 1 + 2;
-	for (const auto &field : fields)
-		size += 4 + static_cast<int>((field.first.length() + field.second.length()) * sizeof(wchar_t));
+	for (const auto &[key, value] : fields)
+		size += 4 + static_cast<int>((key.length() + value.length()) * sizeof(wchar_t));
 	return size;
 }
diff --git a/Minecraft.World/HandshakeManager.cpp b/Minecraft.World/HandshakeManager.cpp
new file mode 100644
index 00000000..2da686db
--- /dev/null
+++ b/Minecraft.World/HandshakeManager.cpp
@@ -0,0 +1,205 @@
+#include "stdafx.h"
+#include "HandshakeManager.h"
+#include "AuthModule.h"
+
+static constexpr auto PROTOCOL_VERSION = L"1.0";
+
+HandshakeManager::HandshakeManager(bool isServer)
+	: isServer(isServer), state(HandshakeState::IDLE), activeModule(nullptr)
+{
+}
+
+HandshakeManager::~HandshakeManager()
+{
+	for (auto &[name, module] : modules)
+		delete module;
+}
+
+void HandshakeManager::registerModule(AuthModule *module)
+{
+	modules[module->schemeName()] = module;
+}
+
+shared_ptr<AuthPacket> HandshakeManager::handlePacket(const shared_ptr<AuthPacket> &packet)
+{
+	return isServer ? handleServer(packet) : handleClient(packet);
+}
+
+shared_ptr<AuthPacket> HandshakeManager::createInitialPacket()
+{
+	state = HandshakeState::VERSION_SENT;
+	return makePacket(AuthStage::ANNOUNCE_VERSION, {{L"version", PROTOCOL_VERSION}});
+}
+
+shared_ptr<AuthPacket> HandshakeManager::handleServer(const shared_ptr<AuthPacket> &packet)
+{
+	switch (packet->stage)
+	{
+	case AuthStage::ANNOUNCE_VERSION:
+	{
+		protocolVersion = L"";
+		for (const auto &[k, v] : packet->fields)
+			if (k == L"version") protocolVersion = v;
+
+		if (protocolVersion != PROTOCOL_VERSION)
+			return fail();
+
+		// Pick first registered module as the scheme
+		if (modules.empty())
+			return fail();
+
+		activeModule = modules.begin()->second;
+		state = HandshakeState::SCHEME_DECLARED;
+		return makePacket(AuthStage::DECLARE_SCHEME, {
+			{L"version", PROTOCOL_VERSION},
+			{L"scheme", activeModule->schemeName()}
+		});
+	}
+
+	case AuthStage::ACCEPT_SCHEME:
+	{
+		wstring variation;
+		for (const auto &[k, v] : packet->fields)
+			if (k == L"variation") variation = v;
+
+		activeVariation = variation;
+		state = HandshakeState::SETTINGS_SENT;
+		auto settings = activeModule->getSettings(activeVariation);
+		return makePacket(AuthStage::SCHEME_SETTINGS, std::move(settings));
+	}
+
+	case AuthStage::BEGIN_AUTH:
+	{
+		state = HandshakeState::AUTH_IN_PROGRESS;
+		return nullptr;
+	}
+
+	case AuthStage::AUTH_DATA:
+	{
+		wstring uid, username;
+		if (!activeModule->onAuthData(packet->fields, uid, username))
+			return fail();
+
+		state = HandshakeState::AUTH_DATA_EXCHANGED;
+		return nullptr;
+	}
+
+	case AuthStage::AUTH_DONE:
+	{
+		wstring uid, username;
+		for (const auto &[k, v] : packet->fields)
+		{
+			if (k == L"uid") uid = v;
+			else if (k == L"username") username = v;
+		}
+
+		if (!activeModule->validate(uid, username))
+			return fail();
+
+		finalUid = uid;
+		finalUsername = username;
+		state = HandshakeState::IDENTITY_ASSIGNED;
+		return makePacket(AuthStage::ASSIGN_IDENTITY, {
+			{L"uid", finalUid},
+			{L"username", finalUsername}
+		});
+	}
+
+	case AuthStage::CONFIRM_IDENTITY:
+	{
+		wstring uid, username;
+		for (const auto &[k, v] : packet->fields)
+		{
+			if (k == L"uid") uid = v;
+			else if (k == L"username") username = v;
+		}
+
+		if (uid != finalUid || username != finalUsername)
+			return fail();
+
+		state = HandshakeState::COMPLETE;
+		return makePacket(AuthStage::AUTH_SUCCESS);
+	}
+
+	default:
+		return fail();
+	}
+}
+
+shared_ptr<AuthPacket> HandshakeManager::handleClient(const shared_ptr<AuthPacket> &packet)
+{
+	switch (packet->stage)
+	{
+	case AuthStage::DECLARE_SCHEME:
+	{
+		wstring scheme;
+		for (const auto &[k, v] : packet->fields)
+		{
+			if (k == L"version") protocolVersion = v;
+			else if (k == L"scheme") scheme = v;
+		}
+
+		if (protocolVersion != PROTOCOL_VERSION)
+			return fail();
+
+		auto it = modules.find(scheme);
+		if (it == modules.end())
+			return fail();
+
+		activeModule = it->second;
+
+		auto variations = activeModule->supportedVariations();
+		activeVariation = variations.empty() ? L"" : variations[0];
+
+		state = HandshakeState::SCHEME_ACCEPTED;
+		return makePacket(AuthStage::ACCEPT_SCHEME, {{L"variation", activeVariation}});
+	}
+
+	case AuthStage::SCHEME_SETTINGS:
+	{
+		state = HandshakeState::AUTH_IN_PROGRESS;
+		return makePacket(AuthStage::BEGIN_AUTH);
+	}
+
+	case AuthStage::ASSIGN_IDENTITY:
+	{
+		for (const auto &[k, v] : packet->fields)
+		{
+			if (k == L"uid") finalUid = v;
+			else if (k == L"username") finalUsername = v;
+		}
+
+		state = HandshakeState::IDENTITY_CONFIRMED;
+		return makePacket(AuthStage::CONFIRM_IDENTITY, {
+			{L"uid", finalUid},
+			{L"username", finalUsername}
+		});
+	}
+
+	case AuthStage::AUTH_SUCCESS:
+	{
+		state = HandshakeState::COMPLETE;
+		return nullptr;
+	}
+
+	case AuthStage::AUTH_FAILURE:
+	{
+		state = HandshakeState::FAILED;
+		return nullptr;
+	}
+
+	default:
+		return fail();
+	}
+}
+
+shared_ptr<AuthPacket> HandshakeManager::makePacket(AuthStage stage, vector<pair<wstring, wstring>> fields)
+{
+	return std::make_shared<AuthPacket>(stage, std::move(fields));
+}
+
+shared_ptr<AuthPacket> HandshakeManager::fail()
+{
+	state = HandshakeState::FAILED;
+	return makePacket(AuthStage::AUTH_FAILURE);
+}
diff --git a/Minecraft.World/HandshakeManager.h b/Minecraft.World/HandshakeManager.h
new file mode 100644
index 00000000..9e9da1c8
--- /dev/null
+++ b/Minecraft.World/HandshakeManager.h
@@ -0,0 +1,57 @@
+#pragma once
+using namespace std;
+
+#include <string>
+#include <unordered_map>
+#include <memory>
+#include "AuthPackets.h"
+
+class AuthModule;
+
+enum class HandshakeState : uint8_t
+{
+	IDLE,
+	VERSION_SENT,
+	SCHEME_DECLARED,
+	SCHEME_ACCEPTED,
+	SETTINGS_SENT,
+	AUTH_IN_PROGRESS,
+	AUTH_DATA_EXCHANGED,
+	IDENTITY_ASSIGNED,
+	IDENTITY_CONFIRMED,
+	COMPLETE,
+	FAILED
+};
+
+class HandshakeManager
+{
+private:
+	bool isServer;
+	HandshakeState state;
+	unordered_map<wstring, AuthModule *> modules;
+	AuthModule *activeModule;
+	wstring activeVariation;
+	wstring protocolVersion;
+
+public:
+	wstring finalUid;
+	wstring finalUsername;
+
+	HandshakeManager(bool isServer);
+	~HandshakeManager();
+
+	void registerModule(AuthModule *module);
+	shared_ptr<AuthPacket> handlePacket(const shared_ptr<AuthPacket> &packet);
+	shared_ptr<AuthPacket> createInitialPacket();
+
+	bool isComplete() const { return state == HandshakeState::COMPLETE; }
+	bool isFailed() const { return state == HandshakeState::FAILED; }
+	HandshakeState getState() const { return state; }
+
+private:
+	shared_ptr<AuthPacket> handleServer(const shared_ptr<AuthPacket> &packet);
+	shared_ptr<AuthPacket> handleClient(const shared_ptr<AuthPacket> &packet);
+
+	shared_ptr<AuthPacket> makePacket(AuthStage stage, vector<pair<wstring, wstring>> fields = {});
+	shared_ptr<AuthPacket> fail();
+};
diff --git a/Minecraft.World/PacketListener.cpp b/Minecraft.World/PacketListener.cpp
index 490922c7..bd340add 100644
--- a/Minecraft.World/PacketListener.cpp
+++ b/Minecraft.World/PacketListener.cpp
@@ -492,7 +492,7 @@ void PacketListener::handleGameCommand(shared_ptr<GameCommandPacket> packet)
 	onUnhandledPacket( (shared_ptr<Packet> ) packet);
 }
 
-void PacketListener::handleAuth(shared_ptr<AuthPacket> packet)
+void PacketListener::handleAuth(const shared_ptr<AuthPacket> &packet)
 {
 	onUnhandledPacket( (shared_ptr<Packet> ) packet);
 }
diff --git a/Minecraft.World/PacketListener.h b/Minecraft.World/PacketListener.h
index 9f5b1b9d..bf2ebdad 100644
--- a/Minecraft.World/PacketListener.h
+++ b/Minecraft.World/PacketListener.h
@@ -229,6 +229,5 @@ public:
 	virtual void handleXZ(shared_ptr<XZPacket> packet);
 	virtual void handleGameCommand(shared_ptr<GameCommandPacket> packet);
 
-	// MCConsoles Auth
-	virtual void handleAuth(shared_ptr<AuthPacket> packet);
+	virtual void handleAuth(const shared_ptr<AuthPacket> &packet);
 };
diff --git a/Minecraft.World/cmake/sources/Common.cmake b/Minecraft.World/cmake/sources/Common.cmake
index eb4a6379..6f45dfdf 100644
--- a/Minecraft.World/cmake/sources/Common.cmake
+++ b/Minecraft.World/cmake/sources/Common.cmake
@@ -318,6 +318,8 @@ set(_MINECRAFT_WORLD_COMMON_NET_MINECRAFT_NETWORK_PACKET
   "${CMAKE_CURRENT_SOURCE_DIR}/GameEventPacket.h"
   "${CMAKE_CURRENT_SOURCE_DIR}/GetInfoPacket.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/GetInfoPacket.h"
+  "${CMAKE_CURRENT_SOURCE_DIR}/HandshakeManager.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/HandshakeManager.h"
   "${CMAKE_CURRENT_SOURCE_DIR}/InteractPacket.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/InteractPacket.h"
   "${CMAKE_CURRENT_SOURCE_DIR}/KeepAlivePacket.cpp"