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Windows: Enable screen protection by default to block screenshots, recordings & Windows Recall. Add configurable setting in Preferences, Installer, and MSI.

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This update introduces a screen protection mechanism that leverages the Windows Display Affinity API to prevent screen capture, screen recording, and inclusion in the Windows 11 Recall feature. By default, all VeraCrypt windows, menus, and tooltips are protected. Users can enable or disable this feature through a new setting available in the application Preferences, as well as in the installer and MSI configurations.

This enhances user privacy by mitigating potential leaks of sensitive interface content.

Note: Due to a regression in Windows 11 affecting layered windows, ComboBox dropdowns cannot currently be protected by this mechanism.
This commit is contained in:
Mounir IDRASSI
2025-05-24 15:28:39 +09:00
parent 44a9f8bcff
commit 9ea5ccc4aa
68 changed files with 691 additions and 40 deletions
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307
src/Common/Dlgcode.c
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@@ -2299,6 +2299,9 @@ BOOL CALLBACK AboutDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lParam
EndDialog (hwndDlg, 0);
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -2369,6 +2372,10 @@ static BOOL CALLBACK StaticModelessWaitDlgProc (HWND hwndDlg, UINT msg, WPARAM w
StaticModelessWaitDlgHandle = NULL;
EndDialog (hwndDlg, 0);
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -3005,6 +3012,7 @@ typedef struct
void ExceptionHandlerThread (void *threadArg)
{
ExceptionHandlerThreadArgs *args = (ExceptionHandlerThreadArgs *) threadArg;
ScreenCaptureBlocker blocker;
EXCEPTION_POINTERS *ep = args->ExceptionPointers;
//DWORD addr;
@@ -3473,6 +3481,25 @@ BOOL WriteMemoryProtectionConfig (BOOL bEnable)
return WriteLocalMachineRegistryDword (L"SYSTEM\\CurrentControlSet\\Services\\veracrypt", VC_ENABLE_MEMORY_PROTECTION, config);
}
BOOL ReadScreenProtectionConfig()
{
DWORD config;
if (!ReadLocalMachineRegistryDword(L"SYSTEM\\CurrentControlSet\\Services\\veracrypt", VC_ENABLE_SCREEN_PROTECTION, &config))
{
// enabled by default
config = 1;
}
return (config) ? TRUE : FALSE;
}
BOOL WriteScreenProtectionConfig(BOOL bEnable)
{
DWORD config = bEnable ? 1 : 0;
return WriteLocalMachineRegistryDword(L"SYSTEM\\CurrentControlSet\\Services\\veracrypt", VC_ENABLE_SCREEN_PROTECTION, config);
}
BOOL LoadSysEncSettings ()
{
BOOL status = TRUE;
@@ -4354,6 +4381,10 @@ BOOL CALLBACK TextEditDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lPa
NormalCursor ();
EndDialog (hwndDlg, 0);
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -4495,6 +4526,10 @@ BOOL CALLBACK TextInfoDialogBoxDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, L
NormalCursor ();
EndDialog (hwndDlg, 0);
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -4685,6 +4720,10 @@ BOOL CALLBACK RawDevicesDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM l
return 1;
}
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
case WM_COMMAND:
case WM_NOTIFY:
// catch non-device line selected
@@ -5776,6 +5815,9 @@ static BOOL CALLBACK LocalizeDialogEnum( HWND hwnd, LPARAM font)
void LocalizeDialog (HWND hwnd, char *stringId)
{
LastDialogId = stringId;
AttachProtectionToCurrentThread(hwnd);
SetWindowLongPtrW (hwnd, GWLP_USERDATA, (LONG_PTR) 'VERA');
SendMessageW (hwnd, WM_SETFONT, (WPARAM) hUserFont, 0);
@@ -6811,6 +6853,10 @@ BOOL CALLBACK BenchmarkDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lP
break;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
}
@@ -6989,6 +7035,9 @@ exit:
return 1;
}
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
}
@@ -7416,6 +7465,10 @@ exit:
NormalCursor ();
return 1;
}
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
}
@@ -7768,6 +7821,10 @@ CipherTestDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
idTestCipher = -1;
EndDialog (hwndDlg, 0);
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -8053,6 +8110,10 @@ BOOL CALLBACK MultiChoiceDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPA
// This prevents the window from being closed by pressing Alt-F4 (the Close button is hidden).
// Note that the OS handles modal MessageBox() dialog windows the same way.
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
}
return 0;
@@ -8499,6 +8560,7 @@ typedef struct
static void _cdecl WaitThread (void* pParam)
{
WaitThreadParam* pThreadParam = (WaitThreadParam*) pParam;
ScreenCaptureBlocker screenCaptureBlocker;
pThreadParam->callback(pThreadParam->pArg, pThreadParam->hwnd);
@@ -8553,6 +8615,10 @@ BOOL CALLBACK WaitDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lParam)
else
return 0;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
return 0;
default:
if (msg == g_wmWaitDlg)
{
@@ -12070,6 +12136,10 @@ BOOL CALLBACK SecurityTokenPasswordDlgProc (HWND hwndDlg, UINT msg, WPARAM wPara
}
return 1;
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
case WM_NCDESTROY:
{
/* unregister drap-n-drop support */
@@ -12142,6 +12212,10 @@ static BOOL CALLBACK NewSecurityTokenKeyfileDlgProc (HWND hwndDlg, UINT msg, WPA
return 1;
}
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
case WM_COMMAND:
switch (lw)
{
@@ -12298,6 +12372,10 @@ BOOL CALLBACK SecurityTokenKeyfileDlgProc (HWND hwndDlg, UINT msg, WPARAM wParam
return 1;
}
case WM_DESTROY:
DetachProtectionFromCurrentThread();
break;
case WM_COMMAND:
case WM_NOTIFY:
if (msg == WM_COMMAND && lw == IDOK || msg == WM_NOTIFY && ((NMHDR *)lParam)->code == LVN_ITEMACTIVATE)
@@ -14097,6 +14175,8 @@ static unsigned int __stdcall SecureDesktopThread( LPVOID lpThreadParameter )
if (bNewDesktopSet)
{
ScreenCaptureBlocker blocker;
// call ImmDisableIME　from imm32.dll to disable IME since it can create issue with secure desktop
// cf: https://keepass.info/help/kb/sec_desk.html#ime
HMODULE hImmDll = LoadLibraryEx (L"imm32.dll", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
@@ -16098,3 +16178,230 @@ cleanup:
return result;
}
#endif
#if !defined(SETUP) && !defined(VC_COMREG)
/*
* Screen Protection Functions
* These functions provide against screen capture, screen recording,
* and Windows 11 Recall feature by leveraging the Windows Display Affinity API.
*
* Main windows/dialogs are protected via HCBT_ACTIVATE hook while menus/tooltips are protected
* via selective window subclassing that allows calling SetWindowDisplayAffinity when they are created.
*
* limitations: ComboBox dropdowns are not protected on Windows 11 because of a regression affecting
* layered windows (combobox dropdowns are layered windows)
*
* Author: Mounir IDRASSI <mounir.idrassi@amcrypto.jp> for the VeraCrypt project
* Date: 2025-05-23
*
*/
#include <atomic>
#include <map>
#include <mutex>
static std::once_flag g_configOnce; // ensures one-time read
static std::atomic_bool g_screenProtectionEnabled; // readonly after init
static thread_local HHOOK g_cbtHook = nullptr; // one per thread
static thread_local int g_protectionRefCount = 0;
std::map<HWND, WNDPROC> g_MenuWndProcs;
std::map<HWND, bool> g_Initialized;
std::mutex g_MenuMutex;
static void InitScreenProtectionFlag()
{
// Runs exactly once thanks to std::call_once
BOOL enabled = ReadScreenProtectionConfig();
g_screenProtectionEnabled.store(enabled, std::memory_order_release);
}
static bool IsScreenProtectionEnabled()
{
std::call_once(g_configOnce, InitScreenProtectionFlag);
return g_screenProtectionEnabled.load(std::memory_order_acquire);
}
// Custom WndProc for menu windows
static LRESULT CALLBACK ProtectedWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
if (msg == WM_CREATE) {
SetWindowDisplayAffinity(hwnd, WDA_EXCLUDEFROMCAPTURE);
}
// Forward to original WndProc
WNDPROC origProc = nullptr;
{
std::lock_guard<std::mutex> lock(g_MenuMutex);
auto it = g_MenuWndProcs.find(hwnd);
if (it != g_MenuWndProcs.end())
origProc = it->second;
}
LRESULT result = 0;
if (origProc) {
result = CallWindowProc(origProc, hwnd, msg, wParam, lParam);
}
else {
// fallback to DefWindowProc if somehow no mapping exists
result = DefWindowProc(hwnd, msg, wParam, lParam);
}
if (msg == WM_NCDESTROY) {
// Clean up the mapping when the window is destroyed
std::lock_guard<std::mutex> lock(g_MenuMutex);
g_MenuWndProcs.erase(hwnd);
g_Initialized.erase(hwnd);
}
return result;
}
void SubclassProtectedWindow(HWND hwnd)
{
WNDPROC origProc = (WNDPROC)GetWindowLongPtr(hwnd, GWLP_WNDPROC);
{
std::lock_guard<std::mutex> lock(g_MenuMutex);
g_MenuWndProcs[hwnd] = origProc;
g_Initialized[hwnd] = false;
}
SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)ProtectedWndProc);
}
BOOL IsMenuWindow(HWND hwnd)
{
TCHAR szClass[256] = { 0 };
GetClassName(hwnd, szClass, 255);
if (!_tcsicmp(szClass, _T("#32768")))
{
return TRUE;
}
else
{
return FALSE;
}
}
BOOL IsTooltipWindow(HWND hwnd)
{
TCHAR szClass[256] = { 0 };
GetClassName(hwnd, szClass, 255);
if (!_tcsicmp(szClass, _T("tooltips_class32")))
{
return TRUE;
}
else if (!_tcsicmp(szClass, _T("SysShadow")))
{
// check if it has WS_EX_TOOLWINDOW style: this helps identify the arrow area of the tooltip
LONG_PTR exStyle = GetWindowLongPtr(hwnd, GWL_EXSTYLE);
if (exStyle & WS_EX_TOOLWINDOW)
{
return TRUE;
}
}
return FALSE;
}
static LRESULT CALLBACK CBT_PROC(int nCode, WPARAM wParam, LPARAM lParam)
{
// for normal windows, HCBT_ACTIVATE is enough but for menus and tooltips we need to subclass them
// in order to call SetWindowDisplayAffinity when they are created
if (nCode == HCBT_ACTIVATE)
{
HWND hwnd = (HWND)(wParam);
LONG_PTR style = GetWindowLongPtr(hwnd, GWL_STYLE);
if ((style & (WS_POPUP | WS_OVERLAPPEDWINDOW)))
{
// get current affinity
DWORD dwAffinity = 0;
if (GetWindowDisplayAffinity(hwnd, &dwAffinity))
{
// if the affinity is not set, set it to exclude from capture
if (dwAffinity != WDA_EXCLUDEFROMCAPTURE)
{
SetWindowDisplayAffinity(hwnd, WDA_EXCLUDEFROMCAPTURE);
}
else
{
dwAffinity = 0;
}
}
else
{
// if we can't get the affinity, set it to exclude from capture
SetWindowDisplayAffinity(hwnd, WDA_EXCLUDEFROMCAPTURE);
}
}
}
if (nCode == HCBT_CREATEWND)
{
HWND hwnd = (HWND)(wParam);
if (IsMenuWindow(hwnd) || IsTooltipWindow(hwnd))
{
SubclassProtectedWindow(hwnd);
}
}
return CallNextHookEx(g_cbtHook, nCode, wParam, lParam);
}
BOOL AttachProtectionToCurrentThread(HWND hwnd)
{
if (!IsScreenProtectionEnabled())
return TRUE;
if (hwnd) SetWindowDisplayAffinity(hwnd, WDA_EXCLUDEFROMCAPTURE);
if (g_protectionRefCount == 0)
{
// From now on, protect every future window/menu automatically.
// Set the hook only once per thread
g_cbtHook = SetWindowsHookExW(WH_CBT, CBT_PROC,
NULL, // procedure lives in EXE
GetCurrentThreadId()); // thread-local hook
if (!g_cbtHook)
{
return FALSE;
}
}
g_protectionRefCount++;
return TRUE;
}
void DetachProtectionFromCurrentThread()
{
if (!IsScreenProtectionEnabled())
return;
if (g_protectionRefCount == 0)
return;
--g_protectionRefCount;
if (g_protectionRefCount == 0)
{
// Last detach for this thread: remove hook
if (g_cbtHook)
{
UnhookWindowsHookEx(g_cbtHook);
g_cbtHook = nullptr;
}
}
}
#else
// Dummy functions for screen protection
BOOL AttachProtectionToCurrentThread(HWND hwnd)
{
return TRUE;
}
void DetachProtectionFromCurrentThread()
{
}
#endif