4 files changed, 117 insertions, 0 deletions
diff --git a/src/Common/BootEncryption.cpp b/src/Common/BootEncryption.cpp
index 0a2afb12..502b4e06 100644
--- a/src/Common/BootEncryption.cpp
+++ b/src/Common/BootEncryption.cpp
@@ -5176,6 +5176,12 @@ namespace VeraCrypt
 		if (IsNonInstallMode())
 			throw ErrorException ("FEATURE_REQUIRES_INSTALLATION", SRC_POS);
 
+		/* check if the system drive is already encrypted by BitLocker */
+		wchar_t windowsDrive = (wchar_t) towupper (GetWindowsDirectory()[0]);
+		BitLockerEncryptionStatus bitLockerStatus = GetBitLockerEncryptionStatus (windowsDrive);
+		if (bitLockerStatus == BL_Status_Protected)
+			throw ErrorException ("SYSENC_BITLOCKER_CONFLICT", SRC_POS);
+
 		SystemDriveConfiguration config = GetSystemDriveConfiguration ();
 
 		if (SystemDriveIsDynamic())
diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index 813f2b07..bd1f6f84 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -14372,3 +14372,105 @@ void GetAppRandomSeed (unsigned char* pbRandSeed, size_t cbRandSeed)
 	burn (&tctx, sizeof(tctx));
 }
 #endif
+
+/*
+ * GetBitLockerEncryptionStatus: retuns the BitLocker encryption status of a given drive.
+ */
+
+typedef enum BitLockerProtectionState
+{
+    BL_State_FullyDecrypted = 0,
+    BL_State_FullyEncrypted = 1, 
+    BL_State_EncryptionInProgress = 2,
+    BL_State_DecryptionInProgress = 3,
+    BL_State_EncryptionSuspended = 4,
+    BL_State_DecryptionSuspended = 5,
+    BL_State_FullyEncryptedWipeInProgress = 6,
+    BL_State_FullyEncryptedWipeSuspended = 7
+} BitLockerProtectionState;
+
+typedef HRESULT (WINAPI *SHCreateItemFromParsingNameFn)(
+    PCWSTR   pszPath,
+    IBindCtx* pbc,
+    REFIID   riid,
+    void** ppv
+);
+
+typedef HRESULT (WINAPI *PSGetPropertyKeyFromNameFn)(
+    _In_ PCWSTR pszName,
+    _Out_ PROPERTYKEY* ppropkey);
+
+
+/*
+   Code derived from https://stackoverflow.com/questions/23841973/how-to-tell-if-drive-is-bitlocker-encrypted-without-admin-privilege/47192128#47192128
+*/
+BitLockerEncryptionStatus GetBitLockerEncryptionStatus(WCHAR driveLetter)
+{    
+    HRESULT hr;
+    BitLockerEncryptionStatus blStatus = BL_Status_Unknown;
+    wchar_t szDllPath[MAX_PATH] = { 0 };
+    HMODULE hShell32 = NULL;
+
+    CoInitialize(NULL);
+
+    if (GetSystemDirectory(szDllPath, MAX_PATH))
+        StringCchCatW(szDllPath, MAX_PATH, L"\\Shell32.dll");
+    else
+        StringCchCopyW(szDllPath, MAX_PATH, L"C:\\Windows\\System32\\Shell32.dll");
+
+    hShell32 = LoadLibrary(szDllPath);
+    if (hShell32)
+    {
+        SHCreateItemFromParsingNameFn SHCreateItemFromParsingNamePtr = (SHCreateItemFromParsingNameFn)GetProcAddress(hShell32, "SHCreateItemFromParsingName");
+        if (SHCreateItemFromParsingNamePtr)
+        {
+            HMODULE hPropsys = NULL;
+
+            if (GetSystemDirectory(szDllPath, MAX_PATH))
+                StringCchCatW(szDllPath, MAX_PATH, L"\\Propsys.dll");
+            else
+                StringCchCopyW(szDllPath, MAX_PATH, L"C:\\Windows\\System32\\Propsys.dll");
+
+            hPropsys = LoadLibrary(szDllPath);
+            if (hPropsys)
+            {
+                PSGetPropertyKeyFromNameFn PSGetPropertyKeyFromNamePtr = (PSGetPropertyKeyFromNameFn)GetProcAddress(hPropsys, "PSGetPropertyKeyFromName");
+                if (PSGetPropertyKeyFromNamePtr)
+                {
+					WCHAR parsingName[3] = {driveLetter, L':', 0};
+                    IShellItem2* drive = NULL;
+                    hr = SHCreateItemFromParsingNamePtr(parsingName, NULL, IID_PPV_ARGS(&drive));
+                    if (SUCCEEDED(hr)) {
+                        PROPERTYKEY pKey;
+                        hr = PSGetPropertyKeyFromNamePtr(L"System.Volume.BitLockerProtection", &pKey);
+                        if (SUCCEEDED(hr)) {
+                            PROPVARIANT prop;
+                            PropVariantInit(&prop);
+                            hr = drive->GetProperty(pKey, &prop);
+                            if (SUCCEEDED(hr)) {
+                                int status = prop.intVal;
+                                if (status == BL_State_FullyEncrypted || status == BL_State_DecryptionInProgress || status == BL_State_DecryptionSuspended)
+                                    blStatus = BL_Status_Protected;
+                                else
+                                    blStatus = BL_Status_Unprotected;
+                            }
+                        }
+                    }
+                    if (drive)
+                        drive->Release();
+                }
+
+                FreeLibrary(hPropsys);
+            }
+        }
+        else
+        {
+            blStatus = BL_Status_Unprotected; // before Vista, there was no Bitlocker
+        }
+
+        FreeLibrary(hShell32);
+    }
+
+    CoUninitialize();
+    return blStatus;
+}
diff --git a/src/Common/Dlgcode.h b/src/Common/Dlgcode.h
index 29a13624..9e77c0a9 100644
--- a/src/Common/Dlgcode.h
+++ b/src/Common/Dlgcode.h
@@ -242,6 +242,13 @@ typedef struct
 
 } OpenVolumeContext;
 
+typedef enum BitLockerEncryptionStatus
+{
+    BL_Status_Unknown = 0,
+    BL_Status_Unprotected,
+    BL_Status_Protected
+} BitLockerEncryptionStatus;
+
 
 #define DEFAULT_VOL_CREATION_WIZARD_MODE	WIZARD_MODE_FILE_CONTAINER
 
@@ -548,6 +555,7 @@ BOOL GetSetupconfigLocation (wchar_t* path, DWORD cchSize);
 BOOL BufferHasPattern (const unsigned char* buffer, size_t bufferLen, const void* pattern, size_t patternLen);
 BOOL EnableProcessProtection();
 void SafeOpenURL (LPCWSTR szUrl);
+BitLockerEncryptionStatus GetBitLockerEncryptionStatus(WCHAR driveLetter);
 #ifdef _WIN64
 void GetAppRandomSeed (unsigned char* pbRandSeed, size_t cbRandSeed);
 #endif
diff --git a/src/Common/Language.xml b/src/Common/Language.xml
index 3c59f762..d071cec4 100644
--- a/src/Common/Language.xml
+++ b/src/Common/Language.xml
@@ -1439,6 +1439,7 @@
     <entry lang="en" key="IDC_DISABLE_MOUNT_MANAGER">Only create virtual device without mounting on selected drive letter</entry>
     <entry lang="en" key="LEGACY_PASSWORD_UTF8_TOO_LONG">The entered password is too long: its UTF-8 representation exceeds 64 bytes.</entry>
     <entry lang="en" key="HIDDEN_CREDS_SAME_AS_OUTER">The Hidden volume can't have the same password, PIM and keyfiles as the Outer volume</entry>
+    <entry lang="en" key="SYSENC_BITLOCKER_CONFLICT">VeraCrypt does not support encrypting a system drive that is already encrypted by BitLocker.</entry>
   </localization>
   <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
     <xs:element name="VeraCrypt">