From b4b51bd909de630ca5715a4eedce2a71d43db268 Mon Sep 17 00:00:00 2001
From: Mounir IDRASSI <mounir.idrassi@idrix.fr>
Date: Fri, 3 Jul 2015 02:02:17 +0200
Subject: Windows: Solve privacy issue inherited from TrueCrypt and linked to
 the update of configuration and history XML files everytime VeraCrypt main
 window is opened, even if there was no modifications. This could give
 information about the usage of VeraCrypt. Now, configuration and history XML
 files are updated only when there are modifications.

---
 src/Format/Tcformat.c | 94 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 73 insertions(+), 21 deletions(-)

(limited to 'src/Format')

diff --git a/src/Format/Tcformat.c b/src/Format/Tcformat.c
index e1a1d65e..bee1e028 100644
--- a/src/Format/Tcformat.c
+++ b/src/Format/Tcformat.c
@@ -712,32 +712,69 @@ static BOOL CreatingHiddenSysVol (void)
 		&& bHiddenVol && !bHiddenVolHost);
 }
 
-static void LoadSettings (HWND hwndDlg)
+static void ConfigReadCompareInt(char *configKey, int defaultValue, int* pOutputValue, BOOL bOnlyCheckModified, BOOL* pbModified)
+{
+	int intValue = ConfigReadInt (configKey, defaultValue);
+	if (pOutputValue)
+	{
+		if (pbModified && (*pOutputValue != intValue))
+			*pbModified = TRUE;
+		if (!bOnlyCheckModified)
+			*pOutputValue = intValue;
+	}
+}
+
+static void ConfigReadCompareString (char *configKey, char *defaultValue, char *str, int maxLen, BOOL bOnlyCheckModified, BOOL *pbModified)
+{
+	char *strValue = (char*) malloc (maxLen);
+	memcpy (strValue, str, maxLen);
+
+	ConfigReadString (configKey, defaultValue, strValue, maxLen);
+
+	if (pbModified && strcmp (str, strValue))
+		*pbModified = TRUE;
+	if (!bOnlyCheckModified)
+		memcpy(str, strValue, maxLen);
+
+	free (strValue);
+}
+
+static void LoadSettingsAndCheckModified (HWND hwndDlg, BOOL bOnlyCheckModified, BOOL* pbSettingsModified, BOOL* pbHistoryModified)
 {
-	EnableHwEncryption ((ReadDriverConfigurationFlags() & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION) ? FALSE : TRUE);
+	if (!bOnlyCheckModified)
+		EnableHwEncryption ((ReadDriverConfigurationFlags() & TC_DRIVER_CONFIG_DISABLE_HARDWARE_ENCRYPTION) ? FALSE : TRUE);
 
 	WipeAlgorithmId savedWipeAlgorithm = TC_WIPE_NONE;
 
-	LoadSysEncSettings (hwndDlg);
+	if (!bOnlyCheckModified)
+		LoadSysEncSettings (hwndDlg);
 
-	if (LoadNonSysInPlaceEncSettings (&savedWipeAlgorithm) != 0)
+	if (!bOnlyCheckModified && LoadNonSysInPlaceEncSettings (&savedWipeAlgorithm) != 0)
 		bInPlaceEncNonSysPending = TRUE;
 
-	defaultKeyFilesParam.EnableKeyFiles = FALSE;
+	if (!bOnlyCheckModified)
+		defaultKeyFilesParam.EnableKeyFiles = FALSE;
 
-	bStartOnLogon =	ConfigReadInt ("StartOnLogon", FALSE);
+	ConfigReadCompareInt ("StartOnLogon", FALSE, &bStartOnLogon, bOnlyCheckModified, pbSettingsModified);
 
-	HiddenSectorDetectionStatus = ConfigReadInt ("HiddenSectorDetectionStatus", 0);
+	ConfigReadCompareInt ("HiddenSectorDetectionStatus", 0, &HiddenSectorDetectionStatus, bOnlyCheckModified, pbSettingsModified);
 
-	bHistory = ConfigReadInt ("SaveVolumeHistory", FALSE);
+	ConfigReadCompareInt ("SaveVolumeHistory", FALSE, &bHistory, bOnlyCheckModified, pbSettingsModified);
 
-	ConfigReadString ("SecurityTokenLibrary", "", SecurityTokenLibraryPath, sizeof (SecurityTokenLibraryPath) - 1);
-	if (SecurityTokenLibraryPath[0])
+	ConfigReadCompareString ("SecurityTokenLibrary", "", SecurityTokenLibraryPath, sizeof (SecurityTokenLibraryPath) - 1, bOnlyCheckModified, pbSettingsModified);
+	if (!bOnlyCheckModified && SecurityTokenLibraryPath[0])
 		InitSecurityTokenLibrary(hwndDlg);
 
+	if (bOnlyCheckModified)
+	{
+		char langid[6] = {0};
+		StringCbCopyA (langid, sizeof(langid), GetPreferredLangId ());
+		ConfigReadCompareString ("Language", "", langid, sizeof (langid), TRUE, pbSettingsModified);
+	}
+
 	if (hwndDlg != NULL)
 	{
-		LoadCombo (GetDlgItem (hwndDlg, IDC_COMBO_BOX));
+		LoadCombo (GetDlgItem (hwndDlg, IDC_COMBO_BOX), bHistory, bOnlyCheckModified, pbHistoryModified);
 		return;
 	}
 
@@ -745,24 +782,39 @@ static void LoadSettings (HWND hwndDlg)
 		return;
 }
 
+static void LoadSettings (HWND hwndDlg)
+{
+	LoadSettingsAndCheckModified (hwndDlg, FALSE, NULL, NULL);
+}
+
 static void SaveSettings (HWND hwndDlg)
 {
 	WaitCursor ();
 
-	if (hwndDlg != NULL)
+	// Check first if modifications ocurred before writing to the settings and history files
+	// This avoids leaking information about VeraCrypt usage when user only mount volumes without changing setttings or history
+	BOOL bSettingsChanged = FALSE;
+	BOOL bHistoryChanged = FALSE;
+
+	LoadSettingsAndCheckModified (hwndDlg, TRUE, &bSettingsChanged, &bHistoryChanged);
+
+	if (bHistoryChanged && hwndDlg != NULL)
 		DumpCombo (GetDlgItem (hwndDlg, IDC_COMBO_BOX), !bHistory);
 
-	ConfigWriteBegin ();
+	if (bSettingsChanged)
+	{
+		ConfigWriteBegin ();
 
-	ConfigWriteInt ("StartOnLogon",	bStartOnLogon);
-	ConfigWriteInt ("HiddenSectorDetectionStatus", HiddenSectorDetectionStatus);
-	ConfigWriteInt ("SaveVolumeHistory", bHistory);
-	ConfigWriteString ("SecurityTokenLibrary", SecurityTokenLibraryPath[0] ? SecurityTokenLibraryPath : "");
+		ConfigWriteInt ("StartOnLogon",	bStartOnLogon);
+		ConfigWriteInt ("HiddenSectorDetectionStatus", HiddenSectorDetectionStatus);
+		ConfigWriteInt ("SaveVolumeHistory", bHistory);
+		ConfigWriteString ("SecurityTokenLibrary", SecurityTokenLibraryPath[0] ? SecurityTokenLibraryPath : "");
 
-	if (GetPreferredLangId () != NULL)
-		ConfigWriteString ("Language", GetPreferredLangId ());
+		if (GetPreferredLangId () != NULL)
+			ConfigWriteString ("Language", GetPreferredLangId ());
 
-	ConfigWriteEnd (hwndDlg);
+		ConfigWriteEnd (hwndDlg);
+	}
 
 	NormalCursor ();
 }
@@ -3783,7 +3835,7 @@ BOOL CALLBACK PageDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
 
 				SendMessage (GetDlgItem (hwndDlg, IDC_COMBO_BOX), CB_LIMITTEXT, TC_MAX_PATH, 0);
 
-				LoadCombo (GetDlgItem (hwndDlg, IDC_COMBO_BOX));
+				LoadCombo (GetDlgItem (hwndDlg, IDC_COMBO_BOX), bHistory, FALSE, NULL);
 
 				SendMessage (GetDlgItem (hwndDlg, IDC_NO_HISTORY), BM_SETCHECK, bHistory ? BST_UNCHECKED : BST_CHECKED, 0);
 
-- 
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