Automate TrueCrypt by using its driver instead of command prompt


If I want to see all the volumes that are mounted with c# then I will have to query the true crypt driver because there is not a command I can send to TrueCrypt.exe that will return me that info.

So if I want to see all the volumes that are mounted and into what drive they are mounted I will call TrueCryptHelper.GetMountedVolumes();:

here is the code:

public static class TrueCryptHelper
    public static Dictionary<char, string> GetMountedVolumes()
        uint size = (uint)Marshal.SizeOf(typeof(MOUNT_LIST_STRUCT));
        IntPtr buffer = Marshal.AllocHGlobal((int)size);
        uint bytesReturned;
        IntPtr _hdev = CreateFile("\\\\.\\TrueCrypt", FileAccess.ReadWrite, FileShare.ReadWrite, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero);
        bool bResult = DeviceIoControl(_hdev, TC_GET_MOUNTED_VOLUMES, buffer, size, buffer, size, out bytesReturned, IntPtr.Zero);
        Marshal.PtrToStructure(buffer, mount);

        Dictionary<char, string> items = new Dictionary<char, string>();

        for (int i = 0; i < 26; i++)
            string filePath = mount.wszVolume[i].ToString().Replace(@"\??\", "");
            if (filePath.Length > 2)
                items[(char)('A' + i)] = filePath;
            //Console.WriteLine("{0}: => {1}", (char)('A' + i), mount.wszVolume[i]);

        return items;

    private static readonly uint TC_GET_DRIVER_VERSION                      = (uint)CTL_CODE(0x00000022, 0x800 + (01), 0, 0);
    private static readonly uint TC_GET_BOOT_LOADER_VERSION                 = (uint)CTL_CODE(0x00000022, 0x800 + (02), 0, 0);
    private static readonly uint TC_MOUNT_VOLUME                            = (uint)CTL_CODE(0x00000022, 0x800 + (03), 0, 0);
    private static readonly uint TC_DISMOUNT_VOLUME                         = (uint)CTL_CODE(0x00000022, 0x800 + (04), 0, 0);
    private static readonly uint TC_DISMOUNT_ALL_VOLUMES                    = (uint)CTL_CODE(0x00000022, 0x800 + (05), 0, 0);
    private static readonly uint TC_GET_MOUNTED_VOLUMES                     = (uint)CTL_CODE(0x00000022, 0x800 + (06), 0, 0);
    private static readonly uint TC_GET_VOLUME_PROPERTIES                   = (uint)CTL_CODE(0x00000022, 0x800 + (07), 0, 0);
    private static readonly uint TC_GET_DEVICE_REFCOUNT                     = (uint)CTL_CODE(0x00000022, 0x800 + (08), 0, 0);
    private static readonly uint TC_WAS_REFERENCED_DEVICE_DELETED           = (uint)CTL_CODE(0x00000022, 0x800 + (09), 0, 0);
    private static readonly uint TC_IS_ANY_VOLUME_MOUNTED                   = (uint)CTL_CODE(0x00000022, 0x800 + (10), 0, 0);
    private static readonly uint TC_GET_PASSWORD_CACHE_STATUS               = (uint)CTL_CODE(0x00000022, 0x800 + (11), 0, 0);
    private static readonly uint TC_WIPE_PASSWORD_CACHE                     = (uint)CTL_CODE(0x00000022, 0x800 + (12), 0, 0);
    private static readonly uint TC_OPEN_TEST                               = (uint)CTL_CODE(0x00000022, 0x800 + (13), 0, 0);
    private static readonly uint TC_GET_DRIVE_PARTITION_INFO                = (uint)CTL_CODE(0x00000022, 0x800 + (14), 0, 0);
    private static readonly uint TC_GET_DRIVE_GEOMETRY                      = (uint)CTL_CODE(0x00000022, 0x800 + (15), 0, 0);
    private static readonly uint TC_PROBE_REAL_DRIVE_SIZE                   = (uint)CTL_CODE(0x00000022, 0x800 + (16), 0, 0);
    private static readonly uint TC_GET_RESOLVED_SYMLINK                    = (uint)CTL_CODE(0x00000022, 0x800 + (17), 0, 0);
    private static readonly uint TC_GET_BOOT_ENCRYPTION_STATUS              = (uint)CTL_CODE(0x00000022, 0x800 + (18), 0, 0);
    private static readonly uint TC_BOOT_ENCRYPTION_SETUP                   = (uint)CTL_CODE(0x00000022, 0x800 + (19), 0, 0);
    private static readonly uint TC_ABORT_BOOT_ENCRYPTION_SETUP             = (uint)CTL_CODE(0x00000022, 0x800 + (20), 0, 0);
    private static readonly uint TC_GET_BOOT_ENCRYPTION_SETUP_RESULT        = (uint)CTL_CODE(0x00000022, 0x800 + (21), 0, 0);
    private static readonly uint TC_GET_BOOT_DRIVE_VOLUME_PROPERTIES        = (uint)CTL_CODE(0x00000022, 0x800 + (22), 0, 0);
    private static readonly uint TC_REOPEN_BOOT_VOLUME_HEADER               = (uint)CTL_CODE(0x00000022, 0x800 + (23), 0, 0);
    private static readonly uint TC_GET_BOOT_ENCRYPTION_ALGORITHM_NAME      = (uint)CTL_CODE(0x00000022, 0x800 + (24), 0, 0);
    private static readonly uint TC_GET_PORTABLE_MODE_STATUS                = (uint)CTL_CODE(0x00000022, 0x800 + (25), 0, 0);
    private static readonly uint TC_SET_PORTABLE_MODE_STATUS                = (uint)CTL_CODE(0x00000022, 0x800 + (26), 0, 0);
    private static readonly uint TC_IS_HIDDEN_SYSTEM_RUNNING                = (uint)CTL_CODE(0x00000022, 0x800 + (27), 0, 0);
    private static readonly uint TC_GET_SYSTEM_DRIVE_CONFIG                 = (uint)CTL_CODE(0x00000022, 0x800 + (28), 0, 0);
    private static readonly uint TC_DISK_IS_WRITABLE                        = (uint)CTL_CODE(0x00000022, 0x800 + (29), 0, 0);
    private static readonly uint TC_START_DECOY_SYSTEM_WIPE                 = (uint)CTL_CODE(0x00000022, 0x800 + (30), 0, 0);
    private static readonly uint TC_ABORT_DECOY_SYSTEM_WIPE                 = (uint)CTL_CODE(0x00000022, 0x800 + (31), 0, 0);
    private static readonly uint TC_GET_DECOY_SYSTEM_WIPE_STATUS            = (uint)CTL_CODE(0x00000022, 0x800 + (32), 0, 0);
    private static readonly uint TC_GET_DECOY_SYSTEM_WIPE_RESULT            = (uint)CTL_CODE(0x00000022, 0x800 + (33), 0, 0);
    private static readonly uint TC_WRITE_BOOT_DRIVE_SECTOR                 = (uint)CTL_CODE(0x00000022, 0x800 + (34), 0, 0);
    private static readonly uint TC_IS_SYSTEM_FAVORITE_VOLUME_DIRTY         = (uint)CTL_CODE(0x00000022, 0x800 + (35), 0, 0);
    private static readonly uint TC_SET_SYSTEM_FAVORITE_VOLUME_DIRTY        = (uint)CTL_CODE(0x00000022, 0x800 + (36), 0, 0);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
    private class MOUNT_LIST_STRUCT
        public readonly UInt32 ulMountedDrives; /* Bitfield of all mounted drive letters */
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 26)]
        public readonly MOUNT_LIST_STRUCT_VOLUME_NAME[] wszVolume;  /* Volume names of mounted volumes */
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 26)]
        public readonly UInt64[] diskLength;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 26)]
        public readonly int[] ea;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 26)]
        public readonly int[] volumeType;   /* Volume type (e.g. PROP_VOL_TYPE_OUTER, PROP_VOL_TYPE_OUTER_VOL_WRITE_PREVENTED, etc.) */

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
        [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.I2, SizeConst = 260)]
        public readonly char[] wszVolume;   /* Volume names of mounted volumes */

        public override string ToString()
            return (new String(wszVolume)).TrimEnd('\0');

    private static int CTL_CODE(int DeviceType, int Function, int Method, int Access)
        return (((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2)
          | (Method));

    /// <summary>
    /// Sends a control code directly to a specified device driver, causing the corresponding device to perform the corresponding operation.
    /// </summary>        
    [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
    static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode,
        IntPtr lpInBuffer, uint nInBufferSize,
        IntPtr lpOutBuffer, uint nOutBufferSize,
        out uint lpBytesReturned, IntPtr lpOverlapped);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CreateFile(
         [MarshalAs(UnmanagedType.LPTStr)] string filename,
         [MarshalAs(UnmanagedType.U4)] FileAccess access,
         [MarshalAs(UnmanagedType.U4)] FileShare share,
         IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
         [MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
         [MarshalAs(UnmanagedType.U4)] FileAttributes flagsAndAttributes,
         IntPtr templateFile);

Note I am using TC_GET_MOUNTED_VOLUMES flag. For example if I will like to mount a volume and use TC_MOUNT_VOLUME how will I specify the password? Where can I find more info on how to use TrueCrypt Driver? So foar I found this nice article:

asked on Stack Overflow Jan 27, 2014 by Tono Nam • edited Jan 27, 2014 by Tono Nam

2 Answers


Actually it's something a bit advanced, it's not easy, you need to go through the C++ code, understand it and re-write it in C#. I can help you with the mounting code, but for other functions you need to understand how Truecrypt UI communicates with the kernel driver and re-write it in C#.

About the mounting...

1) Download the source code of the latest Truecrypt for windows.

2) Locate TrueCryptSource\Common\Dlgcode.c Go to line: 5963 and you'll see MountVolume function:

// Use only cached passwords if password = NULL
// Returns:
// -1 = user aborted mount / error
// 0  = mount failed
// 1  = mount OK
// 2  = mount OK in shared mode
// Note that some code calling this relies on the content of the mountOptions struct
// to remain unmodified (don't remove the 'const' without proper revision).

int MountVolume (HWND hwndDlg,
                 int driveNo,
                 char *volumePath,
                 Password *password,
                 BOOL cachePassword,
                 BOOL sharedAccess,
                 const MountOptions* const mountOptions,
                 BOOL quiet,
                 BOOL bReportWrongPassword)

OK, as you can see, this function receives several parameters and sends them to the kernel driver, but it changes some variable before passing them to kernel, for example when you enter volumepath, if it does have "\?\" in it, the function removes that before passing the string to driver.

For the drive path, it uses VolumeGuidPathToDevicePath to get the full device path to that drive (meaning, converting G: H: I: to full device path e.g. \Device\Harddisk%d\Partition%d)

Then there is mount struct, you need to reconstruct it in C#:


typedef struct
    int nReturnCode;                    /* Return code back from driver */
    BOOL FilesystemDirty;
    BOOL VolumeMountedReadOnlyAfterAccessDenied;
    BOOL VolumeMountedReadOnlyAfterDeviceWriteProtected;

    wchar_t wszVolume[TC_MAX_PATH];     /* Volume to be mounted */
    Password VolumePassword;            /* User password */
    BOOL bCache;                        /* Cache passwords in driver */
    int nDosDriveNo;                    /* Drive number to mount */
    uint32 BytesPerSector;
    BOOL bMountReadOnly;                /* Mount volume in read-only mode */
    BOOL bMountRemovable;               /* Mount volume as removable media */
    BOOL bExclusiveAccess;              /* Open host file/device in exclusive access mode */
    BOOL bMountManager;                 /* Announce volume to mount manager */
    BOOL bPreserveTimestamp;            /* Preserve file container timestamp */
    BOOL bPartitionInInactiveSysEncScope;       /* If TRUE, we are to attempt to mount a partition located on an encrypted system drive without pre-boot authentication. */
    int nPartitionInInactiveSysEncScopeDriveNo; /* If bPartitionInInactiveSysEncScope is TRUE, this contains the drive number of the system drive on which the partition is located. */
    BOOL SystemFavorite;
    // Hidden volume protection
    BOOL bProtectHiddenVolume;          /* TRUE if the user wants the hidden volume within this volume to be protected against being overwritten (damaged) */
    Password ProtectedHidVolPassword;   /* Password to the hidden volume to be protected against overwriting */
    BOOL UseBackupHeader;
    BOOL RecoveryMode;

You need to re-write it in C#, then initialize a new instance of this struct, then set all parameters you need for mounting your volume (password, key files, etc.)

Finally call the driver with the MOUNT_STRUCT instance you've created:

bResult = DeviceIoControl (hDriver, TC_IOCTL_MOUNT_VOLUME, &mount,
        sizeof (mount), &mount, sizeof (mount), &dwResult, NULL);

That's all, also as TrueCrypt does it, don't forget to wipe the password from the memory after sending it to the kernel, for this, TrueCrypt have a function called burn, re-write it in C# as well or simply destroy variables that holds password for the volume as it is too sensitive.

In addition to all I said above, truecrypt does have command line interface and you can mount volumes from command prompt. You can't use the command prompt to see the list of mounted drives so you need a simple C# code to list mounted volumes, but you can use command prompt for mounting:

truecrypt /v /lx /a /p MyPassword /e /b
answered on Stack Overflow Jan 31, 2014 by 72DFBF5B A0DF5BE9 • edited Apr 23, 2018 by 72DFBF5B A0DF5BE9

Edit for clarity:

The TrueCrypt Managed Driver is a rewrite of parts of TrueCrypt source code using Managed .NET concepts on top of the existing TrueCrypt.sys driver.

To use:

Public Sub Main()
    ' Instantiate the TrueCrypt Driver API
    Dim Driver As New TC_Driver("C:\truecrypt.sys") ' Or wherever the compiled TrueCrypt driver exists on your system

End Sub

This calls the internal code:

Public Class TC_Driver
    Implements IDisposable

    Const CURRENT_VER As Integer = &H71A

    Private pDriver32bitLocation As String
    Private pDriver64bitLocation As String
    Private pIsPortableMode As Boolean = False

    Private Property ManagedDriver As ManagedDriver
    Private DriverSetupMutex As Mutex

    Public Sub New(ByVal DriverLocation64bit As String)
        'Checks for 64-bit OS. Currently x64 is the only supported platform
        If Not Environment.Is64BitProcess = Environment.Is64BitOperatingSystem Then
           Throw New PlatformNotSupportedException("TrueCryptAPI needs a 64 bit process to run correctly")
        End If

        ' Set the driver location as specified by DriverLocation64bit
        pDriver64bitLocation = Path.GetFullPath(DriverLocation64bit)

        Dim DriverStatus As TC_ERROR
        Dim DriverLoadAttempts As Integer = 0

        'Load the driver as a service using internal code
        ManagedDriver = New ManagedDriver

        'Attempt to Start the driver, fail with error after 3 attempts
          DriverStatus = StartDriver()
          DriverLoadAttempts += 1
        Loop While DriverStatus = TC_ERROR.FILES_OPEN_LOCK AndAlso DriverLoadAttempts < 3

        If DriverStatus <> TC_ERROR.SUCCESS Then
          Throw New ArgumentException("Driver not loaded. Error:" & DriverStatus)
        End If
    End Sub
End Class

The above code instantiates the TrueCrypt driver running as a service and provides an object for which to run TrueCrypt methods from calling code (such as Mount and DisMount).

To use (con't):

Public Sub Main()
    ' Instantiate the TrueCrypt Driver API
    Dim Driver As New TC_Driver("C:\truecrypt.sys") ' Or wherever the compiled TrueCrypt driver exists on your system

    Dim MyOptions As New MOUNT_OPTIONS With {.Removable = True}

End Sub

The MOUNT_OPTIONS structure:

    Public Structure MOUNT_OPTIONS
        Dim [ReadOnly] As Boolean
        Dim Removable As Boolean
        Dim ProtectHiddenVolume As Boolean
        Dim PreserveTimestamp As Boolean
        Dim PartitionInInactiveSysEncScope As Boolean
        Dim ProtectedHidVolPassword As Password
        Dim UseBackupHeader As Boolean
        Dim RecoveryMode As Boolean
    End Structure

MountContainer method:

Public Function MountContainer(ByVal FileName As String, ByVal DriveLetter As Char, ByVal Password As Password, ByVal Options As MOUNT_OPTIONS) As TC_ERROR
    Dim status As Boolean = False
    Dim mounted As TC_ERROR
    Dim tmp As String = ""

    'Apply the keyfile to the password
    If Not Password.ApplyKeyFile(tmp) Then Return False

    'Attempt to mount the volume using translated TrueCrypt methods
    mounted = MountVolume(Asc(DriveLetter) - Asc("A"), FileName, tmp, False, False, Options, False)

    tmp = ""
    Options.ProtectedHidVolPassword = Nothing

    Return mounted
End Function

Here is a (fairly literal and cumbersome) translation of the C/C++ from TrueCrypt being used for volume mounting:

Partial Public Class TC_Driver

Friend Function MountVolume(ByVal driveNo As Integer, ByVal volumePath As String, ByVal password As String, ByVal cachePassword As Boolean, ByVal sharedAccess As Boolean, ByRef MountOption As MOUNT_OPTIONS, ByVal quiet As Boolean) As TC_ERROR
    Dim mount As MOUNT_STRUCT
    Dim dwResult As UInteger
    Dim bResult As Boolean, bDevice As Boolean
    Dim favoriteMountOnArrivalRetryCount As Integer = 0

    If IsMountedVolume(volumePath) Then Return TC_ERROR.VOL_ALREADY_MOUNTED
    If Not VolumePathExists(volumePath) Then Return TC_ERROR.FILES_OPEN

    mount = New MOUNT_STRUCT
    mount.VolumePassword = New PASSWORD_STUCT
    mount.ProtectedHidVolPassword = New PASSWORD_STUCT

    mount.bExclusiveAccess = Not sharedAccess
    mount.SystemFavorite = False
    mount.UseBackupHeader = MountOption.UseBackupHeader
    mount.RecoveryMode = MountOption.RecoveryMode

    mount.nDosDriveNo = driveNo
    mount.bCache = cachePassword

    mount.bPartitionInInactiveSysEncScope = False

    If StringLen(password) > 0 Then
        mount.VolumePassword = New PASSWORD_STUCT

        mount.VolumePassword.Text = password.PadRight(MAX_PASSWORD + 1, Chr(0))
        mount.VolumePassword.Length = StringLen(password)
        mount.VolumePassword.Pad = "".PadRight(3, Chr(0))
        mount.VolumePassword = New PASSWORD_STUCT

        mount.VolumePassword.Text = "".PadRight(MAX_PASSWORD + 1, Chr(0))
        mount.VolumePassword.Length = 0
        mount.VolumePassword.Pad = "".PadRight(3, Chr(0))
    End If

    If (Not MountOption.ReadOnly) And MountOption.ProtectHiddenVolume Then
        mount.ProtectedHidVolPassword = New PASSWORD_STUCT

        mount.ProtectedHidVolPassword.Pad = "".PadRight(3, Chr(0))

        mount.ProtectedHidVolPassword.Length = StringLen(mount.ProtectedHidVolPassword.Text)

        mount.bProtectHiddenVolume = True
        mount.ProtectedHidVolPassword = New PASSWORD_STUCT
        mount.ProtectedHidVolPassword.Length = 0
        mount.ProtectedHidVolPassword.Text = "".PadRight(MAX_PASSWORD + 1, Chr(0))
        mount.ProtectedHidVolPassword.Pad = "".PadRight(3, Chr(0))

        mount.bProtectHiddenVolume = False
    End If

    mount.bMountReadOnly = MountOption.ReadOnly
    mount.bMountRemovable = MountOption.Removable
    mount.bPreserveTimestamp = MountOption.PreserveTimestamp

    mount.bMountManager = True

    If volumePath.Contains("\\?\") Then volumePath = volumePath.Substring(4)

    If volumePath.Contains("Volume{") And volumePath.LastIndexOf("}\") = volumePath.Length - 2 Then
        Dim resolvedPath As String = VolumeGuidPathToDevicePath(volumePath)

        If Not resolvedPath = "" Then volumePath = resolvedPath
    End If

    mount.wszVolume = volumePath.PadRight(TC_MAX_PATH, Chr(0))

    If Not bDevice Then
        If volumePath.StartsWith("\\") Then
            'Bla bla
        End If

        Dim bps As UInteger, flags As UInteger, d As UInteger
        If GetDiskFreeSpace(Path.GetPathRoot(volumePath), d, bps, d, d) Then
            mount.BytesPerSector = bps
        End If

        If (Not mount.bMountReadOnly) And GetVolumeInformation(Path.GetPathRoot(volumePath), Nothing, 0, Nothing, d, flags, Nothing, 0) Then
            mount.bMountReadOnly = Not (flags And FILE_READ_ONLY_VOLUME) = 0
        End If
    End If

    bResult = DeviceIoControlMount(ManagedDriver.hDriver, TC_IOCTL.MOUNT_VOLUME, mount, Marshal.SizeOf(mount), mount, Marshal.SizeOf(mount), dwResult, Nothing)

    mount.VolumePassword = Nothing
    mount.ProtectedHidVolPassword = Nothing

    If Not bResult Then
        If Marshal.GetLastWin32Error = SYSTEM_ERROR.SHARING_VIOLATION Then

            If Not mount.bExclusiveAccess Then
                Return TC_ERROR.FILES_OPEN_LOCK
                mount.bExclusiveAccess = False
                GoTo retry
            End If

            Return TC_ERROR.ACCESS_DENIED
        End If

        Return TC_ERROR.GENERIC
    End If

    If Not mount.nReturnCode = 0 Then Return mount.nReturnCode

    'Mount successful
    BroadcastDeviceChange(DBT_DEVICE.ARRIVAL, driveNo, 0)

    If Not mount.bExclusiveAccess Then Return TC_ERROR.OUTOFMEMORY

    Return mount.nReturnCode
End Function


This is a very complex operation to explain in code, check out the source if you want to see how it works or check out the NuGet if you just want to use it. Or if you have a specific question, just ask.

Original: I know this is old, but I had similar issues writing a managed TrueCrypt mounter. Check out my GitHub repo: TrueCrypt Managed Driver(VB.NET). It was inspired by this C# Version: truecryptapi dot codeplex dot com. I rewrote a lot of the C# code for a more managed interface, however it's still a work in progress. I also have a NuGet package here you can install in your project.

answered on Stack Overflow Jun 2, 2015 by CShrawder

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