Marshal.SecureStringToCoTaskMemAnsi(SecureString) Method

public:
 static IntPtr SecureStringToCoTaskMemAnsi(System::Security::SecureString ^ s);

public static IntPtr SecureStringToCoTaskMemAnsi(System.Security.SecureString s);

[System.CLSCompliant(false)]
public static IntPtr SecureStringToCoTaskMemAnsi(System.Security.SecureString s);

[System.Security.SecurityCritical]
public static IntPtr SecureStringToCoTaskMemAnsi(System.Security.SecureString s);

static member SecureStringToCoTaskMemAnsi : System.Security.SecureString -> nativeint

[<System.CLSCompliant(false)>]
static member SecureStringToCoTaskMemAnsi : System.Security.SecureString -> nativeint

[<System.Security.SecurityCritical>]
static member SecureStringToCoTaskMemAnsi : System.Security.SecureString -> nativeint

Public Shared Function SecureStringToCoTaskMemAnsi (s As SecureString) As IntPtr

Parameters

Returns

The address, in unmanaged memory, where the s parameter was copied to, or 0 if a null object was supplied.

Attributes

CLSCompliantAttribute SecurityCriticalAttribute

Exceptions

Examples

The following example uses the SecureStringToCoTaskMemAnsi method to marshal and decrypt the contents of a SecureString object to a block of unmanaged memory. It then uses the ZeroFreeCoTaskMemAnsi method to zero out and dispose the unmanaged block.

using System;
using System.Runtime.InteropServices;
using System.Security;

class MarshalExample
{
 static void Main()
 {
 IntPtr unmanagedRef = IntPtr.Zero;

 // Ask the user for a password.
 Console.Write("Please enter your password: ");

 SecureString passWord = GetPassword();

 Console.WriteLine("Copying and decrypting the string to unmanaged memory...");

 // Copy the Secure string to unmanaged memory (and decrypt it).
 unmanagedRef = Marshal.SecureStringToCoTaskMemAnsi(passWord);

 if (unmanagedRef != IntPtr.Zero)
 {
 Console.WriteLine("Zeroing out unmanaged memory...");

 Marshal.ZeroFreeCoTaskMemAnsi(unmanagedRef);
 }
 passWord.Dispose();

 Console.WriteLine("Done.");
 }

 public static SecureString GetPassword()
 {
 SecureString password = new SecureString();

 // get the first character of the password
 ConsoleKeyInfo nextKey = Console.ReadKey(true);

 while (nextKey.Key != ConsoleKey.Enter)
 {
 if (nextKey.Key == ConsoleKey.Backspace)
 {
 if (password.Length > 0)
 {
 password.RemoveAt(password.Length - 1);

 // erase the last * as well
 Console.Write(nextKey.KeyChar);
 Console.Write(" ");
 Console.Write(nextKey.KeyChar);
 }
 }
 else
 {
 password.AppendChar(nextKey.KeyChar);
 Console.Write("*");
 }

 nextKey = Console.ReadKey(true);
 }

 Console.WriteLine();

 // lock the password down
 password.MakeReadOnly();
 return password;
 }
}

Imports System.Runtime.InteropServices
Imports System.Security

Module Example
 Sub Main()
 Dim unmanagedRef As IntPtr

 ' Ask the user for a password.
 Console.Write("Please enter your password: ")
 Dim passWord As SecureString = GetPassword()

 Console.WriteLine("Copying and decrypting the string to unmanaged memory...")

 ' Copy the Secure string to unmanaged memory (and decrypt it).
 unmanagedRef = Marshal.SecureStringToCoTaskMemAnsi(passWord)

 If unmanagedRef <> IntPtr.Size Then
 Console.WriteLine("Zeroing out unmanaged memory...")
 Marshal.ZeroFreeCoTaskMemAnsi(unmanagedRef)
 End If
 passWord.Dispose()

 Console.WriteLine("Done.")
 End Sub



 Function GetPassword() As SecureString
 Dim password As New SecureString()

 ' get the first character of the password
 Dim nextKey As ConsoleKeyInfo = Console.ReadKey(True)

 While nextKey.Key <> ConsoleKey.Enter
 If nextKey.Key = ConsoleKey.BackSpace Then
 If password.Length > 0 Then
 password.RemoveAt(password.Length - 1)

 ' erase the last * as well
 Console.Write(nextKey.KeyChar)
 Console.Write(" ")
 Console.Write(nextKey.KeyChar)
 End If
 Else
 password.AppendChar(nextKey.KeyChar)
 Console.Write("*")
 End If

 nextKey = Console.ReadKey(True)
 End While

 Console.WriteLine()

 ' lock the password down
 password.MakeReadOnly()
 Return password

 End Function
End Module

Remarks

The SecureStringToCoTaskMemAnsi method is useful for custom marshaling or when mixing managed and unmanaged code. Because this method allocates the unmanaged memory required for a string, always free the memory by calling ZeroFreeCoTaskMemAnsi. The characters of the string are copied as ANSI characters.