SecureString.MakeReadOnly Methode
Definition
Wichtig
Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.
Legt den Textwert dieser sicheren Zeichenfolge als schreibgeschützt fest.
public:
void MakeReadOnly();public void MakeReadOnly ();member this.MakeReadOnly : unit -> unitPublic Sub MakeReadOnly ()Ausnahmen
Diese sichere Zeichenfolge wurde bereits verworfen.
Beispiele
Im folgenden Beispiel wird veranschaulicht, wie die AppendChar -Methode und RemoveAt die -Methode verwendet werden können, um die Zeichen in einem Kennwort zu erfassen. Nachdem das Kennwort erfasst wurde, wird es schreibgeschützt.
using namespace System;
using namespace System::Security;
void main()
{
bool go = true;
ConsoleKeyInfo cki;
String^ m = L"\nEnter your password (up to 15 letters, numbers, and underscores)\n"
L"Press BACKSPACE to delete the last character entered. " +
L"\nPress Enter when done, or ESCAPE to quit:";
SecureString ^ password = gcnew SecureString;
int top;
int left;
// The Console.TreatControlCAsInput property prevents CTRL+C from
// ending this example.
Console::TreatControlCAsInput = true;
Console::Clear();
Console::WriteLine(m);
top = Console::CursorTop;
left = Console::CursorLeft;
do {
cki = Console::ReadKey(true);
if (cki.Key == ConsoleKey::Escape)
break;
if (cki.Key == ConsoleKey::Backspace){
if (password->Length > 0) {
Console::SetCursorPosition(left + password->Length - 1, top);
Console::Write(' ');
Console::SetCursorPosition(left + password->Length - 1, top);
password->RemoveAt(password->Length - 1);
}
}
else {
if ((password->Length < 15) &&
(Char::IsLetterOrDigit( cki.KeyChar ) ||
cki.KeyChar == '_') ) {
password->AppendChar( cki.KeyChar );
Console::SetCursorPosition( left + password->Length - 1, top );
Console::Write("*");
}
}
} while (cki.Key != ConsoleKey::Enter & password->Length < 15);
// Make the password read-only to prevent modification.
password->MakeReadOnly();
// Dispose of the SecureString instance.
delete password;
}
// The example displays output like the following:
// Enter your password (up to 15 letters, numbers, and underscores)
// Press BACKSPACE to delete the last character entered.
// Press Enter when done, or ESCAPE to quit:
// ************
using System;
using System.Security;
class Example
{
public static void Main()
{
ConsoleKeyInfo cki;
String m = "\nEnter your password (up to 15 letters, numbers, and underscores)\n" +
"Press BACKSPACE to delete the last character entered. " +
"\nPress Enter when done, or ESCAPE to quit:";
SecureString password = new SecureString();
int top, left;
// The Console.TreatControlCAsInput property prevents CTRL+C from
// ending this example.
Console.TreatControlCAsInput = true;
Console.Clear();
Console.WriteLine(m);
top = Console.CursorTop;
left = Console.CursorLeft;
// Read user input from the console. Store up to 15 letter, digit, or underscore
// characters in a SecureString object, or delete a character if the user enters
// a backspace. Display an asterisk (*) on the console to represent each character
// that is stored.
do {
cki = Console.ReadKey(true);
if (cki.Key == ConsoleKey.Escape) break;
if (cki.Key == ConsoleKey.Backspace) {
if (password.Length > 0) {
Console.SetCursorPosition(left + password.Length - 1, top);
Console.Write(' ');
Console.SetCursorPosition(left + password.Length - 1, top);
password.RemoveAt(password.Length-1);
}
}
else {
if ((password.Length < 15) &&
(Char.IsLetterOrDigit(cki.KeyChar) || cki.KeyChar == '_')) {
password.AppendChar(cki.KeyChar);
Console.SetCursorPosition(left+password.Length-1, top);
Console.Write('*');
}
}
} while (cki.Key != ConsoleKey.Enter & password.Length < 15);
// Make the password read-only to prevent modification.
password.MakeReadOnly();
// Dispose of the SecureString instance.
password.Dispose();
}
}
// This example displays output like the following:
// Enter your password (up to 15 letters, numbers, and underscores)
// Press BACKSPACE to delete the last character entered.
// Press Enter when done, or ESCAPE to quit:
// ************
Imports System.Security
Class Example
Public Shared Sub Main()
Dim cki As ConsoleKeyInfo
Dim m As String = vbCrLf & "Enter your password (up to 15 letters, numbers, and underscores)" &
vbCrLf & "Press BACKSPACE to delete the last character entered. " & vbCrLf &
"Press Enter when done, or ESCAPE to quit: "
Dim password As New SecureString()
Dim top, left As Integer
' The Console.TreatControlCAsInput property prevents CTRL+C from
' ending this example.
Console.TreatControlCAsInput = True
Console.Clear()
Console.WriteLine(m)
top = Console.CursorTop
left = Console.CursorLeft
' Read user input from the console. Store up to 15 letter, digit, or underscore
' characters in a SecureString object, or delete a character if the user enters
' a backspace. Display an asterisk (*) on the console to represent each character
' that is stored.
Do
cki = Console.ReadKey(True)
If cki.Key = ConsoleKey.Escape Then Exit Do
If cki.Key = ConsoleKey.Backspace Then
If password.Length > 0 Then
Console.SetCursorPosition(left + password.Length - 1, top)
Console.Write(" "c)
Console.SetCursorPosition(left + password.Length - 1, top)
password.RemoveAt(password.Length - 1)
End If
Else
If password.Length < 15 AndAlso([Char].IsLetterOrDigit(cki.KeyChar) _
OrElse cki.KeyChar = "_"c) Then
password.AppendChar(cki.KeyChar)
Console.SetCursorPosition(left + password.Length - 1, top)
Console.Write("*"c)
End If
End If
Loop While cki.Key <> ConsoleKey.Enter And password.Length < 15
' Make the password read-only to prevent modification.
password.MakeReadOnly()
' Dispose of the SecureString instance.
password.Dispose()
End Sub
End Class
' The example displays output like the following:
' Enter your password (up to 15 letters, numbers, and underscores)
' Press BACKSPACE to delete the last character entered.
' Press Enter when done, or ESCAPE to quit:
' ************
Hinweise
Initialisieren Sie den Textwert einer Instanz der SecureString -Klasse mit den SecureString Konstruktoren, und ändern Sie den Wert mit den Clear Methoden , , , und RemoveAt SetAt InsertAt AppendChar .
Nachdem Sie die letzten Änderungen vorgenommen haben, verwenden Sie die MakeReadOnly -Methode, um den Wert der Instanz unveränderlich (schreibgeschützt) zu machen. Nachdem der Wert als schreibgeschützt markiert wurde, löst jeder weitere Versuch, ihn zu ändern, eine InvalidOperationException aus.
Der Aufruf von MakeReadOnly ist dauerhaft, da die SecureString -Klasse keine Möglichkeit bietet, die sichere Zeichenfolge wieder änderbar zu machen. Verwenden Sie die IsReadOnly -Methode, um zu testen, ob eine Instanz von SecureString schreibgeschützt ist.