Rfc2898DeriveBytes.IterationCount Eigenschaft

Definition

Namespace:

System.Security.Cryptography

Assembly:

System.Security.Cryptography.dll

Quelle:

Rfc2898DeriveBytes.cs

Ruft die Anzahl der Iterationen für die Operation ab oder legt diese fest.

public:
 property int IterationCount { int get(); void set(int value); };

public int IterationCount { get; set; }

member this.IterationCount : int with get, set

Public Property IterationCount As Integer

Eigenschaftswert

Int32

Die Anzahl der Iterationen für die Operation.

Ausnahmen

ArgumentOutOfRangeException

Die Iterationsanzahl ist kleiner als 1.

Beispiele

Das folgende Beispiel zeigt, wie die IterationCount -Eigenschaft verwendet wird, um die Anzahl der Iterationen anzuzeigen, die bei der Schlüsselgenerierung verwendet werden. Dieses Codebeispiel ist Teil eines größeren Beispiels, das für die Rfc2898DeriveBytes-Klasse bereitgestellt wird.

//The default iteration count is 1000 so the two methods use the same iteration count.
int myIterations = 1000;

try
{
   Rfc2898DeriveBytes ^ k1 = gcnew Rfc2898DeriveBytes( pwd1,salt1,myIterations );
   Rfc2898DeriveBytes ^ k2 = gcnew Rfc2898DeriveBytes( pwd1,salt1 );

   // Encrypt the data.
   Aes^ encAlg = Aes::Create();
   encAlg->Key = k1->GetBytes( 16 );
   MemoryStream^ encryptionStream = gcnew MemoryStream;
   CryptoStream^ encrypt = gcnew CryptoStream( encryptionStream,encAlg->CreateEncryptor(),CryptoStreamMode::Write );
   array<Byte>^utfD1 = (gcnew System::Text::UTF8Encoding( false ))->GetBytes( data1 );

   encrypt->Write( utfD1, 0, utfD1->Length );
   encrypt->FlushFinalBlock();
   encrypt->Close();
   array<Byte>^edata1 = encryptionStream->ToArray();
   k1->Reset();

   // Try to decrypt, thus showing it can be round-tripped.
   Aes^ decAlg = Aes::Create();
   decAlg->Key = k2->GetBytes( 16 );
   decAlg->IV = encAlg->IV;
   MemoryStream^ decryptionStreamBacking = gcnew MemoryStream;
   CryptoStream^ decrypt = gcnew CryptoStream( decryptionStreamBacking,decAlg->CreateDecryptor(),CryptoStreamMode::Write );

   decrypt->Write( edata1, 0, edata1->Length );
   decrypt->Flush();
   decrypt->Close();
   k2->Reset();

   String^ data2 = (gcnew UTF8Encoding( false ))->GetString( decryptionStreamBacking->ToArray() );
   if (  !data1->Equals( data2 ) )
   {
      Console::WriteLine( "Error: The two values are not equal." );
   }
   else
   {
      Console::WriteLine( "The two values are equal." );
      Console::WriteLine( "k1 iterations: {0}", k1->IterationCount );
      Console::WriteLine( "k2 iterations: {0}", k2->IterationCount );
   }

            //The default iteration count is 1000 so the two methods use the same iteration count.
            int myIterations = 1000;
            try
            {
                Rfc2898DeriveBytes k1 = new Rfc2898DeriveBytes(pwd1, salt1,
myIterations);
                Rfc2898DeriveBytes k2 = new Rfc2898DeriveBytes(pwd1, salt1);
                // Encrypt the data.
                Aes encAlg = Aes.Create();
                encAlg.Key = k1.GetBytes(16);
                MemoryStream encryptionStream = new MemoryStream();
                CryptoStream encrypt = new CryptoStream(encryptionStream,
encAlg.CreateEncryptor(), CryptoStreamMode.Write);
                byte[] utfD1 = new System.Text.UTF8Encoding(false).GetBytes(
data1);

                encrypt.Write(utfD1, 0, utfD1.Length);
                encrypt.FlushFinalBlock();
                encrypt.Close();
                byte[] edata1 = encryptionStream.ToArray();
                k1.Reset();

                // Try to decrypt, thus showing it can be round-tripped.
                Aes decAlg = Aes.Create();
                decAlg.Key = k2.GetBytes(16);
                decAlg.IV = encAlg.IV;
                MemoryStream decryptionStreamBacking = new MemoryStream();
                CryptoStream decrypt = new CryptoStream(
decryptionStreamBacking, decAlg.CreateDecryptor(), CryptoStreamMode.Write);
                decrypt.Write(edata1, 0, edata1.Length);
                decrypt.Flush();
                decrypt.Close();
                k2.Reset();
                string data2 = new UTF8Encoding(false).GetString(
decryptionStreamBacking.ToArray());

                if (!data1.Equals(data2))
                {
                    Console.WriteLine("Error: The two values are not equal.");
                }
                else
                {
                    Console.WriteLine("The two values are equal.");
                    Console.WriteLine("k1 iterations: {0}", k1.IterationCount);
                    Console.WriteLine("k2 iterations: {0}", k2.IterationCount);
                }

'The default iteration count is 1000 so the two methods use the same iteration count.
Dim myIterations As Integer = 1000
Try
    Dim k1 As New Rfc2898DeriveBytes(pwd1, salt1, myIterations)
    Dim k2 As New Rfc2898DeriveBytes(pwd1, salt1)
    ' Encrypt the data.
    Dim encAlg As Aes = Aes.Create()
    encAlg.Key = k1.GetBytes(16)
    Dim encryptionStream As New MemoryStream()
    Dim encrypt As New CryptoStream(encryptionStream, encAlg.CreateEncryptor(), CryptoStreamMode.Write)
    Dim utfD1 As Byte() = New System.Text.UTF8Encoding(False).GetBytes(data1)
    encrypt.Write(utfD1, 0, utfD1.Length)
    encrypt.FlushFinalBlock()
    encrypt.Close()
    Dim edata1 As Byte() = encryptionStream.ToArray()
    k1.Reset()

    ' Try to decrypt, thus showing it can be round-tripped.
    Dim decAlg As Aes = Aes.Create()
    decAlg.Key = k2.GetBytes(16)
    decAlg.IV = encAlg.IV
    Dim decryptionStreamBacking As New MemoryStream()
    Dim decrypt As New CryptoStream(decryptionStreamBacking, decAlg.CreateDecryptor(), CryptoStreamMode.Write)
    decrypt.Write(edata1, 0, edata1.Length)
    decrypt.Flush()
    decrypt.Close()
    k2.Reset()
    Dim data2 As String = New UTF8Encoding(False).GetString(decryptionStreamBacking.ToArray())

    If Not data1.Equals(data2) Then
        Console.WriteLine("Error: The two values are not equal.")
    Else
        Console.WriteLine("The two values are equal.")
        Console.WriteLine("k1 iterations: {0}", k1.IterationCount)
        Console.WriteLine("k2 iterations: {0}", k2.IterationCount)
    End If

Hinweise

Die Iterationsanzahl ist die Häufigkeit, mit der ein Vorgang ausgeführt wird. Für diese Methode sollte die Anzahl größer als 0 sein. Die empfohlene Mindestanzahl von Iterationen beträgt 1000.

Weitere Informationen

• Kryptografische Dienste