Rfc2898DeriveBytes.IterationCount Properti

Definisi

Ruang nama:

System.Security.Cryptography

Rakitan:

System.Security.Cryptography.dll

Sumber:

Rfc2898DeriveBytes.cs

Mendapatkan atau mengatur jumlah perulangan untuk operasi.

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

Nilai Properti

Int32

Jumlah perulangan untuk operasi.

Pengecualian

ArgumentOutOfRangeException

Jumlah perulangan kurang dari 1.

Contoh

Contoh berikut menunjukkan cara menggunakan IterationCount properti untuk menampilkan jumlah iterasi yang digunakan dalam pembuatan kunci. Contoh kode ini adalah bagian dari contoh yang lebih besar yang disediakan untuk Rfc2898DeriveBytes kelas .

//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

Keterangan

Jumlah perulangan adalah berapa kali operasi dilakukan. Untuk metode ini, jumlahnya harus lebih besar dari nol. Jumlah iterasi minimum yang direkomendasikan adalah 1000.

Lihat juga

• Layanan Kriptografi