Rfc2898DeriveBytes.IterationCount Propriété
Définition
Important
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Obtient ou définit le nombre d'itérations pour l'opération.
public:
property int IterationCount { int get(); void set(int value); };public int IterationCount { get; set; }member this.IterationCount : int with get, setPublic Property IterationCount As IntegerValeur de propriété
Nombre d'itérations pour l'opération.
Exceptions
Le nombre d'itérations est inférieur à 1.
Exemples
L’exemple suivant montre comment utiliser la IterationCount propriété pour afficher le nombre d’itérations utilisées dans la génération de la clé. Cet exemple de code fait partie d’un exemple plus grand fourni pour la Rfc2898DeriveBytes classe.
//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
Remarques
Le nombre d’itérations est le nombre de fois qu’une opération est effectuée. Pour cette méthode, le nombre doit être supérieur à zéro. Le nombre minimal d’itérations recommandé est de 1 000.