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Rfc2898DeriveBytes::IterationCount Property

Updated: December 2008

Gets or sets the number of iterations for the operation.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

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

Property Value

Type: System::Int32
The number of iterations for the operation.

ExceptionCondition
ArgumentOutOfRangeException

The number of iterations is less than 1.

Iteration count is the number of times an operation is performed. For this method, the count should be greater than zero. The minimum recommended number of iterations is 1000.

The following example shows how to use the IterationCount property to display the number of iterations used in the generation of the key. This code example is part of a larger example provided for the Rfc2898DeriveBytes class.

	  //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.
		 TripleDES^ encAlg = TripleDES::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.
		 TripleDES^ decAlg = TripleDES::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 );
		 }

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

Date

History

Reason

December 2008

Corrected example introduction.

Customer feedback.

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