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TripleDES Class

Represents the base class for Triple Data Encryption Standard algorithms from which all TripleDES implementations must derive.

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

[ComVisibleAttribute(true)] 
public ref class TripleDES abstract : public SymmetricAlgorithm
/** @attribute ComVisibleAttribute(true) */ 
public abstract class TripleDES extends SymmetricAlgorithm
ComVisibleAttribute(true) 
public abstract class TripleDES extends SymmetricAlgorithm

TripleDES uses three successive iterations of the DES algorithm. It can use either two or three 56-bit keys.

This algorithm supports key lengths from 128 bits to 192 bits in increments of 64 bits.

The following code example method uses TripleDESCryptoServiceProvider with the specified key (Key) and initialization vector (IV) to encrypt a file specified by inName. It then outputs the encrypted result to the file specified by outName.

void EncryptData( String^ inName, String^ outName, array<Byte>^tdesKey, array<Byte>^tdesIV )
{
   
   //Create the file streams to handle the input and output files.
   FileStream^ fin = gcnew FileStream( inName,FileMode::Open,FileAccess::Read );
   FileStream^ fout = gcnew FileStream( outName,FileMode::OpenOrCreate,FileAccess::Write );
   fout->SetLength( 0 );
   
   //Create variables to help with read and write.
   array<Byte>^bin = gcnew array<Byte>(100);
   long rdlen = 0; //This is the total number of bytes written.

   long totlen = (long)fin->Length; //This is the total length of the input file.

   int len; //This is the number of bytes to be written at a time.

   TripleDESCryptoServiceProvider^ tdes = gcnew TripleDESCryptoServiceProvider;
   CryptoStream^ encStream = gcnew CryptoStream( fout,tdes->CreateEncryptor( tdesKey, tdesIV ),CryptoStreamMode::Write );
   Console::WriteLine( "Encrypting..." );
   
   //Read from the input file, then encrypt and write to the output file.
   while ( rdlen < totlen )
   {
      len = fin->Read( bin, 0, 100 );
      encStream->Write( bin, 0, len );
      rdlen = rdlen + len;
      Console::WriteLine( "{0} bytes processed", rdlen );
   }

   encStream->Close();
}


private static void EncryptData(String inName, String outName, 
    ubyte tdesKey[],ubyte tdesIV[])
{
    //Create the file streams to handle the input and output files.
    FileStream fin = new FileStream(inName, FileMode.Open,
        FileAccess.Read);
    FileStream fout = new FileStream(outName, FileMode.OpenOrCreate,
        FileAccess.Write);
    fout.SetLength(0);

    //Create variables to help with read and write.
    ubyte bin[] = new ubyte[100];//This is intermediate storage for the 
                                 //encryption.
    long rdlen = 0; //This is the total number of bytes written.
    long totlen = fin.get_Length(); //This is the total length 
                                    //of the input file.
    int len; //This is the number of bytes to be written at a time.

    TripleDESCryptoServiceProvider tdes =
            new TripleDESCryptoServiceProvider();
    CryptoStream encStream = new CryptoStream(fout,
        tdes.CreateEncryptor(tdesKey, tdesIV), CryptoStreamMode.Write);
    Console.WriteLine("Encrypting...");

    //Read from the input file, then encrypt and write to the output file.
    while ((rdlen < totlen)) {
        len = fin.Read(bin, 0, 100);
        encStream.Write(bin, 0, len);
        rdlen = rdlen + len;
        Console.WriteLine("{0} bytes processed",
            System.Convert.ToString(rdlen));
    }
    encStream.Close();
} //EncryptData

Decryption can be handled in the same way; use CreateDecryptor instead of CreateEncryptor. The same key (Key) and initialization vector (IV) used to encrypt the file must be used to decrypt it.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

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