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TripleDES Class

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

For a list of all members of this type, see TripleDES Members.

System.Object
   System.Security.Cryptography.SymmetricAlgorithm
      System.Security.Cryptography.TripleDES
         System.Security.Cryptography.TripleDESCryptoServiceProvider

[Visual Basic]
MustInherit Public Class TripleDES
   Inherits SymmetricAlgorithm
[C#]
public abstract class TripleDES : SymmetricAlgorithm
[C++]
public __gc __abstract class TripleDES : public SymmetricAlgorithm
[JScript]
public abstract class TripleDES extends SymmetricAlgorithm

Thread Safety

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

Remarks

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

Example

[Visual Basic, C#, C++] The following example method uses TripleDESCryptoServiceProvider with the specified Key and initialization vector (IV) to encrypt a file specified by inName, and outputs the encrypted result to the file specified by outName.

[Visual Basic] 
Private Shared Sub EncryptData(inName As String, outName As String, _
   tdesKey() As Byte, tdesIV() As Byte)
   
    'Create the file streams to handle the input and output files.
    Dim fin As New FileStream(inName, FileMode.Open, FileAccess.Read)
    Dim fout As New FileStream(outName, FileMode.OpenOrCreate, _
       FileAccess.Write)
    fout.SetLength(0)
        
    'Create variables to help with read and write.
    Dim bin(100) As Byte 'This is intermediate storage for the encryption.
    Dim rdlen As Long = 0 'This is the total number of bytes written.
    Dim totlen As Long = fin.Length 'This is the total length of the input file.
    Dim len As Integer 'This is the number of bytes to be written at a time.
    Dim tdes As New TripleDESCryptoServiceProvider()
    Dim encStream As 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", rdlen)
    End While
        
    encStream.Close()
End Sub

[C#] 
private static void EncryptData(String inName, String outName, byte[] tdesKey, byte[] 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.
    byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
    long rdlen = 0;              //This is the total number of bytes written.
    long totlen = 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 = 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", rdlen);
    }

    encStream.Close();                     
}

[C++] 
void EncryptData(String* inName, String* outName, Byte tdesKey[], Byte 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.
    Byte bin[] = new Byte[100]; //This is intermediate storage for the encryption.
    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 = new TripleDESCryptoServiceProvider();          
    CryptoStream* encStream = new CryptoStream(fout, tdes->CreateEncryptor(tdesKey, tdesIV), CryptoStreamMode::Write);

    Console::WriteLine(S"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(S"{0} bytes processed", __box(rdlen));
    }

    encStream->Close();                     
}

[Visual Basic, C#, C++] Decryption can be handled in the same way; use CreateDecryptor instead of CreateEncryptor. The same Key and IV used to encrypt the file must be used to decrypt.

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Security.Cryptography

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: Mscorlib (in Mscorlib.dll)

See Also

TripleDES Members | System.Security.Cryptography Namespace | Cryptographic Services

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