DESCryptoServiceProvider Class

Defines a wrapper object to access the cryptographic service provider (CSP) version of the Data Encryption Standard (DES) algorithm. This class cannot be inherited.

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

'Declaration
<ComVisibleAttribute(True)> _
Public NotInheritable Class DESCryptoServiceProvider
	Inherits DES
'Usage
Dim instance As DESCryptoServiceProvider

/** @attribute ComVisibleAttribute(true) */ 
public final class DESCryptoServiceProvider extends DES
ComVisibleAttribute(true) 
public final class DESCryptoServiceProvider extends DES
Not applicable.

This algorithm supports a key length of 64 bits.

The following example uses the DESCryptoServiceProvider class to encrypt some data to memory and then decrypt the data.

' This sample demonstrates using a key based on the cryptographic service provider (CSP) version
' of the Data Encryption Standard (DES)algorithm to encrypt a string to a byte array, and then 
' to decrypt the byte array back to a string.
Imports System
Imports System.IO
Imports System.Text
Imports System.Security.Cryptography



Class CryptoMemoryStream
    
    ' Main method.
    Public Shared Sub Main()
        ' Create a new DES key.
        Dim key As New DESCryptoServiceProvider()
        
        ' Encrypt a string to a byte array.
        Dim buffer As Byte() = Encrypt("This is some plaintext!", key)
        
        ' Decrypt the byte array back to a string.
        Dim plaintext As String = Decrypt(buffer, key)
        
        ' Display the plaintext value to the console.
        Console.WriteLine(plaintext)
    End Sub 'Main
    
    
    ' Encrypt the string.
    Public Shared Function Encrypt(PlainText As String, key As SymmetricAlgorithm) As Byte()
        ' Create a memory stream.
        Dim ms As New MemoryStream()
        
        ' Create a CryptoStream using the memory stream and the 
        ' CSP DES key.  
        Dim encStream As New CryptoStream(ms, key.CreateEncryptor(), CryptoStreamMode.Write)
        
        ' Create a StreamWriter to write a string
        ' to the stream.
        Dim sw As New StreamWriter(encStream)
        
        ' Write the plaintext to the stream.
        sw.WriteLine(PlainText)
        
        ' Close the StreamWriter and CryptoStream.
        sw.Close()
        encStream.Close()
        
        ' Get an array of bytes that represents
        ' the memory stream.
        Dim buffer As Byte() = ms.ToArray()
        
        ' Close the memory stream.
        ms.Close()
        
        ' Return the encrypted byte array.
        Return buffer
    End Function 'Encrypt
    
    
    ' Decrypt the byte array.
    Public Shared Function Decrypt(CypherText() As Byte, key As SymmetricAlgorithm) As String
        ' Create a memory stream to the passed buffer.
        Dim ms As New MemoryStream(CypherText)
        
        ' Create a CryptoStream using the memory stream and the 
        ' CSP DES key. 
        Dim encStream As New CryptoStream(ms, key.CreateDecryptor(), CryptoStreamMode.Read)
        
        ' Create a StreamReader for reading the stream.
        Dim sr As New StreamReader(encStream)
        
        ' Read the stream as a string.
        Dim val As String = sr.ReadLine()
        
        ' Close the streams.
        sr.Close()
        encStream.Close()
        ms.Close()
        
        Return val
    End Function 'Decrypt
End Class 'CryptoMemoryStream

// This sample demonstrates using a key based on the cryptographic 
// service provider (CSP) version
// of the Data Encryption Standard (DES)algorithm to encrypt a string 
// to a byte array, and then to decrypt the byte array back to a string.

import System.*;
import System.IO.*;
import System.Text.*;
import System.Security.Cryptography.*;

class CryptoMemoryStream
{
    // main method.
    public static void main(String[] args)
    {
        // Create a new DES key.
        DESCryptoServiceProvider key = new DESCryptoServiceProvider();

        // Encrypt a string to a byte array.
        ubyte buffer[] = Encrypt("This is some plaintext!", key);

        // Decrypt the byte array back to a string.
        String plainText = Decrypt(buffer, key);

        // Display the plaintext value to the console.
        Console.WriteLine(plainText);
    } //main

    // Encrypt the string.
    public static ubyte[] Encrypt(String plainText, SymmetricAlgorithm key)
    {
        // Create a memory stream.
        MemoryStream ms = new MemoryStream();

        // Create a CryptoStream using the memory stream and the 
        // CSP DES key.  
        CryptoStream encStream = new CryptoStream(ms, key.CreateEncryptor(), 
            CryptoStreamMode.Write);

        // Create a StreamWriter to write a string
        // to the stream.
        StreamWriter sw = new StreamWriter(encStream);

        // Write the plaintext to the stream.
        sw.WriteLine(plainText);

        // Close the StreamWriter and CryptoStream.
        sw.Close();
        encStream.Close();

        // Get an array of bytes that represents
        // the memory stream.
        ubyte buffer[] = ms.ToArray();

        // Close the memory stream.
        ms.Close();

        // Return the encrypted byte array.
        return buffer;
    } //Encrypt

    // Decrypt the byte array.
    public static String Decrypt(ubyte cypherText[], SymmetricAlgorithm key)
    {
        // Create a memory stream to the passed buffer.
        MemoryStream ms = new MemoryStream(cypherText);

        // Create a CryptoStream using the memory stream and the 
        // CSP DES key. 
        CryptoStream encStream = new CryptoStream(ms, key.CreateDecryptor(), 
            CryptoStreamMode.Read);

        // Create a StreamReader for reading the stream.
        StreamReader sr = new StreamReader(encStream);

        // Read the stream as a string.
        String val = sr.ReadLine();

        // Close the streams.
        sr.Close();
        encStream.Close();
        ms.Close();
        return val;
    } //Decrypt
} //CryptoMemoryStream

System.Object
   System.Security.Cryptography.SymmetricAlgorithm
     System.Security.Cryptography.DES
      System.Security.Cryptography.DESCryptoServiceProvider

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 Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0
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