DESCryptoServiceProvider Constructor ()

 

Initializes a new instance of the DESCryptoServiceProvider class.

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

Public Sub New

Exception Condition
CryptographicException

The Data Encryption Standard (DES) cryptographic service provider is not available.

The following code example uses DESCryptoServiceProvider (an implementation of DES) 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.

Private Shared Sub EncryptData(inName As String, outName As String, _
desKey() As Byte, desIV() 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(4096) 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 'Total length of the input file.
    Dim len As Integer 'This is the number of bytes to be written at a time.
    Dim des As New DESCryptoServiceProvider()
    Dim encStream As New CryptoStream(fout, _
       des.CreateEncryptor(desKey, desIV), 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, 4096)
        encStream.Write(bin, 0, len)
        rdlen = Convert.ToInt32(rdlen + len / des.BlockSize * des.BlockSize)
        Console.WriteLine("Processed {0} bytes, {1} bytes total", len, _
           rdlen)
    End While

    encStream.Close()
End Sub

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.

.NET Framework
Available since 1.1
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