VB.Net Tutorial/Security/DES

DES Encrypt/Decrypt

Imports System.Security.Cryptography
Imports System.Text.ASCIIEncoding
Imports System.IO

Public Class Tester
    Public Shared Sub Main
            "Dim str As String = "1234567890asdfgh"
            "must be exactly 16 characters long
            Dim sSource, sKey, sIV, sResult As String
            sSource = "string"
            Dim objDES As New DESCryptoServiceProvider()
            Dim objStream As New MemoryStream(ASCII.GetBytes(sSource), False)
            sKey = "12345678"
            sIV = "12345678"
            objDES.IV = ASCII.GetBytes(sIV)
            objDES.Key = ASCII.GetBytes(sKey)
            sResult = ASCII.GetChars(objDES.CreateEncryptor().TransformFinalBlock(ASCII.GetBytes(sSource), 0, sSource.Length))
            Console.WriteLine(sResult)
            "sResult = ASCII.GetChars(objDES.CreateDecryptor().TransformFinalBlock(ASCII.GetBytes(sSource), 0, sSource.Length))
            "Console.WriteLine(sResult)
    
    End Sub
End Class

Use DES to Decrypt a file

Imports System.Security
Imports System.Security.Cryptography
Imports System.Text
Imports System.IO

Public Class Tester
    Public Shared Sub Main
        Try
            Dim myDESProvider As DESCryptoServiceProvider = New DESCryptoServiceProvider()
            myDESProvider.Key = ASCIIEncoding.ASCII.GetBytes("12345678")
            myDESProvider.IV = ASCIIEncoding.ASCII.GetBytes("12345678")
            Dim DecryptedFile As FileStream = New FileStream("testDes.txt", FileMode.Open, FileAccess.Read)
            Dim myICryptoTransform As ICryptoTransform = myDESProvider.CreateDecryptor(myDESProvider.Key, myDESProvider.IV)
            Dim myCryptoStream As CryptoStream = New CryptoStream(DecryptedFile, myICryptoTransform, CryptoStreamMode.Read)
            Dim myDecStreamReader As New StreamReader(myCryptoStream)
            Dim myDecStreamWriter As New StreamWriter("test.txt")
            myDecStreamWriter.Write(myDecStreamReader.ReadToEnd())
            myCryptoStream.Close()
            myDecStreamReader.Close()
            myDecStreamWriter.Close()
        Catch ex As Exception
            Console.WriteLine(ex.ToString())
        End Try
    End Sub
End Class

Use DES to encrypt a file

Imports System.Security
Imports System.Security.Cryptography
Imports System.Text
Imports System.IO

Public Class Tester
    Public Shared Sub Main
        Try
            Dim myDESProvider As DESCryptoServiceProvider = New DESCryptoServiceProvider()
            myDESProvider.Key = ASCIIEncoding.ASCII.GetBytes("12345678")
            myDESProvider.IV = ASCIIEncoding.ASCII.GetBytes("12345678")
            Dim myICryptoTransform As ICryptoTransform = myDESProvider.CreateEncryptor(myDESProvider.Key, myDESProvider.IV)
            Dim ProcessFileStream As FileStream = New FileStream("test.txt", FileMode.Open, FileAccess.Read)
            Dim ResultFileStream As FileStream = New FileStream("testDes.txt", FileMode.Create, FileAccess.Write)
            Dim myCryptoStream As CryptoStream = New CryptoStream(ResultFileStream, myICryptoTransform, CryptoStreamMode.Write)
            Dim bytearrayinput(ProcessFileStream.Length - 1) As Byte
            ProcessFileStream.Read(bytearrayinput, 0, bytearrayinput.Length)
            myCryptoStream.Write(bytearrayinput, 0, bytearrayinput.Length)
            myCryptoStream.Close()
            ProcessFileStream.Close()
            ResultFileStream.Close()
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class