 Module Module1
    Sub Main()
        Console.WriteLine("Algoritma DES (Data Encryption Standard)")

        '1. Tentukan kalimat yang akan dienkrip
        Console.WriteLine("Masukkan kalimat yang akan dienkrip: ")
        Dim input As String = Console.ReadLine
        Console.WriteLine("")

        '2. Tentukan kata kunci enkripsi yang digunakan
        Console.WriteLine("Masukkan kata kunci enkripsi: ")
        Dim kataKunci As String = Console.ReadLine
        Console.WriteLine("")

        '3. Lakukan inisialisasi variabel yang digunakan oleh metode ini
        'Penjelasan lebih detail tentang fungsi ini dapat dilihat pada penjelasan skrip dibawah ini
        Dim xc As New CryptCore()
        xc.InitCore()
        xc.Key = kataKunci

        '4. Lakukan enkripsi kalimat awal menggunakan algoritma ini
        'Penjelasan lebih detail tentang fungsi ini dapat dilihat pada penjelasan skrip dibawah ini
        Dim hasilEnkripsi As String = xc.Encrypt(input)
        Console.WriteLine("Hasil enkripsi kalimat input adalah: " & vbCrLf & hasilEnkripsi.ToString & vbCrLf)

        '5. Lakukan dekripsi dari kalimat yang telah terenkripsi
        'Penjelasan lebih detail tentang fungsi ini dapat dilihat pada penjelasan skrip dibawah ini
        Dim hasilDekripsi As String = xc.Decrypt(hasilEnkripsi)
        Console.WriteLine("Hasil dekripsi dari kalimat terenkripsi adalah: " & vbCrLf & hasilDekripsi & vbCrLf)

        Console.ReadLine()
    End Sub
End Module

Public Class CryptCore
    Private _key As String = Nothing
    Public Property Key() As String
        Get
            Return _key
        End Get
        Set(value As String)
            _key = Me.formatKey(value)
        End Set
    End Property

    Private Function formatKey(key As String) As String
        If key Is Nothing OrElse key.Length = 0 Then
            Return Nothing
        End If
        Return key.Trim()
    End Function

    Private DefaultKey As String = ""

    Public Sub New()
        DefaultKey = "enkripsi"
    End Sub

    Private _coreSymmetric As CoreAlgoritmaSymmetric

    Public Function InitCore() As Boolean
        _coreSymmetric = New CoreAlgoritmaSymmetric()
        Return True
    End Function

    Public Function Decrypt(src As String) As String
        Dim hasil As String = ""

        If _key Is Nothing Then
            hasil = _coreSymmetric.ProsesDecrypt(src, DefaultKey)
        Else
            hasil = _coreSymmetric.ProsesDecrypt(src, _key)
        End If

        Return hasil
    End Function

    Public Function Decrypt(src As String, key As String) As String
        Dim hasil As String = ""

        hasil = _coreSymmetric.ProsesDecrypt(src, key)

        Return hasil
    End Function

    Public Function Encrypt(src As String) As String
        Dim hasil As String = ""

        If _key Is Nothing Then
            hasil = _coreSymmetric.ProsesEncrypt(src, DefaultKey)
        Else
            hasil = _coreSymmetric.ProsesEncrypt(src, _key)
        End If

        Return hasil
    End Function

    Public Function Encrypt(src As String, key As String) As String
        Dim hasil As String = ""

        hasil = _coreSymmetric.ProsesEncrypt(src, key)

        Return hasil
    End Function

    Public Class CoreAlgoritmaSymmetric
        Private metodeEncode As System.Security.Cryptography.SymmetricAlgorithm

        Public Sub New()
            metodeEncode = New System.Security.Cryptography.DESCryptoServiceProvider()
        End Sub

        Private Function GetValidKey(Key As String) As Byte()
            Dim sTemp As String
            If metodeEncode.LegalKeySizes.Length > 0 Then
                Dim lessSize As Integer = 0, moreSize As Integer = metodeEncode.LegalKeySizes(0).MinSize

                While Key.Length * 8 > moreSize AndAlso metodeEncode.LegalKeySizes(0).SkipSize > 0 AndAlso moreSize < metodeEncode.LegalKeySizes(0).MaxSize
                    lessSize = moreSize
                    moreSize += metodeEncode.LegalKeySizes(0).SkipSize
                End While

                If Key.Length * 8 > moreSize Then
                    sTemp = Key.Substring(0, (moreSize / 8))
                Else
                    sTemp = Key.PadRight(moreSize / 8, " "c)
                End If
            Else
                sTemp = Key
            End If

            'Konversi kata kunci menjadi byte array
            Return System.Text.ASCIIEncoding.ASCII.GetBytes(sTemp)
        End Function

        Private Function GetValidIV(InitVector As [String], panjangValid As Integer) As Byte()
            If InitVector.Length > panjangValid Then
                Return System.Text.ASCIIEncoding.ASCII.GetBytes(InitVector.Substring(0, panjangValid))
            Else
                Return System.Text.ASCIIEncoding.ASCII.GetBytes(InitVector.PadRight(panjangValid, " "c))
            End If
        End Function

        Public Function ProsesEncrypt(Source As String, Key As String) As String
            If Source Is Nothing OrElse Key Is Nothing OrElse Source.Length = 0 OrElse Key.Length = 0 Then
                Return Nothing
            End If

            If metodeEncode Is Nothing Then
                Return Nothing
            End If

            Dim lPanjangStream As Long
            Dim jumlahBufferTerbaca As Integer
            Dim byteBuffer As Byte() = New Byte(2) {}
            Dim srcData As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(Source)
            Dim encData As Byte()
            Dim streamInput As New System.IO.MemoryStream()
            streamInput.Write(srcData, 0, srcData.Length)
            streamInput.Position = 0
            Dim streamOutput As New System.IO.MemoryStream()
            Dim streamEncrypt As System.Security.Cryptography.CryptoStream

            metodeEncode.Key = GetValidKey(Key)
            metodeEncode.IV = GetValidIV(Key, metodeEncode.IV.Length)

            streamEncrypt = New System.Security.Cryptography.CryptoStream(streamOutput, metodeEncode.CreateEncryptor(), System.Security.Cryptography.CryptoStreamMode.Write)
            lPanjangStream = streamInput.Length

            Dim totalBufferTerbaca As Integer = 0
            While totalBufferTerbaca < lPanjangStream
                jumlahBufferTerbaca = streamInput.Read(byteBuffer, 0, byteBuffer.Length)
                streamEncrypt.Write(byteBuffer, 0, jumlahBufferTerbaca)
                totalBufferTerbaca += jumlahBufferTerbaca
            End While
            streamEncrypt.Close()

            encData = streamOutput.ToArray()

            'Konversi menjadi base64 agar hasil dapat digunakan dalam xml
            Return Convert.ToBase64String(encData)
        End Function

        Public Function ProsesDecrypt(Source As String, Key As String) As String
            If Source Is Nothing OrElse Key Is Nothing OrElse Source.Length = 0 OrElse Key.Length = 0 Then
                Return Nothing
            End If

            If metodeEncode Is Nothing Then
                Return Nothing
            End If

            Dim lPanjangStream As Long
            Dim jumlahBufferTerbaca As Integer
            Dim byteBuffer As Byte() = New Byte(2) {}
            Dim encData As Byte() = Convert.FromBase64String(Source)
            Dim decData As Byte()
            Dim streamInput As New System.IO.MemoryStream(encData)
            Dim streamOutput As New System.IO.MemoryStream()
            Dim streamDecrypt As System.Security.Cryptography.CryptoStream

            metodeEncode.Key = GetValidKey(Key)
            metodeEncode.IV = GetValidIV(Key, metodeEncode.IV.Length)

            streamDecrypt = New System.Security.Cryptography.CryptoStream(streamInput, metodeEncode.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Read)
            lPanjangStream = streamInput.Length

            Dim totalBufferTerbaca As Integer = 0
            While totalBufferTerbaca < lPanjangStream
                jumlahBufferTerbaca = streamDecrypt.Read(byteBuffer, 0, byteBuffer.Length)
                If 0 = jumlahBufferTerbaca Then
                    Exit While
                End If

                streamOutput.Write(byteBuffer, 0, jumlahBufferTerbaca)
                totalBufferTerbaca += jumlahBufferTerbaca
            End While
            streamDecrypt.Close()

            decData = streamOutput.ToArray()
            For i As Integer = 0 To decData.Length - 1
                If decData(i) < 8 Then decData(i) = 0
            Next

            Dim encodeASCII As New System.Text.ASCIIEncoding()
            Return encodeASCII.GetString(decData)
        End Function
    End Class
End Class

created 4 years ago

Visual basic (VB.net) Online Compiler

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Public Module Program
	Public Sub Main(args() As string)
	 Dim name as String = Console.ReadLine()    ' Reading input from STDIN
   Console.WriteLine("Hello " & name)           ' Writing output to STDOUT
	End Sub
End Module

About VB.net

Visual Basic is a event driven programming language by Microsoft, first released in the year 1991.

Key Features

Beginner's friendly language.
Simple and object oriented programming language.
User friendly language and easy to develop GUI based applications.

Syntax help

Variables

Variable is a name given to the storage area in order to identify them in our programs.

Simple syntax of Variable declaration is as follows

Dim variableName [ As [ New ] dataType ] [ = initializer ]

Variable initialization

variableName = value

Conditional Statements

1. If

If condition-expression Then 
    'code
End If

2. If-else

If(conditional-expression)Then
   'code if the conditional-expression is true 
Else
  'code if the conditional-expression is false 
End If

3. If-else-if ladder

If(conditional-expression)Then
   'code if the above conditional-expression is true 
Else If(conditional-expression) Then
        'code if the above conditional-expression is true 
    Else
        'code if the above conditional-expression is false 
End If

4. Nested-If

If(conditional-expression)Then
   'code if the above conditional-expression is true
   If(conditional-expression)Then
         'code if the above conditional-expression is true 
   End If
End If

5. Select Case

Select [ Case ] expression
   [ Case expressionlist
      'code ]
   [ Case Else
      'code ]
End Select

Loops

1. For..Next

For counter [ As datatype ] = begin To end [ Step step ]
   'code
   [ Continue For ]
   'code
   [ Exit For ]
   'code
Next [ counter ]

2. For..Each

For Each element [ As datatype ] In group
   'code
   [ Continue For ]
   'code
   [ Exit For ]
   'code
Next [ element ]

3. While

While conditional-expression
   'Code 
   [ Continue While ]
   'Code
   [ Exit While ]
   'Code
End While

4. Do-while

Do { While | Until } conditional-expression
   'Code
   [ Continue Do ]
   'Code
   [ Exit Do ]
   'Code
Loop

Do
   'Code
   [ Continue Do ]
   'Code
   [ Exit Do ]
   'Code
Loop { While | Until } conditional-expression

Procedures

Procedure is a sub-routine which contains set of statements. Usually Procedures are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Procedures are of two types.

1. Functions

Functions return a value when they are called.

[accessModifiers] Function functionName [(parameterList)] As returnType
   'code
End Function

2. Sub-Procedures

Sub-procedures are similar to functions but they don't return any value.

Sub ProcedureName (parameterList)
'Code
End Sub