Making an encryption algorithm

' Start with reversing the string

Public Function ReverseString(ByRef strToReverse As String) As String
        Dim result As String = ""
        For i As Integer = 0 To strToReverse.Length - 1
            result += strToReverse(strToReverse.Length - 1 - i)
        Next
        Return result
    End Function

    'then get byte value

    ' The input String.
    Dim value As String = Textbox1.Text

    ' Convert String to Byte array.
    Dim array() As Byte = System.Text.Encoding.ASCII.GetBytes(value)

    ' Display Bytes.
    For Each b As Byte In array
        Textbox1.Text = ("{0} = {1}", b, ChrW(b))

    'Byte2String

    ' Input Bytes.
    Dim array() As Byte = {86, 66, 46, 78, 69, 84}

    ' Use GetString.
    Dim value As String = System.Text.ASCIIEncoding.ASCII.GetString(array)
    Console.WriteLine(value)

    'Another string 2 byte converter

    Private Shared Function GetBytes(str As String) As Byte()
    Dim bytes As Byte() = New Byte(str.Length * 2 - 1) {}
    System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length)
    Return bytes
End Function

Private Shared Function GetString(bytes As Byte()) As String
    Dim chars As Char() = New Char(bytes.Length / 2 - 1) {}
    System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length)
    Return New String(chars)
End Function


' Byte Encoder

'encryption key
Public Shared Key As Byte() = New Byte() {&H43, &H72, &H6e, &H6d, &H54, &H4d, _
    &H65, &H94, &H16, &H32, &H44, &H84, _
    &H7e, &H18, &H64, &H76, &H6e, &H63, _
    &H64, &H7a, &H5f, &H84, &H7f, &H9a}

'Decrypt byte[]
Public Shared Function Decrypt(data As Byte()) As Byte()
    Dim ms As New MemoryStream()
    Dim alg As Rijndael = Rijndael.Create()
    alg.Key = Key
    Dim cs As New CryptoStream(ms, alg.CreateDecryptor(), CryptoStreamMode.Write)
    cs.Write(data, 0, data.Length)
    cs.Close()
    Dim decryptedData As Byte() = ms.ToArray()
    Return decryptedData
End Function

'Encrypt byte[]
Public Shared Function Encrypt(data As Byte()) As Byte()
    Dim ms As New MemoryStream()
    Dim alg As Rijndael = Rijndael.Create()
    alg.Key = Key
    Dim cs As New CryptoStream(ms, alg.CreateEncryptor(), CryptoStreamMode.Write)
    cs.Write(data, 0, data.Length)
    cs.Close()
    Dim encryptedData As Byte() = ms.ToArray()
    Return encryptedData
End Function

'serialize object to memory stream
Public Shared Function SerializeToStream(o As Object) As MemoryStream
    Dim stream As New MemoryStream()
    Dim formatter As IFormatter = New BinaryFormatter()
    formatter.Serialize(stream, o)
    Return stream
End Function

'deserialize object from memory stream
Public Shared Function DerializeFromStream(Of T As New)(memoryStream As MemoryStream) As T
    If memoryStream Is Nothing Then
        Return New T()
    End If
    Dim o As T
    Dim binaryFormatter As New BinaryFormatter()
    Using memoryStream
        memoryStream.Seek(0, SeekOrigin.Begin)
        o = DirectCast(binaryFormatter.Deserialize(memoryStream), T)
    End Using
    Return o
End Function

'Another byte modifier

Private Shared Sub EncryptThenDecrypt()
    Dim message As Byte()
    ' fill with your bytes
    Dim encMessage As Byte()
    ' the encrypted bytes
    Dim decMessage As Byte()
    ' the decrypted bytes - s/b same as message
    Dim key As Byte()
    Dim iv As Byte()

    Using rijndael = New RijndaelManaged()
        rijndael.GenerateKey()
        rijndael.GenerateIV()
        key = rijndael.Key
        iv = rijndael.IV
        encMessage = EncryptBytes(rijndael, message)
    End Using

    Using rijndael = New RijndaelManaged()
        rijndael.Key = key
        rijndael.IV = iv
        decMessage = DecryptBytes(rijndael, encMessage)
    End Using
End Sub

Private Shared Function EncryptBytes(alg As SymmetricAlgorithm, message As Byte()) As Byte()
    If (message Is Nothing) OrElse (message.Length = 0) Then
        Return message
    End If

    If alg Is Nothing Then
        Throw New ArgumentNullException("alg")
    End If

    Using stream = New MemoryStream()
        Using encryptor = alg.CreateEncryptor()
            Using encrypt = New CryptoStream(stream, encryptor, CryptoStreamMode.Write)
                encrypt.Write(message, 0, message.Length)
                encrypt.FlushFinalBlock()
                Return stream.ToArray()
            End Using
        End Using
    End Using
End Function

Private Shared Function DecryptBytes(alg As SymmetricAlgorithm, message As Byte()) As Byte()
    If (message Is Nothing) OrElse (message.Length = 0) Then
        Return message
    End If

    If alg Is Nothing Then
        Throw New ArgumentNullException("alg")
    End If

    Using stream = New MemoryStream()
        Using decryptor = alg.CreateDecryptor()
            Using encrypt = New CryptoStream(stream, decryptor, CryptoStreamMode.Write)
                encrypt.Write(message, 0, message.Length)
                encrypt.FlushFinalBlock()
                Return stream.ToArray()
            End Using
        End Using
    End Using
End Function