Imports System

Imports System.Security.Cryptography

Imports System.Text

Imports Microsoft.VisualBasic

Imports System.Security.Principal

Imports System.IO

​

Public Module Module1

​

    Public Sub Main()

        Dim md5Hasher As MD5CryptoServiceProvider = New MD5CryptoServiceProvider()

        Dim hashedBytes As Byte()

        hashedBytes = md5Hasher.ComputeHash(Encoding.UTF8.GetBytes("password"))

        Console.WriteLine("Hashed Pass : " & Convert.ToBase64String(hashedBytes)) 'Base64 output

        Console.WriteLine("Encrypted Answer : " & EncryptText("answer", "12345"))

    End Sub

​

    Public Function EncryptText(ByVal text As String, ByVal encryptKey As String) As String

        'remove null characters from text

        text = StripNullCharacters(text)

        Dim bytValue() As Byte = Encoding.UTF8.GetBytes(text.ToCharArray())

        'make sure 32 characters for 128 bit key

        Dim intLength As Integer = Len(encryptKey)

        If intLength >= 32 Then

            encryptKey = Strings.Left(encryptKey, 32)

        Else

            encryptKey = encryptKey & Strings.StrDup(32 - intLength, "X")

        End If

​

        Dim bytEncryptKey() As Byte = Encoding.UTF8.GetBytes(encryptKey.ToCharArray)

        Dim memStream As New MemoryStream()

        Dim cryptoStream As CryptoStream = Nothing

        Dim rijndaelEncryptor As RijndaelManaged = New RijndaelManaged()

        Dim encryptedBytes() As Byte

        Try

            cryptoStream = New CryptoStream(memStream, rijndaelEncryptor.CreateEncryptor(bytEncryptKey, ByteIV), CryptoStreamMode.Write)

            'write encrypted bytes

            cryptoStream.Write(bytValue, 0, bytValue.Length)

            cryptoStream.FlushFinalBlock()

            encryptedBytes = memStream.ToArray

        Catch e As Exception

            Throw e

        Finally

            If memStream IsNot Nothing Then

                memStream.Close()

            End If

​

            If cryptoStream IsNot Nothing Then

                cryptoStream.Close()

            End If

        End Try

​

        '* hexidecimal output

        'Dim strOutput As String = ""

        'For i As Integer = 0 To encryptedBytes.Length - 1

        '    strOutput &= encryptedBytes(i).ToString("x").PadLeft(2, "0")

        'Next

        Return Convert.ToBase64String(encryptedBytes) 'Base64 output

    End Function

​

    Public Function DecryptText(ByVal text As String, ByVal decryptKey As String) As String

        Dim bytEncryptedValue() As Byte = Convert.FromBase64String(text)

        'make sure 32 characters for 128 bit key

        Dim intLength As Integer = Len(decryptKey)

        If intLength >= 32 Then

            decryptKey = Strings.Left(decryptKey, 32)

        Else

            decryptKey = decryptKey & Strings.StrDup(32 - intLength, "X")

        End If

​

        Dim bytDecryptKey() As Byte = Encoding.UTF8.GetBytes(decryptKey.ToCharArray)

        'create stream containing decrypt value

        Dim memStream As MemoryStream = New MemoryStream(bytEncryptedValue)

        Dim cryptoStream As CryptoStream = Nothing

        Dim rijndaelDecryptor As RijndaelManaged = New RijndaelManaged()

        'create byte array to recieved decrypted bytes

        Dim decryptedBytes(bytEncryptedValue.Length) As Byte

        Try

            cryptoStream = New CryptoStream(memStream, rijndaelDecryptor.CreateDecryptor(bytDecryptKey, ByteIV), CryptoStreamMode.Read)

            'read decrypted bytes

            cryptoStream.Read(decryptedBytes, 0, decryptedBytes.Length)

        'cryptoStream.FlushFinalBlock()

        Catch e As Exception

            Throw e

        Finally

            If memStream IsNot Nothing Then

                memStream.Close()

            End If

​

            If cryptoStream IsNot Nothing Then

                cryptoStream.Close()

            End If

        End Try

​

        Return StripNullCharacters(Encoding.UTF8.GetString(decryptedBytes))

    End Function

​

    Public Function StripNullCharacters(ByVal stringWithNulls As String) As String

        Dim intPosition As Integer

        Dim strOutput As String = stringWithNulls

        intPosition = 1

        Do While intPosition > 0

            intPosition = InStr(intPosition, stringWithNulls, vbNullChar)

            If intPosition > 0 Then

                strOutput = Left$(strOutput, intPosition - 1) & Right$(strOutput, Len(strOutput) - intPosition)

            End If

​

            If intPosition > strOutput.Length Then

                Exit Do

            End If

        Loop

​

        Return strOutput

    End Function

​

    Private _byteIV() As Byte

​

    Private ReadOnly Property ByteIV() As Byte()

        Get

            If _byteIV Is Nothing Then

                _byteIV = New Byte() {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}

            End If

​

            Return _byteIV

        End Get

    End Property

End Module

​