Imports System.Security.Cryptography
Imports System.IO
Imports System.Text
Public Class clsEncoder
Public Function EncryptString128Bit(ByVal vstrTextToBeEncrypted As String, _
ByVal vstrEncryptionKey As String) As String
Dim bytValue() As Byte
Dim bytKey() As Byte
Dim bytEncoded() As Byte
Dim bytIV() As Byte = {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}
Dim intLength As Integer
Dim intRemaining As Integer
Dim objMemoryStream As New MemoryStream()
Dim objCryptoStream As CryptoStream
Dim objRijndaelManaged As RijndaelManaged
' **********************************************************************
' ****** Strip any null character from string to be encrypted ******
' **********************************************************************
vstrTextToBeEncrypted = StripNullCharacters(vstrTextToBeEncrypted)
' **********************************************************************
' ****** Value must be within ASCII range (i.e., no DBCS chars) ******
' **********************************************************************
bytValue = Encoding.ASCII.GetBytes(vstrTextToBeEncrypted.ToCharArray)
intLength = Len(vstrEncryptionKey)
' ********************************************************************
' ****** Encryption Key must be 256 bits long (32 bytes) ******
' ****** If it is longer than 32 bytes it will be truncated. ******
' ****** If it is shorter than 32 bytes it will be padded ******
' ****** with upper-case Xs. ******
' ********************************************************************
If intLength >= 32 Then
vstrEncryptionKey = Strings.Left(vstrEncryptionKey, 32)
Else
intLength = Len(vstrEncryptionKey)
intRemaining = 32 - intLength
vstrEncryptionKey = vstrEncryptionKey & Strings.StrDup(intRemaining, "X")
End If
bytKey = Encoding.ASCII.GetBytes(vstrEncryptionKey.ToCharArray)
objRijndaelManaged = New RijndaelManaged()
' ***********************************************************************
' ****** Create the encryptor and write value to it after it is ******
' ****** converted into a byte array ******
Try
objCryptoStream = New CryptoStream(objMemoryStream, _
objRijndaelManaged.CreateEncryptor(bytKey, bytIV), _
CryptoStreamMode.Write)
objCryptoStream.Write(bytValue, 0, bytValue.Length)
objCryptoStream.FlushFinalBlock()
bytEncoded = objMemoryStream.ToArray
objMemoryStream.Close()
objCryptoStream.Close()
Catch
End Try
' ***********************************************************************
' ****** Return encryptes value (converted from byte Array to ******
' ****** a base64 string). Base64 is MIME encoding) ******
' ***********************************************************************
Return Convert.ToBase64String(bytEncoded)
End Function
Public Function DecryptString128Bit(ByVal vstrStringToBeDecrypted As String, _
ByVal vstrDecryptionKey As String) As String
Dim bytDataToBeDecrypted() As Byte
Dim bytTemp() As Byte
Dim bytIV() As Byte = {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}
Dim objRijndaelManaged As New RijndaelManaged()
Dim objMemoryStream As MemoryStream
Dim objCryptoStream As CryptoStream
Dim bytDecryptionKey() As Byte
Dim intLength As Integer
Dim intRemaining As Integer
'Dim intCtr As Integer
Dim strReturnString As String = String.Empty
'Dim achrCharacterArray() As Char
'Dim intIndex As Integer
' *****************************************************************
' ****** Convert base64 encrypted value to byte array ******
' *****************************************************************
bytDataToBeDecrypted = Convert.FromBase64String(vstrStringToBeDecrypted)
' ********************************************************************
' ****** Encryption Key must be 256 bits long (32 bytes) ******
' ****** If it is longer than 32 bytes it will be truncated. ******
' ****** If it is shorter than 32 bytes it will be padded ******
' ****** with upper-case Xs. ******
' ********************************************************************
intLength = Len(vstrDecryptionKey)
If intLength >= 32 Then
vstrDecryptionKey = Strings.Left(vstrDecryptionKey, 32)
Else
intLength = Len(vstrDecryptionKey)
intRemaining = 32 - intLength
vstrDecryptionKey = vstrDecryptionKey & Strings.StrDup(intRemaining, "X")
End If
bytDecryptionKey = Encoding.ASCII.GetBytes(vstrDecryptionKey.ToCharArray)
ReDim bytTemp(bytDataToBeDecrypted.Length)
objMemoryStream = New MemoryStream(bytDataToBeDecrypted)
' ***********************************************************************
' ****** Create the decryptor and write value to it after it is ******
' ****** converted into a byte array ******
' ***********************************************************************
Try
objCryptoStream = New CryptoStream(objMemoryStream, _
objRijndaelManaged.CreateDecryptor(bytDecryptionKey, bytIV), _
CryptoStreamMode.Read)
objCryptoStream.Read(bytTemp, 0, bytTemp.Length)
objCryptoStream.FlushFinalBlock()
objMemoryStream.Close()
objCryptoStream.Close()
Catch
End Try
' *****************************************
' ****** Return decypted value ******
' *****************************************
Return StripNullCharacters(Encoding.ASCII.GetString(bytTemp))
End Function
Public Function StripNullCharacters(ByVal vstrStringWithNulls As String) As String
Dim intPosition As Integer
Dim strStringWithOutNulls As String
intPosition = 1
strStringWithOutNulls = vstrStringWithNulls
Do While intPosition > 0
intPosition = InStr(intPosition, vstrStringWithNulls, vbNullChar)
If intPosition > 0 Then
strStringWithOutNulls = Left$(strStringWithOutNulls, intPosition - 1) & _
Right$(strStringWithOutNulls, Len(strStringWithOutNulls) - intPosition)
End If
If intPosition > strStringWithOutNulls.Length Then
Exit Do
End If
Loop
Return strStringWithOutNulls
End Function
End Class