An Encrypted String Data Type for Visual Studio LightSwitch: Listing 2
EncryptedString.vb
Imports System.IO
Imports System.Reflection
Imports System.Security.Cryptography
Imports System.Text
Public Class EncryptString
Private Key As Byte()
Private IV As Byte()
Public Sub New()
Dim mPassword =
Assembly.GetExecutingAssembly().GetType().GUID.ToString().Replace("-", "")
SetKeyAndIV(mPassword)
End Sub
Private Sub SetKeyAndIV(pw As String)
Try
Dim Salt = pw.Substring(pw.Length - 16)
Dim bytPassword = UTF8Encoding.UTF8.GetBytes(pw)
Dim bytSalt = UTF8Encoding.UTF8.GetBytes(Salt)
Dim rfc2898 = New Rfc2898DeriveBytes(bytPassword, bytSalt, 10000)
Key = rfc2898.GetBytes(32)
IV = rfc2898.GetBytes(16)
Catch ex As Exception
Throw New Exception("Set Key and IV String Error", ex)
End Try
End Sub
Public Function DecryptString(EncryptedText As String) As String
Dim Result = String.Empty
Dim bytEncryptedText = Convert.FromBase64String(EncryptedText)
Try
Using aes As New AesManaged
aes.Key = Key
aes.IV = IV
Dim decryptor = aes.CreateDecryptor(aes.Key, aes.IV)
Using msDecrypt As New MemoryStream(bytEncryptedText)
Using csDecrypt As New CryptoStream(
msDecrypt, decryptor, CryptoStreamMode.Read)
Using srDecrypt As New StreamReader(csDecrypt)
Result = srDecrypt.ReadToEnd
End Using
End Using
Return Result
End Using
End Using
Catch ex As Exception
Throw New Exception("Decrypt String Error", ex)
End Try
Return Result
End Function
Public Function EncryptString(UnencryptedText As String) As String
Dim result = String.Empty
Dim bytEncrypted As Byte()
Try
Using aes As New AesManaged()
aes.Key = Key
aes.IV = IV
Dim encryptor = aes.CreateEncryptor(aes.Key, aes.IV)
Using msEncrypt As New MemoryStream()
Using csEncrypt As New CryptoStream(
msEncrypt, encryptor, CryptoStreamMode.Write)
Using swEncrypt As New StreamWriter(csEncrypt)
swEncrypt.Write(UnencryptedText)
End Using
bytEncrypted = msEncrypt.ToArray()
result = Convert.ToBase64String(bytEncrypted)
End Using
End Using
End Using
Catch ex As Exception
Throw New Exception("Encrypt String Error", ex)
End Try
Return result
End Function
End Class
About the Author
Joe Kunk is a Microsoft MVP in Visual Basic, three-time president of the Greater Lansing User Group for .NET, and developer for Dart Container Corporation of Mason, Michigan. He's been developing software for over 30 years and has worked in the education, government, financial and manufacturing industries. Kunk's co-authored the book "Professional DevExpress ASP.NET Controls" (Wrox Programmer to Programmer, 2009). He can be reached via email at [email protected].