I’m A VB: Gaurav Khanna

My Interview with some of the great VB.NET programmer in MSDN Website. It great to be in the list with leading programmer of VB.NET.

http://blogs.msdn.com/vbteam/pages/i-m-a-vb-gaurav-khanna.aspx

Encrypt/Decrypt Text in VB.NET

In this article I have code which can be used encrypt the text before saving it in the file, database, registry, etc to protect from misuse. There are many article we can find on internet to encrypt/decrypt text in .Net. Each have different ways for encryption with some having very long code. So I have created a  very simple two functions to encrypt/decrypt a text in .Net. Both the functions contains two parameter. First parameter “Text” will be the text which need to encrypted and second parameter is “Key” which is a private key which will help identity during decrypt. So key during decrypt should be same as in encypt to decrypt the text correctly.

Code to encrypt the Text

 

Imports System.Security.Cryptography
Imports System.Text
Imports System.IO

Function Encrypt(ByVal text As String, ByVal key As String) As String
Try
Dim crp As New TripleDESCryptoServiceProvider
Dim uEncode As New UnicodeEncoding
Dim bytPlainText() As Byte = uEncode.GetBytes(text)
Dim stmCipherText As New MemoryStream
Dim slt() As Byte = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
Dim pdb As New Rfc2898DeriveBytes(key, slt)
Dim bytDerivedKey() As Byte = pdb.GetBytes(24)

crp.Key = bytDerivedKey
crp.IV = pdb.GetBytes(8)

Dim csEncrypted As New CryptoStream(stmCipherText, crp.CreateEncryptor(), CryptoStreamMode.Write)

csEncrypted.Write(bytPlainText, 0, bytPlainText.Length)
csEncrypted.FlushFinalBlock()
Return Convert.ToBase64String(stmCipherText.ToArray())
Catch ex As Exception
Throw
End Try
End Function

So for example Encrypt(“Demo”, “12345″) will return 1T5yxecmgLbsxQu4iQx5Bg==”

Code to decrypt the Text

Function Decrypt(ByVal text As String, ByVal key As String) As String
Dim crp As TripleDESCryptoServiceProvider
Try
crp = New TripleDESCryptoServiceProvider
Dim uEncode As New UnicodeEncoding
Dim bytCipherText() As Byte = Convert.FromBase64String(text)
Dim stmPlainText As New MemoryStream
Dim stmCipherText As New MemoryStream(bytCipherText)
Dim slt() As Byte = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
Dim pdb As New Rfc2898DeriveBytes(key, slt)
Dim bytDerivedKey() As Byte = pdb.GetBytes(24)
crp.Key = bytDerivedKey
crp.IV = pdb.GetBytes(8)

Dim csDecrypted As New CryptoStream(stmCipherText, crp.CreateDecryptor(), CryptoStreamMode.Read)
Dim sw As New StreamWriter(stmPlainText)
Dim sr As New StreamReader(csDecrypted)
sw.Write(sr.ReadToEnd)
sw.Flush()
csDecrypted.Clear()
crp.Clear()
Return uEncode.GetString(stmPlainText.ToArray())
Catch ex As Exception
Throw
End Try
End Function

So now when we decrypt the text encrypted above we will get the required text

So Decrypt(“1T5yxecmgLbsxQu4iQx5Bg==”, “12345″) will return “Demo”

Send email with embedded Image

Recently one of my friend wanted to send email containing embedded image, similarly like we can do using Outlook. So I decided to create an example for him. To embed external resource in email we can use LinkedResource class provide in System.Net.Mail. In this article we will send email containing embedded image with smtp server as gmail.

Code:

Private Sub SendEmail()
Dim mail As New MailMessage("fromAddress@gmail.com", "toAddress@gmail.com")
mail.Subject = "This is an embedded image mail"
'create the image resource from image path using LinkedResource class..
Dim imageResource1 As New LinkedResource("C:\MyPhotos\Photo1.jpg", "image/jpeg")
imageResource1.ContentId = "uniqueId1"
imageResource1.TransferEncoding = TransferEncoding.Base64
Dim imageResource2 As New LinkedResource("C:\MyPhotos\Photo2.jpg", "image/jpeg")
imageResource2.ContentId = "uniqueId2"
imageResource2.TransferEncoding = TransferEncoding.Base64
Dim htmlBody As New StringBuilder
htmlBody.AppendLine("")
htmlBody.AppendLine("<b>LIST OF PHOTOS</b>")
htmlBody.AppendLine("</br></br>")
htmlBody.AppendLine("PHOTO 1")
htmlBody.AppendLine("<img alt="""" hspace=0 src=""cid:uniqueId1"" align=baseline border=0 >")
htmlBody.AppendLine("</br></br>")
htmlBody.AppendLine("PHOTO 2")
htmlBody.AppendLine("<img alt="""" hspace=0 src=""cid:uniqueId2"" align=baseline border=0 >")
htmlBody.AppendLine("</br></br>")
Dim htmlView As AlternateView = AlternateView.CreateAlternateViewFromString(htmlBody.ToString, Nothing, "text/html")
'adding the imaged linked to htmlView...
htmlView.LinkedResources.Add(imageResource1)
htmlView.LinkedResources.Add(imageResource2)
mail.AlternateViews.Add(htmlView)
Dim smtp As New SmtpClient("smtp.gmail.com", 587)
'If smtp server requires SSL
smtp.EnableSsl = True
smtp.Credentials = New NetworkCredential("fromAddress@gmail.com", "SMTP Password")
smtp.Send(mail)
End Sub

WPF MessageBox

Introduction

When we open MessageBox in a WPF application, it looks are very similar to that of a Window Form. We cannot inherits or apply style to MessageBox. Using MessageBox in a WPF application with a rich user interface can look bad. So in this article we will create our own WPFMessageBox with rich user interface.

Using the code

WPFMessageBox is very similar to MessageBox in WPF with added functionality and rich user interface. We can apply two different skin to WPFMessageBox just by setting Skin property.

WPFMessageBox with Black Skin

WPFMessageBox with Blue Skin

Code to apply Black Skin and Blue Skin to WPFMessageBox is as below

'Code to apply Black Skin
WpfMessageBox.Skin = DisplaySkin.Black
'Code to apply Blue Skin
WpfMessageBox.Skin = DisplaySkin.Blue

Just like MessageBox, WPFMessageBox also has Show() method with various overloads to set caption, text, icon, buttons and default result.

Various overloaded functions for WPFMessageBox are shown in following code.

Function Show(ByVal text As String) As WpfMessageBoxResult
Function Show(ByVal text As String, ByVal caption As String) As WpfMessageBoxResult 
Function Show(ByVal text As String, ByVal caption As String, ByVal button As WpfMessageBoxButton) As WpfMessageBoxResult
Function Show(ByVal text As String, ByVal caption As String, ByVal button As WpfMessageBoxButton, ByVal icon As WpfMessageBoxImage) As WpfMessageBoxResult
Function Show(ByVal text As String, ByVal caption As String, ByVal button As WpfMessageBoxButton, ByVal icon As WpfMessageBoxImage, ByVal defaultResult As WpfMessageBoxResult) As WpfMessageBoxResult

All these overload functions are shared. So we can use them without creating their object.

WpfMessageBox.Show("Message box with a text and Caption", "WPF Message Box")

Above example will show WPFMessageBox with “Message box with a text and Caption” as text and “WPF Message Box” as caption.

WpfMessageBox.Show("Message with Yes and No", "WPF Message Box", WpfMessageBoxButton.YesNo)

Above example will show “Message with Yes and No” as text, “WPF Message Box” as caption and will contain Yes and No button.

Code for WPFMessageBox.Show have similar overload parameters to MessageBox.Show with great user interface. So one familiar to MessageBox can easily use WPFMessageBox

You can download the code from below link

Download Source Code