Encrypt/Decrypt with Imports System.Security.Cryptography

This little tutorial puts some morge sunshine on the System.Security.Cryptography standard class in VB.net…

There are a few encryption possibilities, but i’m going to encrypt/decrypt on a TripleDes algorithm!

More info on the TripleDES: http://en.wikipedia.org/wiki/Triple_DES

The first thing we have to do is import the class

Imports System.Security.Cryptography

We also make a global (module) variable, for a Service Provider to handle the TripleDES settlement

Private TripleDes As New TripleDESCryptoServiceProvider

We then need 2 functions, A decrypt and Encrypt function…

We’ll start with the Encrypt function…

Public Function EncryptData(ByVal plaintext As String) As String

‘ Convert the plaintext string to a byte array.
Dim plaintextBytes() As Byte = System.Text.Encoding.Unicode.GetBytes(plaintext)

‘ Create the stream.

Dim ms As New System.IO.MemoryStream

‘ Create the encoder to write to the stream.

Dim encStream As New CryptoStream(ms,TripleDes.CreateEncryptor(),System.Security.Cryptography.CryptoStreamMode.Write)

‘ Use the crypto stream to write the byte array to the stream.

encStream.Write(plaintextBytes, 0, plaintextBytes.Length)

encStream.FlushFinalBlock()

‘ Convert the encrypted stream to a printable string.

Return Convert.ToBase64String(ms.ToArray)

End Function

To decrypt the following Encryption we will make the function beneath…

Public Function DecryptData(ByVal encryptedtext As String) As String

‘ Convert the encrypted text string to a byte array.
Dim encryptedBytes() As Byte = Convert.FromBase64String(encryptedtext)

‘ Create the stream.
Dim ms As New System.IO.MemoryStream
‘ Create the decoder to write to the stream.
Dim decStream As New CryptoStream(ms, TripleDes.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Write)

‘ Use the crypto stream to write the byte array to the stream.
decStream.Write(encryptedBytes, 0, encryptedBytes.Length)
decStream.FlushFinalBlock()

‘ Convert the plaintext stream to a string.
Return System.Text.Encoding.Unicode.GetString(ms.ToArray)

End Function

This will do the trick!

Download Code Sample

You can also attach your personal Private / Personal key to the TripleDES Cryprography, here VB uses the standard Keys …

What you will have to do is following,

1. Declare your own private and public key ( wich are an array of bytes)

Dim key() As Byte = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24}
Dim iv() As Byte = {8, 7, 6, 5, 4, 3, 2, 1}

2. edit the line of EncryptData and DecryptData where you attach your own declared keys

Dim decStream As New CryptoStream(ms, TripleDes.CreateDecryptor(key, iv),_ System.Security.Cryptography.CryptoStreamMode.Write)

StreamReader > Reading textfiles into Visual Studio

So what we wanna do in this little tut is to be able to load a text file from our local hard drive into visual basic,

i’ve got this text file that contains different players from a belgian soccer team , with there scores and player names…

So this is what we will do after reading the text file:

We first filter out the team name , we only want the player scores…. , which is the last number in each textline…

Using the Streamreader we can read text files into the Visual Basic program, not as hard as you might think…

Here we go …

First we declare a new StreamReader

Dim fileReader As System.IO.StreamReader

We than provide the StreamReader the file location of our textfile

fileReader = My.Computer.FileSystem.OpenTextFileReader(“C:\test.txt”)

Following we declare a new String variable stringReader, TekstLijn and sSpeeldag

Dim stringReader As String

Dim sSpeeldag As String

Dim TekstLijn As String

Using the Do … Loop Until we run through the text file …

Do
stringReader = fileReader.ReadLine()
TekstLijn = stringReader If TekstLijn.Length > 20 Then
Dim sInfo() As String sInfo = TekstLijn.Split(vbTab) Dim sPunt As String
sPunt = sInfo(5)

MsgBox(“Score: ” & sPunt)

End If

Loop Until TekstLijn Is Nothing

What we actually do in the code above is running through each line of the textfile, we first check if the line we are currently at contains more than 20 characters, hereby we filter out the names of the soccer teams…

What we than do is split the whole line into different items, in this case we only need the player scores, …

So we will use the 5ft item of the split

sInfo(5)

After splitting the text line, we will use the MsgBox command to put the player score on the screen, and this for each textline in the textfile…

Easy afterall for those who didn’t know this function yet…

A StreamReader function is also available in Visial Studio, with this function we will be able to write to textfiles….