How to Encrypt and Decrypt multiple text and image files within folders - vb.net

Question

Encryption and decryption for a single .txt file using the following code works:
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles SelectFile.Click
'Create a File Dialog Box to select the source file
Dim dlg As New OpenFileDialog
'If OK Button is Click then add file name with path to textBox1
If dlg.ShowDialog() = DialogResult.OK Then
TextBox1.Text = dlg.FileName
End If
End Sub
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Encrypt.Click
Dim outputFile As String
outputFile = "M:\Encryptions\Encrypted.txt"
Dim fsInput As New FileStream(TextBox1.Text, FileMode.Open, FileAccess.Read)
Dim fsEncrypted As New FileStream(outputFile, FileMode.Create, FileAccess.Write)
Dim sKey As String
sKey = "Helloabc"
Dim DES As New DESCryptoServiceProvider
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey)
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey)
Dim desencrypt As ICryptoTransform
desencrypt = DES.CreateEncryptor()
Dim cryptostream As New CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write)
Dim bytearrayinput(fsInput.Length) As Byte
fsInput.Read(bytearrayinput, 0, bytearrayinput.Length)
cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length)
cryptostream.Close()
fsInput.Close()
fsEncrypted.Close()
TextBox2.Text = "M:\Encryptions\Encrypted.txt"
End Sub
Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Decrypt.Click
Dim DES As New DESCryptoServiceProvider
Dim sKey As String
sKey = "Helloabc"
DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey)
DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey)
Dim fsread As New FileStream(TextBox2.Text, FileMode.Open, FileAccess.Read)
Dim desdecrypt As ICryptoTransform
desdecrypt = DES.CreateDecryptor()
Dim cryptostreamDecr As New CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read)
Dim fsDecrypted As New StreamWriter("M:\Decryptions\Decrypted.txt")
fsDecrypted.Write(New StreamReader(cryptostreamDecr).ReadToEnd())
fsDecrypted.Flush()
fsDecrypted.Close()
TextBox3.Text = "M:\Decryptions\Decrypted.txt"
End Sub
However when attempting to encrypt/decrypt multiple files, the original output encryption/decryption file ("Encrypted.txt") will be replaced by the new output.
How do you create a loop in order to create multiple encrypted files with different file names?

Answer 1

Use a counter: 0, 1, 2, 3, 4 ... Append the counter to the filename and step the counter after each file is written:
Encrypted00.dat
Encrypted01.dat
Encrypted02.dat
Encrypted03.dat
...
It is probably a mistake to call the encrypted files .txt since they will not be text. They are binary data. If you want them as text then you will need to convert to Base64 format, and convert back to binary data before decrypting.
Alternatively, zip all the files in the directory into a single file and encrypt that single file.