Caesar Cipher Decrypt GUI.ps1

[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing") 
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")  

$Form = New-Object System.Windows.Forms.Form    
$Form.Size = New-Object System.Drawing.Size(600,270)  
$Form.Text = "Caesar Cipher Decryption"
$Form.ShowIcon = $False

###Function used to decrypt the text
function Decrypt {

#Populate $i with the selected shift to apply
$i = $DropDownBox.SelectedItem.ToString()

#Populate $text with the text input
$text = $InputBox.Text

#Transform the text to an array of ascii
$asciis = [int[]][char[]]"$text"

#Add the shift specified to every ascii character
$decrypt = foreach ($ascii in $asciis) {
$ascii - $i
}

#Transform back the ascii to text
$asciitotext = [char[]]$decrypt

#Transform the array to a string to read it easily
$arraytostring = -join $asciitotext

$OutputBox.text = $arraytostring

}

#Label1 to show explanation
$label1 = New-Object System.Windows.Forms.Label
$label1.Location = New-Object System.Drawing.Point(10,10)
$label1.Size = New-Object System.Drawing.Size(280,20)
$label1.Text = 'Enter the text to decrypt : '
$form.Controls.Add($label1)

###Text to decrypt
$InputBox = New-Object System.Windows.Forms.TextBox 
$InputBox.Location = New-Object System.Drawing.Size(10,35) 
$InputBox.Size = New-Object System.Drawing.Size(565,40) 
$InputBox.MultiLine = $True 
$InputBox.ScrollBars = "Vertical" 
$Form.Controls.Add($InputBox) 

###Combox box to select the shift to apply to the text
$DropDownBox = New-Object System.Windows.Forms.ComboBox
$DropDownBox.Location = New-Object System.Drawing.Size(10,80) 
$DropDownBox.Size = New-Object System.Drawing.Size(180,20) 
$DropDownBox.text = "Select the Shift to apply"
$DropDownBox.DropDownHeight = 200 
$Form.Controls.Add($DropDownBox) 

$Numbers=@(1,2,3,4,5,6,7,8,9)

foreach ($Number in $Numbers) {
$DropDownBox.Items.Add($Number)
} 

###Button to launch the decryption							  
$Button = New-Object System.Windows.Forms.Button 
$Button.Location = New-Object System.Drawing.Size(400,80) 
$Button.Size = New-Object System.Drawing.Size(110,80) 
$Button.Text = "Decrypt" 
$Button.Add_Click({Decrypt}) 
$Form.Controls.Add($Button)

#Label2 to show explanation
$label2 = New-Object System.Windows.Forms.Label
$label2.Location = New-Object System.Drawing.Point(10,150)
$label2.Size = New-Object System.Drawing.Size(280,20)
$label2.Text = 'Your text decrypted : '
$form.Controls.Add($label2)

###Show the result of the decryption
$OutputBox = New-Object System.Windows.Forms.TextBox 
$OutputBox.Location = New-Object System.Drawing.Size(10,170) 
$OutputBox.Size = New-Object System.Drawing.Size(565,40) 
$OutputBox.MultiLine = $True
$OutputBox.ScrollBars = "Vertical" 
$Form.Controls.Add($OutputBox) 

###Show the Gui Box
$Form.Add_Shown({$Form.Activate()})
[void] $Form.ShowDialog()