Ciao,
di seguito il codice C# per l’estensione del componente TextBox al fine di mitigare il problema dei “keyLogger”.
Il codice è funzionante anche se sicuramente prototipale.
Spero possa esservi utile.
(Codice presso GitHub: https://github.com/waltzie/CSharp-PasswordTextBox)
using System;
using System.ComponentModel;
using System.Linq;
using System.Windows.Forms;
namespace WaltZie.Windows.Forms
{
///
/// Estensione della casella TextBox per gestire le password in modo che non possano essere intercettate dai keylkoggers
///
// Problema con i caratteri [] gestiti da sendkey
// Problema con digitazione caratteri in contemporanea. Occorre reindirizzare OnKeyPress a thread sequenziali.
public class PasswordTextBox : System.Windows.Forms.TextBox
{
public static PasswordTextBox Instance = new PasswordTextBox();
private string junk = “”;
private uint _junkMax = 4;
private uint _junkMin = 2;
private byte _minchar = 32;
private byte _maxchar = 126;
private string _allowedchars=””;
private string _scramble;
private bool _obfuscate = false;
private static readonly Random random = new Random();
private static readonly object syncLock = new object();
private delegate string del(string s);
public PasswordTextBox() {
}
protected override void OnMouseDown(MouseEventArgs e)
{
if (String.IsNullOrEmpty(this.Text))
{
sendJunkChars();
}
base.OnMouseDown(e);
}
///
///
The AllowedChars represents characters allowed.
/// The AllowedChars gets/sets the value of the string field, _allowedchars.
///
[Category(“Extensions”), Browsable(true), Description(“String containig allowed chars”)]
public string AllowedChars
{
set
{
if ((value.Length) < 256) { this._allowedchars = value; this._scramble = new string(_allowedchars.ToCharArray().OrderBy(x => Guid.NewGuid()).ToArray());
}
}
get
{
return this._allowedchars;
}
}
///
///
The Obfuscate define if typed text must be obfuscate with shuffled allowd chars.
/// The Obfuscate gets/sets the value of the bool field, _obfuscate.
///
[Category(“Extensions”), Browsable(true), Description(“Obfuscate input data”)]
public bool Obfuscate
{
set
{
this._obfuscate = value;
if (this._obfuscate && _allowedchars == “”) this.AllowedChars = ” !\”#$%&'()*+-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~”;
}
get
{
return this._obfuscate;
}
}
///
///
The ClearText represents real typed test.
/// The ClearText gets the value of the de-obfuscated string field, Text.
/// Returns original de-obfuscated typed text.
///
[Category(“Extensions”), Browsable(true), Description(“Clear text”)]
public string ClearText
{
get
{
return deobfuscate(this.Text);
}
}
private bool IsAllowedChar(char c)
{
if (char.IsControl(c)) return false;
if (this._allowedchars.Length > 0)
{
if (this._allowedchars.Contains(c.ToString())) return true;
else return false;
}
else return true;
}
private string Randomchar()
{
return Convert.ToChar(random.Next(this._minchar, this._maxchar)).ToString();
}
private string junkGenerator()
{
string randomString = “”;
for (int i = 0; i < random.Next((int)this._junkMin, (int)this._junkMax); i++)
randomString += Randomchar();
return randomString;
}
private void sendJunkChars()
{
string outchar = “”;
lock (syncLock)
{
this.junk += junkGenerator();
for (int i = 0; i < this.junk.Length; i++)
if (“+^%~(){}”.Contains(this.junk[i])) outchar += “{” + this.junk[i] + “}”;
else outchar += this.junk[i].ToString();
this.Focus();
SendKeys.Send(outchar);
}
}
private char obfuscate(char s) {
lock (syncLock)
{
if (this._obfuscate) return this._scramble[this._allowedchars.IndexOf(s)];
else return s;
}
}
private string deobfuscate(string s) {
if (!this._obfuscate) return s;
string outstr = “”;
for (int i=0; i<this.Text.Length;i++) { outstr += this._allowedchars[this._scramble.IndexOf(this.Text[i])].ToString(); } return outstr; } protected override bool ProcessCmdKey(ref Message msg, Keys keyData) { if (this.junk.Length == 0) { if (keyData == Keys.Delete) OnKeyPress(new KeyPressEventArgs((Char)Keys.Back)); } return base.ProcessCmdKey(ref msg, keyData); } protected override void OnKeyPress(KeyPressEventArgs e) { // Controllare this.SelectedText base.OnKeyPress(e); string keyInput = e.KeyChar.ToString(); if (this.junk.Length > 0)
{
//this char is junk
e.Handled = true;
lock(syncLock) this.junk = this.junk.Remove(this.junk.Length – 1);
}
else if (IsAllowedChar(e.KeyChar))
{
e.KeyChar = obfuscate(e.KeyChar);
sendJunkChars();
}
else if (e.KeyChar == ‘\b’)
{
try
{
// Backspace key is OK
sendJunkChars();
}
catch { e.Handled = true; }
}
else
{
// Consume this invalid key and beep
e.Handled = true;
System.Media.SystemSounds.Exclamation.Play();
}
}
}
}