Learning Python- Intermediate course: Day 27, Entry keypress event

Let us study keypress event in Tkinter entry widget

Yesterday we had made a dummy login program (password manager). But the thing was the password was hidden. The password data can only be accessed by the storepassword() function. But today how about making a secret trapdoor available for hackers to steal the passwords

Keypress event

We can achieve this by writing a piece of code into the main program which scans whatever we write into the password entry widget and prints it in the command prompt. This can be done using the keypress event. e1.bind("<Key>",keypress) Whenever any key is pressed, then the function 'keypress' is executed.

Here is the complete code

from tkinter import *spy=Tk()spy.geometry("300x200")spy.title("spyware")def keypress(event):    try:        print(ord(event.char),end=".")    except: # for blank press        passe1=Entry(spy,show='*')e1.focus_set()e1.bind("<Key>",keypress)# mind the case of 'key'- k must be Ke1.pack()spy.mainloop()

So what is happening? Well, the actual action is taking place in the shell window.

Let me explain what the keypress function does. Whenever any key is pressed, the keypress function is executed. This function first extracts out which key is pressed. Then, it converts the key into an ASCII value and prints it in the command shell using a dot for separation. This way, even characters like backspace and enter key can be detected. Parsing this string to get the password is a piece of cake for the hacker

The code is wrapped in try-except to prevent blank key presses, which results in errors like

Exception in Tkinter callbackTraceback (most recent call last):  File "C:\Users\aatma\AppData\Local\Programs\Python\Python310\libkinter\__init__.py", line 1884, in __call__    return self.func(*args)  File "C:/Users/aatma/AppData/Local/Programs/Python/Python310/spy.py", line 6, in keypress    print(ord(event.char),end=".")TypeError: ord() expected a character, but string of length 0 found

Let us now couple the code with our password manager and see the results.

import tkinter as tk # import the Tkinter moduleform=tk.Tk() # create the blank window.form.title("password manager") # set the title as password managerform.geometry('400x200') # set the default geometry of the window.TB1=tk.Entry(form, width = 20) # make an entry widget with 20 spaces for the usernameTB2=tk.Entry(form,show="*", width = 20)def keypress(event):    try:        print(ord(event.char),end=".")    except: # for blank press        passTB2.bind("<Key>",keypress)# entry widget for password and hide the keys whenever pressed.# TB1 is for username, TB2 is for passwordTB1.pack()TB2.pack()# pack the widgets into 'form'label=tk.Label(form,text="")# make a label to display the usernamedef show(): #function to be executed once the button is pressed.    a=TB1.get() # get username    b=TB2.get() # get password    if(a!="" and b!=""):     label.config(text="Welcome "+a+" to python GUI",fg="Green") # display the label     storepassword(a,b) # store password and username    else:     label.config(text="Please enter a valid username and password.",fg="Red")  # blank screensdef storepassword(username, password):    #//Some mechanism to store password//    pass #stubbedbutton=tk.Button(form,text="Sign Up", command=show) # setup the buttonbutton.pack()label.pack()form.mainloop()show()

So friends that was all for today. Stay tuned for updates.....