import random
def crypto(message, alphabet, offset):
    result = ''
    for sym in message:
        if sym in alphabet:
            index = alphabet.find(sym)
            result += alphabet[(index + offset) % len(alphabet)]
        else:
            result += sym
    return result
def decrypto(message, alphabet, offset):
    result = ''
    for sym in message:
        if sym in alphabet:
            index = alphabet.find(sym)
            result += alphabet[(index - offset) % len(alphabet)]
        else:
            result += sym
    return result
ab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZАБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ'
alphabet = ab + ab.lower()
offset = int(random.uniform(0, 9))
message = input('введите текст: ')
crypto = crypto(message, alphabet, offset)
print(crypto)
decrypto = decrypto(crypto, alphabet, offset)
print(decrypto)

[code python]
import tkinter as tk
from typing import List

win = tk.Tk()
win.title('Алгоритм шифрования подстановкой')
win.geometry('800x800+200+200')
win.resizable(False, False)

label1 = tk.Label(win,text='Текст для шифрования')
label2 = tk.Label(win,text='Ключ')


text = tk.Entry(win)
key = tk.Entry(win)
rslt1 = tk.Entry(win)
rslt2 = tk.Entry(win)

def dlt():
    text1.delete(0, tk.END)
    key.delete(0, tk.END)
    rslt1.delete(0, tk.END)
    rslt2.delete(0, tk.END)

btn1 = tk.Button(win,text='Зашифровать')
btn3 = tk.Button(win,text='Создать рандомный ключ')
btn4 = tk.Button(win,text='Очистить', command=dlt)
btn5 = tk.Button(win,text='Расшифровать')

label1.grid(row=0,column=0,stick='wens')
label2.grid(row=0,column=1,stick='wens')
text.grid(row=1,column=0,stick='wens')
key.grid(row=1,column=1,stick='wens')
btn1.grid(row=2,column=0,columnspan=2,stick='wens')
btn3.grid(row=3,column=0,columnspan=2,stick='wens')
btn4.grid(row=4,column=0,columnspan=2,stick='wens')
btn5.grid(row=5,column=0,columnspan=2,stick='wens')
rslt1.grid(row=6,column=0,stick='wens')
rslt2.grid(row=6,column=1,stick='wens')

win.grid_columnconfigure(0,minsize=400)
win.grid_columnconfigure(1,minsize=400)
win.grid_rowconfigure(0,minsize=40)
win.grid_rowconfigure(1,minsize=40)
win.grid_rowconfigure(2,minsize=40)
win.grid_rowconfigure(3,minsize=40)
win.grid_rowconfigure(4,minsize=40)
win.grid_rowconfigure(5,minsize=40)
win.grid_rowconfigure(6,minsize=40)

win.mainloop()
[/code]

  
import random
import tkinter as tk
def crypto(message, alphabet, offset):
    result = ''
    for sym in message:
        if sym in alphabet:
            index = alphabet.find(sym)
            result += alphabet[(index + offset) % len(alphabet)]
        else:
            result += sym
    return result
 
def decrypto(message, alphabet, offset):
    result = ''
    for sym in message:
        if sym in alphabet:
            index = alphabet.find(sym)
            result += alphabet[(index - offset) % len(alphabet)]
        else:
            result += sym
    return result
ab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZАБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ'
alphabet = ab + ab.lower()
offset = random.randrange(0, 10)
 
def process():
    text = entry_in.get()
    text_crypto = crypto(text, alphabet, offset)
    entry_out.delete(0, 'end')
    entry_out.insert(0, text_crypto)
 
root = tk.Tk()
root.geometry('300x200')
lbl1 = tk.Label(text='текст который нужно зашифровать').pack()
entry_in = tk.Entry(width=20)
entry_in.pack()
lbl2 = tk.Label(text='зашифрованный текст').pack()
entry_out = tk.Entry(width=20)
entry_out.pack()
lbl3 = tk.Label(text=f'ключ шифрования: {offset}').pack()
btn = tk.Button(text='зашифровать', command=process)
btn.pack()
root.mainloop()