root = tkinter.Tk()

text_in_label=tkinter.Label(root,text='Plain text:')
k_in_label=tkinter.Label(root,text='Encryption key:')
encrypted_in_label=tkinter.Label(root,text='Encrypted text:')

text_in = tkinter.Text(root, height=1)
k_in = tkinter.Text(root, width=4, height=1)
encrypted_in = tkinter.Text(root, height=1)

to_enc = tkinter.Button(root, text='Encrypt', command=encrypt_text)
to_dec = tkinter.Button(root, text='Decrypt', command=decrypt_text)

text_in_label.grid(row=0,column=0)
k_in_label.grid(row=0,column=1)
encrypted_in_label.grid(row=0,column=2)
text_in.grid(row=1, column=0)
k_in.grid(row=1, column=1)
encrypted_in.grid(row=1, column=2)
to_enc.grid(row=2, column=0)
to_dec.grid(row=2, column=2)