@echo off
setlocal enabledelayedexpansion
set "svar=abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+-*/~`_=|:;',.<>?"
set "rvar="
set num=12
:loop
set /a num-=1
set /a rand=%random%%%79
set "rvar=%rvar%!svar:~%rand%,1!"
if not %num%==0 goto loop
echo !rvar!
pause>nul