Making a Batch File Faster - batch-file

Question

I have this little piece of code for cracking WinRAR archive passwords using a word list file.
title RAR Crack v_2.0
echo off
color f0
set dest=%temp%\%random%
md %dest%
cls
echo.
echo -----------------------------------------
echo ^| RAR CRACK v_2.0 - BY NOOR (#NullByte) ^|
echo -----------------------------------------
echo.
echo Drag and drop the archive to this window and press ENTER
set /p arch=
echo.
echo Drag and drop the wordlist to this window and press ENTER
set /p word=
cls
echo.
echo Starting Process . .
timeout /t 2 /nobreak>nul
color f5
cls
echo.
echo Starting Process . . .
timeout /t 1 /nobreak>nul
:start
for /F %%A in (%word%) do call :process %%A
color 0c
cls
echo.
echo -----------------------------------------
echo ^| RAR CRACK v_2.0 - BY NOOR (#NullByte) ^|
echo -----------------------------------------
echo.
echo.
echo PASSWORD NOT FOUND!
echo.
echo.
echo Author: Hussain Noor Mohamed (#NullByte)
echo E-mail: noor.xbyte#mail.com
echo.
echo Your suggestions are of great value!
pause>nul
exit
:process
cls
echo.
echo Current Password: %1
unrar e -inul -p%1 "%arch%" "%dest%"
if /i %errorlevel% equ 10 goto error
if /i %errorlevel% equ 0 goto finish %1
exit /b
:finish
color 0a
cls
echo.
echo -----------------------------------------
echo ^| RAR CRACK v_2.0 - BY NOOR (#NullByte) ^|
echo -----------------------------------------
echo.
echo.
echo PASSWORD FOUND!
echo.
echo ARCHIVE : %arch%
echo WORDLIST : %word%
echo PASSWORD : %1
echo.
echo.
echo Author: Hussain Noor Mohamed (#NullByte)
echo E-mail: noor.xbyte#mail.com
echo.
echo Your suggestions are of great value!
pause>nul
exit
:error
color ce
cls
echo.
echo "%arch%" is not a valid rar file!
pause>nul
exit
The problem is that it is not that fast. (It is fast, but does not meet my expectations.) It would be really grateful if you people can suggest a way to make the program faster.
P.S Please don't copy my source code!!

Answer 1

As Stephan said, most of your CPU time goes into unrar running. Here are some things that I believe could help you.
You run unrar on all files. If your archive contains large/many files and you know they all have the same password (which is the usual case), then you can save some time by doing this: get the name of the first file in the archive (unrar lb ....) and only test that one (unrar t ... FILE). You should get the file name only once, before starting to test passwords.
You are running unrar sequentially, which means you do not take advantage of modern CPU features (like multi-core/threading). Most password crackers start multiple parallel processes/threads to test more passwords simultaneously, thus increasing the throughput. This is harder to do with batch files though.
You run unrar in extract mode, which assumes some disk activity (at minimum opening and closing a file). You could save some extra CPU ticks if you run it in test mode (unrar t), but this would be minimal.
Because the files don't change and you use them intensively, Windows will cache unrar and your archive (if possible) in RAM, so a RAM disk will provide little benefit to you (see also #3).
I believe 1 and 2 are the most important issues that would gain you some speed. In any case, cracking passwords is a time consuming task by itself.