Cipher tool

@echo off&setlocal enabledelayedexpansion&chcp 65001>nul&goto x
:e.2
if %ecx% GTR %cl% goto ei
set "ec=%ea:~0,1%"&set /a ecx+=1
if "%ec%"=="%es%" goto e%m%
set "ea=%ea:~1%"&goto e.2
:e0
set /a enx=((%ecx%+%k%+%em%)%%%cl%+%cl%)%%%cl%
set /a em+=((%ecx%-%k%)%%%cl%+%cl%)%%%cl%
goto e.3
:e1
set /a enx=(((%ecx%-%k%-2-%em%)%%%cl%+%cl%)%%%cl%)-1
set /a em+=((%enx%-%k%+1)%%%cl%+%cl%)%%%cl%
goto e.3
:e.1
if not defined ei_ goto e.e
set "es=%ei_:~0,1%"&set ecx=0
set /a p+=1
set /a _p=%p%*100/%ilen%
title Processing... %_p%%%
goto e.2
:e.3
set "en=!c:~%enx%,1!"
set "eo=%eo%%en%"&set "ei_=%ei_:~1%"&set "ea=%c%"&goto e.1
:x
set m=0
set "mc=0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/="&call :l "!mc!"&set cl=!il!
set /a r_cl=!cl!-1
set r_n=0&for /l %%A in (1,1,%r_cl%) do set "r_n=!r_n!, %%A"
:k
cls&set /p "k=Numerical key> "&if !k! EQU +!k! (if !k! LEQ 2147483333 (call :r "!k!"&goto m) else (echo Invalid key&timeout /t 2 >nul&goto k)) else (echo Invalid key.&timeout /t 2 >nul&goto k)
:m
title Cipher tool 3.0 - %USERNAME% Edition&cls&echo.&echo  Your key:  !k!&echo.&echo. /k ^<key^> to change key&echo.&set /p i="Message> "&if "!i:~0,3!"=="/k " (set "tk=!i:~3!"&if !tk! EQU +!tk! (if !tk! LEQ 2147483333 (call :r "!tk!"&set k=!tk!) else (echo Invalid key&timeout /t 2 >nul)) else (echo Invalid key&timeout /t 2 >nul))&goto m
if "!i!"=="" goto m
if "!i:~0,4!"=="_MCD" (set "i=!i:~4!"&if !m!==0 call :a) else if !m!==1 call :a
if !m!==0 call :d0
call :l "!i!"&set ilen=!il!
echo.&call :e "!i!"&goto m
:e
setlocal
set "ei=%~1"&set "ei_=%~1"&if !m!==0 (set em=3) else set em=2
set "ea=!c!"&goto e.1
:e.e
if !m!==1 call :d1
if !m!==0 (if "!eo!"=="" (echo ERROR) else echo._MCD!eo!
<nul set /p _="```_MCD!eo!```"|clip&pause>nul) else if "!eo!"=="" (echo ERROR) else echo.!eo!&pause>nul
endlocal&goto :eof
:l
set "l_i=%~1"&set il=0
goto z
:z
if not defined l_i goto :eof
set /a il+=1
set "l_i=!l_i:~0,-1!"&goto z
:a
if !m!==0 (set m=1) else set m=0
goto :eof
:r
set "c="&for /f "usebackq tokens=*" %%A in (`powershell -command "%r_n% | get-random -count %cl% -setseed %~1"`) do set "c=!c!!mc:~%%A,1!"
call :l "!c!"&if !il! LSS !cl! echo.INVALID SHUFFLE:&echo.c  ^(!cl!^) = !c!&echo.mc ^(!il!^) = !mc!&pause>nul&exit
goto :eof
:ei
echo ERROR: CHARACTER INDEX OUT OF RANGE ^(!es!^).&pause>nul&endlocal&goto :eof
:d0
set ds=!i:"=\`"!
set ds=!ds:'=''!
set ds=!ds:+=\+!
set "ps=powershell -command "$b = [System.Text.Encoding]::UTF8.GetBytes('!ds!'); ^
    [System.Convert]::ToBase64String($b)""
for /f "usebackq tokens=*" %%A in (`%ps%`) do set "i=%%A"
goto :eof
:d1
set "ps=powershell -command "$b = [System.Convert]::FromBase64String('!eo!'); ^
    [System.Text.Encoding]::UTF8.GetString($b)""
for /f "usebackq tokens=*" %%A in (`%ps%`) do set "eo=%%A"
set eo=!eo:\`="!
set eo=!eo:\+=+!
goto :eof