how do you make a letter password generator in batch?

Question

I'm having a hard time figuring out how to make a password generator with random letters in it. For example, ASWED-ASDWAD-EFEST. So far I can only make random numbers by using the code

@echo off

:password

echo %random%-%random%-%random
pause
goto password

PS: my OS is windows vista.

all help will be appreciated.

I added %RANDOM% to cmd.exe in windows NT. Glad to see it is still useful. — mosh, Jun 13, 2017 at 12:13

Run5k · Accepted Answer · 2018-05-08 17:26:16Z

There is a discussion here that you could adapt for your purposes.

@Echo Off
Setlocal EnableDelayedExpansion
Set _RNDLength=8
Set _Alphanumeric=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
Set _Str=%_Alphanumeric%987654321
:_LenLoop
IF NOT "%_Str:~18%"=="" SET _Str=%_Str:~9%& SET /A _Len+=9& GOTO :_LenLoop
SET _tmp=%_Str:~9,1%
SET /A _Len=_Len+_tmp
Set _count=0
SET _RndAlphaNum=
:_loop
Set /a _count+=1
SET _RND=%Random%
Set /A _RND=_RND%%%_Len%
SET _RndAlphaNum=!_RndAlphaNum!!_Alphanumeric:~%_RND%,1!
If !_count! lss %_RNDLength% goto _loop
Echo Random string is !_RndAlphaNum!

TheOutcaste explains the above:

I've modified it so you can easily specify the length and add or remove characters without having to change any other part of the code.

For example, you might not want to use both 0 and O (zero and Uppercase O), or 1 and l (one and lowercase L).

You can use punctuation except for these characters:
! % ^ & < >
You can use ^ and %, but must enter them in the _Alphanumeric variable twice as ^^ or %%. However, if you want to use the result (_RndAlphaNum) later in the batch file (other than Echoing to the screen), they might require special handling.

You can even use a space, as long as it's not the last character in the string. If it ends up as the last character in the generated string though, it will not be used, so you would only have 7 characters.

thanks for the help, I am kind of new to batch so I was wondering if you could help me interpret the code that you showed me. I want to simplify it so I can see what code exactly generates the random letters, thanks. — mendez, Oct 23, 2011 at 0:23
These seem to be the primary non-explanatory lines: Set /A _RND=_RND%%61 - _RND was previously set to a random number, and this then does a modulus 61 on it to get a number between 0 and 61. SET _rndalphanum=!_Alphanumeric:~%_RND%,1! It then does a substring of _Alphanumeric at position _RND for 1 character. So it is choosing a number between 0 and 61 then pulling that character from A-Za-z. You can then build up a alpha string of random chars by repeating the process. — Paul, Oct 23, 2011 at 1:57
sorry I haven't been on lately but thanks again for all of you guys for your help, I appreciate it. — mendez, Oct 25, 2011 at 14:44

Scott Chamberlain · Accepted Answer · 2013-07-09 04:02:44Z

3

rem 16 stings pwd

setlocal ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
set alfanum=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789

set pwd=
FOR /L %%b IN (0, 1, 16) DO (
SET /A rnd_num=!RANDOM! * 62 / 32768 + 1
for /F %%c in ('echo %%alfanum:~!rnd_num!^,1%%') do set pwd=!pwd!%%c
)

echo pwd=%pwd%

edited Jul 9, 2013 at 4:02

Scott Chamberlain

30.9k7 gold badges97 silver badges109 bronze badges

answered Mar 25, 2013 at 12:10

drakfox

311 bronze badge

3

Can you add some explanation to the answer.
– ChrisF
Mar 25, 2013 at 12:37
When you paste code please be sure to highlight the code and press the button that looks like { } otherwise it makes it very hard to read.
– Scott Chamberlain
Jul 9, 2013 at 4:03

Add a comment |

cartoonstig · Accepted Answer · 2019-06-28 22:15:42Z

1

This is a simple and elegant solution to this

@echo off
setlocal enableextensions enabledelayedexpansion

set /P _length=Password Length: %==%
set /a z = %_length%
set "string=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
set "password="
for /L %%i in (1,1,!z!) do call :_genRand
echo Password is:  %password%
goto :EOF

:_genRand
set /a x=%random% %% 62
set password=%password%!string:~%x%,1!
goto :eof

answered Jun 28, 2019 at 22:15

cartoonstig

111 bronze badge

Add a comment |

Scott Chamberlain · Accepted Answer · 2013-07-09 04:01:56Z

here is mine. Ameture, but it works

@Echo OFF
@echo Would You Like Me To Make You A Password? Type Your Response And Press Enter.
set /p ans=
if %ans%==yes (goto yes
)
if %ans%==no (goto exit
)

:exit
cls
@echo Are You Sure?
set /p ans=
if %ans%==yes (goto exit
)
if %ans% NEQ yes (goto yes
)
:yes
cls 
@echo Loading...

@echo OFF
ping localhost -n 4 > Nul
goto hardpart





:hardpart
@echo OFF
cls
@echo Get a peice of paper so you will remember
pause
cls
@echo OFF
set /A r=%RANDOM% %% 25 + 1
cls
if %r%==1 goto 1
if %r%==2 goto 2
if %r%==3 goto 3
if %r%==4 goto 4
if %r%==5 goto 5
if %r%==6 goto 6
if %r%==7 goto 7
if %r%==8 goto 8
if %r%==9 goto 9
if %r%==10 goto 10
if %r%==11 goto 11
if %r%==12 goto 12
if %r%==13 goto 13
if %r%==14 goto 14
if %r%==15 goto 15
if %r%==16 goto 16
if %r%==17 goto 17
if %r%==18 goto 18
if %r%==19 goto 19
if %r%==20 goto 20
if %r%==21 goto 21
if %r%==22 goto 22
if %r%==23 goto 23
if %r%==24 goto 24
if %r%==25 goto 25
if %r%==26 goto 26
:1 
@echo 1st letter is a
goto number2
pause
goto number2
:2
@echo 1st letter is b
pause
goto number2
:3
@echo 1st letter is c
pause
goto number2
:4
@echo 1st letter is d
pause
goto number2
:5
@echo 1st letter is e
pause
goto number2
:6
@echo 1st letter is f
pause
goto number2
:7
@echo 1st letter is g
pause
goto number2
:8
@echo 1st letter is h
pause
goto number2
:9
@echo 1st letter is i
pause
goto number2
:10
@echo 1st letter is j
pause
goto number2
:11
@echo 1st letter is k
pause
goto number2
:12
@echo 1st letter is l
pause
goto number2
:13
@echo 1st letter is m
pause
goto number2
:14
@echo 1st letter is n
pause
goto number2
:15
@echo 1st letter is o
pause
goto number2
:16
@echo 1st letter is p
pause
goto number2
:17
@echo 1st letter is q
pause
goto number2
:18
@echo 1st letter is r
pause
goto number2
:19
@echo 1st letter is s
pause
goto number2
:20
@echo 1st letter is t
pause
goto number2
:21
@echo 1st letter is u
pause
goto number2
:22
@echo 1st letter is v
pause
goto number2
:23
@echo 1st letter is w
pause
goto number2
:24
@echo 1st letter is x
pause
goto number2
:25
@echo 1st letter is y
pause
goto number2
:26
@echo 1st letter is z
pause
goto number2
:number2
@echo OFF
set /A s=%RANDOM% %% 25 + 1
cls
if %s%==1 goto 1a
if %s%==2 goto 2a
if %s%==3 goto 3a
if %s%==4 goto 4a
if %s%==5 goto 5a
if %s%==6 goto 6a
if %s%==7 goto 7a
if %s%==8 goto 8a
if %s%==9 goto 9a
if %s%==10 goto 10a
if %s%==11 goto 11a
if %s%==12 goto 12a
if %s%==13 goto 13a
if %s%==14 goto 14a
if %s%==15 goto 15a
if %s%==16 goto 16a
if %s%==17 goto 17a
if %s%==18 goto 18a
if %s%==19 goto 19a
if %s%==20 goto 20a
if %s%==21 goto 21a
if %s%==22 goto 22a
if %s%==23 goto 23a
if %s%==24 goto 24a
if %s%==25 goto 25a
if %s%==26 goto 26a
:1a 
@echo The next letter is a
pause
goto number2
:2a
@echo The next letter is b
pause
goto number2
:3a
@echo The next letter is c
pause
goto number2
:4a
@echo The next letter is d
pause
goto number2
:5a
@echo The next letter is e
pause
goto number2
:6a
@echo The next letter is f
pause
goto number2
:7a
@echo The next letter is g
pause
goto number2
:8a
@echo The next letter is h
pause
goto number2
:9a
@echo The next letter is i
pause
goto number2
:10a
@echo The next letter is j
pause
goto number2
:11a
@echo The next letter is k
pause
goto number2
:12a
@echo The next letter is l
pause
goto number2
:13a
@echo The next letter is m
pause
goto number2
:14a
@echo The next letter is n
pause
goto number2
:15a
@echo The next letter is o
pause
goto number2
:16a
@echo The next letter is p
pause
goto number2
:17a
@echo The next letter is q
pause
goto number2
:18a
@echo The next letter is r
pause
goto number2
:19a
@echo The next letter is s
pause
goto number2
:20a
@echo The next letter is t
pause
goto number2
:21a
@echo The next letter is u
pause
goto number2
:22a
@echo The next letter is v
pause
goto number2
:23a
@echo The next letter is w
pause
goto number2
:24a
@echo The next letter is x
pause
goto number2
:25a
@echo The next letter is y
pause
goto number2
:26a
@echo The next letter is z
pause
goto number2

When you paste code please be sure to highlight the code and press the button that looks like { } otherwise it makes it very hard to read. — Scott Chamberlain, Jul 9, 2013 at 4:02

Tog · Accepted Answer · 2014-03-26 22:01:55Z

I edited pauls one:

@Echo Off
color 0a
set /P lengthnumberuser="What length do you want your password to be?   "
pause
cls
Setlocal EnableDelayedExpansion
Set _RNDLength=%lengthnumberuser%
Set _Alphanumeric=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
Set _Str=%_Alphanumeric%987654321
:_LenLoop
IF NOT "%_Str:~18%"=="" SET _Str=%_Str:~9%& SET /A _Len+=9& GOTO :_LenLoop
SET _tmp=%_Str:~9,1%
SET /A _Len=_Len+_tmp
Set _count=0
SET _RndAlphaNum=
:_loop
Set /a _count+=1
SET _RND=%Random%
Set /A _RND=_RND%%%_Len%
SET _RndAlphaNum=!_RndAlphaNum!!_Alphanumeric:~%_RND%,1!
If !_count! lss %_RNDLength% goto _loop
Echo Password is: is !_RndAlphaNum!

pause

bummi · Accepted Answer · 2015-02-11 23:56:31Z

:generator
@Echo Off
Setlocal EnableDelayedExpansion
Set _RNDLength=8
Set _Alphanumeric=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
Set _Str=%_Alphanumeric%987654321
:_LenLoop
IF NOT "%_Str:~18%"=="" SET _Str=%_Str:~9%& SET /A _Len+=9& GOTO :_LenLoop
SET _tmp=%_Str:~9,1%
SET /A _Len=_Len+_tmp
Set _count=0
SET _RndAlphaNum=
:_loop
Set /a _count+=1
SET _RND=%Random%
Set /A _RND=_RND%%%_Len%
SET _RndAlphaNum=!_RndAlphaNum!!_Alphanumeric:~%_RND%,1!
If !_count! lss %_RNDLength% goto _loop
Echo Random string is !_RndAlphaNum!

This works but doesn't quite act right when we recall it as sub. (i.e. unpredictably malfunctions when you call the subroutine :generator.

Is that somewhat different from @Paul's answer?
– stevefestl
Jun 13, 2017 at 9:19 — stevefestl, Jun 13, 2017 at 9:19

KuroRXX · Accepted Answer · 2020-05-11 20:04:08Z

This is a fully made version with 16 characters including uppercase, lowercase, and numbers. It's a rookie version so it doesn't include any complex commands like "for", but it works well. Only downside is it can lag and occasionally stop working if you generate too many lines.

@echo off
title Random
:trigger
set trigger=16
:genKeys
set /a trigger=%trigger% - 1
set /a choose=(%random%*3/32767)+1
if %choose% == 1 goto lowercase
if %choose% == 2 goto uppercase
if %choose% == 3 goto number
:lowercase
set /a lower=(%random%*25/32767)+0
if %lower% == 0 set gen%trigger%=a
if %lower% == 1 set gen%trigger%=b
if %lower% == 2 set gen%trigger%=c
if %lower% == 3 set gen%trigger%=d
if %lower% == 4 set gen%trigger%=e
if %lower% == 5 set gen%trigger%=f
if %lower% == 6 set gen%trigger%=g
if %lower% == 7 set gen%trigger%=h
if %lower% == 8 set gen%trigger%=i
if %lower% == 9 set gen%trigger%=j
if %lower% == 10 set gen%trigger%=k
if %lower% == 11 set gen%trigger%=l
if %lower% == 12 set gen%trigger%=m
if %lower% == 13 set gen%trigger%=n
if %lower% == 14 set gen%trigger%=o
if %lower% == 15 set gen%trigger%=p
if %lower% == 16 set gen%trigger%=q
if %lower% == 17 set gen%trigger%=r
if %lower% == 18 set gen%trigger%=s
if %lower% == 19 set gen%trigger%=t
if %lower% == 20 set gen%trigger%=u
if %lower% == 21 set gen%trigger%=v
if %lower% == 22 set gen%trigger%=w
if %lower% == 23 set gen%trigger%=x
if %lower% == 24 set gen%trigger%=y
if %lower% == 25 set gen%trigger%=z
if %trigger% == 0 goto keys
goto genKeys
:uppercase
set /a upper=(%random%*25/32767)+0
if %upper% == 0 set gen%trigger%=A
if %upper% == 1 set gen%trigger%=B
if %upper% == 2 set gen%trigger%=C
if %upper% == 3 set gen%trigger%=D
if %upper% == 4 set gen%trigger%=E
if %upper% == 5 set gen%trigger%=F
if %upper% == 6 set gen%trigger%=G
if %upper% == 7 set gen%trigger%=H
if %upper% == 8 set gen%trigger%=I
if %upper% == 9 set gen%trigger%=J
if %upper% == 10 set gen%trigger%=K
if %upper% == 11 set gen%trigger%=L
if %upper% == 12 set gen%trigger%=M
if %upper% == 13 set gen%trigger%=N
if %upper% == 14 set gen%trigger%=O
if %upper% == 15 set gen%trigger%=P
if %upper% == 16 set gen%trigger%=Q
if %upper% == 17 set gen%trigger%=R
if %upper% == 18 set gen%trigger%=S
if %upper% == 19 set gen%trigger%=T
if %upper% == 20 set gen%trigger%=U
if %upper% == 21 set gen%trigger%=V
if %upper% == 22 set gen%trigger%=W
if %upper% == 23 set gen%trigger%=X
if %upper% == 24 set gen%trigger%=Y
if %upper% == 25 set gen%trigger%=Z
if %trigger% == 0 goto keys
goto genKeys
:number
set /a number=(%random%*9/32767)+0
set gen%trigger%=%number%
goto genKeys
:keys
cls
echo %gen15%%gen14%%gen13%%gen12%%gen11%%gen10%%gen9%%gen8%%gen7%%gen6%%gen5%%gen4%%gen3%%gen2%%gen1%%gen0%
pause >nul
goto trigger

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