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Published by: silconsystem, on 2013-05-09 19:55:31
I'm writing a little utitilty in Perl to combine words together to to generate password-like combinations and I'd like to write a bit about it to give a bit back to the community and get some feedback on my programming.
Practical Extraction and Reporting Language is what Perl stands for and its exactly what its good at; doing what-not with text files.
It can be used for many other things aswell and its a very handy language to know if your working with Linux which is the OS I'm using.
I use Vim for small programs and if it gets bigger Padre, a Perl IDE with lots of features and customizable plugins but any text editor will do the trick. For useful Perl tips&tuts go to perlmonks.org
What I want to achieve is a program that can take a dictionary/name file and a list of dates/years and combine them like this: user1957, penguin3104, bob0157, etc...
There's probably hundreds of these programs but its a good exercise to create one step by step.
When the program has generated thousands of combinations they can be used for creating hashes with coWPAtty/genpmk , drtgen/drcrack , Cain&Abel or good-old brute-force cracking.
the user should be able to input his name/dictionary, his year/date list, give a maximum value for results and a filename and a location to store the result.
also I'd like to add an option to weed out dictionary/names that have less than 4 and more then 8 or maybe 10 letters.
The ingredients for this program is a dictionary, this we can find easily in Linux by opening a terminal and issuing the 'whereis' command followed by dict which we want to find, in my case it resides here: /usr/share/dict, here I have: american-english and british-english so there's plenty of words to play around with. a list of names we have to google for.
You will probably find a lot of files containing the type of passwords I want to generate with this program aswell but where's the fun in that ??
First I want to make a list with years that you usually find in a datepicker, this spans some 100 years normally but it could be that someone has a password like 'future2030' so I want control over these numbers.
perl has a great feature to populate arrays, if we would make this script:
CODE :
#!/usr/bin/perl
@yearArray = (1900..2000);
print @yearArray;
perl will output this:
1900190119021903.(all the rest).2000
This output is not very handy for the program since its just a huge number so I want it formatted, for this we could add a delimiter by using 'join':
CODE :
#!/usr/bin/perl
@yearArray = (1900..2000);
# followed by the join keyword is our delimiter in single quotes
my $textFormat = join ' ', @yearArray;
print $textformat;
Now the script outputs this:
1900 1901 1902 1903 1904 ... 2000
Thats already better but I want every number on another line, for this we can use 'map' where I can use $_ followed by a delimiter of my choice to get the output I want:
CODE :
#!/usr/bin/perl
@yearArray = (1900..2000);
# now I've added map with qq option wich adds a newline as delimiter
my $textFormat = join ' ', map {qq/$_\n/} @yearArray;
print $textformat;
Now I've got the proper formatting and I want to write and create a textfile, I'll create a folder in the same directory as my program (or save in the same directory). There have to be read&write permissions on the directory aswell or writing will fail. In the terminal go back one directory (../) and use 'ls -la' to see if you got rw for each group, if not use (sudo) chmod 666 on the directory your program is in.
Now we will add this to the program:
CODE :
#!/usr/bin/perl
@yearArray = (1900..2000);
my $textFormat = join ' ', @yearArray;
# create a file location
my $file = "files/yearlist.txt";
# write to the file or die on error
unless(open FILE, '>' .$file)
{
# die or error
die "\nUnable to create $file: $!\n";
}
# and write it to file
print FILE $textFormat;
Thats it !! Before I said I wanted to have some control over the numbers and the filenames so I can make more combinations so here is the final code with some comments:
CODE :
#!/usr/bin/perl
# yearlist utility, by R. van Ardenne
# NOTE: I dont use strict here since it will give some errors
# NOTE: I do use warnings in case there is a slipup somewhere
use warnings;
# promt user
print "Yearlist generator, for HackThisSite.\n"
print "This program generates a list of years with user input";
print "Have fun !!\n";
# I've used sleep() to make the program a bit nicer, just a detail though
sleep(1);
# now I get the variables by user input
# NOTE: use chomp to get rid of any trailing nasties like a newline character
# http://perldoc.perl.org/functions/chomp.html
print "Please enter the year to start with: ";
my $startYear = <STDIN>;
chomp $startYear;
print "Please enter the end year: ";
my $endYear = <STDIN>;
chomp $endYear;
print "Enter the filename without extension: ";
my $fileName = <STDIN>;
chomp SfileName;
# now I populate the array with the given variables
@yearRange = ($startYear..$endYear);
print "populating array...\n";
sleep(1);
# format the output using join and map
my $textFormat = join ' ', map {qq/$_\n/} @yearRange;
print "formatting output...\n";
sleep(1);
# create the file (the directory is optional and changable offcourse)
my $file = "file/$fileName.txt";
print "creating file...\n";
sleep(1);
# open the file
unless(open FILE, '>' .$file)
{
# die on error ($! gives us info on the error)
die "\nUnable to create file: $!\n";
}
# write to the file
print FILE $textFormat;
print "writing to file...\n\n";
sleep(1);
close FILE;
print "file created !\n";
sleep(1);
exit 1;
And thats that, a fully functioning little Perl utility to generate sequencial numbers from user input, creating and writing it to file. This is a very simple program, and I'd like to extend it a bit further later so it can create dates in DDMM format aswell and write about weeding out a dictionary file for useful password candidates and concatinating strings to create new words.
I hope people had fun reading and will come back for the next part.
Cheers, Rob
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