bash_obfus.pl

#!/usr/bin/perl -w
use strict;
use warnings;
use feature ':5.10';

sub print_usage() {
    say "$0 is a bash shell script minifier/obfuscator.";
    say "It deletes full line comments, whitespaces and tabs, and obfuscates variable names.";
    say "Usage:";
    say "\t $0 -h \t This help message.";
    say "\t $0 -i <input_file> -o <output_file> [-V <new_var_string>] -C -F";
    say "\t Where:";
    say "\t\t<input_file>\tis the shell script you want to obfuscate";
    say "\t\t<output_file>\tis where you want to save the obfuscated script";
    say "\t\t<new_var_string>\tis an optional argument that defines what all variables will be changed to.";
    say "\t\t\tThe default is 'a', which means all variables will be changed to a0,a1,a2,a3,...";
    say "\t\t-C\tis an option to clean out full line comments and blank lines.";
    say "\t\t-F\tis an option to flatten out the code (remove indentations)";
    exit 0;
}

sub parse_cmd_args {
    my $input_file="";
    my $output_file="";
    my $delete_blanks="";
    my $flatten="";
    my $new_variable_prefix="a";
    for my $argnum (0 .. $#ARGV) {
        if ($ARGV[$argnum] eq "-i") {
            $input_file=$ARGV[$argnum+1];
            $argnum++;
        } elsif ($ARGV[$argnum] eq "-o") {
            $output_file=$ARGV[$argnum+1];
            $argnum++;
        } elsif ($ARGV[$argnum] eq "-h") {
            &print_usage();
        } elsif ($ARGV[$argnum] eq "-V") {
            $new_variable_prefix=$ARGV[$argnum+1];
            $argnum++;
        } elsif ($ARGV[$argnum] eq "-C") {
            $delete_blanks=1;
        } elsif ($ARGV[$argnum] eq "-F") {
            $flatten=1;
        }
    }
    if ($input_file eq "" || $output_file eq "") {
        say "Input or output file not specified!!";
        &print_usage();
    }
    return ($input_file,$output_file,$new_variable_prefix,$delete_blanks,$flatten);
}

sub parse_vars_from_file {
    my $file_name=shift;
    open(my $file_handle, "<", $file_name) || die "Couldn't open '".$file_name."' for reading because: ".$!;
    my %vars=();
    while(my $line=<$file_handle>) {
        # First pull var names from declarations
        if ($line =~ m/^[ \t]*([a-z]+[a-z0-9_]*)=/) {
            $vars{$1}=1;
        # Then, from read statements
        } elsif (($line =~ m/^[ \t]*read -s ([a-z]+[a-z0-9_]*)/) || ($line =~ m/^[ \t]*read ([a-z]+[a-z0-9_]*)/)) {
            $vars{$1}=1;
        # Then, from for loops
        } elsif ($line =~ m/^[ \t]*for ([a-z]+[a-z0-9_]*) /) {
            $vars{$1}=1;
        # Then, from array access
        } elsif ($line =~ m/^[ \t]*([a-z]+[a-z0-9_]*)\[.+\]=/) {
            $vars{$1}=1;
        }
    }
    close $file_handle;
    return keys %vars;
}

sub obfuscate {
    my $input_file=shift;
    my $output_file=shift;
    my $new_variable_prefix=shift;
    my $delete_blanks=shift;
    my $flatten=shift;
    my @sorted_vars=@_;

    open(my $ifh, "<", $input_file) || die "Couldn't open '".$input_file."' for reading because: ".$!;
    open(my $ofh, ">", $output_file) || die "Couldn't open '".$output_file."' for writing because: ".$!;
    my %var_obfus=();
    my $var_index=0;
    for my $var (@sorted_vars) {
        $var_obfus{$var}=$new_variable_prefix.$var_index;
        $var_index++;
    }
    my %vars=();
    while(my $line=<$ifh>) {
        if ($delete_blanks && (($line =~ m/^[ \t]*#[^!].*/) || ($line =~ m/^[ \t]*$/))) {
            next;
        }
        if ($flatten) {
            $line =~ s/^[ \t]*//;
        }
        for my $var (@sorted_vars) {
            # Substitute var names in declarations
            $line =~ s/^([ \t]*)$var=/$1$var_obfus{$var}=/;
            # Then, in read statements
            $line =~ s/^([ \t]*read .*)$var/$1$var_obfus{$var}/;
            # Then, in for loops
            $line =~ s/^([ \t]*for )$var/$1$var_obfus{$var}/;
            # Then, in array access
            $line =~ s/^([ \t]*)$var(\[.+\]=)/$1$var_obfus{$var}$2/;
            # General "$" usage while making sure we're not inside ''
            while ($line =~ m/^(([^\']*('[^']*')*[^']*)*)\$$var/) {
                $line =~ s/^(([^\']*('[^']*')*[^']*)*)\$$var/$1\$$var_obfus{$var}/;
            }
            # Only allow a $var to be replaced between '' if they're already inside ""
            while ($line =~ m/^([^']*(('[^']*')*("[^"]")*)*"[^"]*)\$$var/) {
                $line =~ s/^([^']*(('[^']*')*("[^"]")*)*"[^"]*)\$$var/$1\$$var_obfus{$var}/;
            }
            # Special case ${var} usage while making sure we're not inside ''
            while ($line =~ m/^(([^']*('[^']*')*[^']*)*)\$\{$var/) {
                $line =~ s/^(([^']*('[^']*')*[^']*)*)\$\{$var/$1\$\{$var_obfus{$var}/;
            }
            # Likewise, allow ${var} between '' only if we're already between ""
            while ($line =~ m/^([^']*(('[^']*')*("[^"]")*)*"[^"]*)\$\{$var/) {
                $line =~ s/^([^']*(('[^']*')*("[^"]")*)*"[^"]*)\$\{$var/$1\$\{$var_obfus{$var}/;
            }
        }
        # Print whatever got through the filters
        print $ofh $line
    }
    close $ifh;
    close $ofh;
}

my ($input_file,$output_file,$new_variable_prefix,$delete_blanks,$flatten)=&parse_cmd_args();
my @parsed_vars=&parse_vars_from_file($input_file);
my @sorted_vars = sort { length($b) <=> length($a) } @parsed_vars;
&obfuscate($input_file,$output_file,$new_variable_prefix,$delete_blanks,$flatten,@sorted_vars);