binary file editing

binaryedit.perl

#!/usr/bin/perl
#
use strict;
use warnings;
use bytes;


my $filein = 'cm_cert.cer';
my $fileout = 'temp.cer';
my @pos1 = (328..340);
my @pos2 = (352..368);
local *INPUT;
local *OUTPUT;
my @NEW_MAC = ('001122334455');

open INPUT, $filein or die "Error opening $filein certificate\n";
open OUTPUT, ">$fileout" or die "Error opening $fileout for writing\n";
binmode INPUT;
binmode OUTPUT;

my $base_chars = map(chr, 0..255);
my ($bytesread, $buffer, $total);
my @data;

while (($bytesread = sysread(INPUT, $buffer, 1)) == 1) {
  $total += $bytesread;
	push (@data, $buffer);
}
print "Total bytes: $total\n";
print "--Begin MC Certificates--\n";
print "Original MAC:",@data[ @pos1 ];
print "\nOriginal MAC:",@data[ @pos2 ];
my @s = ('112233445566');

foreach my $i (@pos1) {
$data[ $i ] = $new_mac[$i];
}

print "\nChanged MAC: ",@data[ @pos1 ];
print "\nChanged MAC: ",@data[@pos2];


print "\n--End MC Certificates--\n";
close INPUT;
close OUTPUT or die "Error opening $fileout for writing\n" ;
print "MC Certificate alteration complete\n";

__END__