look for binary data in other data

diff --git a/tools/rfidtest.pl b/tools/rfidtest.pl
new file mode 100644 (file)
index 0000000..db898d3
--- /dev/null
+++ b/tools/rfidtest.pl
@@ -0,0 +1,119 @@
+#!/usr/bin/perl
+# -samy kamkar, rfid@samy.pl
+
+use strict;
+
+die "usage: $0 <file with data> <binary to search for>\n" unless @ARGV == 2;
+
+my ($file, $search) = @ARGV;
+$search =~ s/\s//g;
+
+# sure, these aren't perfect, but simplifies usability if you know what you're doing
+# if in doubt, use binary
+
+# binary, cool
+if ($search =~ /^[01]+$/) { }
+# decimal
+elsif ($search =~ /^\d+$/)
+{
+       $search = unpack("B*", pack("N", $search));
+       $search =~ s/^0*//;
+}
+# hex
+elsif ($search =~ /^[\da-fA-F]+$/)
+{
+       $search = unpack("B*", pack("H*", $search));
+       $search =~ s/^0*//;
+}
+# ascii
+else
+{
+       $search = unpack("B*", $search);
+       $search =~ s/^0*//;
+}
+
+
+# read file contents
+open(F, "<$file") || die "Can't read $file: $!";
+my $data = join("", <F>);
+close(F);
+
+# convert to binary
+$data =~ s/\s//g;
+# binary, great
+if ($data =~ /^[01]+$/) { }
+elsif ($data =~ /^[\da-fA-F]+$/)
+{
+       $data = unpack("B*", pack("H*", $data));
+       $search =~ s/^0*//;
+}
+else
+{
+       die "Seriously. What sort of data is this file? Binary or hex only please.\n";
+}
+
+
+# search every method we know how
+print "Testing normally...\n";
+test_all($data, $search);
+
+print "Testing with flipped bits...\n";
+test_all($data, $search, 1);
+
+# now try manchester demodulating
+my @bits = split(//, $data);
+my $man;
+my $last = 0;
+for (my $i = 1; $i < @bits; $i++)
+{
+       # if we changed, flip our bit
+       if ($bits[$i-1] == 1)
+       {
+               $last ^= 1;
+       }
+       $man .= $last;
+}
+
+print "Testing with manchester demodulation...\n";
+test_all($man, $search);
+
+print "Testing with flipped manchester demodulation...\n";
+test_all($man, $search, 1);
+
+
+sub test_all
+{
+       my ($data, $search, $flip) = @_;
+       
+       if ($flip)
+       {
+               $data =~ s/(.)/$1 ^ 1/eg;
+       }
+       
+       # first just see if our data is in the stream
+       if ($data =~ /$search/)
+       {
+               print "Found $search in our stream ($data)\n";
+       }
+
+       # try removing parity every 4 and 8 bits
+       foreach my $parity (4, 8)
+       {
+               # try removing a parity bit every $parity bits
+               # test by cutting off a bit at a time in case we're in the wrong bit position
+               my $tmp = $data;
+               foreach (1 .. $parity)
+               {
+                       my $test = $tmp;
+                       $test =~ s/(.{$parity})./$1/g;
+               
+                       if ($test =~ /$search/)
+                       {
+                               print "Found $search with parity every " . ($parity + 1) . "th bit, round $_ out of $parity ($test)\n";
+                       }
+               
+                       # chop of a bit to change our bit position next round
+                       $tmp =~ s/^.//;
+               }
+       }
+}