added spa-entropy/ directory for measuring entropy across SPA packets

diff --git a/extras/spa-entropy/spa-entropy.pl b/extras/spa-entropy/spa-entropy.pl
new file mode 100755 (executable)
index 0000000..0f375cd
--- /dev/null
+++ b/extras/spa-entropy/spa-entropy.pl
@@ -0,0 +1,209 @@
+#!/usr/bin/perl -w
+
+use MIME::Base64;
+use IPC::Open2;
+use Data::Password::Entropy;
+use strict;
+
+my %min_max_entropy = (
+    'min' => {
+        'val' => 0,
+        'pos' => 0,
+    },
+    'max' => {
+        'val' => 0,
+        'pos' => 0,
+    }
+);
+my @encrypted_data = ();
+my @cross_pkt_data = ();
+
+while (<STDIN>) {
+    next unless $_ =~ /\S/;
+    chomp;
+
+    push @encrypted_data, $_;
+    next;
+
+    my $base64_str = $_;
+    unless ($base64_str =~ /^U2FsdGVkX1/) {
+        $base64_str = 'U2FsdGVkX1' . $base64_str;
+    }
+    my ($equals_rv, $equals_padding) = &base64_equals_padding($base64_str);
+    if ($equals_padding) {
+        $base64_str .= $equals_padding;
+    }
+    push @encrypted_data, decode_base64($base64_str);
+}
+
+### calculate minimum length
+my $min_len = 0;
+for my $line (@encrypted_data) {
+    chomp $line;
+    next unless $line =~ /\S/;
+    my $len = length($line);
+    if ($min_len == 0) {
+        $min_len = $len;
+    } else {
+        if ($len < $min_len) {
+            $min_len = $len;
+        }
+    }
+}
+
+my $l_ctr = 0;
+for my $line (@encrypted_data) {
+    my @chars = split //, $line;
+    my $c_ctr = 0;
+    for my $char (@chars) {
+        $cross_pkt_data[$c_ctr] .= $char;
+        last if $c_ctr == $min_len;
+        $c_ctr++;
+    }
+    $l_ctr++;
+}
+
+open F, "> entropy.dat" or die $!;
+my $pos = 0;
+for my $str (@cross_pkt_data) {
+
+    my $entropy = &get_entropy($str);
+
+    print F "$pos $entropy\n";
+
+    if ($min_max_entropy{'min'}{'val'} == 0
+            and $min_max_entropy{'max'}{'val'} == 0) {
+        $min_max_entropy{'min'}{'val'} = $entropy;
+        $min_max_entropy{'min'}{'pos'} = $pos;
+        $min_max_entropy{'max'}{'val'} = $entropy;
+        $min_max_entropy{'max'}{'pos'} = $pos;
+    } else {
+        if ($entropy < $min_max_entropy{'min'}{'val'}) {
+            $min_max_entropy{'min'}{'val'} = $entropy;
+            $min_max_entropy{'min'}{'pos'} = $pos;
+        }
+        if ($entropy > $min_max_entropy{'max'}{'val'}) {
+            $min_max_entropy{'max'}{'val'} = $entropy;
+            $min_max_entropy{'max'}{'pos'} = $pos;
+        }
+    }
+    $pos++;
+}
+close F;
+
+my $min = $min_max_entropy{'min'}{'val'};
+my $max = $min_max_entropy{'max'}{'val'};
+print "Min entropy: $min at position: $min_max_entropy{'min'}{'pos'}\n";
+print "Max entropy: $max at position: $min_max_entropy{'max'}{'pos'}\n";
+
+open F, "> entropy.gnu" or die $!;
+print F <<_GNUPLOT_;
+set title "entropy measurement"
+set terminal gif nocrop enhanced
+set output "entropy.gif"
+set grid
+plot 'entropy.dat' using 1:2 with lines title 'min: $min, max: $max'
+_GNUPLOT_
+close F;
+
+system "gnuplot entropy.gnu";
+
+exit 0;
+
+sub get_entropy() {
+    my $data = shift;
+
+    #return password_entropy($data);
+
+    my $entropy = '';
+
+    ### Entropy = 5.637677 bits per byte.
+#    system "echo -n $data | ent | grep Entropy > tmp.ent";
+#    open ENT, "< tmp.ent" or die $!;
+#    my $line = <ENT>;
+#    if ($line =~ /\s=\s(\d\S+)/) {
+#        $entropy = $1;
+#    }
+#    close ENT;
+#    return $entropy;
+
+    my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'ent');
+
+    print CHLD_IN $data;
+    close CHLD_IN;
+
+    while (<CHLD_OUT>) {
+        if (/Entropy\s=\s(\d\S+)/) {
+            $entropy = $1;
+            last;
+        }
+    }
+
+    close CHLD_OUT;
+
+    waitpid( $pid, 0 );
+    my $child_exit_status = $? >> 8;
+
+    return $entropy;
+}
+
+sub base64_equals_padding() {
+    my $msg = shift;
+    my $padding = '';
+
+    return 1, $padding if $msg =~ /=$/;
+
+    my $remainder = 4 - length($msg) % 4;
+
+    if ($remainder == 3) {
+        ### not possible for valid base64 data - should only have
+        ### pad with one or two '=' chars
+        return 0, $padding;
+    }
+
+    unless ($remainder == 4) {
+        $padding .= '='x$remainder;
+    }
+    return 1, $padding;
+}
+
+sub hex_dump() {
+    my $data = shift;
+
+    my @chars = split //, $data;
+    my $ctr = 0;
+    my $ascii_str = '';
+    for my $char (@chars) {
+        if ($ctr % 16 == 0) {
+            print STDOUT " $ascii_str\n" if $ascii_str;
+            printf STDOUT "        0x%.4x:  ", $ctr;
+            $ascii_str = '';
+        }
+        printf STDOUT "%.2x", ord($char);
+
+        if ((($ctr+1) % 2 == 0) and ($ctr % 16 != 0)) {
+            print STDOUT ' ';
+        }
+
+        if ($char =~ /[^\x20-\x7e]/) {
+            $ascii_str .= '.';
+        } else {
+            $ascii_str .= $char;
+        }
+        $ctr++;
+    }
+    if ($ascii_str) {
+        my $remainder = 1;
+        if ($ctr % 16 != 0) {
+            $remainder = 16 - $ctr % 16;
+            if ($remainder % 2 == 0) {
+                $remainder = 2*$remainder + int($remainder/2) + 1;
+            } else {
+                $remainder = 2*$remainder + int($remainder/2) + 2;
+            }
+        }
+        print STDOUT ' 'x$remainder, $ascii_str;
+    }
+    print STDOUT "\n";
+    return;
+}