diff --git a/tools/fasc.pl b/tools/fasc.pl
new file mode 100644
index 0000000..a5e8ced
--- /dev/null
+++ b/tools/fasc.pl
@@ -0,0 +1,99 @@
+#!/usr/bin/perl
+
+# Copyright (c) 2014 Yubico AB
+# All rights reserved.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+# Additional permission under GNU GPL version 3 section 7
+#
+# If you modify this program, or any covered work, by linking or
+# combining it with the OpenSSL project's OpenSSL library (or a
+# modified version of that library), containing parts covered by the
+# terms of the OpenSSL or SSLeay licenses, We grant you additional 
+# permission to convey the resulting work. Corresponding Source for a
+# non-source form of such a combination shall include the source code
+# for the parts of OpenSSL used as well as that of the covered work.
+
+use strict;
+use Bit::Vector;
+
+my %encoding = (
+  0 => "00001",
+  1 => "10000",
+  2 => "00100",
+  3 => "00111",
+  4 => "01000",
+  5 => "01011",
+  6 => "01101",
+  7 => "01110",
+  8 => "10000",
+  9 => "10011",
+  S => "10110",
+  F => "11010",
+  E => "11111",
+);
+
+my $in = shift;
+
+my @ones = (0, 0, 0, 0);
+
+my $bits;
+foreach my $char (split(//, $in)) {
+  my $enc = $encoding{$char};
+  for(my $i = 0; $i < 4; $i++) {
+    my $char = substr($enc, $i, 1);
+    if($char eq '1') {
+      $ones[$i]++;
+    }
+  }
+  $bits .= $enc;
+}
+my $lrc = "";
+my $lrc_one = 0;
+foreach my $one (@ones) {
+  if($one % 2 == 0) {
+    $lrc .= '0';
+  } else {
+    $lrc .= '1';
+    $lrc_one++;
+  }
+}
+if($lrc_one % 2 == 0) {
+  $lrc .= '1';
+} else {
+  $lrc .= '0';
+}
+$bits .= $lrc;
+
+my $vector = Bit::Vector->new(200);
+$vector->from_Bin($bits);
+my $hex = $vector->to_Hex();
+for(my $i = 0; $i < length($hex); $i += 2) {
+  print "0x" . substr($hex, $i , 2) . ", ";
+}
+
+print "\n";
+__END__
+
+for(my $i = 0; $i < length($in); $i += 8) {
+  my $part = substr($in, $i, $i + 8);
+  my $bits = "0b";
+  foreach my $char (split(//, $part)) {
+    $bits .= $encoding{$char};
+  }
+
+  my $num = eval($bits);
+  warn $num;
+}