diff --git a/tools/test_modules/m31800.pm b/tools/test_modules/m31800.pm
new file mode 100644
index 000000000..91311cfe1
--- /dev/null
+++ b/tools/test_modules/m31800.pm
@@ -0,0 +1,174 @@
+#!/usr/bin/env perl
+
+##
+## Author......: See docs/credits.txt
+## License.....: MIT
+##
+
+use strict;
+use warnings;
+
+use Crypt::PBKDF2;
+use Crypt::AuthEnc::GCM;
+use MIME::Base64 qw (decode_base64 encode_base64);
+use Crypt::KeyDerivation ':all';
+
+sub module_constraints { [[0, 256], [32, 32], [-1, -1], [-1, -1], [-1, -1]] }
+
+sub module_generate_hash
+{
+  my $word              = shift;
+  my $salt              = shift;
+  my $iterations        = shift;
+  my $email             = shift;
+  my $algorithm         = shift;
+  my $secret_key        = shift;
+  my $ct                = shift;
+  my $plaintext_length  = shift;
+  my $iv                = shift;
+  my $cryptext          = shift;
+  my $expected_hmac     = shift;
+  my $hmac_d_data       = shift;
+
+  my $salt_bin = pack ("H*", $salt);
+
+  my $hkdf_pass_salt = hkdf ($salt_bin, $email, 'SHA256', 32, "PBES2g-HS256");
+
+  my $kdf = Crypt::PBKDF2->new
+  (
+    hasher     => Crypt::PBKDF2->hasher_from_algorithm ('HMACSHA2', 256),
+    iterations => $iterations,
+    output_len => 32
+  );
+
+  my $password_key = $kdf->PBKDF2 ($hkdf_pass_salt, $word);
+
+  my $hkdf_key = hkdf ("798JRYLJVD423DC286TVMH43EB", "ASWWYB", 'SHA256', 32, "A3");
+
+  my $muk = xor_len ($password_key, $hkdf_key, 32);
+
+  my $pt;
+
+  my $iv_bin;
+
+  if (defined $ct)
+  {
+    my $ct_bin = pack ("H*", $ct);
+
+    $iv_bin = substr ($ct_bin, 0 + length ("opdata01"), 16);
+
+    my $data_bin = substr ($ct_bin, 0 + length ("opdata01") + 16, -16);
+    my $tag_bin  = substr ($ct_bin, -16);
+
+    my $aes = Crypt::AuthEnc::GCM->new ("AES", $muk, $iv_bin);
+
+    $pt = $aes->decrypt_add ($data_bin);
+
+    my $result_tag = $aes->decrypt_done ($tag_bin);
+
+    if ($result_tag == 1)
+    {
+      ## correct password
+    }
+    else
+    {
+      $pt = "{'key_ops': ['decrypt', 'encrypt'], 'kty': 'oct', 'alg': 'A256GCM', 'k': 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=', 'ext': True, 'kid': 'xxxxxxxxxxxxxxxxxxxxxxxxxx'}";
+    }
+  }
+  else
+  {
+    $pt = "{'key_ops': ['decrypt', 'encrypt'], 'kty': 'oct', 'alg': 'A256GCM', 'k': 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=', 'ext': True, 'kid': 'xxxxxxxxxxxxxxxxxxxxxxxxxx'}";
+  }
+
+  my $aes = Crypt::AuthEnc::GCM->new ("AES", $muk, $iv_bin);
+
+  my $ct_bin = $aes->encrypt_add ($pt);
+
+  my $tag_bin = $aes->encrypt_done ();
+
+  ## so far so good
+
+  my $hash = sprintf
+  (
+    '$mobilekeychain$%s',
+
+     unpack ("H*", "opdata01" . $iv_bin . $ct_bin . $tag_bin)
+  );
+
+
+
+  return $hash;
+}
+
+sub module_verify_hash
+{
+  my $line = shift;
+
+  my $idx = index ($line, ':');
+
+  return unless $idx >= 0;
+
+  my $hash = substr ($line, 0, $idx);
+  my $word = substr ($line, $idx + 1);
+
+  return unless substr ($hash, 0, 16) eq '$mobilekeychain$';
+
+  my (undef, $signature, $email, $salt_len, $salt, $algorithm, $secret_key, $iterations, $ct_len, $ct, $plaintext_length, $iv_len, $iv, $cryptext_len, $cryptext, $expected_hmac_len, $expected_hmac, $hmac_d_data_len, $hmac_d_data) = split '\$', $hash;
+
+  return unless defined $signature;
+  return unless defined $email;
+  return unless defined $salt_len;
+  return unless defined $salt;
+  return unless defined $algorithm;
+  return unless defined $secret_key;
+  return unless defined $iterations;
+  return unless defined $ct_len;
+  return unless defined $ct;
+  return unless defined $plaintext_length;
+  return unless defined $iv_len;
+  return unless defined $iv;
+  return unless defined $cryptext_len;
+  return unless defined $cryptext;
+  return unless defined $expected_hmac_len;
+  return unless defined $expected_hmac;
+  return unless defined $hmac_d_data_len;
+  return unless defined $hmac_d_data;
+
+  my $salt_bin          = pack ("H*", $salt);
+  my $ct_bin            = pack ("H*", $ct);
+  my $iv_bin            = pack ("H*", $iv);
+  my $cryptext_bin      = pack ("H*", $cryptext);
+  my $expected_hmac_bin = pack ("H*", $expected_hmac);
+  my $hmac_d_data_bin   = pack ("H*", $hmac_d_data);
+
+  return unless length ($salt_bin)          == $salt_len;
+  return unless length ($ct_bin)            == $ct_len;
+  return unless length ($iv_bin)            == $iv_len;
+  return unless length ($cryptext_bin)      == $cryptext_len;
+  return unless length ($expected_hmac_bin) == $expected_hmac_len;
+  return unless length ($hmac_d_data_bin)   == $hmac_d_data_len;
+
+  my $word_packed = pack_if_HEX_notation ($word);
+
+  my $new_hash = module_generate_hash ($word_packed, $salt, $iterations, $email, $algorithm, $secret_key, $ct, $plaintext_length, $iv, $cryptext, $expected_hmac, $hmac_d_data);
+
+  return ($new_hash, $word);
+}
+
+sub xor_len
+{
+  my $in1 = shift;
+  my $in2 = shift;
+  my $len = shift;
+
+  my $out;
+
+  for (my $i = 0; $i < $len; $i++)
+  {
+    $out .= chr (ord (substr ($in1, $i, 1)) ^ ord (substr ($in2, $i, 1)));
+  }
+
+  return $out;
+}
+
+1;