Update m31900.pm

adapt mode's unit-test for longer CT sections

tools/test_modules/m31900.pm

@@ -46,7 +46,7 @@ sub module_generate_hash
 
   my $pt = "[{\"type\":\"HD Key Tree\",\"data\":{\"mnemonic\":\"ocean hidden kidney famous rich season gloom husband spring convince attitude boy\",\"numberOfAccounts\":1,\"hdPath\":\"m/44'/60'/0'/0\"}}]";
 
-  my $ct1 = substr ($cipher->encrypt ($pt), 0, 16);
+  my $ct1 = substr ($cipher->encrypt ($pt), 0, 32);
 
   my $hash = sprintf ('$metamaskMobile$%s$%s$%s', $salt_b64, $iv, encode_base64 ($ct1, ""));
 
@@ -79,7 +79,7 @@ sub module_verify_hash
 
   return unless length $salt_b64 == 16;
   return unless length $iv_bin   == 16;
-  return unless length $ct_bin   == 16;
+  return unless length $ct_bin   == 32;
 
   my $word_packed = pack_if_HEX_notation ($word);