1/* Part of SWI-Prolog 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2018, VU University Amsterdam 7 All rights reserved. 8 9 Redistribution and use in source and binary forms, with or without 10 modification, are permitted provided that the following conditions 11 are met: 12 13 1. Redistributions of source code must retain the above copyright 14 notice, this list of conditions and the following disclaimer. 15 16 2. Redistributions in binary form must reproduce the above copyright 17 notice, this list of conditions and the following disclaimer in 18 the documentation and/or other materials provided with the 19 distribution. 20 21 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 29 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 31 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 POSSIBILITY OF SUCH DAMAGE. 33*/ 34 35:- module(obfuscate, []).

Code obfuscating

This module provides an implementation for obfuscate_identifiers/1, a hook into library(qsave) that allows mapping atoms to other atoms while creating a saved state.

This library is used by qsave_program/2 and the -c option. The following is good way to create a binary version of your code that runs on a machine with the same version of SWI-Prolog installed.

swipl -o myprog -O --autoload=false --obfuscate=true -c load.pl

This implementation is overly conservative: atoms are only renamed if they are used once. This is verified by checking the atom reference count. If this is 1, the atom is only used in the functor that defines the predicate.

To be done: - Using the current obfuscation scheme we must verify that all usage of an atom refers to a predicate name. Right now, declarations such as :- dynamic p/1. ensure p is used in p/1 and p(_) and thus has two references. */

60:- dynamic 61 nomap/1. 62 63prolog:obfuscate_identifiers(_) :- 64 print_message(informational, obfuscate(start)), 65 flag('$obfuscate_id', Old, 1), 66 forall(module_property(M, class(user)), 67 obfuscate_module(M)), 68 flag('$obfuscate_id', End, Old), 69 Obfuscated is End-Old, 70 print_message(informational, obfuscate(done(Obfuscated))). 71 72obfuscate_module(M) :- 73 forall(private_predicate(M:P), 74 obfuscate_predicate(M:P)). 75 76private_predicate(M:Head) :- 77 current_predicate(M:Name/Arity), 78 functor(Head, Name, Arity), 79 \+ predicate_property(M:Head, imported_from(_)), 80% \+ predicate_property(M:Head, exported), 81 \+ predicate_property(M:Head, foreign), 82 \+ predicate_property(M:Head, public). 83 84obfuscate_predicate(_M:P) :- 85 functor(P, Name, _Arity), 86 '$atom_references'(Name, 1), 87 !, 88 flag('$obfuscate_id', Id, Id+1), 89 atom_concat('$P$', Id, Name2), 90 ( nomap(Name) 91 -> true 92 ; catch('$map_id'(Name, Name2), _, fail) 93 -> print_message(silent, obfuscate(map(Name, Name2))) 94 ; '$unmap_id'(Name), 95 asserta(nomap(Name)) 96 ). 97obfuscate_predicate(_). 98 99 100 /******************************* 101 * MESSAGES * 102 *******************************/ 103 104:- multifile 105 prolog:message//1. 106 107prolog:message(obfuscate(Msg)) --> 108 message(Msg). 109 110message(start) --> 111 [ 'Obfuscating predicates names (conservative) ...'-[] ]. 112message(done(Count)) --> 113 [ 'Obfuscated ~D predicate names'-[Count] ]. 114message(map(From, To)) --> 115 [ 'Obfuscating ~q as ~q'-[From, To] ]