Implement NTRU_AVOID_HAMMING_WT_PATENT; make Makefiles more consistent

The NTRU_AVOID_HAMMING_WT_PATENT preprocessor flag removes all code affected by U.S. patent 7031468.
This commit also applies commits 1308bb4 and 67a2fbf to Makefile.win and Makefile.osx for consistency.

Makefile

@@ -16,6 +16,7 @@ INST_HEADERS=ntru.h types.h key.h encparams.h hash.h rand.h err.h
 LIB_OBJS_PATHS=$(patsubst %,$(SRCDIR)/%,$(LIB_OBJS))
 TEST_OBJS_PATHS=$(patsubst %,$(TESTDIR)/%,$(TEST_OBJS))
 DIST_NAME=libntru-$(VERSION)
+MAKEFILENAME=$(lastword $(MAKEFILE_LIST))
 
 .PHONY: all
 all: lib
@@ -60,9 +61,25 @@ dist:
 	tar cf $(DIST_NAME).tar.xz $(DIST_NAME) --lzma
 	rm -rf $(DIST_NAME)
 
-test: lib $(TEST_OBJS_PATHS)
-	$(CC) $(CFLAGS) $(CPPFLAGS) -o test $(TEST_OBJS_PATHS) $(LDFLAGS) -L. -lntru -lm
-	LD_LIBRARY_PATH=. ./test
+.PHONY: test
+test:
+	$(MAKE) -f $(MAKEFILENAME) testnoham
+	@echo
+	@echo Testing patent-reduced build
+	LD_LIBRARY_PATH=. ./testnoham
+	$(MAKE) -f $(MAKEFILENAME) testham
+	@echo
+	@echo Testing full build
+	LD_LIBRARY_PATH=. ./testham
+
+testham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testham $(TEST_OBJS_PATHS) -L. -lntru -lm
+
+testnoham: CFLAGS += -DNTRU_AVOID_HAMMING_WT_PATENT
+testnoham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testnoham $(TEST_OBJS_PATHS) -L. -lntru -lm
 
 bench: lib $(SRCDIR)/bench.o
 	$(CC) $(CFLAGS) $(CPPFLAGS) -o bench $(SRCDIR)/bench.o $(LDFLAGS) -L. -lntru
@@ -76,7 +93,7 @@ tests/%.o: tests/%.c
 .PHONY: clean
 clean:
 	@# also clean files generated on other OSes
-	rm -f $(SRCDIR)/*.o $(TESTDIR)/*.o libntru.so libntru.dylib libntru.dll test test.exe bench bench.exe
+	rm -f $(SRCDIR)/*.o $(TESTDIR)/*.o libntru.so libntru.dylib libntru.dll testham testnoham testham.exe testnoham.exe bench bench.exe
 
 .PHONY: distclean
 distclean: clean

Makefile.osx

@@ -1,44 +1,50 @@
 CC=gcc
 CFLAGS=-g -Wall -Wextra -Wno-unused-parameter -O2
+LIBS+=-lrt
 SRCDIR=src
 TESTDIR=tests
 LIB_OBJS=bitstring.o encparams.o hash.o idxgen.o key.o mgf.o ntru.o poly.o rand.o sha1.o sha2.o
 TEST_OBJS=test_bitstring.o test_hash.o test_idxgen.o test_key.o test_ntru.o test.o test_poly.o test_util.o
 VERSION=0.2
+INST_PFX=/usr
+INST_LIBDIR=$(INST_PFX)/lib
+INST_INCLUDE=$(INST_PFX)/include/libntru
+INST_DOCDIR=$(INST_PFX)/share/doc/libntru
 INST_HEADERS=ntru.h types.h key.h encparams.h hash.h rand.h err.h
 
 LIB_OBJS_PATHS=$(patsubst %,$(SRCDIR)/%,$(LIB_OBJS))
 TEST_OBJS_PATHS=$(patsubst %,$(TESTDIR)/%,$(TEST_OBJS))
 DIST_NAME=libntru-$(VERSION)
+MAKEFILENAME=$(lastword $(MAKEFILE_LIST))
 
 .PHONY: all
 all: lib
 
 .PHONY: lib
 lib: $(LIB_OBJS_PATHS)
-	$(CC) $(CFLAGS) -dynamiclib -o libntru.dylib $(LIB_OBJS_PATHS) $(LDFLAGS)
+	$(CC) $(CFLAGS) $(CPPFLAGS) -dynamiclib -o libntru.dylib $(LIB_OBJS_PATHS) $(LDFLAGS) $(LIBS)
 
 .PHONY: install
 install: lib
-	test -d $(INST_PFX) || mkdir -p $(INST_PFX)
-	test -d $(INST_PFX)/lib || mkdir $(INST_PFX)/lib
-	test -d $(INST_PFX)/include/libntru || mkdir -p $(INST_PFX)/include/libntru
-	test -d $(INST_PFX)/share/doc/libntru || mkdir -p $(INST_PFX)/share/doc/libntru
-	install -m 0755 libntru.so $(INST_PFX)/lib/libntru.so
-	install -m 0644 README.md $(INST_PFX)/share/doc/libntru/README.md
-	for header in $(INST_HEADERS); do \
-	    install -m 0644 $(SRCDIR)/$$header $(INST_PFX)/include/libntru/; \
+	test -d "$(DESTDIR)$(INST_PFX)" || mkdir -p "$(DESTDIR)$(INST_PFX)"
+	test -d "$(DESTDIR)$(INST_LIBDIR)" || mkdir "$(DESTDIR)$(INST_LIBDIR)"
+	test -d "$(DESTDIR)$(INST_INCLUDE)" || mkdir -p "$(DESTDIR)$(INST_INCLUDE)"
+	test -d "$(DESTDIR)$(INST_DOCDIR)" || mkdir -p "$(DESTDIR)$(INST_DOCDIR)"
+	install -m 0755 libntru.so "$(DESTDIR)$(INST_LIBDIR)/libntru.so"
+	install -m 0644 README.md "$(DESTDIR)$(INST_DOCDIR)/README.md"
+	for header in $(INST_HEADERS) ; do \
+	    install -m 0644 "$(SRCDIR)/$$header" "$(DESTDIR)$(INST_INCLUDE)/" ; \
 	done
 
 .PHONY: uninstall
 uninstall:
-	rm -f $(INST_PFX)/lib/libntru.so
-	rm -f $(INST_PFX)/share/doc/libntru/README.md
-	rmdir $(INST_PFX)/share/doc/libntru/
-	for header in $(INST_HEADERS); do \
-	    rm $(INST_PFX)/include/libntru/$$header; \
+	rm -f "$(DESTDIR)$(INST_LIBDIR)/libntru.so"
+	rm -f "$(DESTDIR)$(INST_DOCDIR)/README.md"
+	rmdir "$(DESTDIR)$(INST_DOCDIR)/"
+	for header in $(INST_HEADERS) ; do \
+	    rm "$(DESTDIR)$(INST_INCLUDE)/$$header" ; \
 	done
-	rmdir $(INST_PFX)/include/libntru/
+	rmdir "$(DESTDIR)$(INST_INCLUDE)/"
 
 .PHONY: dist
 dist:
@@ -54,23 +60,39 @@ dist:
 	tar cf $(DIST_NAME).tar.xz $(DIST_NAME) --lzma
 	rm -rf $(DIST_NAME)
 
-test: lib $(TEST_OBJS_PATHS)
-	$(CC) $(CFLAGS) -o test $(TEST_OBJS_PATHS) -L. -lntru -lm
-	DYLD_LIBRARY_PATH=. ./test
+.PHONY: test
+test:
+	$(MAKE) -f $(MAKEFILENAME) testnoham
+	@echo
+	@echo Testing patent-reduced build
+	DYLD_LIBRARY_PATH=. ./testnoham
+	$(MAKE) -f $(MAKEFILENAME) testham
+	@echo
+	@echo Testing full build
+	DYLD_LIBRARY_PATH=. ./testham
+
+testham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testham $(TEST_OBJS_PATHS) -L. -lntru -lm
+
+testnoham: CFLAGS += -DNTRU_AVOID_HAMMING_WT_PATENT
+testnoham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testnoham $(TEST_OBJS_PATHS) -L. -lntru -lm
 
 bench: lib $(SRCDIR)/bench.o
-	$(CC) $(CFLAGS) -o bench $(SRCDIR)/bench.o -L. -lntru
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o bench $(SRCDIR)/bench.o $(LDFLAGS) -L. -lntru
 
 $(SRCDIR)/%.o: $(SRCDIR)/%.c
-	$(CC) $(CFLAGS) -c -fPIC $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c -fPIC $< -o $@
 
 tests/%.o: tests/%.c
-	$(CC) $(CFLAGS) -fPIC -I$(SRCDIR) -c $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -fPIC -I$(SRCDIR) -c $< -o $@
 
 .PHONY: clean
 clean:
 	@# also clean files generated on other OSes
-	rm -f $(SRCDIR)/*.o $(TESTDIR)/*.o libntru.so libntru.dylib libntru.dll test test.exe bench bench.exe
+	rm -f $(SRCDIR)/*.o $(TESTDIR)/*.o libntru.so libntru.dylib libntru.dll testham testnoham testham.exe testnoham.exe bench bench.exe
 
 .PHONY: distclean
 distclean: clean

Makefile.win

@@ -1,40 +1,49 @@
 CC?=gcc
-CFLAGS=-g -Wall -Wextra -Wno-unused-parameter -O2
+CFLAGS?=-g -O2
+CFLAGS+=-Wall -Wextra -Wno-unused-parameter
+LIBS+=-lrt
 SRCDIR=src
 TESTDIR=tests
 LIB_OBJS=bitstring.o encparams.o hash.o idxgen.o key.o mgf.o ntru.o poly.o rand.o sha1.o sha2.o
 TEST_OBJS=test_bitstring.o test_hash.o test_idxgen.o test_key.o test_ntru.o test.o test_poly.o test_util.o
 VERSION=0.2
 INST_PFX=%PROGRAMFILES%
+INST_LIBDIR=$(INST_PFX)\libntru
+INST_INCLUDE=$(INST_PFX)\libntru\include
+INST_DOCDIR=$(INST_PFX)\libntru
 INST_HEADERS=ntru.h types.h key.h encparams.h hash.h rand.h err.h
 
 LIB_OBJS_PATHS=$(patsubst %,$(SRCDIR)/%,$(LIB_OBJS))
 TEST_OBJS_PATHS=$(patsubst %,$(TESTDIR)/%,$(TEST_OBJS))
 DIST_NAME=libntru-$(VERSION)
+MAKEFILENAME=$(lastword $(MAKEFILE_LIST))
 
 .PHONY: all
 all: lib
 
 .PHONY: lib
 lib: $(LIB_OBJS_PATHS)
-	$(CC) $(CFLAGS) -shared -o libntru.dll $(LIB_OBJS_PATHS) -lws2_32 -ladvapi32
+	$(CC) $(CFLAGS) $(CPPFLAGS) -shared -o libntru.dll $(LIB_OBJS_PATHS) -lws2_32 -ladvapi32
 
 .PHONY: install
 install: lib
-	if not exist "%PROGRAMFILES%\libntru" mkdir "%PROGRAMFILES%\libntru"
-	if not exist "%PROGRAMFILES%\libntru\include" mkdir "%PROGRAMFILES%\libntru\include"
-	copy libntru.dll "%PROGRAMFILES%\libntru"
-	copy README.md "%PROGRAMFILES%\libntru"
+	if not exist "$(DESTDIR)$(INST_PFX)" mkdir "$(DESTDIR)$(INST_PFX)"
+	if not exist "$(DESTDIR)$(INST_LIBDIR)" mkdir "$(DESTDIR)$(INST_LIBDIR)"
+	if not exist "$(DESTDIR)$(INST_INCLUDE)" mkdir "$(DESTDIR)$(INST_INCLUDE)"
+	if not exist "$(DESTDIR)$(INST_DOCDIR)" mkdir "$(DESTDIR)$(INST_DOCDIR)"
+	copy libntru.dll "$(DESTDIR)$(INST_LIBDIR)"
+	copy README.md "$(DESTDIR)$(INST_DOCDIR)"
 	for %%h in ($(INST_HEADERS)) do \
-	    copy $(SRCDIR)\%%h "%PROGRAMFILES%\libntru\include"
+	    copy $(SRCDIR)\%%h "$(INST_INCLUDE)"
 
 uninstall:
-	if exist "%PROGRAMFILES%\libntru\libntru.dll" del "%PROGRAMFILES%\libntru\libntru.dll"
-	if exist "%PROGRAMFILES%\libntru\README.md" del "%PROGRAMFILES%\libntru\README.md"
-	for %%h in ($(INST_HEADERS)) do \
-	    if exist "%PROGRAMFILES%\libntru\include\%%h" del "%PROGRAMFILES%\libntru\include\%%h"
-	if exist "%PROGRAMFILES%\libntru\include" rmdir "%PROGRAMFILES%\libntru\include"
-	if exist "%PROGRAMFILES%\libntru" rmdir "%PROGRAMFILES%\libntru"
+	if exist "$(DESTDIR)$(INST_LIBDIR)\libntru.dll" del "$(DESTDIR)$(INST_LIBDIR)\libntru.dll"
+	if exist "$(DESTDIR)$(INST_DOCDIR)\README.md" del "$(DESTDIR)$(INST_DOCDIR)\README.md"
+	for %%h in ($(DESTDIR)$(INST_HEADERS)) do \
+	    if exist "$(DESTDIR)$(INST_INCLUDE)\%%h" del "$(DESTDIR)$(INST_INCLUDE)\%%h"
+	if exist "$(DESTDIR)$(INST_INCLUDE)" rmdir "$(DESTDIR)$(INST_INCLUDE)"
+	if exist "$(DESTDIR)$(INST_LIBDIR)" rmdir "$(DESTDIR)$(INST_LIBDIR)"
+	if exist "$(DESTDIR)$(INST_DOCDIR)" rmdir "$(DESTDIR)$(INST_DOCDIR)"
 
 .PHONY: dist
 dist:
@@ -62,30 +71,48 @@ dist:
 	@rem zip is provided by MinGW
 	zip -rm $(DIST_NAME).zip $(DIST_NAME)
 
-test: lib $(TEST_OBJS_PATHS)
-	$(CC) $(CFLAGS) -o test.exe $(TEST_OBJS_PATHS) -L. -lntru -lm
-	test.exe
+.PHONY: test
+test:
+	$(MAKE) -f $(MAKEFILENAME) testnoham
+	@echo.
+	@echo Testing patent-reduced build
+	testnoham.exe
+	$(MAKE) -f $(MAKEFILENAME) testham
+	@echo.
+	@echo Testing full build
+	testham.exe
+
+testham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testham.exe $(TEST_OBJS_PATHS) -L. -lntru -lm
+
+testnoham: CFLAGS += -DNTRU_AVOID_HAMMING_WT_PATENT
+testnoham: clean lib $(TEST_OBJS_PATHS)
+	@echo CFLAGS=$(CFLAGS)
+	$(CC) $(CFLAGS) -o testnoham.exe $(TEST_OBJS_PATHS) -L. -lntru -lm
 
 bench: lib $(SRCDIR)/bench.o
-	$(CC) $(CFLAGS) -o bench $(SRCDIR)/bench.o -L. -lntru
+	$(CC) $(CFLAGS) $(CPPFLAGS) -o bench $(SRCDIR)/bench.o -L. -lntru
 
 $(SRCDIR)/%.o: $(SRCDIR)/%.c
-	$(CC) $(CFLAGS) -c $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 $(TESTDIR)/%.o: tests/%.c
-	$(CC) $(CFLAGS) -I$(SRCDIR) -c $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -I$(SRCDIR) -c $< -o $@
 
 .PHONY: clean
 clean:
 	@if exist $(SRCDIR)\*.o del $(SRCDIR)\*.o
 	@if exist $(TESTDIR)\*.o del $(TESTDIR)\*.o
 	@if exist libntru.dll del libntru.dll
-	@if exist test.exe del test.exe
+	@if exist testham.exe del testham.exe
+	@if exist testnoham.exe del testnoham.exe
 	@if exist bench.exe del bench.exe
 	@rem ***** clean files generated on other OSes *****
 	@if exist libntru.so del libntru.so
 	@if exist libntru.dylib del libntru.dylib
-	@if exist test del test
+	@if exist testham del testnoham
+	@if exist testnoham del testnoham
 	@if exist bench del bench
 
 .PHONY: distclean

README.md

@@ -4,8 +4,8 @@ An implementation of the public-key encryption scheme NTRUEncrypt in C.
 
 NTRU's main strengths are high performance and resistance to quantum computer
 attacks. Its main drawback is that it is patent encumbered. The patents expire
-in 2020; it is possible to modify this implementation so it becomes patent-free
-in 2017.
+in 2020; when built with the NTRU_AVOID_HAMMING_WT_PATENT flag, libntru becomes
+patent-free in 2017.
 For more information on the NTRUEncrypt algorithm, see the NTRU introduction
 page:
 

src/encparams.h

@@ -384,6 +384,7 @@ typedef struct NtruEncParams {
     256            /* pklen */\
 }
 
+#ifndef NTRU_AVOID_HAMMING_WT_PATENT
 /*
  * A product-form parameter set that gives 112 bits of security.
  */
@@ -479,6 +480,7 @@ typedef struct NtruEncParams {
     32,            /* hlen */\
     256            /* pklen */\
 }
+#endif   /* NTRU_AVOID_HAMMING_WT_PATENT */
 
 uint16_t ntru_enc_len(NtruEncParams *params);
 

src/key.c

@@ -85,7 +85,11 @@ uint16_t ntru_export_priv(NtruEncPrivKey *key, uint8_t *arr) {
     uint8_t prod_flag = key->prod_flag;
 
     /* write N */
+#ifndef NTRU_AVOID_HAMMING_WT_PATENT
     uint16_t N_endian = prod_flag ? htons(key->t.prod.N) : htons(key->t.tern.N);
+#else
+    uint16_t N_endian = htons(key->t.tern.N);
+#endif   /* NTRU_AVOID_HAMMING_WT_PATENT */
     memcpy(arr_head, &N_endian, sizeof N_endian);
     arr_head += sizeof N_endian;
 
@@ -99,12 +103,14 @@ uint16_t ntru_export_priv(NtruEncPrivKey *key, uint8_t *arr) {
     arr_head++;
 
     /* write f1, f2, f3 */
+#ifndef NTRU_AVOID_HAMMING_WT_PATENT
     if (prod_flag) {
         arr_head += ntru_tern_to_arr(&key->t.prod.f1, arr_head);
         arr_head += ntru_tern_to_arr(&key->t.prod.f2, arr_head);
         arr_head += ntru_tern_to_arr(&key->t.prod.f3, arr_head);
     }
     else
+#endif   /* NTRU_AVOID_HAMMING_WT_PATENT */
         arr_head += ntru_tern_to_arr(&key->t.tern, arr_head);
 
     return arr_head - arr;
@@ -160,13 +166,16 @@ void ntru_import_priv(uint8_t *arr, NtruEncPrivKey *key) {
     key->prod_flag = (flags&4) != 0;
     arr++;
 
+#ifndef NTRU_AVOID_HAMMING_WT_PATENT
     if (key->prod_flag) {
         key->t.prod.N = N;
         arr += ntru_tern_from_arr(arr, N, &key->t.prod.f1);
         arr += ntru_tern_from_arr(arr, N, &key->t.prod.f2);
         arr += ntru_tern_from_arr(arr, N, &key->t.prod.f3);
     }
-    else {
+    else
+#endif   /* NTRU_AVOID_HAMMING_WT_PATENT */
+    {
         key->t.tern.N = N;
         arr += ntru_tern_from_arr(arr, key->t.tern.N, &key->t.tern);
     }