Implemented polynomial interpolation with hazmat gf256 code

slip39/Makefile

@@ -3,13 +3,16 @@ CFLAGS += -g -O2 -m64 -std=c99 -pedantic \
  -Werror=format-security -Wstrict-prototypes -Wmissing-prototypes \
  -D_FORTIFY_SOURCE=2 -fPIC -fno-strict-overflow
 
-SRCS = gf256.c gf256_interpolate.c slip39_encrypt.c slip39_rs1024.c \
- slip39_shamir.c slip39_wordlist.c slip39_mnemonics.c
+SRCS = slip39_encrypt.c slip39_rs1024.c \
+ slip39_shamir.c slip39_wordlist.c slip39_mnemonics.c hazmat.c
 
 OBJS := ${SRCS:.c=.o}
 
 all: libslip39.a
 
+libslip39.so: libslip39.so
+ $(CC) -shared $(CFLAGS) $^ -o $@
+
 libslip39.a: ../randombytes/librandombytes.a $(OBJS)
  $(AR) -rcs $@ $^
 
@@ -21,23 +24,17 @@ slip39_tests.c: vectors_to_tests.js vectors.json
 
 slip39_tests.o: slip39_tests.c
 
-slip39_tests.out: slip39_tests.o gf256.o gf256_interpolate.o slip39_wordlist.o slip39_rs1024.o \
+slip39_tests.out: slip39_tests.o hazmat.o slip39_wordlist.o slip39_rs1024.o \
  slip39_shamir.o slip39_mnemonics.o test_random.o slip39_encrypt.o
  $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ -l crypto
  $(MEMCHECK) ./$@
 
-gf256%.o: gf256&%.c gf256.h gf256%.h
- $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $<
-
-test_gf256.o: test_gf256.c gf256.h
-
-test_gf256.out: test_gf256.o gf256.o
- $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS)
- $(MEMCHECK) ./$@
+#gf256%.o: gf256&%.c hazmat.h gf256%.h
+# $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $<
 
-test_gf256_interpolate.o: test_gf256_interpolate.c
+test_interpolate.o: test_interpolate.c
 
-test_gf256_interpolate.out: gf256_interpolate.o gf256.o test_gf256_interpolate.o
+test_interpolate.out: hazmat.o test_interpolate.o
  $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS)
  $(MEMCHECK) ./$@
 
@@ -55,29 +52,29 @@ test_slip39_shamir.o: test_slip39_shamir.c slip39.h
 
 slip39_shamir.o: slip39_shamir.c slip39.h
 
-test_slip39_shamir.out: test_slip39_shamir.o slip39_shamir.o gf256.o gf256_interpolate.o test_random.o
+test_slip39_shamir.out: test_slip39_shamir.o slip39_shamir.o hazmat.o test_random.o
  gcc $^ -o $@ -l crypto
  ./$@
 
 
 slip39_encrypt.o: slip39_encrypt.c slip39.h
 
-test_slip39_encrypt.out: test_slip39_encrypt.o slip39_encrypt.o 
+test_slip39_encrypt.out: test_slip39_encrypt.o slip39_encrypt.o
  gcc $^ -o $@ -l crypto
  ./$@
 
 
 test_generate_combine.o: test_generate_combine.c
 
-test_generate_combine.out: test_generate_combine.o gf256.o gf256_interpolate.o slip39_wordlist.o \
+test_generate_combine.out: test_generate_combine.o hazmat.o slip39_wordlist.o \
  slip39_rs1024.o slip39_shamir.o slip39_mnemonics.o slip39_encrypt.o ../randombytes/librandombytes.a
  $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) -l crypto
  $(MEMCHECK) ./$@
 
 slip39: slip39_cli.c libslip39.a ../randombytes/librandombytes.a
  $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) -l crypto
 
-check: test_gf256.out test_gf256_interpolate.out test_slip39_wordlist.out \
+check: test_interpolate.out test_slip39_wordlist.out \
  test_slip39_shamir.out test_slip39_encrypt.out test_generate_combine.out slip39_tests.out
 
 .PHONY: check check_slip39

slip39/README.md

@@ -8,25 +8,24 @@ standard for doing so:
 
 Along with the proposed specification, they also have provided a
 [python reference implementation](https://github.com/trezor/python-shamir-mnemonic)
-and a set of 
+and a set of
 [sest vectors](https://github.com/trezor/python-shamir-mnemonic/blob/master/vectors.json).
 
 This branch intends to provide an implementation of the specification in C. Note that SLIP39
 differs from standard implementations of Shamir Sharing in a couple of ways - it adds some
-digest checking that allows you to give you some assurance that the result is correct at 
+digest checking that allows you to give you some assurance that the result is correct at
 the expense of a few bits of security, it has a two-level grouping scheme, etc. At its heart,
 it ends up making more use of polynomical interpolation than other implementations do.
 
 The file vectors_to_tests.js contains some javascript that uses the published test vectors
 to produce C code that can be used to verify that the code implements the spec.
 
-gf256.c provides a naive, table-lookup implementation of gf256 operations. 
-
-gf256_interpolate.c provides an implementation for interpolating a polynomial going 
-through n arbitray points at an arbitrary x-coordinate. The y-coordinates are represented
-as arrays of gf256 values, and while this implementation does calculations byte-by-byte,
-it is probably feasible to adapt this implementation to using the bit-slicing approach
-used in hazmat.c to give an implementation with fewer side-channel attacks.
+hazmat.c provides a side-channel attack resistant implementation of gf256 operations
+32 elements at a time, with a couple of additional functions dealing with lagrange
+polynomials and polynomial interpolation. Note that this file was copied from
+the Daan's original implementation of the hazmat code in the outer directory, and
+then his inperpolation functions were removed and new lagrange and interpolation
+functions added.
 
 test_random.c implements some code to act as filler for random number generation when testing.
 It is clearly not designed to be used in any real life application.
@@ -41,12 +40,12 @@ imbedding a digest into the shares which requires a sha256. Again this implement
 on openssl for sha256.
 
 slip39_wordlists.c implements functions for converting byte buffers to wordlists and
-and the encoding and decoding of slip39 words into 10-bit integers. the toWords and 
+and the encoding and decoding of slip39 words into 10-bit integers. the toWords and
 fromWords functions do/check the appropriate left padding of bits described in slip39.
 slip39_wordlist_english.h contains the actual word list used.
 
 There are various and sundry test files that test key parts of the implementation. You can
-build and run them all by building the make target 'check'. 
+build and run them all by building the make target 'check'.
 
 There is also a quick and dirty command line. You can build it with the make target 'slip39'. Here
 is a sample of running it to generate a share set and then combine some of those shares