add first ZKP including test case

7 files changed, 149 insertions, 80 deletions

diff --git a/Makefile.am b/Makefile.am
index 8264db3..76820c6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,10 +7,11 @@ lib_LTLIBRARIES = \
 libbrandt_la_SOURCES = \
   brandt.c \
   crypto.c \
-  util.c
+  util.c \
+  smc.c
 
 libbrandt_la_LIBADD = \
-  -lpari
+  -lgcrypt -lgpg-error
 
 libbrandt_la_LDFLAGS = \
   -version-info 0:0:0
diff --git a/crypto.c b/crypto.c
index e78032e..7f2940a 100644
--- a/crypto.c
+++ b/crypto.c
@@ -243,17 +243,19 @@ brandt_ec_skey_create (gcry_mpi_t* skey)
 {
 	gcry_sexp_t  s_keyparam;
 	gcry_sexp_t  priv_sexp;
-	gcry_mpi_t   d;
 	gcry_error_t rc;
 
 	rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")"
 	                      "(flags)))");
 	brandt_assert_gpgerr (rc);
+
 	rc = gcry_pk_genkey (&priv_sexp, s_keyparam);
 	brandt_assert_gpgerr (rc);
 	gcry_sexp_release (s_keyparam);
+
 	rc = key_from_sexp (skey, priv_sexp, "private-key", "d");
 	brandt_assert_gpgerr (rc);
+
 	gcry_sexp_release (priv_sexp);
 }
 
@@ -268,10 +270,10 @@ brandt_ec_pkey_compute (gcry_mpi_point_t* pkey, const gcry_mpi_t skey)
 void
 brandt_ec_keypair_create (gcry_mpi_point_t* pkey, gcry_mpi_t* skey)
 {
-	gcry_error_t rc;
+	gcry_ctx_t   ctx;
 	gcry_sexp_t  s_keyparam;
 	gcry_sexp_t  priv_sexp;
-	gcry_ctx_t   ctx;
+	gcry_error_t rc;
 
 	rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecc(curve \"" CURVE "\")"
 	                      "(flags)))");
@@ -294,6 +296,46 @@ brandt_ec_keypair_create (gcry_mpi_point_t* pkey, gcry_mpi_t* skey)
 }
 
 
+void
+brandt_ec_keypair_create_base (gcry_mpi_point_t* pkey, gcry_mpi_t* skey, const gcry_mpi_point_t base)
+{
+	brandt_ec_skey_create(skey);
+	brandt_assert(*skey);
+	*pkey = gcry_mpi_point_new(0);
+	brandt_assert(*pkey);
+	gcry_mpi_ec_mul(*pkey, *skey, base, ec_ctx);
+}
+
+
+int
+brandt_ec_point_cmp (const gcry_mpi_point_t a, const gcry_mpi_point_t b)
+{
+	int ret = 1;
+	gcry_mpi_t ax = gcry_mpi_new(0);
+	gcry_mpi_t bx = gcry_mpi_new(0);
+	gcry_mpi_t ay = gcry_mpi_new(0);
+	gcry_mpi_t by = gcry_mpi_new(0);
+
+	brandt_assert (a && b);
+	if (!ax || !bx || !ay || !by)
+	{
+		weprintf("could not init point in point_cmp");
+		return 1;
+	}
+
+	if (!gcry_mpi_ec_get_affine(ax, ay, a, ec_ctx) && !gcry_mpi_ec_get_affine(bx, by, b, ec_ctx))
+	{
+		ret = gcry_mpi_cmp(ax, bx) || gcry_mpi_cmp(ay, by);
+	}
+
+	gcry_mpi_release(ax);
+	gcry_mpi_release(bx);
+	gcry_mpi_release(ay);
+	gcry_mpi_release(by);
+	return ret;
+}
+
+
 /**
  * Convert the given private key from the network format to the
  * S-expression that can be used by libgcrypt.
diff --git a/crypto.h b/crypto.h
index 28bf4eb..0df73e4 100644
--- a/crypto.h
+++ b/crypto.h
@@ -25,10 +25,6 @@
 #include <gcrypt.h>
 #include <stdint.h>
 
-extern gcry_mpi_point_t ec_gen;
-extern gcry_ctx_t ec_ctx;
-
-
 void brandt_crypto_init ();
 
 
@@ -57,5 +53,7 @@ void brandt_mpi_scan_unsigned (gcry_mpi_t *result, const void *data, size_t size
 void brandt_ec_skey_create (gcry_mpi_t* skey);
 void brandt_ec_pkey_compute (gcry_mpi_point_t* pkey, const gcry_mpi_t skey);
 void brandt_ec_keypair_create (gcry_mpi_point_t* pkey, gcry_mpi_t* skey);
+void brandt_ec_keypair_create_base (gcry_mpi_point_t* pkey, gcry_mpi_t* skey, const gcry_mpi_point_t base);
+int brandt_ec_point_cmp (const gcry_mpi_point_t a, const gcry_mpi_point_t b);
 
 #endif /* ifndef _BRANDT_CRYPTO_H */
diff --git a/smc.c b/smc.c
index 399f031..52afa35 100644
--- a/smc.c
+++ b/smc.c
@@ -19,17 +19,55 @@
  * @brief Implementation of the smc primitives.
  */
 
+#include <gcrypt.h>
+
+#include "crypto.h"
 #include "util.h"
+#include "smc.h"
+
+extern gcry_ctx_t ec_ctx;
+
+void
+smc_zkp_dl (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_t x, gcry_mpi_point_t *a, gcry_mpi_t *c, gcry_mpi_t *r)
+{
+	gcry_mpi_t z = gcry_mpi_new(0);
+
+	brandt_ec_keypair_create_base(a, &z, g);
+	/**TODO: generate c from HASH(g,v,a) and don't output it */
+	brandt_ec_skey_create(c);
+	*r = gcry_mpi_new(0);
+	gcry_mpi_mul(*r, *c, x);
+	gcry_mpi_add(*r, *r, z);
+
+	gcry_mpi_release(z);
+}
+
+int
+smc_zkp_dl_check (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_point_t a, gcry_mpi_t c, gcry_mpi_t r)
+{
+	int ret;
+	gcry_mpi_point_t left = gcry_mpi_point_new(0);
+	gcry_mpi_point_t right = gcry_mpi_point_new(0);
+
+	gcry_mpi_ec_mul(left, r, g, ec_ctx);
+	gcry_mpi_ec_mul(right, c, v, ec_ctx);
+	gcry_mpi_ec_add(right, a, right, ec_ctx);
 
-#include <pari/pari.h>
+	ret = brandt_ec_point_cmp(left, right);
+	gcry_mpi_point_release(left);
+	gcry_mpi_point_release(right);
 
+	return ret;
+}
+
+/*
 GEN
-smc_hextodec (const char *s)                      /* int */
+smc_hextodec (const char *s)
 {
 	size_t i;
 	char c;
 	pari_sp ltop = avma;
-	GEN ret = gen_0;                        /* int */
+	GEN ret = gen_0;
 
 	for (i = 0; i < strlen (s); i++)
 	{
@@ -43,49 +81,4 @@ smc_hextodec (const char *s)                      /* int */
 	}
 	return gerepilecopy (ltop, ret);
 }
-
-
-void
-smc_genbid (struct AuctionData *ad, uint16_t bid)
-{
-	uint16_t j;
-	pari_sp ltop = avma;
-	GEN ret = cgetg (itos (ad->k)+1, t_VEC);         /* vec */
-
-	for (j = 1; j <= ad->k; j++)
-	{
-		gel (ret, j) = gpowgs (ad->g, bid == j);
-	}
-	ad->b = gerepilecopy (ltop, ret);
-}
-
-
-void
-smc_genalpha (struct AuctionData *ad)
-{
-	uint16_t j;
-	pari_sp ltop = avma;
-	GEN ret = cgetg (ad->k+1, t_VEC);
-
-	for (j = 1; j <= ad->k; ++j)
-	{
-		gel (ret, j) = gmul (gel (ad->b, j), gpowgi (ad->y, gel (ad->r, j)));
-	}
-	ad->alpha = gerepilecopy (ltop, ret);
-}
-
-
-void
-smc_genbeta (struct AuctionData *ad)
-{
-	uint16_t j;
-	pari_sp ltop = avma;
-	GEN ret = cgetg (ad->k+1, t_VEC);
-
-	for (j = 1; j <= ad->k; ++j)
-	{
-		gel (ret, j) = gpowgi (ad->g, gel (ad->r, j));
-	}
-	ad->beta = gerepilecopy (ltop, ret);
-}
-
+*/
diff --git a/smc.h b/smc.h
new file mode 100644
index 0000000..d5a13cf
--- /dev/null
+++ b/smc.h
@@ -0,0 +1,10 @@
+
+#ifndef _BRANDT_SMC_H
+#define _BRANDT_SMC_H
+
+#include <gcrypt.h>
+
+void smc_zkp_dl (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_t x, gcry_mpi_point_t *a, gcry_mpi_t *c, gcry_mpi_t *r);
+int smc_zkp_dl_check (gcry_mpi_point_t v, gcry_mpi_point_t g, gcry_mpi_point_t a, gcry_mpi_t c, gcry_mpi_t r);
+
+#endif
diff --git a/test.h b/test.h
index db63350..45ace82 100644
--- a/test.h
+++ b/test.h
@@ -6,7 +6,7 @@
 int tests_run = 0;
 int ret = 0;
 
-#define check(cond, message) do { if (!(cond)) { fputs(message, stderr); return 0; } } while (0)
+#define check(cond, message) do { if (!(cond)) { fputs(message, stderr); fputc('\n', stderr); return 0; } } while (0)
 #define run(test) do { tests_run++; if (!test()) ret = 1; } while (0)
 
 #endif
diff --git a/test_crypto.c b/test_crypto.c
index 67894eb..1bfc321 100644
--- a/test_crypto.c
+++ b/test_crypto.c
@@ -1,16 +1,16 @@
 
 #include "brandt.h"
 #include "crypto.h"
+#include "smc.h"
 #include "test.h"
 
+extern gcry_mpi_point_t ec_gen;
+extern gcry_ctx_t ec_ctx;
+
 int
 test_brandt_ec_keypair_create ()
 {
 	gcry_mpi_t skey;
-	gcry_mpi_t x1 = gcry_mpi_new(0);
-	gcry_mpi_t x2 = gcry_mpi_new(0);
-	gcry_mpi_t y1 = gcry_mpi_new(0);
-	gcry_mpi_t y2 = gcry_mpi_new(0);
 	gcry_mpi_point_t pkey1;
 	gcry_mpi_point_t pkey2 = gcry_mpi_point_new(0);
 
@@ -18,30 +18,58 @@ test_brandt_ec_keypair_create ()
 	check(skey, "no sec key created");
 	check(pkey1, "no pub key created");
 	check(pkey2, "could not init pkey2");
-	check(x1, "could not init x1");
-	check(x2, "could not init x2");
-	check(y1, "could not init y1");
-	check(y2, "could not init y2");
 
 	gcry_mpi_ec_mul(pkey2, skey, ec_gen, ec_ctx);
-	check(!gcry_mpi_ec_get_affine(x1, y1, pkey1, ec_ctx), "could not get affine coords for pkey1");
-	check(!gcry_mpi_ec_get_affine(x2, y2, pkey2, ec_ctx), "could not get affine coords for pkey1");
-	check(!gcry_mpi_cmp(x1, x2), "x component does not match");
-	check(!gcry_mpi_cmp(y1, y2), "y component does not match");
+	check(!brandt_ec_point_cmp(pkey1, pkey2), "pkeys do not match");
 
 	gcry_mpi_release(skey);
-	gcry_mpi_release(x1);
-	gcry_mpi_release(x2);
-	gcry_mpi_release(y1);
-	gcry_mpi_release(y2);
 	gcry_mpi_point_release(pkey1);
 	gcry_mpi_point_release(pkey2);
 }
 
 int
+test_smc_zkp_dl ()
+{
+	static int first = 1;
+	gcry_mpi_t c;
+	gcry_mpi_t r;
+	gcry_mpi_t s;
+	gcry_mpi_t x;
+	gcry_mpi_point_t a;
+	gcry_mpi_point_t g;
+	gcry_mpi_point_t v = gcry_mpi_point_new(0);
+
+	check(v, "no pub key initialized");
+	brandt_ec_keypair_create (&g, &s);
+	check(g, "no gen created");
+
+	if (first)
+	{
+		gcry_mpi_ec_mul(g, GCRYMPI_CONST_ONE, ec_gen, ec_ctx);
+		first = 0;
+	}
+
+	brandt_ec_skey_create(&x);
+	check(x, "no sec key created");
+	gcry_mpi_ec_mul(v, x, g, ec_ctx);
+	check(v, "no pub key created");
+
+	smc_zkp_dl(v, g, x, &a, &c, &r);
+	check(!smc_zkp_dl_check(v, g, a, c, r), "zkp was false, should be true");
+
+	gcry_mpi_release(c);
+	gcry_mpi_release(r);
+	gcry_mpi_release(s);
+	gcry_mpi_release(x);
+	gcry_mpi_point_release(a);
+	gcry_mpi_point_release(g);
+	gcry_mpi_point_release(v);
+}
+
+int
 main (int argc, char *argv[])
 {
-	int repeat = 100;
+	int repeat = 50;
 	int i;
 
 	BRANDT_init();
@@ -49,11 +77,8 @@ main (int argc, char *argv[])
 	for (i = 0; i < repeat; i++)
 	{
 		run(test_brandt_ec_keypair_create);
+		run(test_smc_zkp_dl);
 	}
 
-	if (!ret)
-	{
-		fputs("All tests passed", stderr);
-	}
 	return ret;
 }