Add functions EC_POINT_mul and EC_GROUP_precompute.

The latter does nothing for now, but its existence means
that applications can request precomputation when appropriate.

CHANGES

@@ -4,7 +4,11 @@
  Changes between 0.9.6 and 0.9.7  [xx XXX 2000]
 
   *) Function EC_POINTs_mul for simultaneous scalar multiplication
-     of an arbitrary number of elliptic curve points.
+     of an arbitrary number of elliptic curve points, optionally
+     including the generator defined for the EC_GROUP.
+     EC_POINT_mul is a simple wrapper function for the typical case
+     that the point list has just one item (besides the optional
+     generator).
      [Bodo Moeller]
 
   *) First EC_METHODs for curves over GF(p):

crypto/ec/ec.h

@@ -160,7 +160,9 @@ int EC_POINT_make_affine(const EC_GROUP *, EC_POINT *, BN_CTX *);
 int EC_POINTs_make_affine(const EC_GROUP *, size_t num, EC_POINT *[], BN_CTX *);
 
 
-int EC_POINTs_mul(const EC_GROUP *, EC_POINT *r, BIGNUM *, size_t num, EC_POINT *[], BIGNUM *[], BN_CTX *);
+int EC_POINTs_mul(const EC_GROUP *, EC_POINT *r, const BIGNUM *, size_t num, const EC_POINT *[], const BIGNUM *[], BN_CTX *);
+int EC_POINT_mul(const EC_GROUP *, EC_POINT *r, const BIGNUM *, const EC_POINT *, const BIGNUM *, BN_CTX *);
+int EC_GROUP_precompute(EC_GROUP *, BN_CTX *);
 
 
 
@@ -193,6 +195,7 @@ void ERR_load_EC_strings(void);
 #define EC_F_EC_GROUP_GET_EXTRA_DATA			 107
 #define EC_F_EC_GROUP_GET_ORDER				 141
 #define EC_F_EC_GROUP_NEW				 108
+#define EC_F_EC_GROUP_PRECOMPUTE			 142
 #define EC_F_EC_GROUP_SET_CURVE_GFP			 109
 #define EC_F_EC_GROUP_SET_EXTRA_DATA			 110
 #define EC_F_EC_GROUP_SET_GENERATOR			 111
@@ -231,6 +234,7 @@ void ERR_load_EC_strings(void);
 #define EC_R_POINT_IS_NOT_ON_CURVE			 107
 #define EC_R_SLOT_FULL					 108
 #define EC_R_UNDEFINED_GENERATOR			 113
+#define EC_R_UNKNOWN_ORDER				 114
 
 #ifdef  __cplusplus
 }

crypto/ec/ec_err.c

@@ -86,6 +86,7 @@ static ERR_STRING_DATA EC_str_functs[]=
 {ERR_PACK(0,EC_F_EC_GROUP_GET_EXTRA_DATA,0),	"EC_GROUP_get_extra_data"},
 {ERR_PACK(0,EC_F_EC_GROUP_GET_ORDER,0),	"EC_GROUP_get_order"},
 {ERR_PACK(0,EC_F_EC_GROUP_NEW,0),	"EC_GROUP_new"},
+{ERR_PACK(0,EC_F_EC_GROUP_PRECOMPUTE,0),	"EC_GROUP_precompute"},
 {ERR_PACK(0,EC_F_EC_GROUP_SET_CURVE_GFP,0),	"EC_GROUP_set_curve_GFp"},
 {ERR_PACK(0,EC_F_EC_GROUP_SET_EXTRA_DATA,0),	"EC_GROUP_set_extra_data"},
 {ERR_PACK(0,EC_F_EC_GROUP_SET_GENERATOR,0),	"EC_GROUP_set_generator"},
@@ -127,6 +128,7 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {EC_R_POINT_IS_NOT_ON_CURVE              ,"point is not on curve"},
 {EC_R_SLOT_FULL                          ,"slot full"},
 {EC_R_UNDEFINED_GENERATOR                ,"undefined generator"},
+{EC_R_UNKNOWN_ORDER                      ,"unknown order"},
 {0,NULL}
 	};
 

crypto/ec/ec_mult.c

@@ -77,8 +77,8 @@
  *      scalar*generator
  * is included in the addition if scalar != NULL
  */
-int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, BIGNUM *scalar,
+int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
-	size_t num, EC_POINT *points[], BIGNUM *scalars[], BN_CTX *ctx)
+	size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
 	{
 	BN_CTX *new_ctx = NULL;
 	EC_POINT *generator = NULL;
@@ -228,7 +228,7 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, BIGNUM *scalar,
 			{
 			if (wbits[i] == 0)
 				{
-				BIGNUM *s;
+				const BIGNUM *s;
 
 				s = i < num ? scalars[i] : scalar;
 
@@ -295,3 +295,59 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, BIGNUM *scalar,
 		}
 	return ret;
 	}
+
+
+int EC_POINT_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar, const EC_POINT *point, const BIGNUM *p_scalar, BN_CTX *ctx)
+	{
+	const EC_POINT *points[1];
+	const BIGNUM *scalars[1];
+
+	points[0] = point;
+	scalars[0] = p_scalar;
+
+	return EC_POINTs_mul(group, r, g_scalar, (point != NULL && p_scalar != NULL), points, scalars, ctx);
+	}
+
+
+int EC_GROUP_precompute(EC_GROUP *group, BN_CTX *ctx)
+	{
+	const EC_POINT *generator;
+	BN_CTX *new_ctx = NULL;
+	BIGNUM *order;
+	int ret = 0;
+
+	generator = EC_GROUP_get0_generator(group);
+	if (generator == NULL)
+		{
+		ECerr(EC_F_EC_GROUP_PRECOMPUTE, EC_R_UNDEFINED_GENERATOR);
+		return 0;
+		}
+
+	if (ctx == NULL)
+		{
+		ctx = new_ctx = BN_CTX_new();
+		if (ctx == NULL)
+			return 0;
+		}
+	
+	BN_CTX_start(ctx);
+	order = BN_CTX_get(ctx);
+	if (order == NULL) goto err;
+	
+	if (!EC_GROUP_get_order(group, order, ctx)) return 0;
+	if (BN_is_zero(order))
+		{
+		ECerr(EC_F_EC_GROUP_PRECOMPUTE, EC_R_UNKNOWN_ORDER);
+		goto err;
+		}
+
+	/* TODO */
+
+	ret = 1;
+	
+ err:
+	BN_CTX_end(ctx);
+	if (new_ctx != NULL)
+		BN_CTX_free(new_ctx);
+	return ret;
+	}

crypto/ec/ectest.c

@@ -80,8 +80,6 @@ void timings(EC_GROUP *group, int simult, BN_CTX *ctx)
 	int i, j;
 	BIGNUM *s, *s0;
 	EC_POINT *P;
-	EC_POINT *points[1];
-	BIGNUM *scalars[1];
 		
 	s = BN_new();
 	s0 = BN_new();
@@ -97,9 +95,6 @@ void timings(EC_GROUP *group, int simult, BN_CTX *ctx)
 	if (P == NULL) ABORT;
 	EC_POINT_copy(P, EC_GROUP_get0_generator(group));
 
-	points[0] = P;
-	scalars[0] = s0;
-
 	clck = clock();
 	for (i = 0; i < 10; i++)
 		{
@@ -110,7 +105,7 @@ void timings(EC_GROUP *group, int simult, BN_CTX *ctx)
 			}
 		for (j = 0; j < 10; j++)
 			{
-			if (!EC_POINTs_mul(group, P, s, simult != 0, points, scalars, ctx)) ABORT;
+			if (!EC_POINT_mul(group, P, s, simult ? P : NULL, simult ? s0 : NULL, ctx)) ABORT;
 			}
 		fprintf(stdout, ".");
 		fflush(stdout);
@@ -322,12 +317,17 @@ int main(int argc, char *argv[])
 	if (!BN_hex2bn(&z, "07192B95FFC8DA78631011ED6B24CDD573F977A11E794811")) ABORT;
 	if (0 != BN_cmp(y, z)) ABORT;
 	
-	fprintf(stdout, "verify group order ... ");
+	fprintf(stdout, "verify group order ...");
 	fflush(stdout);
 	if (!EC_GROUP_get_order(group, z, ctx)) ABORT;
-	if (!EC_POINTs_mul(group, Q, z, 0, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
 	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
-	fprintf(stdout, "ok\n");
+	fprintf(stdout, ".");
+	fflush(stdout);
+	if (!EC_GROUP_precompute(group, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+	fprintf(stdout, " ok\n");
 
 	if (!(P_192 = EC_GROUP_new(EC_GROUP_method_of(group)))) ABORT;
 	if (!EC_GROUP_copy(P_192, group)) ABORT;
@@ -357,13 +357,18 @@ int main(int argc, char *argv[])
 	if (!BN_hex2bn(&z, "BD376388B5F723FB4C22DFE6CD4375A05A07476444D5819985007E34")) ABORT;
 	if (0 != BN_cmp(y, z)) ABORT;
 	
-	fprintf(stdout, "verify group order ... ");
+	fprintf(stdout, "verify group order ...");
 	fflush(stdout);
 	if (!EC_GROUP_get_order(group, z, ctx)) ABORT;
-	if (!EC_POINTs_mul(group, Q, z, 0, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
 	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
-	fprintf(stdout, "ok\n");
+	fprintf(stdout, ".");
-	
+	fflush(stdout);
+	if (!EC_GROUP_precompute(group, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+	fprintf(stdout, " ok\n");
+
 	if (!(P_224 = EC_GROUP_new(EC_GROUP_method_of(group)))) ABORT;
 	if (!EC_GROUP_copy(P_224, group)) ABORT;
 
@@ -393,13 +398,18 @@ int main(int argc, char *argv[])
 	if (!BN_hex2bn(&z, "4FE342E2FE1A7F9B8EE7EB4A7C0F9E162BCE33576B315ECECBB6406837BF51F5")) ABORT;
 	if (0 != BN_cmp(y, z)) ABORT;
 	
-	fprintf(stdout, "verify group order ... ");
+	fprintf(stdout, "verify group order ...");
 	fflush(stdout);
 	if (!EC_GROUP_get_order(group, z, ctx)) ABORT;
-	if (!EC_POINTs_mul(group, Q, z, 0, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
 	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
-	fprintf(stdout, "ok\n");
+	fprintf(stdout, ".");
-	
+	fflush(stdout);
+	if (!EC_GROUP_precompute(group, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+	fprintf(stdout, " ok\n");
+
 	if (!(P_256 = EC_GROUP_new(EC_GROUP_method_of(group)))) ABORT;
 	if (!EC_GROUP_copy(P_256, group)) ABORT;
 
@@ -434,13 +444,18 @@ int main(int argc, char *argv[])
 		"7CE9DA3113B5F0B8C00A60B1CE1D7E819D7A431D7C90EA0E5F")) ABORT;
 	if (0 != BN_cmp(y, z)) ABORT;
 	
-	fprintf(stdout, "verify group order ... ");
+	fprintf(stdout, "verify group order ...");
 	fflush(stdout);
 	if (!EC_GROUP_get_order(group, z, ctx)) ABORT;
-	if (!EC_POINTs_mul(group, Q, z, 0, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
 	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
-	fprintf(stdout, "ok\n");
+	fprintf(stdout, ".");
-	
+	fflush(stdout);
+	if (!EC_GROUP_precompute(group, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+	fprintf(stdout, " ok\n");
+
 	if (!(P_384 = EC_GROUP_new(EC_GROUP_method_of(group)))) ABORT;
 	if (!EC_GROUP_copy(P_384, group)) ABORT;
 
@@ -481,12 +496,17 @@ int main(int argc, char *argv[])
 		"7086A272C24088BE94769FD16650")) ABORT;
 	if (0 != BN_cmp(y, z)) ABORT;
 	
-	fprintf(stdout, "verify group order ... ");
+	fprintf(stdout, "verify group order ...");
 	fflush(stdout);
 	if (!EC_GROUP_get_order(group, z, ctx)) ABORT;
-	if (!EC_POINTs_mul(group, Q, z, 0, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
 	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
-	fprintf(stdout, "ok\n");
+	fprintf(stdout, ".");
+	fflush(stdout);
+	if (!EC_GROUP_precompute(group, ctx)) ABORT;
+	if (!EC_POINT_mul(group, Q, z, NULL, NULL, ctx)) ABORT;
+	if (!EC_POINT_is_at_infinity(group, Q)) ABORT;
+	fprintf(stdout, " ok\n");
 
 	if (!(P_521 = EC_GROUP_new(EC_GROUP_method_of(group)))) ABORT;
 	if (!EC_GROUP_copy(P_521, group)) ABORT;
@@ -505,17 +525,17 @@ int main(int argc, char *argv[])
 	if (!EC_POINT_is_at_infinity(group, R)) ABORT; /* R = P + 2Q */
 
 	{
-		EC_POINT *points[2];
+		const EC_POINT *points[3];
-		BIGNUM *scalars[2];
+		const BIGNUM *scalars[3];
 	
 		if (EC_POINT_is_at_infinity(group, Q)) ABORT;
+		points[0] = Q;
+		points[1] = Q;
+		points[2] = Q;
 
 		if (!BN_add(y, z, BN_value_one())) ABORT;
 		if (BN_is_odd(y)) ABORT;
 		if (!BN_rshift1(y, y)) ABORT;
-
-		points[0] = Q;
-		points[1] = Q;
 		scalars[0] = y; /* (group order + 1)/2,  so  y*Q + y*Q = Q */
 		scalars[1] = y;
 
@@ -534,20 +554,30 @@ int main(int argc, char *argv[])
 		if (!BN_pseudo_rand(y, BN_num_bits(y), 0, 0)) ABORT;
 		if (!BN_copy(z, y)) ABORT;
 		z->neg = 1;
-
-		points[0] = Q;
-		points[1] = Q;
 		scalars[0] = y;
-		scalars[1] = z;
+		scalars[1] = z; /* z = -y */
 
 		if (!EC_POINTs_mul(group, P, NULL, 2, points, scalars, ctx)) ABORT;
 		if (!EC_POINT_is_at_infinity(group, P)) ABORT;
 
+		fprintf(stdout, ".");
+		fflush(stdout);
+
+		if (!BN_pseudo_rand(x, BN_num_bits(y) - 1, 0, 0)) ABORT;
+		if (!BN_add(z, x, y)) ABORT;
+		z->neg = 1;
+		scalars[0] = x;
+		scalars[1] = y;
+		scalars[2] = z; /* z = -(x+y) */
+
+		if (!EC_POINTs_mul(group, P, NULL, 3, points, scalars, ctx)) ABORT;
+		if (!EC_POINT_is_at_infinity(group, P)) ABORT;
+
 		fprintf(stdout, " ok\n\n");
 	}
 
 
-#if 0
+#if 1
 	timings(P_192, 0, ctx);
 	timings(P_192, 1, ctx);
 	timings(P_224, 0, ctx);