Fix crypto/ec/ec_mult.c to work properly with scalars of value 0

CHANGES

@@ -501,6 +501,10 @@
 
  Changes between 0.9.8e and 0.9.8f  [xx XXX xxxx]
 
+  *) Fix crypto/ec/ec_mult.c to work properly with scalars of value 0
+     (which previously caused an internal error).
+     [Bodo Moeller]
+
   *) Squeeze another 10% out of IGE mode when in != out.
      [Ben Laurie]
 

crypto/ec/ec.h

@@ -931,7 +931,7 @@ void ERR_load_EC_strings(void);
 #define EC_F_D2I_ECPKPARAMETERS				 145
 #define EC_F_D2I_ECPRIVATEKEY				 146
 #define EC_F_DO_EC_KEY_PRINT				 221
-#define EC_F_ECKEY_PARAM2TYPE				 196
+#define EC_F_ECKEY_PARAM2TYPE				 223
 #define EC_F_ECKEY_PARAM_DECODE				 212
 #define EC_F_ECKEY_PRIV_DECODE				 213
 #define EC_F_ECKEY_PRIV_ENCODE				 214
@@ -1033,6 +1033,7 @@ void ERR_load_EC_strings(void);
 #define EC_F_EC_POINT_SET_JPROJECTIVE_COORDINATES_GFP	 126
 #define EC_F_EC_POINT_SET_TO_INFINITY			 127
 #define EC_F_EC_PRE_COMP_DUP				 207
+#define EC_F_EC_PRE_COMP_NEW				 196
 #define EC_F_EC_WNAF_MUL				 187
 #define EC_F_EC_WNAF_PRECOMPUTE_MULT			 188
 #define EC_F_I2D_ECPARAMETERS				 190

crypto/ec/ec_err.c

@@ -177,6 +177,7 @@ static ERR_STRING_DATA EC_str_functs[]=
 {ERR_FUNC(EC_F_EC_POINT_SET_JPROJECTIVE_COORDINATES_GFP),	"EC_POINT_set_Jprojective_coordinates_GFp"},
 {ERR_FUNC(EC_F_EC_POINT_SET_TO_INFINITY),	"EC_POINT_set_to_infinity"},
 {ERR_FUNC(EC_F_EC_PRE_COMP_DUP),	"EC_PRE_COMP_DUP"},
+{ERR_FUNC(EC_F_EC_PRE_COMP_NEW),	"EC_PRE_COMP_NEW"},
 {ERR_FUNC(EC_F_EC_WNAF_MUL),	"ec_wNAF_mul"},
 {ERR_FUNC(EC_F_EC_WNAF_PRECOMPUTE_MULT),	"ec_wNAF_precompute_mult"},
 {ERR_FUNC(EC_F_I2D_ECPARAMETERS),	"i2d_ECParameters"},

crypto/ec/ec_mult.c

@@ -3,7 +3,7 @@
  * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
  */
 /* ====================================================================
- * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1998-2007 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -104,7 +104,10 @@ static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group)
 
 	ret = (EC_PRE_COMP *)OPENSSL_malloc(sizeof(EC_PRE_COMP));
 	if (!ret)
+		{
+		ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
 		return ret;
+		}
 	ret->group = group;
 	ret->blocksize = 8; /* default */
 	ret->numblocks = 0;
@@ -194,6 +197,19 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
 	int bit, next_bit, mask;
 	size_t len = 0, j;
 	
+	if (BN_is_zero(scalar))
+		{
+		r = OPENSSL_malloc(1);
+		if (!r)
+			{
+			ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
+			goto err;
+			}
+		r[0] = 0;
+		*ret_len = 1;
+		return r;
+		}
+		
 	if (w <= 0 || w > 7) /* 'signed char' can represent integers with absolute values less than 2^7 */
 		{
 		ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
@@ -212,7 +228,11 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
 	r = OPENSSL_malloc(len + 1); /* modified wNAF may be one digit longer than binary representation
 	                              * (*ret_len will be set to the actual length, i.e. at most
 	                              * BN_num_bits(scalar) + 1) */
-	if (r == NULL) goto err;
+	if (r == NULL)
+		{
+		ECerr(EC_F_COMPUTE_WNAF, ERR_R_MALLOC_FAILURE);
+		goto err;
+		}
 
 	if (scalar->d == NULL || scalar->top == 0)
 		{
@@ -425,7 +445,10 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
 	val_sub  = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
 		 
 	if (!wsize || !wNAF_len || !wNAF || !val_sub)
+		{
+		ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
 		goto err;
+		}
 
 	wNAF[0] = NULL;	/* preliminary pivot */
 
@@ -538,6 +561,7 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
 					wNAF[i] = OPENSSL_malloc(wNAF_len[i]);
 					if (wNAF[i] == NULL)
 						{
+						ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
 						OPENSSL_free(tmp_wNAF);
 						goto err;
 						}
@@ -564,7 +588,11 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
 	 * 'val_sub[i]' is a pointer to the subarray for the i-th point,
 	 * or to a subarray of 'pre_comp->points' if we already have precomputation. */
 	val = OPENSSL_malloc((num_val + 1) * sizeof val[0]);
-	if (val == NULL) goto err;
+	if (val == NULL)
+		{
+		ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
+		goto err;
+		}
 	val[num_val] = NULL; /* pivot element */
 
 	/* allocate points for precomputation */

crypto/ec/ectest.c

@@ -649,13 +649,15 @@ void prime_field_tests()
 	if (!EC_POINT_is_at_infinity(group, R)) ABORT; /* R = P + 2Q */
 
 	{
-		const EC_POINT *points[3];
-		const BIGNUM *scalars[3];
+		const EC_POINT *points[4];
+		const BIGNUM *scalars[4];
+		BIGNUM scalar3;
 	
 		if (EC_POINT_is_at_infinity(group, Q)) ABORT;
 		points[0] = Q;
 		points[1] = Q;
 		points[2] = Q;
+		points[3] = Q;
 
 		if (!BN_add(y, z, BN_value_one())) ABORT;
 		if (BN_is_odd(y)) ABORT;
@@ -694,10 +696,16 @@ void prime_field_tests()
 		scalars[1] = y;
 		scalars[2] = z; /* z = -(x+y) */
 
-		if (!EC_POINTs_mul(group, P, NULL, 3, points, scalars, ctx)) ABORT;
+		BN_init(&scalar3);
+		BN_zero(&scalar3);
+		scalars[3] = &scalar3;
+
+		if (!EC_POINTs_mul(group, P, NULL, 4, points, scalars, ctx)) ABORT;
 		if (!EC_POINT_is_at_infinity(group, P)) ABORT;
 
 		fprintf(stdout, " ok\n\n");
+
+		BN_free(&scalar3);
 	}