1 files changed, 68 insertions, 31 deletions

diff --git a/src/lib/libcrypto/ec/ec_lib.c b/src/lib/libcrypto/ec/ec_lib.c
index 0d062111b5..5580375321 100644
--- a/src/lib/libcrypto/ec/ec_lib.c
+++ b/src/lib/libcrypto/ec/ec_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_lib.c,v 1.24 2017/05/02 03:59:44 deraadt Exp $ */
+/* $OpenBSD: ec_lib.c,v 1.25 2018/07/10 21:55:49 tb Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -1026,47 +1026,88 @@ EC_POINTs_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[],
 }
 
 
-/* Functions for point multiplication.
- *
- * If group->meth->mul is 0, we use the wNAF-based implementations in ec_mult.c;
- * otherwise we dispatch through methods.
- */
-
+/* Functions for point multiplication */
 int 
 EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
     size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
 {
-        if (group->meth->mul == 0)
-                /* use default */
-                return ec_wNAF_mul(group, r, scalar, num, points, scalars, ctx);
-
-        return group->meth->mul(group, r, scalar, num, points, scalars, ctx);
+        /*
+         * The function pointers must be set, and only support num == 0 and
+         * num == 1.
+         */
+        if (group->meth->mul_generator_ct == NULL ||
+            group->meth->mul_single_ct == NULL ||
+            group->meth->mul_double_nonct == NULL ||
+            num > 1) {
+                ECerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+                return 0;
+        }
+        
+        /* Either bP or aG + bP, this is sane. */
+        if (num == 1 && points != NULL && scalars != NULL)
+                return EC_POINT_mul(group, r, scalar, points[0], scalars[0],
+                    ctx);
+        
+        /* aG, this is sane */
+        if (scalar != NULL && points == NULL && scalars == NULL)
+                return EC_POINT_mul(group, r, scalar, NULL, NULL, ctx);
+        
+        /* anything else is an error */
+        ECerror(ERR_R_EC_LIB);
+        return 0;
 }
 
 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)
 {
-        /* just a convenient interface to EC_POINTs_mul() */
-
-        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);
+        if (group->meth->mul_generator_ct == NULL ||
+            group->meth->mul_single_ct == NULL ||
+            group->meth->mul_double_nonct == NULL) {
+                ECerror(ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
+                return 0;
+        }
+        if (g_scalar != NULL && point == NULL && p_scalar == NULL) {
+                /*
+                 * In this case we want to compute g_scalar * GeneratorPoint:
+                 * this codepath is reached most prominently by (ephemeral) key
+                 * generation of EC cryptosystems (i.e. ECDSA keygen and sign
+                 * setup, ECDH keygen/first half), where the scalar is always
+                 * secret. This is why we ignore if BN_FLG_CONSTTIME is actually
+                 * set and we always call the constant time version.
+                 */
+                return group->meth->mul_generator_ct(group, r, g_scalar, ctx);
+        }
+        if (g_scalar == NULL && point != NULL && p_scalar != NULL) {
+                /* In this case we want to compute p_scalar * GenericPoint:
+                 * this codepath is reached most prominently by the second half
+                 * of ECDH, where the secret scalar is multiplied by the peer's
+                 * public point. To protect the secret scalar, we ignore if
+                 * BN_FLG_CONSTTIME is actually set and we always call the
+                 * constant time version.
+                 */
+                return group->meth->mul_single_ct(group, r, p_scalar, point,
+                    ctx);
+        }
+        if (g_scalar != NULL && point != NULL && p_scalar != NULL) {
+                /*
+                 * In this case we want to compute
+                 *   g_scalar * GeneratorPoint + p_scalar * GenericPoint:
+                 * this codepath is reached most prominently by ECDSA signature
+                 * verification. So we call the non-ct version.
+                 */
+                return group->meth->mul_double_nonct(group, r, g_scalar,
+                    p_scalar, point, ctx);
+        }
+                
+        /* Anything else is an error. */
+        ECerror(ERR_R_EC_LIB);
+        return 0;
 }
 
 int 
 EC_GROUP_precompute_mult(EC_GROUP * group, BN_CTX * ctx)
 {
-        if (group->meth->mul == 0)
-                /* use default */
-                return ec_wNAF_precompute_mult(group, ctx);
-
         if (group->meth->precompute_mult != 0)
                 return group->meth->precompute_mult(group, ctx);
         else
@@ -1076,10 +1117,6 @@ EC_GROUP_precompute_mult(EC_GROUP * group, BN_CTX * ctx)
 int 
 EC_GROUP_have_precompute_mult(const EC_GROUP * group)
 {
-        if (group->meth->mul == 0)
-                /* use default */
-                return ec_wNAF_have_precompute_mult(group);
-
         if (group->meth->have_precompute_mult != 0)
                 return group->meth->have_precompute_mult(group);
         else