Move the REF_PRINT support from e_os.h to internal/refcount.h.
[openssl.git] / crypto / ec / ec_mult.c
index 236b66c18a6be7f747f63cf0361abb1782e1ce76..c7557882facb3da527bdeaae9c78cd9d1daa5e44 100644 (file)
-/* crypto/ec/ec_mult.c */
 /*
- * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
- */
-/* ====================================================================
- * Copyright (c) 1998-2003 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
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer. 
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * 3. All advertising materials mentioning features or use of this
- *    software must display the following acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- *    endorse or promote products derived from this software without
- *    prior written permission. For written permission, please contact
- *    openssl-core@openssl.org.
+ * Copyright 2001-2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
  *
- * 5. Products derived from this software may not be called "OpenSSL"
- *    nor may "OpenSSL" appear in their names without prior written
- *    permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- *    acknowledgment:
- *    "This product includes software developed by the OpenSSL Project
- *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- * ====================================================================
- *
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com).  This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com).
- *
- */
-/* ====================================================================
- * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
- * Portions of this software developed by SUN MICROSYSTEMS, INC.,
- * and contributed to the OpenSSL project.
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  */
 
 #include <string.h>
-
 #include <openssl/err.h>
 
+#include "internal/cryptlib.h"
+#include "internal/bn_int.h"
 #include "ec_lcl.h"
-
+#include "internal/refcount.h"
 
 /*
- * This file implements the wNAF-based interleaving multi-exponentation method
- * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>);
- * for multiplication with precomputation, we use wNAF splitting
- * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp>).
+ * This file implements the wNAF-based interleaving multi-exponentiation method
+ * Formerly at:
+ *   http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp
+ * You might now find it here:
+ *   http://link.springer.com/chapter/10.1007%2F3-540-45537-X_13
+ *   http://www.bmoeller.de/pdf/TI-01-08.multiexp.pdf
+ * For multiplication with precomputation, we use wNAF splitting, formerly at:
+ *   http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#fastexp
  */
 
-
-
-
 /* structure for precomputed multiples of the generator */
-typedef struct ec_pre_comp_st {
-       const EC_GROUP *group; /* parent EC_GROUP object */
-       size_t blocksize;      /* block size for wNAF splitting */
-       size_t numblocks;      /* max. number of blocks for which we have precomputation */
-       size_t w;              /* window size */
-       EC_POINT **points;     /* array with pre-calculated multiples of generator:
-                               * 'num' pointers to EC_POINT objects followed by a NULL */
-       size_t num;            /* numblocks * 2^(w-1) */
-       int references;
-} EC_PRE_COMP;
-/* functions to manage EC_PRE_COMP within the EC_GROUP extra_data framework */
-static void *ec_pre_comp_dup(void *);
-static void ec_pre_comp_free(void *);
-static void ec_pre_comp_clear_free(void *);
+struct ec_pre_comp_st {
+    const EC_GROUP *group;      /* parent EC_GROUP object */
+    size_t blocksize;           /* block size for wNAF splitting */
+    size_t numblocks;           /* max. number of blocks for which we have
+                                 * precomputation */
+    size_t w;                   /* window size */
+    EC_POINT **points;          /* array with pre-calculated multiples of
+                                 * generator: 'num' pointers to EC_POINT
+                                 * objects followed by a NULL */
+    size_t num;                 /* numblocks * 2^(w-1) */
+    CRYPTO_REF_COUNT references;
+    CRYPTO_RWLOCK *lock;
+};
 
 static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group)
-       {
-       EC_PRE_COMP *ret = NULL;
-
-       if (!group)
-               return NULL;
-
-       ret = (EC_PRE_COMP *)OPENSSL_malloc(sizeof(EC_PRE_COMP));
-       if (!ret)
-               return ret;
-       ret->group = group;
-       ret->blocksize = 8; /* default */
-       ret->numblocks = 0;
-       ret->w = 4; /* default */
-       ret->points = NULL;
-       ret->num = 0;
-       ret->references = 1;
-       return ret;
-       }
-
-static void *ec_pre_comp_dup(void *src_)
-       {
-       EC_PRE_COMP *src = src_;
-
-       /* no need to actually copy, these objects never change! */
-
-       CRYPTO_add(&src->references, 1, CRYPTO_LOCK_EC_PRE_COMP);
-
-       return src_;
-       }
-
-static void ec_pre_comp_free(void *pre_)
-       {
-       int i;
-       EC_PRE_COMP *pre = pre_;
-
-       if (!pre)
-               return;
-
-       i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
-       if (i > 0)
-               return;
-
-       if (pre->points)
-               {
-               EC_POINT **p;
-
-               for (p = pre->points; *p != NULL; p++)
-                       EC_POINT_free(*p);
-               OPENSSL_free(pre->points);
-               }
-       OPENSSL_free(pre);
-       }
-
-static void ec_pre_comp_clear_free(void *pre_)
-       {
-       int i;
-       EC_PRE_COMP *pre = pre_;
-
-       if (!pre)
-               return;
-
-       i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
-       if (i > 0)
-               return;
-
-       if (pre->points)
-               {
-               EC_POINT **p;
-
-               for (p = pre->points; *p != NULL; p++)
-                       EC_POINT_clear_free(*p);
-               OPENSSL_cleanse(pre->points, sizeof pre->points);
-               OPENSSL_free(pre->points);
-               }
-       OPENSSL_cleanse(pre, sizeof pre);
-       OPENSSL_free(pre);
-       }
-
-
-
-
-/* Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'.
- * This is an array  r[]  of values that are either zero or odd with an
- * absolute value less than  2^w  satisfying
- *     scalar = \sum_j r[j]*2^j
- * where at most one of any  w+1  consecutive digits is non-zero
- * with the exception that the most significant digit may be only
- * w-1 zeros away from that next non-zero digit.
- */
-static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len)
-       {
-       int window_val;
-       int ok = 0;
-       signed char *r = NULL;
-       int sign = 1;
-       int bit, next_bit, mask;
-       size_t len = 0, j;
-       
-       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);
-               goto err;
-               }
-       bit = 1 << w; /* at most 128 */
-       next_bit = bit << 1; /* at most 256 */
-       mask = next_bit - 1; /* at most 255 */
-
-       if (BN_get_sign(scalar))
-               {
-               sign = -1;
-               }
-
-       len = BN_num_bits(scalar);
-       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 (scalar->d == NULL || scalar->top == 0)
-               {
-               ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
-               goto err;
-               }
-       window_val = scalar->d[0] & mask;
-       j = 0;
-       while ((window_val != 0) || (j + w + 1 < len)) /* if j+w+1 >= len, window_val will not increase */
-               {
-               int digit = 0;
-
-               /* 0 <= window_val <= 2^(w+1) */
-
-               if (window_val & 1)
-                       {
-                       /* 0 < window_val < 2^(w+1) */
-
-                       if (window_val & bit)
-                               {
-                               digit = window_val - next_bit; /* -2^w < digit < 0 */
-
-#if 1 /* modified wNAF */
-                               if (j + w + 1 >= len)
-                                       {
-                                       /* special case for generating modified wNAFs:
-                                        * no new bits will be added into window_val,
-                                        * so using a positive digit here will decrease
-                                        * the total length of the representation */
-                                       
-                                       digit = window_val & (mask >> 1); /* 0 < digit < 2^w */
-                                       }
-#endif
-                               }
-                       else
-                               {
-                               digit = window_val; /* 0 < digit < 2^w */
-                               }
-                       
-                       if (digit <= -bit || digit >= bit || !(digit & 1))
-                               {
-                               ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }
-
-                       window_val -= digit;
-
-                       /* now window_val is 0 or 2^(w+1) in standard wNAF generation;
-                        * for modified window NAFs, it may also be 2^w
-                        */
-                       if (window_val != 0 && window_val != next_bit && window_val != bit)
-                               {
-                               ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }
-                       }
-
-               r[j++] = sign * digit;
-
-               window_val >>= 1;
-               window_val += bit * BN_is_bit_set(scalar, j + w);
-
-               if (window_val > next_bit)
-                       {
-                       ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
-                       goto err;
-                       }
-               }
-
-       if (j > len + 1)
-               {
-               ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR);
-               goto err;
-               }
-       len = j;
-       ok = 1;
+{
+    EC_PRE_COMP *ret = NULL;
+
+    if (!group)
+        return NULL;
+
+    ret = OPENSSL_zalloc(sizeof(*ret));
+    if (ret == NULL) {
+        ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
+        return ret;
+    }
+
+    ret->group = group;
+    ret->blocksize = 8;         /* default */
+    ret->w = 4;                 /* default */
+    ret->references = 1;
+
+    ret->lock = CRYPTO_THREAD_lock_new();
+    if (ret->lock == NULL) {
+        ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
+        OPENSSL_free(ret);
+        return NULL;
+    }
+    return ret;
+}
+
+EC_PRE_COMP *EC_ec_pre_comp_dup(EC_PRE_COMP *pre)
+{
+    int i;
+    if (pre != NULL)
+        CRYPTO_UP_REF(&pre->references, &i, pre->lock);
+    return pre;
+}
+
+void EC_ec_pre_comp_free(EC_PRE_COMP *pre)
+{
+    int i;
+
+    if (pre == NULL)
+        return;
+
+    CRYPTO_DOWN_REF(&pre->references, &i, pre->lock);
+    REF_PRINT_COUNT("EC_ec", pre);
+    if (i > 0)
+        return;
+    REF_ASSERT_ISNT(i < 0);
+
+    if (pre->points != NULL) {
+        EC_POINT **pts;
+
+        for (pts = pre->points; *pts != NULL; pts++)
+            EC_POINT_free(*pts);
+        OPENSSL_free(pre->points);
+    }
+    CRYPTO_THREAD_lock_free(pre->lock);
+    OPENSSL_free(pre);
+}
 
- err:
-       if (!ok)
-               {
-               OPENSSL_free(r);
-               r = NULL;
-               }
-       if (ok)
-               *ret_len = len;
-       return r;
-       }
-
-
-/* TODO: table should be optimised for the wNAF-based implementation,
- *       sometimes smaller windows will give better performance
- *       (thus the boundaries should be increased)
+/*
+ * TODO: table should be optimised for the wNAF-based implementation,
+ * sometimes smaller windows will give better performance (thus the
+ * boundaries should be increased)
  */
 #define EC_window_bits_for_scalar_size(b) \
-               ((size_t) \
-                ((b) >= 2000 ? 6 : \
-                 (b) >=  800 ? 5 : \
-                 (b) >=  300 ? 4 : \
-                 (b) >=   70 ? 3 : \
-                 (b) >=   20 ? 2 : \
-                 1))
-
-/* Compute
+                ((size_t) \
+                 ((b) >= 2000 ? 6 : \
+                  (b) >=  800 ? 5 : \
+                  (b) >=  300 ? 4 : \
+                  (b) >=   70 ? 3 : \
+                  (b) >=   20 ? 2 : \
+                  1))
+
+/*-
+ * Compute
  *      \sum scalars[i]*points[i],
  * also including
  *      scalar*generator
  * in the addition if scalar != NULL
  */
 int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
-       size_t num, const EC_POINT *points[], const BIGNUM *scalars[], BN_CTX *ctx)
-       {
-       BN_CTX *new_ctx = NULL;
-       EC_POINT *generator = NULL;
-       EC_POINT *tmp = NULL;
-       size_t totalnum;
-       size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
-       size_t pre_points_per_block = 0;
-       size_t i, j;
-       int k;
-       int r_is_inverted = 0;
-       int r_is_at_infinity = 1;
-       size_t *wsize = NULL; /* individual window sizes */
-       signed char **wNAF = NULL; /* individual wNAFs */
-       size_t *wNAF_len = NULL;
-       size_t max_len = 0;
-       size_t num_val;
-       EC_POINT **val = NULL; /* precomputation */
-       EC_POINT **v;
-       EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or 'pre_comp->points' */
-       const EC_PRE_COMP *pre_comp = NULL;
-       int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be treated like other scalars,
-                            * i.e. precomputation is not available */
-       int ret = 0;
-       
-       if (group->meth != r->meth)
-               {
-               ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
-               return 0;
-               }
-
-       if ((scalar == NULL) && (num == 0))
-               {
-               return EC_POINT_set_to_infinity(group, r);
-               }
-
-       for (i = 0; i < num; i++)
-               {
-               if (group->meth != points[i]->meth)
-                       {
-                       ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
-                       return 0;
-                       }
-               }
-
-       if (ctx == NULL)
-               {
-               ctx = new_ctx = BN_CTX_new();
-               if (ctx == NULL)
-                       goto err;
-               }
-
-       if (scalar != NULL)
-               {
-               generator = EC_GROUP_get0_generator(group);
-               if (generator == NULL)
-                       {
-                       ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR);
-                       goto err;
-                       }
-               
-               /* look if we can use precomputed multiples of generator */
-
-               pre_comp = EC_GROUP_get_extra_data(group, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
-
-               if (pre_comp && pre_comp->numblocks && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) == 0))
-                       {
-                       blocksize = pre_comp->blocksize;
-
-                       /* determine maximum number of blocks that wNAF splitting may yield
-                        * (NB: maximum wNAF length is bit length plus one) */
-                       numblocks = (BN_num_bits(scalar) / blocksize) + 1;
-
-                       /* we cannot use more blocks than we have precomputation for */
-                       if (numblocks > pre_comp->numblocks)
-                               numblocks = pre_comp->numblocks;
-
-                       pre_points_per_block = 1u << (pre_comp->w - 1);
-
-                       /* check that pre_comp looks sane */
-                       if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block))
-                               {
-                               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }
-                       }
-               else
-                       {
-                       /* can't use precomputation */
-                       pre_comp = NULL;
-                       numblocks = 1;
-                       num_scalar = 1; /* treat 'scalar' like 'num'-th element of 'scalars' */
-                       }
-               }
-       
-       totalnum = num + numblocks;
-
-       wsize    = OPENSSL_malloc(totalnum * sizeof wsize[0]);
-       wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]);
-       wNAF     = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space for pivot */
-       val_sub  = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
-                
-       if (!wsize || !wNAF_len || !wNAF || !val_sub)
-               goto err;
-
-       wNAF[0] = NULL; /* preliminary pivot */
-
-       /* num_val will be the total number of temporarily precomputed points */
-       num_val = 0;
-
-       for (i = 0; i < num + num_scalar; i++)
-               {
-               size_t bits;
-
-               bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar);
-               wsize[i] = EC_window_bits_for_scalar_size(bits);
-               num_val += 1u << (wsize[i] - 1);
-               wNAF[i + 1] = NULL; /* make sure we always have a pivot */
-               wNAF[i] = compute_wNAF((i < num ? scalars[i] : scalar), wsize[i], &wNAF_len[i]);
-               if (wNAF[i] == NULL)
-                       goto err;
-               if (wNAF_len[i] > max_len)
-                       max_len = wNAF_len[i];
-               }
-
-       if (numblocks)
-               {
-               /* we go here iff scalar != NULL */
-               
-               if (pre_comp == NULL)
-                       {
-                       if (num_scalar != 1)
-                               {
-                               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }
-                       /* we have already generated a wNAF for 'scalar' */
-                       }
-               else
-                       {
-                       signed char *tmp_wNAF = NULL;
-                       size_t tmp_len = 0;
-                       
-                       if (num_scalar != 0)
-                               {
-                               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }
-
-                       /* use the window size for which we have precomputation */
-                       wsize[num] = pre_comp->w;
-                       tmp_wNAF = compute_wNAF(scalar, wsize[num], &tmp_len);
-                       if (!tmp_wNAF)
-                               goto err;
-
-                       if (tmp_len <= max_len)
-                               {
-                               /* One of the other wNAFs is at least as long
-                                * as the wNAF belonging to the generator,
-                                * so wNAF splitting will not buy us anything. */
-
-                               numblocks = 1;
-                               totalnum = num + 1; /* don't use wNAF splitting */
-                               wNAF[num] = tmp_wNAF;
-                               wNAF[num + 1] = NULL;
-                               wNAF_len[num] = tmp_len;
-                               if (tmp_len > max_len)
-                                       max_len = tmp_len;
-                               /* pre_comp->points starts with the points that we need here: */
-                               val_sub[num] = pre_comp->points;
-                               }
-                       else
-                               {
-                               /* don't include tmp_wNAF directly into wNAF array
-                                * - use wNAF splitting and include the blocks */
-
-                               signed char *pp;
-                               EC_POINT **tmp_points;
-                               
-                               if (tmp_len < numblocks * blocksize)
-                                       {
-                                       /* possibly we can do with fewer blocks than estimated */
-                                       numblocks = (tmp_len + blocksize - 1) / blocksize;
-                                       if (numblocks > pre_comp->numblocks)
-                                               {
-                                               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                                               goto err;
-                                               }
-                                       totalnum = num + numblocks;
-                                       }
-                               
-                               /* split wNAF in 'numblocks' parts */
-                               pp = tmp_wNAF;
-                               tmp_points = pre_comp->points;
-
-                               for (i = num; i < totalnum; i++)
-                                       {
-                                       if (i < totalnum - 1)
-                                               {
-                                               wNAF_len[i] = blocksize;
-                                               if (tmp_len < blocksize)
-                                                       {
-                                                       ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                                                       goto err;
-                                                       }
-                                               tmp_len -= blocksize;
-                                               }
-                                       else
-                                               /* last block gets whatever is left
-                                                * (this could be more or less than 'blocksize'!) */
-                                               wNAF_len[i] = tmp_len;
-                                       
-                                       wNAF[i + 1] = NULL;
-                                       wNAF[i] = OPENSSL_malloc(wNAF_len[i]);
-                                       if (wNAF[i] == NULL)
-                                               {
-                                               OPENSSL_free(tmp_wNAF);
-                                               goto err;
-                                               }
-                                       memcpy(wNAF[i], pp, wNAF_len[i]);
-                                       if (wNAF_len[i] > max_len)
-                                               max_len = wNAF_len[i];
-
-                                       if (*tmp_points == NULL)
-                                               {
-                                               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-                                               OPENSSL_free(tmp_wNAF);
-                                               goto err;
-                                               }
-                                       val_sub[i] = tmp_points;
-                                       tmp_points += pre_points_per_block;
-                                       pp += blocksize;
-                                       }
-                               OPENSSL_free(tmp_wNAF);
-                               }
-                       }
-               }
-
-       /* All points we precompute now go into a single array 'val'.
-        * '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;
-       val[num_val] = NULL; /* pivot element */
-
-       /* allocate points for precomputation */
-       v = val;
-       for (i = 0; i < num + num_scalar; i++)
-               {
-               val_sub[i] = v;
-               for (j = 0; j < (1u << (wsize[i] - 1)); j++)
-                       {
-                       *v = EC_POINT_new(group);
-                       if (*v == NULL) goto err;
-                       v++;
-                       }
-               }
-       if (!(v == val + num_val))
-               {
-               ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
-               goto err;
-               }
-
-       if (!(tmp = EC_POINT_new(group)))
-               goto err;
-
-       /* prepare precomputed values:
-        *    val_sub[i][0] :=     points[i]
-        *    val_sub[i][1] := 3 * points[i]
-        *    val_sub[i][2] := 5 * points[i]
-        *    ...
-        */
-       for (i = 0; i < num + num_scalar; i++)
-               {
-               if (i < num)
-                       {
-                       if (!EC_POINT_copy(val_sub[i][0], points[i])) goto err;
-                       }
-               else
-                       {
-                       if (!EC_POINT_copy(val_sub[i][0], generator)) goto err;
-                       }
-
-               if (wsize[i] > 1)
-                       {
-                       if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) goto err;
-                       for (j = 1; j < (1u << (wsize[i] - 1)); j++)
-                               {
-                               if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err;
-                               }
-                       }
-               }
-
-#if 1 /* optional; EC_window_bits_for_scalar_size assumes we do this step */
-       if (!EC_POINTs_make_affine(group, num_val, val, ctx))
-               goto err;
-#endif
-
-       r_is_at_infinity = 1;
-
-       for (k = max_len - 1; k >= 0; k--)
-               {
-               if (!r_is_at_infinity)
-                       {
-                       if (!EC_POINT_dbl(group, r, r, ctx)) goto err;
-                       }
-               
-               for (i = 0; i < totalnum; i++)
-                       {
-                       if (wNAF_len[i] > (size_t)k)
-                               {
-                               int digit = wNAF[i][k];
-                               int is_neg;
-
-                               if (digit) 
-                                       {
-                                       is_neg = digit < 0;
-
-                                       if (is_neg)
-                                               digit = -digit;
-
-                                       if (is_neg != r_is_inverted)
-                                               {
-                                               if (!r_is_at_infinity)
-                                                       {
-                                                       if (!EC_POINT_invert(group, r, ctx)) goto err;
-                                                       }
-                                               r_is_inverted = !r_is_inverted;
-                                               }
-
-                                       /* digit > 0 */
-
-                                       if (r_is_at_infinity)
-                                               {
-                                               if (!EC_POINT_copy(r, val_sub[i][digit >> 1])) goto err;
-                                               r_is_at_infinity = 0;
-                                               }
-                                       else
-                                               {
-                                               if (!EC_POINT_add(group, r, r, val_sub[i][digit >> 1], ctx)) goto err;
-                                               }
-                                       }
-                               }
-                       }
-               }
-
-       if (r_is_at_infinity)
-               {
-               if (!EC_POINT_set_to_infinity(group, r)) goto err;
-               }
-       else
-               {
-               if (r_is_inverted)
-                       if (!EC_POINT_invert(group, r, ctx)) goto err;
-               }
-       
-       ret = 1;
+                size_t num, const EC_POINT *points[], const BIGNUM *scalars[],
+                BN_CTX *ctx)
+{
+    BN_CTX *new_ctx = NULL;
+    const EC_POINT *generator = NULL;
+    EC_POINT *tmp = NULL;
+    size_t totalnum;
+    size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
+    size_t pre_points_per_block = 0;
+    size_t i, j;
+    int k;
+    int r_is_inverted = 0;
+    int r_is_at_infinity = 1;
+    size_t *wsize = NULL;       /* individual window sizes */
+    signed char **wNAF = NULL;  /* individual wNAFs */
+    size_t *wNAF_len = NULL;
+    size_t max_len = 0;
+    size_t num_val;
+    EC_POINT **val = NULL;      /* precomputation */
+    EC_POINT **v;
+    EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or
+                                 * 'pre_comp->points' */
+    const EC_PRE_COMP *pre_comp = NULL;
+    int num_scalar = 0;         /* flag: will be set to 1 if 'scalar' must be
+                                 * treated like other scalars, i.e.
+                                 * precomputation is not available */
+    int ret = 0;
+
+    if (group->meth != r->meth) {
+        ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
+        return 0;
+    }
+
+    if ((scalar == NULL) && (num == 0)) {
+        return EC_POINT_set_to_infinity(group, r);
+    }
+
+    for (i = 0; i < num; i++) {
+        if (group->meth != points[i]->meth) {
+            ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
+            return 0;
+        }
+    }
+
+    if (ctx == NULL) {
+        ctx = new_ctx = BN_CTX_new();
+        if (ctx == NULL)
+            goto err;
+    }
+
+    if (scalar != NULL) {
+        generator = EC_GROUP_get0_generator(group);
+        if (generator == NULL) {
+            ECerr(EC_F_EC_WNAF_MUL, EC_R_UNDEFINED_GENERATOR);
+            goto err;
+        }
+
+        /* look if we can use precomputed multiples of generator */
+
+        pre_comp = group->pre_comp.ec;
+        if (pre_comp && pre_comp->numblocks
+            && (EC_POINT_cmp(group, generator, pre_comp->points[0], ctx) ==
+                0)) {
+            blocksize = pre_comp->blocksize;
+
+            /*
+             * determine maximum number of blocks that wNAF splitting may
+             * yield (NB: maximum wNAF length is bit length plus one)
+             */
+            numblocks = (BN_num_bits(scalar) / blocksize) + 1;
+
+            /*
+             * we cannot use more blocks than we have precomputation for
+             */
+            if (numblocks > pre_comp->numblocks)
+                numblocks = pre_comp->numblocks;
+
+            pre_points_per_block = (size_t)1 << (pre_comp->w - 1);
+
+            /* check that pre_comp looks sane */
+            if (pre_comp->num != (pre_comp->numblocks * pre_points_per_block)) {
+                ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                goto err;
+            }
+        } else {
+            /* can't use precomputation */
+            pre_comp = NULL;
+            numblocks = 1;
+            num_scalar = 1;     /* treat 'scalar' like 'num'-th element of
+                                 * 'scalars' */
+        }
+    }
+
+    totalnum = num + numblocks;
+
+    wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]);
+    wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]);
+    wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); /* includes space
+                                                             * for pivot */
+    val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
+
+    /* Ensure wNAF is initialised in case we end up going to err */
+    if (wNAF != NULL)
+        wNAF[0] = NULL;         /* preliminary pivot */
+
+    if (wsize == NULL || wNAF_len == NULL || wNAF == NULL || val_sub == NULL) {
+        ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    /*
+     * num_val will be the total number of temporarily precomputed points
+     */
+    num_val = 0;
+
+    for (i = 0; i < num + num_scalar; i++) {
+        size_t bits;
+
+        bits = i < num ? BN_num_bits(scalars[i]) : BN_num_bits(scalar);
+        wsize[i] = EC_window_bits_for_scalar_size(bits);
+        num_val += (size_t)1 << (wsize[i] - 1);
+        wNAF[i + 1] = NULL;     /* make sure we always have a pivot */
+        wNAF[i] =
+            bn_compute_wNAF((i < num ? scalars[i] : scalar), wsize[i],
+                            &wNAF_len[i]);
+        if (wNAF[i] == NULL)
+            goto err;
+        if (wNAF_len[i] > max_len)
+            max_len = wNAF_len[i];
+    }
+
+    if (numblocks) {
+        /* we go here iff scalar != NULL */
+
+        if (pre_comp == NULL) {
+            if (num_scalar != 1) {
+                ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                goto err;
+            }
+            /* we have already generated a wNAF for 'scalar' */
+        } else {
+            signed char *tmp_wNAF = NULL;
+            size_t tmp_len = 0;
+
+            if (num_scalar != 0) {
+                ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                goto err;
+            }
+
+            /*
+             * use the window size for which we have precomputation
+             */
+            wsize[num] = pre_comp->w;
+            tmp_wNAF = bn_compute_wNAF(scalar, wsize[num], &tmp_len);
+            if (!tmp_wNAF)
+                goto err;
+
+            if (tmp_len <= max_len) {
+                /*
+                 * One of the other wNAFs is at least as long as the wNAF
+                 * belonging to the generator, so wNAF splitting will not buy
+                 * us anything.
+                 */
+
+                numblocks = 1;
+                totalnum = num + 1; /* don't use wNAF splitting */
+                wNAF[num] = tmp_wNAF;
+                wNAF[num + 1] = NULL;
+                wNAF_len[num] = tmp_len;
+                /*
+                 * pre_comp->points starts with the points that we need here:
+                 */
+                val_sub[num] = pre_comp->points;
+            } else {
+                /*
+                 * don't include tmp_wNAF directly into wNAF array - use wNAF
+                 * splitting and include the blocks
+                 */
+
+                signed char *pp;
+                EC_POINT **tmp_points;
+
+                if (tmp_len < numblocks * blocksize) {
+                    /*
+                     * possibly we can do with fewer blocks than estimated
+                     */
+                    numblocks = (tmp_len + blocksize - 1) / blocksize;
+                    if (numblocks > pre_comp->numblocks) {
+                        ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                        OPENSSL_free(tmp_wNAF);
+                        goto err;
+                    }
+                    totalnum = num + numblocks;
+                }
+
+                /* split wNAF in 'numblocks' parts */
+                pp = tmp_wNAF;
+                tmp_points = pre_comp->points;
+
+                for (i = num; i < totalnum; i++) {
+                    if (i < totalnum - 1) {
+                        wNAF_len[i] = blocksize;
+                        if (tmp_len < blocksize) {
+                            ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                            OPENSSL_free(tmp_wNAF);
+                            goto err;
+                        }
+                        tmp_len -= blocksize;
+                    } else
+                        /*
+                         * last block gets whatever is left (this could be
+                         * more or less than 'blocksize'!)
+                         */
+                        wNAF_len[i] = tmp_len;
+
+                    wNAF[i + 1] = NULL;
+                    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;
+                    }
+                    memcpy(wNAF[i], pp, wNAF_len[i]);
+                    if (wNAF_len[i] > max_len)
+                        max_len = wNAF_len[i];
+
+                    if (*tmp_points == NULL) {
+                        ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+                        OPENSSL_free(tmp_wNAF);
+                        goto err;
+                    }
+                    val_sub[i] = tmp_points;
+                    tmp_points += pre_points_per_block;
+                    pp += blocksize;
+                }
+                OPENSSL_free(tmp_wNAF);
+            }
+        }
+    }
+
+    /*
+     * All points we precompute now go into a single array 'val'.
+     * '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) {
+        ECerr(EC_F_EC_WNAF_MUL, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+    val[num_val] = NULL;        /* pivot element */
+
+    /* allocate points for precomputation */
+    v = val;
+    for (i = 0; i < num + num_scalar; i++) {
+        val_sub[i] = v;
+        for (j = 0; j < ((size_t)1 << (wsize[i] - 1)); j++) {
+            *v = EC_POINT_new(group);
+            if (*v == NULL)
+                goto err;
+            v++;
+        }
+    }
+    if (!(v == val + num_val)) {
+        ECerr(EC_F_EC_WNAF_MUL, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+
+    if ((tmp = EC_POINT_new(group)) == NULL)
+        goto err;
+
+    /*-
+     * prepare precomputed values:
+     *    val_sub[i][0] :=     points[i]
+     *    val_sub[i][1] := 3 * points[i]
+     *    val_sub[i][2] := 5 * points[i]
+     *    ...
+     */
+    for (i = 0; i < num + num_scalar; i++) {
+        if (i < num) {
+            if (!EC_POINT_copy(val_sub[i][0], points[i]))
+                goto err;
+        } else {
+            if (!EC_POINT_copy(val_sub[i][0], generator))
+                goto err;
+        }
+
+        if (wsize[i] > 1) {
+            if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx))
+                goto err;
+            for (j = 1; j < ((size_t)1 << (wsize[i] - 1)); j++) {
+                if (!EC_POINT_add
+                    (group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx))
+                    goto err;
+            }
+        }
+    }
+
+    if (!EC_POINTs_make_affine(group, num_val, val, ctx))
+        goto err;
+
+    r_is_at_infinity = 1;
+
+    for (k = max_len - 1; k >= 0; k--) {
+        if (!r_is_at_infinity) {
+            if (!EC_POINT_dbl(group, r, r, ctx))
+                goto err;
+        }
+
+        for (i = 0; i < totalnum; i++) {
+            if (wNAF_len[i] > (size_t)k) {
+                int digit = wNAF[i][k];
+                int is_neg;
+
+                if (digit) {
+                    is_neg = digit < 0;
+
+                    if (is_neg)
+                        digit = -digit;
+
+                    if (is_neg != r_is_inverted) {
+                        if (!r_is_at_infinity) {
+                            if (!EC_POINT_invert(group, r, ctx))
+                                goto err;
+                        }
+                        r_is_inverted = !r_is_inverted;
+                    }
+
+                    /* digit > 0 */
+
+                    if (r_is_at_infinity) {
+                        if (!EC_POINT_copy(r, val_sub[i][digit >> 1]))
+                            goto err;
+                        r_is_at_infinity = 0;
+                    } else {
+                        if (!EC_POINT_add
+                            (group, r, r, val_sub[i][digit >> 1], ctx))
+                            goto err;
+                    }
+                }
+            }
+        }
+    }
+
+    if (r_is_at_infinity) {
+        if (!EC_POINT_set_to_infinity(group, r))
+            goto err;
+    } else {
+        if (r_is_inverted)
+            if (!EC_POINT_invert(group, r, ctx))
+                goto err;
+    }
+
+    ret = 1;
 
  err:
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       if (tmp != NULL)
-               EC_POINT_free(tmp);
-       if (wsize != NULL)
-               OPENSSL_free(wsize);
-       if (wNAF_len != NULL)
-               OPENSSL_free(wNAF_len);
-       if (wNAF != NULL)
-               {
-               signed char **w;
-               
-               for (w = wNAF; *w != NULL; w++)
-                       OPENSSL_free(*w);
-               
-               OPENSSL_free(wNAF);
-               }
-       if (val != NULL)
-               {
-               for (v = val; *v != NULL; v++)
-                       EC_POINT_clear_free(*v);
-
-               OPENSSL_free(val);
-               }
-       if (val_sub != NULL)
-               {
-               OPENSSL_free(val_sub);
-               }
-       return ret;
-       }
-
-
-/* ec_wNAF_precompute_mult()
+    BN_CTX_free(new_ctx);
+    EC_POINT_free(tmp);
+    OPENSSL_free(wsize);
+    OPENSSL_free(wNAF_len);
+    if (wNAF != NULL) {
+        signed char **w;
+
+        for (w = wNAF; *w != NULL; w++)
+            OPENSSL_free(*w);
+
+        OPENSSL_free(wNAF);
+    }
+    if (val != NULL) {
+        for (v = val; *v != NULL; v++)
+            EC_POINT_clear_free(*v);
+
+        OPENSSL_free(val);
+    }
+    OPENSSL_free(val_sub);
+    return ret;
+}
+
+/*-
+ * ec_wNAF_precompute_mult()
  * creates an EC_PRE_COMP object with preprecomputed multiples of the generator
  * for use with wNAF splitting as implemented in ec_wNAF_mul().
- * 
+ *
  * 'pre_comp->points' is an array of multiples of the generator
  * of the following form:
  * points[0] =     generator;
@@ -733,177 +522,159 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
  * points[2^(w-1)*numblocks]       = NULL
  */
 int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
-       {
-       const EC_POINT *generator;
-       EC_POINT *tmp_point = NULL, *base = NULL, **var;
-       BN_CTX *new_ctx = NULL;
-       BIGNUM *order;
-       size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num;
-       EC_POINT **points = NULL;
-       EC_PRE_COMP *pre_comp;
-       int ret = 0;
-
-       /* if there is an old EC_PRE_COMP object, throw it away */
-       EC_GROUP_free_extra_data(group, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free);
-
-       if ((pre_comp = ec_pre_comp_new(group)) == NULL)
-               return 0;
-
-       generator = EC_GROUP_get0_generator(group);
-       if (generator == NULL)
-               {
-               ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
-               goto err;
-               }
-
-       if (ctx == NULL)
-               {
-               ctx = new_ctx = BN_CTX_new();
-               if (ctx == NULL)
-                       goto err;
-               }
-       
-       BN_CTX_start(ctx);
-       order = BN_CTX_get(ctx);
-       if (order == NULL) goto err;
-       
-       if (!EC_GROUP_get_order(group, order, ctx)) goto err;           
-       if (BN_is_zero(order))
-               {
-               ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
-               goto err;
-               }
-
-       bits = BN_num_bits(order);
-       /* The following parameters mean we precompute (approximately)
-        * one point per bit.
-        *
-        * TBD: The combination  8, 4  is perfect for 160 bits; for other
-        * bit lengths, other parameter combinations might provide better
-        * efficiency.
-        */
-       blocksize = 8;
-       w = 4;
-       if (EC_window_bits_for_scalar_size(bits) > w)
-               {
-               /* let's not make the window too small ... */
-               w = EC_window_bits_for_scalar_size(bits);
-               }
-
-       numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks to use for wNAF splitting */
-       
-       pre_points_per_block = 1u << (w - 1);
-       num = pre_points_per_block * numblocks; /* number of points to compute and store */
-
-       points = OPENSSL_malloc(sizeof (EC_POINT*)*(num + 1));
-       if (!points)
-               {
-               ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
-               goto err;
-               }
-
-       var = points;
-       var[num] = NULL; /* pivot */
-       for (i = 0; i < num; i++)
-               {
-               if ((var[i] = EC_POINT_new(group)) == NULL)
-                       {
-                       ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
-                       goto err;
-                       }
-               }
-
-       if (!(tmp_point = EC_POINT_new(group)) || !(base = EC_POINT_new(group)))
-               {
-               ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
-               goto err;
-               }       
-       
-       if (!EC_POINT_copy(base, generator))
-               goto err;
-       
-       /* do the precomputation */
-       for (i = 0; i < numblocks; i++)
-               {
-               size_t j;
-
-               if (!EC_POINT_dbl(group, tmp_point, base, ctx))
-                       goto err;
-
-               if (!EC_POINT_copy(*var++, base))
-                       goto err;
-
-               for (j = 1; j < pre_points_per_block; j++, var++)
-                       {
-                       /* calculate odd multiples of the current base point */
-                       if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx))
-                               goto err;
-                       }
-
-               if (i < numblocks - 1)
-                       {
-                       /* get the next base (multiply current one by 2^blocksize) */
-                       size_t k;
-
-                       if (blocksize <= 2)
-                               {
-                               ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR);
-                               goto err;
-                               }                               
-
-                       if (!EC_POINT_dbl(group, base, tmp_point, ctx))
-                               goto err;
-                       for (k = 2; k < blocksize; k++)
-                               {
-                               if (!EC_POINT_dbl(group,base,base,ctx))
-                                       goto err;
-                               }
-                       }
-               }
-
-       if (!EC_POINTs_make_affine(group, num, points, ctx))
-               goto err;
-       
-       pre_comp->group = group;
-       pre_comp->blocksize = blocksize;
-       pre_comp->numblocks = numblocks;
-       pre_comp->w = w;
-       pre_comp->points = points;
-       points = NULL;
-       pre_comp->num = num;
-
-       if (!EC_GROUP_set_extra_data(group, pre_comp,
-               ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free))
-               goto err;
-       pre_comp = NULL;
-
-       ret = 1;
- err:
-       BN_CTX_end(ctx);
-       if (new_ctx != NULL)
-               BN_CTX_free(new_ctx);
-       if (pre_comp)
-               ec_pre_comp_free(pre_comp);
-       if (points)
-               {
-               EC_POINT **p;
-
-               for (p = points; *p != NULL; p++)
-                       EC_POINT_free(*p);
-               OPENSSL_free(points);
-               }
-       if (tmp_point)
-               EC_POINT_free(tmp_point);
-       if (base)
-               EC_POINT_free(base);
-       return ret;
-       }
+{
+    const EC_POINT *generator;
+    EC_POINT *tmp_point = NULL, *base = NULL, **var;
+    BN_CTX *new_ctx = NULL;
+    const BIGNUM *order;
+    size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num;
+    EC_POINT **points = NULL;
+    EC_PRE_COMP *pre_comp;
+    int ret = 0;
+
+    /* if there is an old EC_PRE_COMP object, throw it away */
+    EC_pre_comp_free(group);
+    if ((pre_comp = ec_pre_comp_new(group)) == NULL)
+        return 0;
+
+    generator = EC_GROUP_get0_generator(group);
+    if (generator == NULL) {
+        ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
+        goto err;
+    }
+
+    if (ctx == NULL) {
+        ctx = new_ctx = BN_CTX_new();
+        if (ctx == NULL)
+            goto err;
+    }
+
+    BN_CTX_start(ctx);
+
+    order = EC_GROUP_get0_order(group);
+    if (order == NULL)
+        goto err;
+    if (BN_is_zero(order)) {
+        ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
+        goto err;
+    }
+
+    bits = BN_num_bits(order);
+    /*
+     * The following parameters mean we precompute (approximately) one point
+     * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other
+     * bit lengths, other parameter combinations might provide better
+     * efficiency.
+     */
+    blocksize = 8;
+    w = 4;
+    if (EC_window_bits_for_scalar_size(bits) > w) {
+        /* let's not make the window too small ... */
+        w = EC_window_bits_for_scalar_size(bits);
+    }
+
+    numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks
+                                                     * to use for wNAF
+                                                     * splitting */
+
+    pre_points_per_block = (size_t)1 << (w - 1);
+    num = pre_points_per_block * numblocks; /* number of points to compute
+                                             * and store */
+
+    points = OPENSSL_malloc(sizeof(*points) * (num + 1));
+    if (points == NULL) {
+        ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    var = points;
+    var[num] = NULL;            /* pivot */
+    for (i = 0; i < num; i++) {
+        if ((var[i] = EC_POINT_new(group)) == NULL) {
+            ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
+            goto err;
+        }
+    }
+
+    if ((tmp_point = EC_POINT_new(group)) == NULL
+        || (base = EC_POINT_new(group)) == NULL) {
+        ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    if (!EC_POINT_copy(base, generator))
+        goto err;
+
+    /* do the precomputation */
+    for (i = 0; i < numblocks; i++) {
+        size_t j;
+
+        if (!EC_POINT_dbl(group, tmp_point, base, ctx))
+            goto err;
+
+        if (!EC_POINT_copy(*var++, base))
+            goto err;
+
+        for (j = 1; j < pre_points_per_block; j++, var++) {
+            /*
+             * calculate odd multiples of the current base point
+             */
+            if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx))
+                goto err;
+        }
+
+        if (i < numblocks - 1) {
+            /*
+             * get the next base (multiply current one by 2^blocksize)
+             */
+            size_t k;
+
+            if (blocksize <= 2) {
+                ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR);
+                goto err;
+            }
+
+            if (!EC_POINT_dbl(group, base, tmp_point, ctx))
+                goto err;
+            for (k = 2; k < blocksize; k++) {
+                if (!EC_POINT_dbl(group, base, base, ctx))
+                    goto err;
+            }
+        }
+    }
+
+    if (!EC_POINTs_make_affine(group, num, points, ctx))
+        goto err;
+
+    pre_comp->group = group;
+    pre_comp->blocksize = blocksize;
+    pre_comp->numblocks = numblocks;
+    pre_comp->w = w;
+    pre_comp->points = points;
+    points = NULL;
+    pre_comp->num = num;
+    SETPRECOMP(group, ec, pre_comp);
+    pre_comp = NULL;
+    ret = 1;
 
+ err:
+    if (ctx != NULL)
+        BN_CTX_end(ctx);
+    BN_CTX_free(new_ctx);
+    EC_ec_pre_comp_free(pre_comp);
+    if (points) {
+        EC_POINT **p;
+
+        for (p = points; *p != NULL; p++)
+            EC_POINT_free(*p);
+        OPENSSL_free(points);
+    }
+    EC_POINT_free(tmp_point);
+    EC_POINT_free(base);
+    return ret;
+}
 
 int ec_wNAF_have_precompute_mult(const EC_GROUP *group)
-       {
-       if (EC_GROUP_get_extra_data(group, ec_pre_comp_dup, ec_pre_comp_free, ec_pre_comp_clear_free) != NULL)
-               return 1;
-       else
-               return 0;
-       }
+{
+    return HAVEPRECOMP(group, ec);
+}