b4faea50c3
For a local variable: TYPE *p; Allocations like this are "risky": p = OPENSSL_malloc(sizeof(TYPE)); if the type of p changes, and the malloc call isn't updated, you could get memory corruption. Instead do this: p = OPENSSL_malloc(sizeof(*p)); Also fixed a few memset() calls that I noticed while doing this. Reviewed-by: Richard Levitte <levitte@openssl.org>
766 lines
24 KiB
C
766 lines
24 KiB
C
/* crypto/ec/ec_mult.c */
|
|
/*
|
|
* Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
|
|
*/
|
|
/* ====================================================================
|
|
* 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
|
|
* 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.
|
|
*
|
|
* 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).
|
|
*
|
|
*/
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|
/* ====================================================================
|
|
* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
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|
* Portions of this software developed by SUN MICROSYSTEMS, INC.,
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|
* and contributed to the OpenSSL project.
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|
*/
|
|
|
|
#include <string.h>
|
|
#include <openssl/err.h>
|
|
|
|
#include "internal/bn_int.h"
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|
#include "ec_lcl.h"
|
|
|
|
/*
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|
* This file implements the wNAF-based interleaving multi-exponentation method
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|
* (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>);
|
|
* for multiplication with precomputation, we use wNAF splitting
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|
* (<URL: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 */
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|
size_t blocksize; /* block size for wNAF splitting */
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|
size_t numblocks; /* max. number of blocks for which we have
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|
* precomputation */
|
|
size_t w; /* window size */
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|
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 *);
|
|
|
|
static EC_PRE_COMP *ec_pre_comp_new(const EC_GROUP *group)
|
|
{
|
|
EC_PRE_COMP *ret = NULL;
|
|
|
|
if (!group)
|
|
return NULL;
|
|
|
|
ret = OPENSSL_malloc(sizeof(*ret));
|
|
if (!ret) {
|
|
ECerr(EC_F_EC_PRE_COMP_NEW, ERR_R_MALLOC_FAILURE);
|
|
return ret;
|
|
}
|
|
ret->group = group;
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|
ret->blocksize = 8; /* default */
|
|
ret->numblocks = 0;
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|
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;
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|
EC_PRE_COMP *pre = pre_;
|
|
|
|
if (!pre)
|
|
return;
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|
|
|
i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
|
|
if (i > 0)
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|
return;
|
|
|
|
if (pre->points) {
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|
EC_POINT **p;
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|
|
|
for (p = pre->points; *p != NULL; p++)
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|
EC_POINT_free(*p);
|
|
OPENSSL_free(pre->points);
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|
}
|
|
OPENSSL_free(pre);
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|
}
|
|
|
|
static void ec_pre_comp_clear_free(void *pre_)
|
|
{
|
|
int i;
|
|
EC_PRE_COMP *pre = pre_;
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|
|
|
if (!pre)
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|
return;
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|
|
|
i = CRYPTO_add(&pre->references, -1, CRYPTO_LOCK_EC_PRE_COMP);
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|
if (i > 0)
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|
return;
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|
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|
if (pre->points) {
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|
EC_POINT **p;
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|
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|
for (p = pre->points; *p != NULL; p++) {
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|
EC_POINT_clear_free(*p);
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|
OPENSSL_cleanse(p, sizeof(*p));
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|
}
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|
OPENSSL_free(pre->points);
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|
}
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|
OPENSSL_clear_free(pre, sizeof(*pre));
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|
}
|
|
|
|
/*
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|
* TODO: table should be optimised for the wNAF-based implementation,
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|
* sometimes smaller windows will give better performance (thus the
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|
* boundaries should be increased)
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|
*/
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|
#define EC_window_bits_for_scalar_size(b) \
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|
((size_t) \
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((b) >= 2000 ? 6 : \
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|
(b) >= 800 ? 5 : \
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|
(b) >= 300 ? 4 : \
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|
(b) >= 70 ? 3 : \
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|
(b) >= 20 ? 2 : \
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|
1))
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|
|
|
/*-
|
|
* Compute
|
|
* \sum scalars[i]*points[i],
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|
* also including
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|
* scalar*generator
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|
* in the addition if scalar != NULL
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|
*/
|
|
int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar,
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|
size_t num, const EC_POINT *points[], const BIGNUM *scalars[],
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|
BN_CTX *ctx)
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|
{
|
|
BN_CTX *new_ctx = NULL;
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|
const EC_POINT *generator = NULL;
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|
EC_POINT *tmp = NULL;
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|
size_t totalnum;
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|
size_t blocksize = 0, numblocks = 0; /* for wNAF splitting */
|
|
size_t pre_points_per_block = 0;
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|
size_t i, j;
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|
int k;
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|
int r_is_inverted = 0;
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|
int r_is_at_infinity = 1;
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|
size_t *wsize = NULL; /* individual window sizes */
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|
signed char **wNAF = NULL; /* individual wNAFs */
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|
size_t *wNAF_len = NULL;
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|
size_t max_len = 0;
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|
size_t num_val;
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|
EC_POINT **val = NULL; /* precomputation */
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|
EC_POINT **v;
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|
EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' or
|
|
* 'pre_comp->points' */
|
|
const EC_PRE_COMP *pre_comp = NULL;
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|
int num_scalar = 0; /* flag: will be set to 1 if 'scalar' must be
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|
* treated like other scalars, i.e.
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|
* precomputation is not available */
|
|
int ret = 0;
|
|
|
|
if (group->meth != r->meth) {
|
|
ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS);
|
|
return 0;
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|
}
|
|
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|
if ((scalar == NULL) && (num == 0)) {
|
|
return EC_POINT_set_to_infinity(group, r);
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|
}
|
|
|
|
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_EX_DATA_get_data(group->extra_data, 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 = (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)
|
|
wNAF[0] = NULL; /* preliminary pivot */
|
|
|
|
if (!wsize || !wNAF_len || !wNAF || !val_sub) {
|
|
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;
|
|
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) {
|
|
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)))
|
|
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:
|
|
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;
|
|
* points[1] = 3 * generator;
|
|
* ...
|
|
* points[2^(w-1)-1] = (2^(w-1)-1) * generator;
|
|
* points[2^(w-1)] = 2^blocksize * generator;
|
|
* points[2^(w-1)+1] = 3 * 2^blocksize * generator;
|
|
* ...
|
|
* points[2^(w-1)*(numblocks-1)-1] = (2^(w-1)) * 2^(blocksize*(numblocks-2)) * generator
|
|
* points[2^(w-1)*(numblocks-1)] = 2^(blocksize*(numblocks-1)) * generator
|
|
* ...
|
|
* points[2^(w-1)*numblocks-1] = (2^(w-1)) * 2^(blocksize*(numblocks-1)) * generator
|
|
* 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_EX_DATA_free_data(&group->extra_data, 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 = (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) {
|
|
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_EX_DATA_set_data(&group->extra_data, pre_comp,
|
|
ec_pre_comp_dup, ec_pre_comp_free,
|
|
ec_pre_comp_clear_free))
|
|
goto err;
|
|
pre_comp = NULL;
|
|
|
|
ret = 1;
|
|
err:
|
|
if (ctx != NULL)
|
|
BN_CTX_end(ctx);
|
|
BN_CTX_free(new_ctx);
|
|
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_EX_DATA_get_data
|
|
(group->extra_data, ec_pre_comp_dup, ec_pre_comp_free,
|
|
ec_pre_comp_clear_free) != NULL)
|
|
return 1;
|
|
else
|
|
return 0;
|
|
}
|