-/* crypto/ec/ec_mult.c */
-/* ====================================================================
- * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
+/*
+ * Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright (c) 2002, Oracle and/or its affiliates. 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.
+ * Licensed under the Apache License 2.0 (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
+ */
+
+/*
+ * ECDSA low level APIs are deprecated for public use, but still ok for
+ * internal use.
+ */
+#include "internal/deprecated.h"
+
+#include <string.h>
+#include <openssl/err.h>
+
+#include "internal/cryptlib.h"
+#include "crypto/bn.h"
+#include "ec_local.h"
+#include "internal/refcount.h"
+
+/*
+ * 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 */
+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 = 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);
+}
+
+#define EC_POINT_BN_set_flags(P, flags) do { \
+ BN_set_flags((P)->X, (flags)); \
+ BN_set_flags((P)->Y, (flags)); \
+ BN_set_flags((P)->Z, (flags)); \
+} while(0)
+
+/*-
+ * This functions computes a single point multiplication over the EC group,
+ * using, at a high level, a Montgomery ladder with conditional swaps, with
+ * various timing attack defenses.
*
- * 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/)"
+ * It performs either a fixed point multiplication
+ * (scalar * generator)
+ * when point is NULL, or a variable point multiplication
+ * (scalar * point)
+ * when point is not NULL.
*
- * 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.
+ * `scalar` cannot be NULL and should be in the range [0,n) otherwise all
+ * constant time bets are off (where n is the cardinality of the EC group).
*
- * 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.
+ * This function expects `group->order` and `group->cardinality` to be well
+ * defined and non-zero: it fails with an error code otherwise.
*
- * 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/)"
+ * NB: This says nothing about the constant-timeness of the ladder step
+ * implementation (i.e., the default implementation is based on EC_POINT_add and
+ * EC_POINT_dbl, which of course are not constant time themselves) or the
+ * underlying multiprecision arithmetic.
*
- * 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.
- * ====================================================================
+ * The product is stored in `r`.
*
- * This product includes cryptographic software written by Eric Young
- * (eay@cryptsoft.com). This product includes software written by Tim
- * Hudson (tjh@cryptsoft.com).
+ * This is an internal function: callers are in charge of ensuring that the
+ * input parameters `group`, `r`, `scalar` and `ctx` are not NULL.
*
+ * Returns 1 on success, 0 otherwise.
*/
+int ec_scalar_mul_ladder(const EC_GROUP *group, EC_POINT *r,
+ const BIGNUM *scalar, const EC_POINT *point,
+ BN_CTX *ctx)
+{
+ int i, cardinality_bits, group_top, kbit, pbit, Z_is_one;
+ EC_POINT *p = NULL;
+ EC_POINT *s = NULL;
+ BIGNUM *k = NULL;
+ BIGNUM *lambda = NULL;
+ BIGNUM *cardinality = NULL;
+ int ret = 0;
+
+ /* early exit if the input point is the point at infinity */
+ if (point != NULL && EC_POINT_is_at_infinity(group, point))
+ return EC_POINT_set_to_infinity(group, r);
+
+ if (BN_is_zero(group->order)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, EC_R_UNKNOWN_ORDER);
+ return 0;
+ }
+ if (BN_is_zero(group->cofactor)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, EC_R_UNKNOWN_COFACTOR);
+ return 0;
+ }
+
+ BN_CTX_start(ctx);
+
+ if (((p = EC_POINT_new(group)) == NULL)
+ || ((s = EC_POINT_new(group)) == NULL)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_MALLOC_FAILURE);
+ goto err;
+ }
+
+ if (point == NULL) {
+ if (!EC_POINT_copy(p, group->generator)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_EC_LIB);
+ goto err;
+ }
+ } else {
+ if (!EC_POINT_copy(p, point)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_EC_LIB);
+ goto err;
+ }
+ }
+
+ EC_POINT_BN_set_flags(p, BN_FLG_CONSTTIME);
+ EC_POINT_BN_set_flags(r, BN_FLG_CONSTTIME);
+ EC_POINT_BN_set_flags(s, BN_FLG_CONSTTIME);
+
+ cardinality = BN_CTX_get(ctx);
+ lambda = BN_CTX_get(ctx);
+ k = BN_CTX_get(ctx);
+ if (k == NULL) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_MALLOC_FAILURE);
+ goto err;
+ }
+
+ if (!BN_mul(cardinality, group->order, group->cofactor, ctx)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+
+ /*
+ * Group cardinalities are often on a word boundary.
+ * So when we pad the scalar, some timing diff might
+ * pop if it needs to be expanded due to carries.
+ * So expand ahead of time.
+ */
+ cardinality_bits = BN_num_bits(cardinality);
+ group_top = bn_get_top(cardinality);
+ if ((bn_wexpand(k, group_top + 2) == NULL)
+ || (bn_wexpand(lambda, group_top + 2) == NULL)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+
+ if (!BN_copy(k, scalar)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+
+ BN_set_flags(k, BN_FLG_CONSTTIME);
+
+ if ((BN_num_bits(k) > cardinality_bits) || (BN_is_negative(k))) {
+ /*-
+ * this is an unusual input, and we don't guarantee
+ * constant-timeness
+ */
+ if (!BN_nnmod(k, k, cardinality, ctx)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+ }
+
+ if (!BN_add(lambda, k, cardinality)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+ BN_set_flags(lambda, BN_FLG_CONSTTIME);
+ if (!BN_add(k, lambda, cardinality)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+ /*
+ * lambda := scalar + cardinality
+ * k := scalar + 2*cardinality
+ */
+ kbit = BN_is_bit_set(lambda, cardinality_bits);
+ BN_consttime_swap(kbit, k, lambda, group_top + 2);
+
+ group_top = bn_get_top(group->field);
+ if ((bn_wexpand(s->X, group_top) == NULL)
+ || (bn_wexpand(s->Y, group_top) == NULL)
+ || (bn_wexpand(s->Z, group_top) == NULL)
+ || (bn_wexpand(r->X, group_top) == NULL)
+ || (bn_wexpand(r->Y, group_top) == NULL)
+ || (bn_wexpand(r->Z, group_top) == NULL)
+ || (bn_wexpand(p->X, group_top) == NULL)
+ || (bn_wexpand(p->Y, group_top) == NULL)
+ || (bn_wexpand(p->Z, group_top) == NULL)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
+ goto err;
+ }
+
+ /* ensure input point is in affine coords for ladder step efficiency */
+ if (!p->Z_is_one && (group->meth->make_affine == NULL
+ || !group->meth->make_affine(group, p, ctx))) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_EC_LIB);
+ goto err;
+ }
+
+ /* Initialize the Montgomery ladder */
+ if (!ec_point_ladder_pre(group, r, s, p, ctx)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, EC_R_LADDER_PRE_FAILURE);
+ goto err;
+ }
+
+ /* top bit is a 1, in a fixed pos */
+ pbit = 1;
+
+#define EC_POINT_CSWAP(c, a, b, w, t) do { \
+ BN_consttime_swap(c, (a)->X, (b)->X, w); \
+ BN_consttime_swap(c, (a)->Y, (b)->Y, w); \
+ BN_consttime_swap(c, (a)->Z, (b)->Z, w); \
+ t = ((a)->Z_is_one ^ (b)->Z_is_one) & (c); \
+ (a)->Z_is_one ^= (t); \
+ (b)->Z_is_one ^= (t); \
+} while(0)
+
+ /*-
+ * The ladder step, with branches, is
+ *
+ * k[i] == 0: S = add(R, S), R = dbl(R)
+ * k[i] == 1: R = add(S, R), S = dbl(S)
+ *
+ * Swapping R, S conditionally on k[i] leaves you with state
+ *
+ * k[i] == 0: T, U = R, S
+ * k[i] == 1: T, U = S, R
+ *
+ * Then perform the ECC ops.
+ *
+ * U = add(T, U)
+ * T = dbl(T)
+ *
+ * Which leaves you with state
+ *
+ * k[i] == 0: U = add(R, S), T = dbl(R)
+ * k[i] == 1: U = add(S, R), T = dbl(S)
+ *
+ * Swapping T, U conditionally on k[i] leaves you with state
+ *
+ * k[i] == 0: R, S = T, U
+ * k[i] == 1: R, S = U, T
+ *
+ * Which leaves you with state
+ *
+ * k[i] == 0: S = add(R, S), R = dbl(R)
+ * k[i] == 1: R = add(S, R), S = dbl(S)
+ *
+ * So we get the same logic, but instead of a branch it's a
+ * conditional swap, followed by ECC ops, then another conditional swap.
+ *
+ * Optimization: The end of iteration i and start of i-1 looks like
+ *
+ * ...
+ * CSWAP(k[i], R, S)
+ * ECC
+ * CSWAP(k[i], R, S)
+ * (next iteration)
+ * CSWAP(k[i-1], R, S)
+ * ECC
+ * CSWAP(k[i-1], R, S)
+ * ...
+ *
+ * So instead of two contiguous swaps, you can merge the condition
+ * bits and do a single swap.
+ *
+ * k[i] k[i-1] Outcome
+ * 0 0 No Swap
+ * 0 1 Swap
+ * 1 0 Swap
+ * 1 1 No Swap
+ *
+ * This is XOR. pbit tracks the previous bit of k.
+ */
+
+ for (i = cardinality_bits - 1; i >= 0; i--) {
+ kbit = BN_is_bit_set(k, i) ^ pbit;
+ EC_POINT_CSWAP(kbit, r, s, group_top, Z_is_one);
+
+ /* Perform a single step of the Montgomery ladder */
+ if (!ec_point_ladder_step(group, r, s, p, ctx)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, EC_R_LADDER_STEP_FAILURE);
+ goto err;
+ }
+ /*
+ * pbit logic merges this cswap with that of the
+ * next iteration
+ */
+ pbit ^= kbit;
+ }
+ /* one final cswap to move the right value into r */
+ EC_POINT_CSWAP(pbit, r, s, group_top, Z_is_one);
+#undef EC_POINT_CSWAP
+
+ /* Finalize ladder (and recover full point coordinates) */
+ if (!ec_point_ladder_post(group, r, s, p, ctx)) {
+ ECerr(EC_F_EC_SCALAR_MUL_LADDER, EC_R_LADDER_POST_FAILURE);
+ goto err;
+ }
+
+ ret = 1;
-#include <openssl/err.h>
-
-#include "ec_lcl.h"
-
-
-/* TODO: width-m NAFs */
+ err:
+ EC_POINT_free(p);
+ EC_POINT_clear_free(s);
+ BN_CTX_end(ctx);
-/* TODO: optional Lim-Lee precomputation for the generator */
+ return ret;
+}
+#undef EC_POINT_BN_set_flags
-/* this is just BN_window_bits_for_exponent_size from bn_lcl.h for now;
- * the table should be updated for EC */ /* TODO */
+/*
+ * 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) \
- ((b) > 671 ? 6 : \
- (b) > 239 ? 5 : \
- (b) > 79 ? 4 : \
- (b) > 23 ? 3 : 1)
-
-/* Compute
- * \sum scalars[i]*points[i]
- * where
+ ((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
- * is included in the addition if scalar != NULL
+ * 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)
+{
+ 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 (!BN_is_zero(group->order) && !BN_is_zero(group->cofactor)) {
+ /*-
+ * Handle the common cases where the scalar is secret, enforcing a
+ * scalar multiplication implementation based on a Montgomery ladder,
+ * with various timing attack defenses.
+ */
+ if ((scalar != group->order) && (scalar != NULL) && (num == 0)) {
+ /*-
+ * In this case we want to compute 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 ladder version.
+ */
+ return ec_scalar_mul_ladder(group, r, scalar, NULL, ctx);
+ }
+ if ((scalar == NULL) && (num == 1) && (scalars[0] != group->order)) {
+ /*-
+ * In this case we want to compute scalar * VariablePoint: 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 ladder version.
+ */
+ return ec_scalar_mul_ladder(group, r, scalars[0], points[0], ctx);
+ }
+ }
+
+ 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]));
+ /* include space for pivot */
+ wNAF = OPENSSL_malloc((totalnum + 1) * sizeof(wNAF[0]));
+ 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 (group->meth->points_make_affine == NULL
+ || !group->meth->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;
+
+ /*-
+ * Apply coordinate blinding for EC_POINT.
+ *
+ * The underlying EC_METHOD can optionally implement this function:
+ * ec_point_blind_coordinates() returns 0 in case of errors or 1 on
+ * success or if coordinate blinding is not implemented for this
+ * group.
+ */
+ if (!ec_point_blind_coordinates(group, r, ctx)) {
+ ECerr(EC_F_EC_WNAF_MUL, EC_R_POINT_COORDINATES_BLIND_FAILURE);
+ 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:
+ 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_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)
- {
- BN_CTX *new_ctx = NULL;
- EC_POINT *generator = NULL;
- EC_POINT *tmp = NULL;
- size_t totalnum;
- size_t i, j;
- int k, t;
- int r_is_at_infinity = 1;
- size_t max_bits = 0;
- size_t *wsize = NULL; /* individual window sizes */
- unsigned long *wbits = NULL; /* individual window contents */
- int *wpos = NULL; /* position of bottom bit of current individual windows
- * (wpos[i] is valid if wbits[i] != 0) */
- size_t num_val;
- EC_POINT **val = NULL; /* precomputation */
- EC_POINT **v;
- EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' */
- int ret = 0;
-
- if (scalar != NULL)
- {
- generator = EC_GROUP_get0_generator(group);
- if (generator == NULL)
- {
- ECerr(EC_F_EC_POINTS_MUL, EC_R_UNDEFINED_GENERATOR);
- return 0;
- }
- }
-
- for (i = 0; i < num; i++)
- {
- if (group->meth != points[i]->meth)
- {
- ECerr(EC_F_EC_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS);
- return 0;
- }
- }
-
- totalnum = num + (scalar != NULL);
-
- wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]);
- wbits = OPENSSL_malloc(totalnum * sizeof wbits[0]);
- wpos = OPENSSL_malloc(totalnum * sizeof wpos[0]);
- if (wsize == NULL || wbits == NULL || wpos == NULL) goto err;
-
- /* num_val := total number of points to precompute */
- num_val = 0;
- for (i = 0; i < totalnum; 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 += 1 << (wsize[i] - 1);
- if (bits > max_bits)
- max_bits = bits;
- wbits[i] = 0;
- wpos[i] = 0;
- }
-
- /* all precomputed points go into a single array 'val',
- * 'val_sub[i]' is a pointer to the subarray for the i-th point */
- val = OPENSSL_malloc((num_val + 1) * sizeof val[0]);
- if (val == NULL) goto err;
- val[num_val] = NULL; /* pivot element */
-
- val_sub = OPENSSL_malloc(totalnum * sizeof val_sub[0]);
- if (val_sub == NULL) goto err;
-
- /* allocate points for precomputation */
- v = val;
- for (i = 0; i < totalnum; i++)
- {
- val_sub[i] = v;
- for (j = 0; j < (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_POINTS_MUL, ERR_R_INTERNAL_ERROR);
- goto err;
- }
-
- if (ctx == NULL)
- {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL)
- goto err;
- }
-
- tmp = EC_POINT_new(group);
- if (tmp == 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 < totalnum; i++)
- {
- if (i < num)
- {
- if (!EC_POINT_copy(val_sub[i][0], points[i])) goto err;
- if (scalars[i]->neg)
- {
- if (!EC_POINT_invert(group, val_sub[i][0], ctx)) goto err;
- }
- }
- else
- {
- if (!EC_POINT_copy(val_sub[i][0], generator)) goto err;
- if (scalar->neg)
- {
- if (!EC_POINT_invert(group, val_sub[i][0], ctx)) goto err;
- }
- }
-
- if (wsize[i] > 1)
- {
- if (!EC_POINT_dbl(group, tmp, val_sub[i][0], ctx)) goto err;
- for (j = 1; j < (1 << (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, maybe we should only do this if total_num > 1 */
- if (!EC_POINTs_make_affine(group, num_val, val, ctx)) goto err;
+int ec_wNAF_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
+{
+ const EC_POINT *generator;
+ EC_POINT *tmp_point = NULL, *base = NULL, **var;
+ 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;
+#ifndef FIPS_MODULE
+ BN_CTX *new_ctx = NULL;
#endif
- r_is_at_infinity = 1;
-
- for (k = max_bits - 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 (wbits[i] == 0)
- {
- const BIGNUM *s;
-
- s = i < num ? scalars[i] : scalar;
-
- if (BN_is_bit_set(s, k))
- {
- /* look at bits k - wsize[i] + 1 .. k for this window */
- t = k - wsize[i] + 1;
- while (!BN_is_bit_set(s, t)) /* BN_is_bit_set is false for t < 0 */
- t++;
- wpos[i] = t;
- wbits[i] = 1;
- for (t = k - 1; t >= wpos[i]; t--)
- {
- wbits[i] <<= 1;
- if (BN_is_bit_set(s, t))
- wbits[i]++;
- }
- /* now wbits[i] is the odd bit pattern at bits wpos[i] .. k */
- }
- }
-
- if ((wbits[i] != 0) && (wpos[i] == k))
- {
- if (r_is_at_infinity)
- {
- if (!EC_POINT_copy(r, val_sub[i][wbits[i] >> 1])) goto err;
- r_is_at_infinity = 0;
- }
- else
- {
- if (!EC_POINT_add(group, r, r, val_sub[i][wbits[i] >> 1], ctx)) goto err;
- }
- wbits[i] = 0;
- }
- }
- }
-
- if (r_is_at_infinity)
- if (!EC_POINT_set_to_infinity(group, r)) goto err;
-
- ret = 1;
+ /* 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;
+ }
+
+#ifndef FIPS_MODULE
+ if (ctx == NULL)
+ ctx = new_ctx = BN_CTX_new();
+#endif
+ 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 (group->meth->points_make_affine == NULL
+ || !group->meth->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 (new_ctx != NULL)
- BN_CTX_free(new_ctx);
- if (tmp != NULL)
- EC_POINT_free(tmp);
- if (wsize != NULL)
- OPENSSL_free(wsize);
- if (wbits != NULL)
- OPENSSL_free(wbits);
- if (wpos != NULL)
- OPENSSL_free(wpos);
- 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;
- }
-
-
-int EC_POINT_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *g_scalar, const EC_POINT *point, const BIGNUM *p_scalar, BN_CTX *ctx)
- {
- const EC_POINT *points[1];
- const BIGNUM *scalars[1];
-
- points[0] = point;
- scalars[0] = p_scalar;
-
- return EC_POINTs_mul(group, r, g_scalar, (point != NULL && p_scalar != NULL), points, scalars, ctx);
- }
-
-
-int EC_GROUP_precompute_mult(EC_GROUP *group, BN_CTX *ctx)
- {
- const EC_POINT *generator;
- BN_CTX *new_ctx = NULL;
- BIGNUM *order;
- int ret = 0;
-
- generator = EC_GROUP_get0_generator(group);
- if (generator == NULL)
- {
- ECerr(EC_F_EC_GROUP_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR);
- return 0;
- }
-
- if (ctx == NULL)
- {
- ctx = new_ctx = BN_CTX_new();
- if (ctx == NULL)
- return 0;
- }
-
- BN_CTX_start(ctx);
- order = BN_CTX_get(ctx);
- if (order == NULL) goto err;
-
- if (!EC_GROUP_get_order(group, order, ctx)) return 0;
- if (BN_is_zero(order))
- {
- ECerr(EC_F_EC_GROUP_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER);
- goto err;
- }
-
- /* TODO */
-
- ret = 1;
-
- err:
- BN_CTX_end(ctx);
- if (new_ctx != NULL)
- BN_CTX_free(new_ctx);
- return ret;
- }
+ BN_CTX_end(ctx);
+#ifndef FIPS_MODULE
+ BN_CTX_free(new_ctx);
+#endif
+ 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)
+{
+ return HAVEPRECOMP(group, ec);
+}
projects / openssl.git / blobdiff