-/* TODO */
/* crypto/ec/ec_mult.c */
+/*
+ * Originally written by Bodo Moeller and Nils Larsch for the OpenSSL project.
+ */
/* ====================================================================
- * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
+ * 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
* 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.
+ */
+
+#include <string.h>
+
+#include <openssl/err.h>
#include "ec_lcl.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>).
+ */
+
+
+
+
+/* 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 *);
+
+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_is_negative(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;
+
+ 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)
+ */
+#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
+ * \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;
+ 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 = 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 = 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;
+
+ 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()
+ * 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 = 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_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:
+ 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;
+ }
+
+
+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;
+ }
projects / openssl.git / blobdiff