diff options
Diffstat (limited to 'usr/src/common/openssl/crypto/ec/ec_mult.c')
| -rw-r--r-- | usr/src/common/openssl/crypto/ec/ec_mult.c | 642 |
1 files changed, 533 insertions, 109 deletions
diff --git a/usr/src/common/openssl/crypto/ec/ec_mult.c b/usr/src/common/openssl/crypto/ec/ec_mult.c index 16822a73cf..7320e31c5c 100644 --- a/usr/src/common/openssl/crypto/ec/ec_mult.c +++ b/usr/src/common/openssl/crypto/ec/ec_mult.c @@ -1,6 +1,9 @@ /* 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 @@ -52,41 +55,145 @@ * 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" -/* TODO: optional precomputation of multiples of the generator */ +/* + * 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>). + */ -/* - * wNAF-based interleaving multi-exponentation method - * (<URL:http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller.html#multiexp>) - */ +/* 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_; -/* Determine the width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'. + 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. + * 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, BN_CTX *ctx) +static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len) { - BIGNUM *c; + int window_val; int ok = 0; signed char *r = NULL; int sign = 1; int bit, next_bit, mask; size_t len = 0, j; - BN_CTX_start(ctx); - c = BN_CTX_get(ctx); - if (c == NULL) goto err; - 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); @@ -96,60 +203,86 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B next_bit = bit << 1; /* at most 256 */ mask = next_bit - 1; /* at most 255 */ - if (!BN_copy(c, scalar)) goto err; - if (c->neg) + if (BN_is_negative(scalar)) { sign = -1; - c->neg = 0; } - len = BN_num_bits(c) + 1; /* wNAF may be one digit longer than binary representation */ - r = OPENSSL_malloc(len); + 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 (!BN_is_zero(c)) + while ((window_val != 0) || (j + w + 1 < len)) /* if j+w+1 >= len, window_val will not increase */ { - int u = 0; + int digit = 0; + + /* 0 <= window_val <= 2^(w+1) */ - if (BN_is_odd(c)) + if (window_val & 1) { - if (c->d == NULL || c->top == 0) + /* 0 < window_val < 2^(w+1) */ + + if (window_val & bit) { - ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); - goto err; + 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 } - u = c->d[0] & mask; - if (u & bit) + else { - u -= next_bit; - /* u < 0 */ - if (!BN_add_word(c, -u)) goto err; + digit = window_val; /* 0 < digit < 2^w */ } - else + + if (digit <= -bit || digit >= bit || !(digit & 1)) { - /* u > 0 */ - if (!BN_sub_word(c, u)) goto err; + ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); + goto err; } - if (u <= -bit || u >= bit || !(u & 1) || c->neg) + 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 * u; - - if (BN_is_odd(c)) + 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 (!BN_rshift1(c, c)) goto err; } - if (j > len) + if (j > len + 1) { ECerr(EC_F_COMPUTE_WNAF, ERR_R_INTERNAL_ERROR); goto err; @@ -158,7 +291,6 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B ok = 1; err: - BN_CTX_end(ctx); if (!ok) { OPENSSL_free(r); @@ -181,7 +313,7 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B (b) >= 300 ? 4 : \ (b) >= 70 ? 3 : \ (b) >= 20 ? 2 : \ - 1)) + 1)) /* Compute * \sum scalars[i]*points[i], @@ -189,13 +321,15 @@ static signed char *compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len, B * scalar*generator * in the addition if scalar != NULL */ -int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, +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; + 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; @@ -207,12 +341,15 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, size_t num_val; EC_POINT **val = NULL; /* precomputation */ EC_POINT **v; - EC_POINT ***val_sub = NULL; /* pointers to sub-arrays of 'val' */ + 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_POINTS_MUL, EC_R_INCOMPATIBLE_OBJECTS); + ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); return 0; } @@ -221,59 +358,218 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, return EC_POINT_set_to_infinity(group, r); } - 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); + ECerr(EC_F_EC_WNAF_MUL, EC_R_INCOMPATIBLE_OBJECTS); return 0; } } - totalnum = num + (scalar != NULL); + if (ctx == NULL) + { + ctx = new_ctx = BN_CTX_new(); + if (ctx == NULL) + goto err; + } - wsize = OPENSSL_malloc(totalnum * sizeof wsize[0]); - wNAF_len = OPENSSL_malloc(totalnum * sizeof wNAF_len[0]); - wNAF = OPENSSL_malloc((totalnum + 1) * sizeof wNAF[0]); - if (wNAF != NULL) + if (scalar != NULL) { - wNAF[0] = NULL; /* preliminary pivot */ + 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' */ + } } - if (wsize == NULL || wNAF_len == NULL || wNAF == NULL) goto err; + + totalnum = num + numblocks; - /* num_val := total number of points to precompute */ + 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 < totalnum; i++) + + 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]; } - /* all precomputed points go into a single array 'val', - * 'val_sub[i]' is a pointer to the subarray for the i-th point */ + 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 */ - 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++) + for (i = 0; i < num + num_scalar; i++) { val_sub[i] = v; for (j = 0; j < (1u << (wsize[i] - 1)); j++) @@ -285,19 +581,12 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, } if (!(v == val + num_val)) { - ECerr(EC_F_EC_POINTS_MUL, ERR_R_INTERNAL_ERROR); + ECerr(EC_F_EC_WNAF_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; + if (!(tmp = EC_POINT_new(group))) + goto err; /* prepare precomputed values: * val_sub[i][0] := points[i] @@ -305,7 +594,7 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, * val_sub[i][2] := 5 * points[i] * ... */ - for (i = 0; i < totalnum; i++) + for (i = 0; i < num + num_scalar; i++) { if (i < num) { @@ -324,16 +613,11 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, if (!EC_POINT_add(group, val_sub[i][j], val_sub[i][j - 1], tmp, ctx)) goto err; } } - - 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], ctx); - if (wNAF[i] == NULL) goto err; - if (wNAF_len[i] > max_len) - max_len = wNAF_len[i]; } #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; + if (!EC_POINTs_make_affine(group, num_val, val, ctx)) + goto err; #endif r_is_at_infinity = 1; @@ -429,57 +713,197 @@ int EC_POINTs_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, } -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) +/* 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_GROUP_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); - return 0; + 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) - return 0; + goto err; } 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 (!EC_GROUP_get_order(group, order, ctx)) goto err; if (BN_is_zero(order)) { - ECerr(EC_F_EC_GROUP_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); goto err; } - /* TODO */ + 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); + } - ret = 1; + 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; + } |