diff options
Diffstat (limited to 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl/crypto/ec/ec_mult.c')
| -rw-r--r-- | roms/edk2/CryptoPkg/Library/OpensslLib/openssl/crypto/ec/ec_mult.c | 976 |
1 files changed, 976 insertions, 0 deletions
diff --git a/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/crypto/ec/ec_mult.c b/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/crypto/ec/ec_mult.c new file mode 100644 index 000000000..9a1e3974e --- /dev/null +++ b/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/crypto/ec/ec_mult.c @@ -0,0 +1,976 @@ +/* + * Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved. + * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved + * + * Licensed under the OpenSSL license (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +#include <string.h> +#include <openssl/err.h> + +#include "internal/cryptlib.h" +#include "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. + * + * 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. + * + * `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). + * + * This function expects `group->order` and `group->cardinality` to be well + * defined and non-zero: it fails with an error code otherwise. + * + * 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. + * + * The product is stored in `r`. + * + * 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 && !EC_POINT_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; + + err: + EC_POINT_free(p); + EC_POINT_clear_free(s); + BN_CTX_end(ctx); + + return ret; +} + +#undef EC_POINT_BN_set_flags + +/* + * 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) +{ + 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 (!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; + + /*- + * 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_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; + const BIGNUM *order; + size_t i, bits, w, pre_points_per_block, blocksize, numblocks, num; + EC_POINT **points = NULL; + EC_PRE_COMP *pre_comp; + int ret = 0; + + /* if there is an old EC_PRE_COMP object, throw it away */ + EC_pre_comp_free(group); + if ((pre_comp = ec_pre_comp_new(group)) == NULL) + return 0; + + generator = EC_GROUP_get0_generator(group); + if (generator == NULL) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNDEFINED_GENERATOR); + goto err; + } + + if (ctx == NULL) { + ctx = new_ctx = BN_CTX_new(); + if (ctx == NULL) + goto err; + } + + BN_CTX_start(ctx); + + order = EC_GROUP_get0_order(group); + if (order == NULL) + goto err; + if (BN_is_zero(order)) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, EC_R_UNKNOWN_ORDER); + goto err; + } + + bits = BN_num_bits(order); + /* + * The following parameters mean we precompute (approximately) one point + * per bit. TBD: The combination 8, 4 is perfect for 160 bits; for other + * bit lengths, other parameter combinations might provide better + * efficiency. + */ + blocksize = 8; + w = 4; + if (EC_window_bits_for_scalar_size(bits) > w) { + /* let's not make the window too small ... */ + w = EC_window_bits_for_scalar_size(bits); + } + + numblocks = (bits + blocksize - 1) / blocksize; /* max. number of blocks + * to use for wNAF + * splitting */ + + pre_points_per_block = (size_t)1 << (w - 1); + num = pre_points_per_block * numblocks; /* number of points to compute + * and store */ + + points = OPENSSL_malloc(sizeof(*points) * (num + 1)); + if (points == NULL) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); + goto err; + } + + var = points; + var[num] = NULL; /* pivot */ + for (i = 0; i < num; i++) { + if ((var[i] = EC_POINT_new(group)) == NULL) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); + goto err; + } + } + + if ((tmp_point = EC_POINT_new(group)) == NULL + || (base = EC_POINT_new(group)) == NULL) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_MALLOC_FAILURE); + goto err; + } + + if (!EC_POINT_copy(base, generator)) + goto err; + + /* do the precomputation */ + for (i = 0; i < numblocks; i++) { + size_t j; + + if (!EC_POINT_dbl(group, tmp_point, base, ctx)) + goto err; + + if (!EC_POINT_copy(*var++, base)) + goto err; + + for (j = 1; j < pre_points_per_block; j++, var++) { + /* + * calculate odd multiples of the current base point + */ + if (!EC_POINT_add(group, *var, tmp_point, *(var - 1), ctx)) + goto err; + } + + if (i < numblocks - 1) { + /* + * get the next base (multiply current one by 2^blocksize) + */ + size_t k; + + if (blocksize <= 2) { + ECerr(EC_F_EC_WNAF_PRECOMPUTE_MULT, ERR_R_INTERNAL_ERROR); + goto err; + } + + if (!EC_POINT_dbl(group, base, tmp_point, ctx)) + goto err; + for (k = 2; k < blocksize; k++) { + if (!EC_POINT_dbl(group, base, base, ctx)) + goto err; + } + } + } + + if (!EC_POINTs_make_affine(group, num, points, ctx)) + goto err; + + pre_comp->group = group; + pre_comp->blocksize = blocksize; + pre_comp->numblocks = numblocks; + pre_comp->w = w; + pre_comp->points = points; + points = NULL; + pre_comp->num = num; + SETPRECOMP(group, ec, pre_comp); + pre_comp = NULL; + ret = 1; + + err: + BN_CTX_end(ctx); + BN_CTX_free(new_ctx); + EC_ec_pre_comp_free(pre_comp); + if (points) { + EC_POINT **p; + + for (p = points; *p != NULL; p++) + EC_POINT_free(*p); + OPENSSL_free(points); + } + EC_POINT_free(tmp_point); + EC_POINT_free(base); + return ret; +} + +int ec_wNAF_have_precompute_mult(const EC_GROUP *group) +{ + return HAVEPRECOMP(group, ec); +} |