2 * Copyright 1998-2023 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #include <openssl/opensslconf.h>
11 #include "internal/cryptlib.h"
14 #define BN_BLINDING_COUNTER 32
16 struct bn_blinding_st {
20 BIGNUM *mod; /* just a reference */
25 int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
26 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
30 BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
32 BN_BLINDING *ret = NULL;
36 if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL)
39 ret->lock = CRYPTO_THREAD_lock_new();
40 if (ret->lock == NULL) {
41 ERR_raise(ERR_LIB_BN, ERR_R_CRYPTO_LIB);
46 BN_BLINDING_set_current_thread(ret);
49 if ((ret->A = BN_dup(A)) == NULL)
54 if ((ret->Ai = BN_dup(Ai)) == NULL)
58 /* save a copy of mod in the BN_BLINDING structure */
59 if ((ret->mod = BN_dup(mod)) == NULL)
62 if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
63 BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
66 * Set the counter to the special value -1 to indicate that this is
67 * never-used fresh blinding that does not need updating before first
75 BN_BLINDING_free(ret);
79 void BN_BLINDING_free(BN_BLINDING *r)
87 CRYPTO_THREAD_lock_free(r->lock);
91 int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
95 if ((b->A == NULL) || (b->Ai == NULL)) {
96 ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
100 if (b->counter == -1)
103 if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
104 !(b->flags & BN_BLINDING_NO_RECREATE)) {
105 /* re-create blinding parameters */
106 if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
108 } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
109 if (b->m_ctx != NULL) {
110 if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
111 || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
114 if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
115 || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
122 if (b->counter == BN_BLINDING_COUNTER)
127 int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
129 return BN_BLINDING_convert_ex(n, NULL, b, ctx);
132 int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
138 if ((b->A == NULL) || (b->Ai == NULL)) {
139 ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
143 if (b->counter == -1)
144 /* Fresh blinding, doesn't need updating. */
146 else if (!BN_BLINDING_update(b, ctx))
149 if (r != NULL && (BN_copy(r, b->Ai) == NULL))
152 if (b->m_ctx != NULL)
153 ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
155 ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
160 int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
162 return BN_BLINDING_invert_ex(n, NULL, b, ctx);
165 int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
172 if (r == NULL && (r = b->Ai) == NULL) {
173 ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
177 if (b->m_ctx != NULL) {
178 /* ensure that BN_mod_mul_montgomery takes pre-defined path */
179 if (n->dmax >= r->top) {
180 size_t i, rtop = r->top, ntop = n->top;
183 for (i = 0; i < rtop; i++) {
184 mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
187 mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
188 /* always true, if (rtop >= ntop) n->top = r->top; */
189 n->top = (int)(rtop & ~mask) | (ntop & mask);
190 n->flags |= (BN_FLG_FIXED_TOP & ~mask);
192 ret = bn_mul_mont_fixed_top(n, n, r, b->m_ctx, ctx);
193 bn_correct_top_consttime(n);
195 ret = BN_mod_mul(n, n, r, b->mod, ctx);
202 int BN_BLINDING_is_current_thread(BN_BLINDING *b)
204 return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
207 void BN_BLINDING_set_current_thread(BN_BLINDING *b)
209 b->tid = CRYPTO_THREAD_get_current_id();
212 int BN_BLINDING_lock(BN_BLINDING *b)
214 return CRYPTO_THREAD_write_lock(b->lock);
217 int BN_BLINDING_unlock(BN_BLINDING *b)
219 return CRYPTO_THREAD_unlock(b->lock);
222 unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
227 void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
232 BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
233 const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
234 int (*bn_mod_exp) (BIGNUM *r,
242 int retry_counter = 32;
243 BN_BLINDING *ret = NULL;
246 ret = BN_BLINDING_new(NULL, NULL, m);
253 if (ret->A == NULL && (ret->A = BN_new()) == NULL)
255 if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
265 if (bn_mod_exp != NULL)
266 ret->bn_mod_exp = bn_mod_exp;
272 if (!BN_priv_rand_range_ex(ret->A, ret->mod, 0, ctx))
274 if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))
278 * this should almost never happen for good RSA keys
283 if (retry_counter-- == 0) {
284 ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
289 if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
290 if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
293 if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
297 if (ret->m_ctx != NULL) {
298 if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
299 || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
306 BN_BLINDING_free(ret);