/src/openssl30/crypto/bn/bn_blind.c

Source (jump to first uncovered line)
/*
 * Copyright 1998-2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * 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
 */

#include <openssl/opensslconf.h>
#include "internal/cryptlib.h"
#include "bn_local.h"

#define BN_BLINDING_COUNTER     32

struct bn_blinding_st {
    BIGNUM *A;
    BIGNUM *Ai;
    BIGNUM *e;
    BIGNUM *mod;                /* just a reference */
    CRYPTO_THREAD_ID tid;
    int counter;
    unsigned long flags;
    BN_MONT_CTX *m_ctx;
    int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
                       const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
    CRYPTO_RWLOCK *lock;
};

BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
{
    BN_BLINDING *ret = NULL;

    bn_check_top(mod);

    if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
        ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    ret->lock = CRYPTO_THREAD_lock_new();
    if (ret->lock == NULL) {
        ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
        OPENSSL_free(ret);
        return NULL;
    }

    BN_BLINDING_set_current_thread(ret);

    if (A != NULL) {
        if ((ret->A = BN_dup(A)) == NULL)
            goto err;
    }

    if (Ai != NULL) {
        if ((ret->Ai = BN_dup(Ai)) == NULL)
            goto err;
    }

    /* save a copy of mod in the BN_BLINDING structure */
    if ((ret->mod = BN_dup(mod)) == NULL)
        goto err;

    if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
        BN_set_flags(ret->mod, BN_FLG_CONSTTIME);

    /*
     * Set the counter to the special value -1 to indicate that this is
     * never-used fresh blinding that does not need updating before first
     * use.
     */
    ret->counter = -1;

    return ret;

 err:
    BN_BLINDING_free(ret);
    return NULL;
}

void BN_BLINDING_free(BN_BLINDING *r)
{
    if (r == NULL)
        return;
    BN_free(r->A);
    BN_free(r->Ai);
    BN_free(r->e);
    BN_free(r->mod);
    CRYPTO_THREAD_lock_free(r->lock);
    OPENSSL_free(r);
}

int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
{
    int ret = 0;

    if ((b->A == NULL) || (b->Ai == NULL)) {
        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
        goto err;
    }

    if (b->counter == -1)
        b->counter = 0;

    if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
        !(b->flags & BN_BLINDING_NO_RECREATE)) {
        /* re-create blinding parameters */
        if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
            goto err;
    } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
        if (b->m_ctx != NULL) {
            if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
                || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
                goto err;
        } else {
            if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
                || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
                goto err;
        }
    }

    ret = 1;
 err:
    if (b->counter == BN_BLINDING_COUNTER)
        b->counter = 0;
    return ret;
}

int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
{
    return BN_BLINDING_convert_ex(n, NULL, b, ctx);
}

int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
{
    int ret = 1;

    bn_check_top(n);

    if ((b->A == NULL) || (b->Ai == NULL)) {
        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
        return 0;
    }

    if (b->counter == -1)
        /* Fresh blinding, doesn't need updating. */
        b->counter = 0;
    else if (!BN_BLINDING_update(b, ctx))
        return 0;

    if (r != NULL && (BN_copy(r, b->Ai) == NULL))
        return 0;

    if (b->m_ctx != NULL)
        ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
    else
        ret = BN_mod_mul(n, n, b->A, b->mod, ctx);

    return ret;
}

int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
{
    return BN_BLINDING_invert_ex(n, NULL, b, ctx);
}

int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
                          BN_CTX *ctx)
{
    int ret;

    bn_check_top(n);

    if (r == NULL && (r = b->Ai) == NULL) {
        ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
        return 0;
    }

    if (b->m_ctx != NULL) {
        /* ensure that BN_mod_mul_montgomery takes pre-defined path */
        if (n->dmax >= r->top) {
            size_t i, rtop = r->top, ntop = n->top;
            BN_ULONG mask;

            for (i = 0; i < rtop; i++) {
                mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
                n->d[i] &= mask;
            }
            mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
            /* always true, if (rtop >= ntop) n->top = r->top; */
            n->top = (int)(rtop & ~mask) | (ntop & mask);
            n->flags |= (BN_FLG_FIXED_TOP & ~mask);
        }
        ret = bn_mul_mont_fixed_top(n, n, r, b->m_ctx, ctx);
        bn_correct_top_consttime(n);
    } else {
        ret = BN_mod_mul(n, n, r, b->mod, ctx);
    }

    bn_check_top(n);
    return ret;
}

int BN_BLINDING_is_current_thread(BN_BLINDING *b)
{
    return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
}

void BN_BLINDING_set_current_thread(BN_BLINDING *b)
{
    b->tid = CRYPTO_THREAD_get_current_id();
}

int BN_BLINDING_lock(BN_BLINDING *b)
{
    return CRYPTO_THREAD_write_lock(b->lock);
}

int BN_BLINDING_unlock(BN_BLINDING *b)
{
    return CRYPTO_THREAD_unlock(b->lock);
}

unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
{
    return b->flags;
}

void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
{
    b->flags = flags;
}

BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
                                      const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
                                      int (*bn_mod_exp) (BIGNUM *r,
                                                         const BIGNUM *a,
                                                         const BIGNUM *p,
                                                         const BIGNUM *m,
                                                         BN_CTX *ctx,
                                                         BN_MONT_CTX *m_ctx),
                                      BN_MONT_CTX *m_ctx)
{
    int retry_counter = 32;
    BN_BLINDING *ret = NULL;

    if (b == NULL)
        ret = BN_BLINDING_new(NULL, NULL, m);
    else
        ret = b;

    if (ret == NULL)
        goto err;

    if (ret->A == NULL && (ret->A = BN_new()) == NULL)
        goto err;
    if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
        goto err;

    if (e != NULL) {
        BN_free(ret->e);
        ret->e = BN_dup(e);
    }
    if (ret->e == NULL)
        goto err;

    if (bn_mod_exp != NULL)
        ret->bn_mod_exp = bn_mod_exp;
    if (m_ctx != NULL)
        ret->m_ctx = m_ctx;

    do {
        int rv;
        if (!BN_priv_rand_range_ex(ret->A, ret->mod, 0, ctx))
            goto err;
        if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))
            break;

        /*
         * this should almost never happen for good RSA keys
         */
        if (!rv)
            goto err;

        if (retry_counter-- == 0) {
            ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
            goto err;
        }
    } while (1);

    if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
        if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
            goto err;
    } else {
        if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
            goto err;
    }

    if (ret->m_ctx != NULL) {
        if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
            || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
            goto err;
    }

    return ret;
 err:
    if (b == NULL) {
        BN_BLINDING_free(ret);
        ret = NULL;
    }

    return ret;
}

Coverage Report

Created: 2025-06-13 06:58

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 1998-2023 The OpenSSL Project Authors. All Rights Reserved.
3		*
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
8		*/
9
10		#include <openssl/opensslconf.h>
11		#include "internal/cryptlib.h"
12		#include "bn_local.h"
13
14	0	#define BN_BLINDING_COUNTER 32
15
16		struct bn_blinding_st {
17		BIGNUM *A;
18		BIGNUM *Ai;
19		BIGNUM *e;
20		BIGNUM mod; / just a reference */
21		CRYPTO_THREAD_ID tid;
22		int counter;
23		unsigned long flags;
24		BN_MONT_CTX *m_ctx;
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);
27		CRYPTO_RWLOCK *lock;
28		};
29
30		BN_BLINDING BN_BLINDING_new(const BIGNUM A, const BIGNUM Ai, BIGNUM mod)
31	8.87k	{
32	8.87k	BN_BLINDING *ret = NULL;
33
34	8.87k	bn_check_top(mod);
35
36	8.87k	if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
37	0	ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
38	0	return NULL;
39	0	}
40
41	8.87k	ret->lock = CRYPTO_THREAD_lock_new();
42	8.87k	if (ret->lock == NULL) {
43	0	ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
44	0	OPENSSL_free(ret);
45	0	return NULL;
46	0	}
47
48	8.87k	BN_BLINDING_set_current_thread(ret);
49
50	8.87k	if (A != NULL) {
51	0	if ((ret->A = BN_dup(A)) == NULL)
52	0	goto err;
53	0	}
54
55	8.87k	if (Ai != NULL) {
56	0	if ((ret->Ai = BN_dup(Ai)) == NULL)
57	0	goto err;
58	0	}
59
60		/* save a copy of mod in the BN_BLINDING structure */
61	8.87k	if ((ret->mod = BN_dup(mod)) == NULL)
62	0	goto err;
63
64	8.87k	if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
65	8.87k	BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
66
67		/*
68		* Set the counter to the special value -1 to indicate that this is
69		* never-used fresh blinding that does not need updating before first
70		* use.
71		*/
72	8.87k	ret->counter = -1;
73
74	8.87k	return ret;
75
76	0	err:
77	0	BN_BLINDING_free(ret);
78	0	return NULL;
79	8.87k	}
80
81		void BN_BLINDING_free(BN_BLINDING *r)
82	810k	{
83	810k	if (r == NULL)
84	802k	return;
85	8.87k	BN_free(r->A);
86	8.87k	BN_free(r->Ai);
87	8.87k	BN_free(r->e);
88	8.87k	BN_free(r->mod);
89	8.87k	CRYPTO_THREAD_lock_free(r->lock);
90	8.87k	OPENSSL_free(r);
91	8.87k	}
92
93		int BN_BLINDING_update(BN_BLINDING b, BN_CTX ctx)
94	0	{
95	0	int ret = 0;
96
97	0	if ((b->A == NULL) \|\| (b->Ai == NULL)) {
98	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
99	0	goto err;
100	0	}
101
102	0	if (b->counter == -1)
103	0	b->counter = 0;
104
105	0	if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
106	0	!(b->flags & BN_BLINDING_NO_RECREATE)) {
107		/* re-create blinding parameters */
108	0	if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
109	0	goto err;
110	0	} else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
111	0	if (b->m_ctx != NULL) {
112	0	if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
113	0	\|\| !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
114	0	goto err;
115	0	} else {
116	0	if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
117	0	\|\| !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
118	0	goto err;
119	0	}
120	0	}
121
122	0	ret = 1;
123	0	err:
124	0	if (b->counter == BN_BLINDING_COUNTER)
125	0	b->counter = 0;
126	0	return ret;
127	0	}
128
129		int BN_BLINDING_convert(BIGNUM n, BN_BLINDING b, BN_CTX *ctx)
130	0	{
131	0	return BN_BLINDING_convert_ex(n, NULL, b, ctx);
132	0	}
133
134		int BN_BLINDING_convert_ex(BIGNUM n, BIGNUM r, BN_BLINDING b, BN_CTX ctx)
135	8.87k	{
136	8.87k	int ret = 1;
137
138	8.87k	bn_check_top(n);
139
140	8.87k	if ((b->A == NULL) \|\| (b->Ai == NULL)) {
141	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
142	0	return 0;
143	0	}
144
145	8.87k	if (b->counter == -1)
146		/* Fresh blinding, doesn't need updating. */
147	8.87k	b->counter = 0;
148	0	else if (!BN_BLINDING_update(b, ctx))
149	0	return 0;
150
151	8.87k	if (r != NULL && (BN_copy(r, b->Ai) == NULL))
152	0	return 0;
153
154	8.87k	if (b->m_ctx != NULL)
155	8.87k	ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
156	0	else
157	0	ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
158
159	8.87k	return ret;
160	8.87k	}
161
162		int BN_BLINDING_invert(BIGNUM n, BN_BLINDING b, BN_CTX *ctx)
163	0	{
164	0	return BN_BLINDING_invert_ex(n, NULL, b, ctx);
165	0	}
166
167		int BN_BLINDING_invert_ex(BIGNUM n, const BIGNUM r, BN_BLINDING *b,
168		BN_CTX *ctx)
169	8.87k	{
170	8.87k	int ret;
171
172	8.87k	bn_check_top(n);
173
174	8.87k	if (r == NULL && (r = b->Ai) == NULL) {
175	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
176	0	return 0;
177	0	}
178
179	8.87k	if (b->m_ctx != NULL) {
180		/* ensure that BN_mod_mul_montgomery takes pre-defined path */
181	8.87k	if (n->dmax >= r->top) {
182	8.87k	size_t i, rtop = r->top, ntop = n->top;
183	8.87k	BN_ULONG mask;
184
185	292k	for (i = 0; i < rtop; i++) {
186	284k	mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
187	284k	n->d[i] &= mask;
188	284k	}
189	8.87k	mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
190		/* always true, if (rtop >= ntop) n->top = r->top; */
191	8.87k	n->top = (int)(rtop & ~mask) \| (ntop & mask);
192	8.87k	n->flags \|= (BN_FLG_FIXED_TOP & ~mask);
193	8.87k	}
194	8.87k	ret = bn_mul_mont_fixed_top(n, n, r, b->m_ctx, ctx);
195	8.87k	bn_correct_top_consttime(n);
196	8.87k	} else {
197	0	ret = BN_mod_mul(n, n, r, b->mod, ctx);
198	0	}
199
200	8.87k	bn_check_top(n);
201	8.87k	return ret;
202	8.87k	}
203
204		int BN_BLINDING_is_current_thread(BN_BLINDING *b)
205	8.87k	{
206	8.87k	return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
207	8.87k	}
208
209		void BN_BLINDING_set_current_thread(BN_BLINDING *b)
210	17.7k	{
211	17.7k	b->tid = CRYPTO_THREAD_get_current_id();
212	17.7k	}
213
214		int BN_BLINDING_lock(BN_BLINDING *b)
215	0	{
216	0	return CRYPTO_THREAD_write_lock(b->lock);
217	0	}
218
219		int BN_BLINDING_unlock(BN_BLINDING *b)
220	0	{
221	0	return CRYPTO_THREAD_unlock(b->lock);
222	0	}
223
224		unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
225	0	{
226	0	return b->flags;
227	0	}
228
229		void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
230	0	{
231	0	b->flags = flags;
232	0	}
233
234		BN_BLINDING BN_BLINDING_create_param(BN_BLINDING b,
235		const BIGNUM e, BIGNUM m, BN_CTX *ctx,
236		int (bn_mod_exp) (BIGNUM r,
237		const BIGNUM *a,
238		const BIGNUM *p,
239		const BIGNUM *m,
240		BN_CTX *ctx,
241		BN_MONT_CTX *m_ctx),
242		BN_MONT_CTX *m_ctx)
243	8.87k	{
244	8.87k	int retry_counter = 32;
245	8.87k	BN_BLINDING *ret = NULL;
246
247	8.87k	if (b == NULL)
248	8.87k	ret = BN_BLINDING_new(NULL, NULL, m);
249	0	else
250	0	ret = b;
251
252	8.87k	if (ret == NULL)
253	0	goto err;
254
255	8.87k	if (ret->A == NULL && (ret->A = BN_new()) == NULL)
256	0	goto err;
257	8.87k	if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
258	0	goto err;
259
260	8.87k	if (e != NULL) {
261	8.87k	BN_free(ret->e);
262	8.87k	ret->e = BN_dup(e);
263	8.87k	}
264	8.87k	if (ret->e == NULL)
265	0	goto err;
266
267	8.87k	if (bn_mod_exp != NULL)
268	8.87k	ret->bn_mod_exp = bn_mod_exp;
269	8.87k	if (m_ctx != NULL)
270	8.87k	ret->m_ctx = m_ctx;
271
272	8.87k	do {
273	8.87k	int rv;
274	8.87k	if (!BN_priv_rand_range_ex(ret->A, ret->mod, 0, ctx))
275	0	goto err;
276	8.87k	if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))
277	8.87k	break;
278
279		/*
280		* this should almost never happen for good RSA keys
281		*/
282	0	if (!rv)
283	0	goto err;
284
285	0	if (retry_counter-- == 0) {
286	0	ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
287	0	goto err;
288	0	}
289	0	} while (1);
290
291	8.87k	if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
292	8.87k	if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
293	0	goto err;
294	8.87k	} else {
295	0	if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
296	0	goto err;
297	0	}
298
299	8.87k	if (ret->m_ctx != NULL) {
300	8.87k	if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
301	8.87k	\|\| !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
302	0	goto err;
303	8.87k	}
304
305	8.87k	return ret;
306	0	err:
307	0	if (b == NULL) {
308	0	BN_BLINDING_free(ret);
309	0	ret = NULL;
310	0	}
311
312	0	return ret;
313	8.87k	}