/src/rauc/subprojects/openssl-3.0.8/crypto/bn/bn_blind.c

Source
/*
 * 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

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_mod_mul_montgomery(n, n, r, b->m_ctx, ctx);
    } 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: 2025-12-31 07:05

Line	Count	Source
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		BN_BLINDING BN_BLINDING_new(const BIGNUM A, const BIGNUM Ai, BIGNUM mod)
17	0	{
18	0	BN_BLINDING *ret = NULL;
19
20	0	bn_check_top(mod);
21
22	0	if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
23	0	ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
24	0	return NULL;
25	0	}
26
27	0	ret->lock = CRYPTO_THREAD_lock_new();
28	0	if (ret->lock == NULL) {
29	0	ERR_raise(ERR_LIB_BN, ERR_R_MALLOC_FAILURE);
30	0	OPENSSL_free(ret);
31	0	return NULL;
32	0	}
33
34	0	BN_BLINDING_set_current_thread(ret);
35
36	0	if (A != NULL) {
37	0	if ((ret->A = BN_dup(A)) == NULL)
38	0	goto err;
39	0	}
40
41	0	if (Ai != NULL) {
42	0	if ((ret->Ai = BN_dup(Ai)) == NULL)
43	0	goto err;
44	0	}
45
46		/* save a copy of mod in the BN_BLINDING structure */
47	0	if ((ret->mod = BN_dup(mod)) == NULL)
48	0	goto err;
49
50	0	if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
51	0	BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
52
53		/*
54		* Set the counter to the special value -1 to indicate that this is
55		* never-used fresh blinding that does not need updating before first
56		* use.
57		*/
58	0	ret->counter = -1;
59
60	0	return ret;
61
62	0	err:
63	0	BN_BLINDING_free(ret);
64	0	return NULL;
65	0	}
66
67		void BN_BLINDING_free(BN_BLINDING *r)
68	720	{
69	720	if (r == NULL)
70	720	return;
71	0	BN_free(r->A);
72	0	BN_free(r->Ai);
73	0	BN_free(r->e);
74	0	BN_free(r->mod);
75	0	CRYPTO_THREAD_lock_free(r->lock);
76	0	OPENSSL_free(r);
77	0	}
78
79		int BN_BLINDING_update(BN_BLINDING b, BN_CTX ctx)
80	0	{
81	0	int ret = 0;
82
83	0	if ((b->A == NULL) \|\| (b->Ai == NULL)) {
84	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
85	0	goto err;
86	0	}
87
88	0	if (b->counter == -1)
89	0	b->counter = 0;
90
91	0	if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
92	0	!(b->flags & BN_BLINDING_NO_RECREATE)) {
93		/* re-create blinding parameters */
94	0	if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
95	0	goto err;
96	0	} else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
97	0	if (b->m_ctx != NULL) {
98	0	if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
99	0	\|\| !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
100	0	goto err;
101	0	} else {
102	0	if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
103	0	\|\| !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
104	0	goto err;
105	0	}
106	0	}
107
108	0	ret = 1;
109	0	err:
110	0	if (b->counter == BN_BLINDING_COUNTER)
111	0	b->counter = 0;
112	0	return ret;
113	0	}
114
115		int BN_BLINDING_convert(BIGNUM n, BN_BLINDING b, BN_CTX *ctx)
116	0	{
117	0	return BN_BLINDING_convert_ex(n, NULL, b, ctx);
118	0	}
119
120		int BN_BLINDING_convert_ex(BIGNUM n, BIGNUM r, BN_BLINDING b, BN_CTX ctx)
121	0	{
122	0	int ret = 1;
123
124	0	bn_check_top(n);
125
126	0	if ((b->A == NULL) \|\| (b->Ai == NULL)) {
127	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
128	0	return 0;
129	0	}
130
131	0	if (b->counter == -1)
132		/* Fresh blinding, doesn't need updating. */
133	0	b->counter = 0;
134	0	else if (!BN_BLINDING_update(b, ctx))
135	0	return 0;
136
137	0	if (r != NULL && (BN_copy(r, b->Ai) == NULL))
138	0	return 0;
139
140	0	if (b->m_ctx != NULL)
141	0	ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
142	0	else
143	0	ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
144
145	0	return ret;
146	0	}
147
148		int BN_BLINDING_invert(BIGNUM n, BN_BLINDING b, BN_CTX *ctx)
149	0	{
150	0	return BN_BLINDING_invert_ex(n, NULL, b, ctx);
151	0	}
152
153		int BN_BLINDING_invert_ex(BIGNUM n, const BIGNUM r, BN_BLINDING *b,
154		BN_CTX *ctx)
155	0	{
156	0	int ret;
157
158	0	bn_check_top(n);
159
160	0	if (r == NULL && (r = b->Ai) == NULL) {
161	0	ERR_raise(ERR_LIB_BN, BN_R_NOT_INITIALIZED);
162	0	return 0;
163	0	}
164
165	0	if (b->m_ctx != NULL) {
166		/* ensure that BN_mod_mul_montgomery takes pre-defined path */
167	0	if (n->dmax >= r->top) {
168	0	size_t i, rtop = r->top, ntop = n->top;
169	0	BN_ULONG mask;
170
171	0	for (i = 0; i < rtop; i++) {
172	0	mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
173	0	n->d[i] &= mask;
174	0	}
175	0	mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
176		/* always true, if (rtop >= ntop) n->top = r->top; */
177	0	n->top = (int)(rtop & ~mask) \| (ntop & mask);
178	0	n->flags \|= (BN_FLG_FIXED_TOP & ~mask);
179	0	}
180	0	ret = BN_mod_mul_montgomery(n, n, r, b->m_ctx, ctx);
181	0	} else {
182	0	ret = BN_mod_mul(n, n, r, b->mod, ctx);
183	0	}
184
185	0	bn_check_top(n);
186	0	return ret;
187	0	}
188
189		int BN_BLINDING_is_current_thread(BN_BLINDING *b)
190	0	{
191	0	return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
192	0	}
193
194		void BN_BLINDING_set_current_thread(BN_BLINDING *b)
195	0	{
196	0	b->tid = CRYPTO_THREAD_get_current_id();
197	0	}
198
199		int BN_BLINDING_lock(BN_BLINDING *b)
200	0	{
201	0	return CRYPTO_THREAD_write_lock(b->lock);
202	0	}
203
204		int BN_BLINDING_unlock(BN_BLINDING *b)
205	0	{
206	0	return CRYPTO_THREAD_unlock(b->lock);
207	0	}
208
209		unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
210	0	{
211	0	return b->flags;
212	0	}
213
214		void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
215	0	{
216	0	b->flags = flags;
217	0	}
218
219		BN_BLINDING BN_BLINDING_create_param(BN_BLINDING b,
220		const BIGNUM e, BIGNUM m, BN_CTX *ctx,
221		int (bn_mod_exp) (BIGNUM r,
222		const BIGNUM *a,
223		const BIGNUM *p,
224		const BIGNUM *m,
225		BN_CTX *ctx,
226		BN_MONT_CTX *m_ctx),
227		BN_MONT_CTX *m_ctx)
228	0	{
229	0	int retry_counter = 32;
230	0	BN_BLINDING *ret = NULL;
231
232	0	if (b == NULL)
233	0	ret = BN_BLINDING_new(NULL, NULL, m);
234	0	else
235	0	ret = b;
236
237	0	if (ret == NULL)
238	0	goto err;
239
240	0	if (ret->A == NULL && (ret->A = BN_new()) == NULL)
241	0	goto err;
242	0	if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
243	0	goto err;
244
245	0	if (e != NULL) {
246	0	BN_free(ret->e);
247	0	ret->e = BN_dup(e);
248	0	}
249	0	if (ret->e == NULL)
250	0	goto err;
251
252	0	if (bn_mod_exp != NULL)
253	0	ret->bn_mod_exp = bn_mod_exp;
254	0	if (m_ctx != NULL)
255	0	ret->m_ctx = m_ctx;
256
257	0	do {
258	0	int rv;
259	0	if (!BN_priv_rand_range_ex(ret->A, ret->mod, 0, ctx))
260	0	goto err;
261	0	if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))
262	0	break;
263
264		/*
265		* this should almost never happen for good RSA keys
266		*/
267	0	if (!rv)
268	0	goto err;
269
270	0	if (retry_counter-- == 0) {
271	0	ERR_raise(ERR_LIB_BN, BN_R_TOO_MANY_ITERATIONS);
272	0	goto err;
273	0	}
274	0	} while (1);
275
276	0	if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
277	0	if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
278	0	goto err;
279	0	} else {
280	0	if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
281	0	goto err;
282	0	}
283
284	0	if (ret->m_ctx != NULL) {
285	0	if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
286	0	\|\| !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
287	0	goto err;
288	0	}
289
290	0	return ret;
291	0	err:
292	0	if (b == NULL) {
293	0	BN_BLINDING_free(ret);
294	0	ret = NULL;
295	0	}
296
297	0	return ret;
298	0	}