crypto/bn/bn_recp.c

/* crypto/bn/bn_recp.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"

void BN_RECP_CTX_init(BN_RECP_CTX *recp)
{
    BN_init(&(recp->N));
    BN_init(&(recp->Nr));
    recp->num_bits = 0;
    recp->flags = 0;
}

BN_RECP_CTX *BN_RECP_CTX_new(void)
{
    BN_RECP_CTX *ret;

    if ((ret = (BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
        return (NULL);

    BN_RECP_CTX_init(ret);
    ret->flags = BN_FLG_MALLOCED;
    return (ret);
}

void BN_RECP_CTX_free(BN_RECP_CTX *recp)
{
    if (recp == NULL)
        return;

    BN_free(&(recp->N));
    BN_free(&(recp->Nr));
    if (recp->flags & BN_FLG_MALLOCED)
        OPENSSL_free(recp);
}

int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
{
    if (!BN_copy(&(recp->N), d))
        return 0;
    BN_zero(&(recp->Nr));
    recp->num_bits = BN_num_bits(d);
    recp->shift = 0;
    return (1);
}

int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
                          BN_RECP_CTX *recp, BN_CTX *ctx)
{
    int ret = 0;
    BIGNUM *a;
    const BIGNUM *ca;

    BN_CTX_start(ctx);
    if ((a = BN_CTX_get(ctx)) == NULL)
        goto err;
    if (y != NULL) {
        if (x == y) {
            if (!BN_sqr(a, x, ctx))
                goto err;
        } else {
            if (!BN_mul(a, x, y, ctx))
                goto err;
        }
        ca = a;
    } else
        ca = x;                 /* Just do the mod */

    ret = BN_div_recp(NULL, r, ca, recp, ctx);
 err:
    BN_CTX_end(ctx);
    bn_check_top(r);
    return (ret);
}

int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
                BN_RECP_CTX *recp, BN_CTX *ctx)
{
    int i, j, ret = 0;
    BIGNUM *a, *b, *d, *r;

    BN_CTX_start(ctx);
    a = BN_CTX_get(ctx);
    b = BN_CTX_get(ctx);
    if (dv != NULL)
        d = dv;
    else
        d = BN_CTX_get(ctx);
    if (rem != NULL)
        r = rem;
    else
        r = BN_CTX_get(ctx);
    if (a == NULL || b == NULL || d == NULL || r == NULL)
        goto err;

    if (BN_ucmp(m, &(recp->N)) < 0) {
        BN_zero(d);
        if (!BN_copy(r, m)) {
            BN_CTX_end(ctx);
            return 0;
        }
        BN_CTX_end(ctx);
        return (1);
    }

    /*
     * We want the remainder Given input of ABCDEF / ab we need multiply
     * ABCDEF by 3 digests of the reciprocal of ab
     */

    /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */
    i = BN_num_bits(m);
    j = recp->num_bits << 1;
    if (j > i)
        i = j;

    /* Nr := round(2^i / N) */
    if (i != recp->shift)
        recp->shift = BN_reciprocal(&(recp->Nr), &(recp->N), i, ctx);
    /* BN_reciprocal could have returned -1 for an error */
    if (recp->shift == -1)
        goto err;

    /*-
     * d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
     *    = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
     *   <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
     *    = |m/N|
     */
    if (!BN_rshift(a, m, recp->num_bits))
        goto err;
    if (!BN_mul(b, a, &(recp->Nr), ctx))
        goto err;
    if (!BN_rshift(d, b, i - recp->num_bits))
        goto err;
    d->neg = 0;

    if (!BN_mul(b, &(recp->N), d, ctx))
        goto err;
    if (!BN_usub(r, m, b))
        goto err;
    r->neg = 0;

#if 1
    j = 0;
    while (BN_ucmp(r, &(recp->N)) >= 0) {
        if (j++ > 2) {
            BNerr(BN_F_BN_DIV_RECP, BN_R_BAD_RECIPROCAL);
            goto err;
        }
        if (!BN_usub(r, r, &(recp->N)))
            goto err;
        if (!BN_add_word(d, 1))
            goto err;
    }
#endif

    r->neg = BN_is_zero(r) ? 0 : m->neg;
    d->neg = m->neg ^ recp->N.neg;
    ret = 1;
 err:
    BN_CTX_end(ctx);
    bn_check_top(dv);
    bn_check_top(rem);
    return (ret);
}

/*
 * len is the expected size of the result We actually calculate with an extra
 * word of precision, so we can do faster division if the remainder is not
 * required.
 */
/* r := 2^len / m */
int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
{
    int ret = -1;
    BIGNUM *t;

    BN_CTX_start(ctx);
    if ((t = BN_CTX_get(ctx)) == NULL)
        goto err;

    if (!BN_set_bit(t, len))
        goto err;

    if (!BN_div(r, NULL, t, m, ctx))
        goto err;

    ret = len;
 err:
    bn_check_top(r);
    BN_CTX_end(ctx);
    return (ret);
}
Revision:	7389
Committed:	Sat Dec 5 17:55:33 2015 UTC (8 years, 4 months ago) by laffer1
Content type:	text/plain
File size:	7551 byte(s)
Log Message:	openssl 1.0.1q
#	Content
1	/* crypto/bn/bn_recp.c */
2	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3	* All rights reserved.
4	*
5	* This package is an SSL implementation written
6	* by Eric Young (eay@cryptsoft.com).
7	* The implementation was written so as to conform with Netscapes SSL.
8	*
9	* This library is free for commercial and non-commercial use as long as
10	* the following conditions are aheared to. The following conditions
11	* apply to all code found in this distribution, be it the RC4, RSA,
12	* lhash, DES, etc., code; not just the SSL code. The SSL documentation
13	* included with this distribution is covered by the same copyright terms
14	* except that the holder is Tim Hudson (tjh@cryptsoft.com).
15	*
16	* Copyright remains Eric Young's, and as such any Copyright notices in
17	* the code are not to be removed.
18	* If this package is used in a product, Eric Young should be given attribution
19	* as the author of the parts of the library used.
20	* This can be in the form of a textual message at program startup or
21	* in documentation (online or textual) provided with the package.
22	*
23	* Redistribution and use in source and binary forms, with or without
24	* modification, are permitted provided that the following conditions
25	* are met:
26	* 1. Redistributions of source code must retain the copyright
27	* notice, this list of conditions and the following disclaimer.
28	* 2. Redistributions in binary form must reproduce the above copyright
29	* notice, this list of conditions and the following disclaimer in the
30	* documentation and/or other materials provided with the distribution.
31	* 3. All advertising materials mentioning features or use of this software
32	* must display the following acknowledgement:
33	* "This product includes cryptographic software written by
34	* Eric Young (eay@cryptsoft.com)"
35	* The word 'cryptographic' can be left out if the rouines from the library
36	* being used are not cryptographic related :-).
37	* 4. If you include any Windows specific code (or a derivative thereof) from
38	* the apps directory (application code) you must include an acknowledgement:
39	* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40	*
41	* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51	* SUCH DAMAGE.
52	*
53	* The licence and distribution terms for any publically available version or
54	* derivative of this code cannot be changed. i.e. this code cannot simply be
55	* copied and put under another distribution licence
56	* [including the GNU Public Licence.]
57	*/
58
59	#include <stdio.h>
60	#include "cryptlib.h"
61	#include "bn_lcl.h"
62
63	void BN_RECP_CTX_init(BN_RECP_CTX *recp)
64	{
65	BN_init(&(recp->N));
66	BN_init(&(recp->Nr));
67	recp->num_bits = 0;
68	recp->flags = 0;
69	}
70
71	BN_RECP_CTX *BN_RECP_CTX_new(void)
72	{
73	BN_RECP_CTX *ret;
74
75	if ((ret = (BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
76	return (NULL);
77
78	BN_RECP_CTX_init(ret);
79	ret->flags = BN_FLG_MALLOCED;
80	return (ret);
81	}
82
83	void BN_RECP_CTX_free(BN_RECP_CTX *recp)
84	{
85	if (recp == NULL)
86	return;
87
88	BN_free(&(recp->N));
89	BN_free(&(recp->Nr));
90	if (recp->flags & BN_FLG_MALLOCED)
91	OPENSSL_free(recp);
92	}
93
94	int BN_RECP_CTX_set(BN_RECP_CTX recp, const BIGNUM d, BN_CTX *ctx)
95	{
96	if (!BN_copy(&(recp->N), d))
97	return 0;
98	BN_zero(&(recp->Nr));
99	recp->num_bits = BN_num_bits(d);
100	recp->shift = 0;
101	return (1);
102	}
103
104	int BN_mod_mul_reciprocal(BIGNUM r, const BIGNUM x, const BIGNUM *y,
105	BN_RECP_CTX recp, BN_CTX ctx)
106	{
107	int ret = 0;
108	BIGNUM *a;
109	const BIGNUM *ca;
110
111	BN_CTX_start(ctx);
112	if ((a = BN_CTX_get(ctx)) == NULL)
113	goto err;
114	if (y != NULL) {
115	if (x == y) {
116	if (!BN_sqr(a, x, ctx))
117	goto err;
118	} else {
119	if (!BN_mul(a, x, y, ctx))
120	goto err;
121	}
122	ca = a;
123	} else
124	ca = x; /* Just do the mod */
125
126	ret = BN_div_recp(NULL, r, ca, recp, ctx);
127	err:
128	BN_CTX_end(ctx);
129	bn_check_top(r);
130	return (ret);
131	}
132
133	int BN_div_recp(BIGNUM dv, BIGNUM rem, const BIGNUM *m,
134	BN_RECP_CTX recp, BN_CTX ctx)
135	{
136	int i, j, ret = 0;
137	BIGNUM a, b, d, r;
138
139	BN_CTX_start(ctx);
140	a = BN_CTX_get(ctx);
141	b = BN_CTX_get(ctx);
142	if (dv != NULL)
143	d = dv;
144	else
145	d = BN_CTX_get(ctx);
146	if (rem != NULL)
147	r = rem;
148	else
149	r = BN_CTX_get(ctx);
150	if (a == NULL \|\| b == NULL \|\| d == NULL \|\| r == NULL)
151	goto err;
152
153	if (BN_ucmp(m, &(recp->N)) < 0) {
154	BN_zero(d);
155	if (!BN_copy(r, m)) {
156	BN_CTX_end(ctx);
157	return 0;
158	}
159	BN_CTX_end(ctx);
160	return (1);
161	}
162
163	/*
164	* We want the remainder Given input of ABCDEF / ab we need multiply
165	* ABCDEF by 3 digests of the reciprocal of ab
166	*/
167
168	/* i := max(BN_num_bits(m), 2BN_num_bits(N)) /
169	i = BN_num_bits(m);
170	j = recp->num_bits << 1;
171	if (j > i)
172	i = j;
173
174	/* Nr := round(2^i / N) */
175	if (i != recp->shift)
176	recp->shift = BN_reciprocal(&(recp->Nr), &(recp->N), i, ctx);
177	/* BN_reciprocal could have returned -1 for an error */
178	if (recp->shift == -1)
179	goto err;
180
181	/*-
182	* d := \|round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))\|
183	* = \|round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))\|
184	* <= \|(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)\|
185	* = \|m/N\|
186	*/
187	if (!BN_rshift(a, m, recp->num_bits))
188	goto err;
189	if (!BN_mul(b, a, &(recp->Nr), ctx))
190	goto err;
191	if (!BN_rshift(d, b, i - recp->num_bits))
192	goto err;
193	d->neg = 0;
194
195	if (!BN_mul(b, &(recp->N), d, ctx))
196	goto err;
197	if (!BN_usub(r, m, b))
198	goto err;
199	r->neg = 0;
200
201	#if 1
202	j = 0;
203	while (BN_ucmp(r, &(recp->N)) >= 0) {
204	if (j++ > 2) {
205	BNerr(BN_F_BN_DIV_RECP, BN_R_BAD_RECIPROCAL);
206	goto err;
207	}
208	if (!BN_usub(r, r, &(recp->N)))
209	goto err;
210	if (!BN_add_word(d, 1))
211	goto err;
212	}
213	#endif
214
215	r->neg = BN_is_zero(r) ? 0 : m->neg;
216	d->neg = m->neg ^ recp->N.neg;
217	ret = 1;
218	err:
219	BN_CTX_end(ctx);
220	bn_check_top(dv);
221	bn_check_top(rem);
222	return (ret);
223	}
224
225	/*
226	* len is the expected size of the result We actually calculate with an extra
227	* word of precision, so we can do faster division if the remainder is not
228	* required.
229	*/
230	/* r := 2^len / m */
231	int BN_reciprocal(BIGNUM r, const BIGNUM m, int len, BN_CTX *ctx)
232	{
233	int ret = -1;
234	BIGNUM *t;
235
236	BN_CTX_start(ctx);
237	if ((t = BN_CTX_get(ctx)) == NULL)
238	goto err;
239
240	if (!BN_set_bit(t, len))
241	goto err;
242
243	if (!BN_div(r, NULL, t, m, ctx))
244	goto err;
245
246	ret = len;
247	err:
248	bn_check_top(r);
249	BN_CTX_end(ctx);
250	return (ret);
251	}