/src/openssl/crypto/bn/bn_add.c

Source (jump to first uncovered line)
/* crypto/bn/bn_add.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"

/* r can == a or b */
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
    const BIGNUM *tmp;
    int a_neg = a->neg, ret;

    bn_check_top(a);
    bn_check_top(b);

    /*-
     *  a +  b      a+b
     *  a + -b      a-b
     * -a +  b      b-a
     * -a + -b      -(a+b)
     */
    if (a_neg ^ b->neg) {
        /* only one is negative */
        if (a_neg) {
            tmp = a;
            a = b;
            b = tmp;
        }

        /* we are now a - b */

        if (BN_ucmp(a, b) < 0) {
            if (!BN_usub(r, b, a))
                return (0);
            r->neg = 1;
        } else {
            if (!BN_usub(r, a, b))
                return (0);
            r->neg = 0;
        }
        return (1);
    }

    ret = BN_uadd(r, a, b);
    r->neg = a_neg;
    bn_check_top(r);
    return ret;
}

/* unsigned add of b to a */
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
    int max, min, dif;
    BN_ULONG *ap, *bp, *rp, carry, t1, t2;
    const BIGNUM *tmp;

    bn_check_top(a);
    bn_check_top(b);

    if (a->top < b->top) {
        tmp = a;
        a = b;
        b = tmp;
    }
    max = a->top;
    min = b->top;
    dif = max - min;

    if (bn_wexpand(r, max + 1) == NULL)
        return 0;

    r->top = max;

    ap = a->d;
    bp = b->d;
    rp = r->d;

    carry = bn_add_words(rp, ap, bp, min);
    rp += min;
    ap += min;
    bp += min;

    if (carry) {
        while (dif) {
            dif--;
            t1 = *(ap++);
            t2 = (t1 + 1) & BN_MASK2;
            *(rp++) = t2;
            if (t2) {
                carry = 0;
                break;
            }
        }
        if (carry) {
            /* carry != 0 => dif == 0 */
            *rp = 1;
            r->top++;
        }
    }
    if (dif && rp != ap)
        while (dif--)
            /* copy remaining words if ap != rp */
            *(rp++) = *(ap++);
    r->neg = 0;
    bn_check_top(r);
    return 1;
}

/* unsigned subtraction of b from a, a must be larger than b. */
int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
    int max, min, dif;
    register BN_ULONG t1, t2, *ap, *bp, *rp;
    int i, carry;
#if defined(IRIX_CC_BUG) && !defined(LINT)
    int dummy;
#endif

    bn_check_top(a);
    bn_check_top(b);

    max = a->top;
    min = b->top;
    dif = max - min;

    if (dif < 0) {              /* hmm... should not be happening */
        BNerr(BN_F_BN_USUB, BN_R_ARG2_LT_ARG3);
        return (0);
    }

    if (bn_wexpand(r, max) == NULL)
        return (0);

    ap = a->d;
    bp = b->d;
    rp = r->d;

#if 1
    carry = 0;
    for (i = min; i != 0; i--) {
        t1 = *(ap++);
        t2 = *(bp++);
        if (carry) {
            carry = (t1 <= t2);
            t1 = (t1 - t2 - 1) & BN_MASK2;
        } else {
            carry = (t1 < t2);
            t1 = (t1 - t2) & BN_MASK2;
        }
# if defined(IRIX_CC_BUG) && !defined(LINT)
        dummy = t1;
# endif
        *(rp++) = t1 & BN_MASK2;
    }
#else
    carry = bn_sub_words(rp, ap, bp, min);
    ap += min;
    bp += min;
    rp += min;
#endif
    if (carry) {                /* subtracted */
        if (!dif)
            /* error: a < b */
            return 0;
        while (dif) {
            dif--;
            t1 = *(ap++);
            t2 = (t1 - 1) & BN_MASK2;
            *(rp++) = t2;
            if (t1)
                break;
        }
    }
#if 0
    memcpy(rp, ap, sizeof(*rp) * (max - i));
#else
    if (rp != ap) {
        for (;;) {
            if (!dif--)
                break;
            rp[0] = ap[0];
            if (!dif--)
                break;
            rp[1] = ap[1];
            if (!dif--)
                break;
            rp[2] = ap[2];
            if (!dif--)
                break;
            rp[3] = ap[3];
            rp += 4;
            ap += 4;
        }
    }
#endif

    r->top = max;
    r->neg = 0;
    bn_correct_top(r);
    return (1);
}

int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
{
    int max;
    int add = 0, neg = 0;
    const BIGNUM *tmp;

    bn_check_top(a);
    bn_check_top(b);

    /*-
     *  a -  b      a-b
     *  a - -b      a+b
     * -a -  b      -(a+b)
     * -a - -b      b-a
     */
    if (a->neg) {
        if (b->neg) {
            tmp = a;
            a = b;
            b = tmp;
        } else {
            add = 1;
            neg = 1;
        }
    } else {
        if (b->neg) {
            add = 1;
            neg = 0;
        }
    }

    if (add) {
        if (!BN_uadd(r, a, b))
            return (0);
        r->neg = neg;
        return (1);
    }

    /* We are actually doing a - b :-) */

    max = (a->top > b->top) ? a->top : b->top;
    if (bn_wexpand(r, max) == NULL)
        return (0);
    if (BN_ucmp(a, b) < 0) {
        if (!BN_usub(r, b, a))
            return (0);
        r->neg = 1;
    } else {
        if (!BN_usub(r, a, b))
            return (0);
        r->neg = 0;
    }
    bn_check_top(r);
    return (1);
}

Coverage Report

Created: 2022-11-30 06:20

Line	Count	Source (jump to first uncovered line)
1		/* crypto/bn/bn_add.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		/* r can == a or b */
64		int BN_add(BIGNUM r, const BIGNUM a, const BIGNUM *b)
65	0	{
66	0	const BIGNUM *tmp;
67	0	int a_neg = a->neg, ret;
68
69	0	bn_check_top(a);
70	0	bn_check_top(b);
71
72		/*-
73		* a + b a+b
74		* a + -b a-b
75		* -a + b b-a
76		* -a + -b -(a+b)
77		*/
78	0	if (a_neg ^ b->neg) {
79		/* only one is negative */
80	0	if (a_neg) {
81	0	tmp = a;
82	0	a = b;
83	0	b = tmp;
84	0	}
85
86		/* we are now a - b */
87
88	0	if (BN_ucmp(a, b) < 0) {
89	0	if (!BN_usub(r, b, a))
90	0	return (0);
91	0	r->neg = 1;
92	0	} else {
93	0	if (!BN_usub(r, a, b))
94	0	return (0);
95	0	r->neg = 0;
96	0	}
97	0	return (1);
98	0	}
99
100	0	ret = BN_uadd(r, a, b);
101	0	r->neg = a_neg;
102	0	bn_check_top(r);
103	0	return ret;
104	0	}
105
106		/* unsigned add of b to a */
107		int BN_uadd(BIGNUM r, const BIGNUM a, const BIGNUM *b)
108	0	{
109	0	int max, min, dif;
110	0	BN_ULONG ap, bp, *rp, carry, t1, t2;
111	0	const BIGNUM *tmp;
112
113	0	bn_check_top(a);
114	0	bn_check_top(b);
115
116	0	if (a->top < b->top) {
117	0	tmp = a;
118	0	a = b;
119	0	b = tmp;
120	0	}
121	0	max = a->top;
122	0	min = b->top;
123	0	dif = max - min;
124
125	0	if (bn_wexpand(r, max + 1) == NULL)
126	0	return 0;
127
128	0	r->top = max;
129
130	0	ap = a->d;
131	0	bp = b->d;
132	0	rp = r->d;
133
134	0	carry = bn_add_words(rp, ap, bp, min);
135	0	rp += min;
136	0	ap += min;
137	0	bp += min;
138
139	0	if (carry) {
140	0	while (dif) {
141	0	dif--;
142	0	t1 = *(ap++);
143	0	t2 = (t1 + 1) & BN_MASK2;
144	0	*(rp++) = t2;
145	0	if (t2) {
146	0	carry = 0;
147	0	break;
148	0	}
149	0	}
150	0	if (carry) {
151		/* carry != 0 => dif == 0 */
152	0	*rp = 1;
153	0	r->top++;
154	0	}
155	0	}
156	0	if (dif && rp != ap)
157	0	while (dif--)
158		/* copy remaining words if ap != rp */
159	0	(rp++) = (ap++);
160	0	r->neg = 0;
161	0	bn_check_top(r);
162	0	return 1;
163	0	}
164
165		/* unsigned subtraction of b from a, a must be larger than b. */
166		int BN_usub(BIGNUM r, const BIGNUM a, const BIGNUM *b)
167	0	{
168	0	int max, min, dif;
169	0	register BN_ULONG t1, t2, ap, bp, *rp;
170	0	int i, carry;
171		#if defined(IRIX_CC_BUG) && !defined(LINT)
172		int dummy;
173		#endif
174
175	0	bn_check_top(a);
176	0	bn_check_top(b);
177
178	0	max = a->top;
179	0	min = b->top;
180	0	dif = max - min;
181
182	0	if (dif < 0) { /* hmm... should not be happening */
183	0	BNerr(BN_F_BN_USUB, BN_R_ARG2_LT_ARG3);
184	0	return (0);
185	0	}
186
187	0	if (bn_wexpand(r, max) == NULL)
188	0	return (0);
189
190	0	ap = a->d;
191	0	bp = b->d;
192	0	rp = r->d;
193
194	0	#if 1
195	0	carry = 0;
196	0	for (i = min; i != 0; i--) {
197	0	t1 = *(ap++);
198	0	t2 = *(bp++);
199	0	if (carry) {
200	0	carry = (t1 <= t2);
201	0	t1 = (t1 - t2 - 1) & BN_MASK2;
202	0	} else {
203	0	carry = (t1 < t2);
204	0	t1 = (t1 - t2) & BN_MASK2;
205	0	}
206		# if defined(IRIX_CC_BUG) && !defined(LINT)
207		dummy = t1;
208		# endif
209	0	*(rp++) = t1 & BN_MASK2;
210	0	}
211		#else
212		carry = bn_sub_words(rp, ap, bp, min);
213		ap += min;
214		bp += min;
215		rp += min;
216		#endif
217	0	if (carry) { /* subtracted */
218	0	if (!dif)
219		/* error: a < b */
220	0	return 0;
221	0	while (dif) {
222	0	dif--;
223	0	t1 = *(ap++);
224	0	t2 = (t1 - 1) & BN_MASK2;
225	0	*(rp++) = t2;
226	0	if (t1)
227	0	break;
228	0	}
229	0	}
230		#if 0
231		memcpy(rp, ap, sizeof(rp) (max - i));
232		#else
233	0	if (rp != ap) {
234	0	for (;;) {
235	0	if (!dif--)
236	0	break;
237	0	rp[0] = ap[0];
238	0	if (!dif--)
239	0	break;
240	0	rp[1] = ap[1];
241	0	if (!dif--)
242	0	break;
243	0	rp[2] = ap[2];
244	0	if (!dif--)
245	0	break;
246	0	rp[3] = ap[3];
247	0	rp += 4;
248	0	ap += 4;
249	0	}
250	0	}
251	0	#endif
252
253	0	r->top = max;
254	0	r->neg = 0;
255	0	bn_correct_top(r);
256	0	return (1);
257	0	}
258
259		int BN_sub(BIGNUM r, const BIGNUM a, const BIGNUM *b)
260	0	{
261	0	int max;
262	0	int add = 0, neg = 0;
263	0	const BIGNUM *tmp;
264
265	0	bn_check_top(a);
266	0	bn_check_top(b);
267
268		/*-
269		* a - b a-b
270		* a - -b a+b
271		* -a - b -(a+b)
272		* -a - -b b-a
273		*/
274	0	if (a->neg) {
275	0	if (b->neg) {
276	0	tmp = a;
277	0	a = b;
278	0	b = tmp;
279	0	} else {
280	0	add = 1;
281	0	neg = 1;
282	0	}
283	0	} else {
284	0	if (b->neg) {
285	0	add = 1;
286	0	neg = 0;
287	0	}
288	0	}
289
290	0	if (add) {
291	0	if (!BN_uadd(r, a, b))
292	0	return (0);
293	0	r->neg = neg;
294	0	return (1);
295	0	}
296
297		/* We are actually doing a - b :-) */
298
299	0	max = (a->top > b->top) ? a->top : b->top;
300	0	if (bn_wexpand(r, max) == NULL)
301	0	return (0);
302	0	if (BN_ucmp(a, b) < 0) {
303	0	if (!BN_usub(r, b, a))
304	0	return (0);
305	0	r->neg = 1;
306	0	} else {
307	0	if (!BN_usub(r, a, b))
308	0	return (0);
309	0	r->neg = 0;
310	0	}
311	0	bn_check_top(r);
312	0	return (1);
313	0	}