[apple/security.git] / libsecurity_apple_csp / open_ssl / bn / bn_gcd.c

/*
 * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
 * 
 * The contents of this file constitute Original Code as defined in and are
 * subject to the Apple Public Source License Version 1.2 (the 'License').
 * You may not use this file except in compliance with the License. Please obtain
 * a copy of the License at http://www.apple.com/publicsource and read it before
 * using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
 * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
 * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
 * specific language governing rights and limitations under the License.
 */


/* crypto/bn/bn_gcd.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"

static BIGNUM *euclid(BIGNUM *a, BIGNUM *b);

int BN_gcd(BIGNUM *r, BIGNUM *in_a, BIGNUM *in_b, BN_CTX *ctx)
	{
	BIGNUM *a,*b,*t;
	int ret=0;

	bn_check_top(in_a);
	bn_check_top(in_b);

	BN_CTX_start(ctx);
	a = BN_CTX_get(ctx);
	b = BN_CTX_get(ctx);
	if (a == NULL || b == NULL) goto err;

	if (BN_copy(a,in_a) == NULL) goto err;
	if (BN_copy(b,in_b) == NULL) goto err;

	if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; }
	t=euclid(a,b);
	if (t == NULL) goto err;

	if (BN_copy(r,t) == NULL) goto err;
	ret=1;
err:
	BN_CTX_end(ctx);
	return(ret);
	}

static BIGNUM *euclid(BIGNUM *a, BIGNUM *b)
	{
	BIGNUM *t;
	int shifts=0;

	bn_check_top(a);
	bn_check_top(b);

	for (;;)
		{
		if (BN_is_zero(b))
			break;

		if (BN_is_odd(a))
			{
			if (BN_is_odd(b))
				{
				if (!BN_sub(a,a,b)) goto err;
				if (!BN_rshift1(a,a)) goto err;
				if (BN_cmp(a,b) < 0)
					{ t=a; a=b; b=t; }
				}
			else		/* a odd - b even */
				{
				if (!BN_rshift1(b,b)) goto err;
				if (BN_cmp(a,b) < 0)
					{ t=a; a=b; b=t; }
				}
			}
		else			/* a is even */
			{
			if (BN_is_odd(b))
				{
				if (!BN_rshift1(a,a)) goto err;
				if (BN_cmp(a,b) < 0)
					{ t=a; a=b; b=t; }
				}
			else		/* a even - b even */
				{
				if (!BN_rshift1(a,a)) goto err;
				if (!BN_rshift1(b,b)) goto err;
				shifts++;
				}
			}
		}
	if (shifts)
		{
		if (!BN_lshift(a,a,shifts)) goto err;
		}
	return(a);
err:
	return(NULL);
	}

/* solves ax == 1 (mod n) */
BIGNUM *BN_mod_inverse(BIGNUM *in, BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
	{
	BIGNUM *A,*B,*X,*Y,*M,*D,*R=NULL;
	BIGNUM *T,*ret=NULL;
	int sign;

	bn_check_top(a);
	bn_check_top(n);

	BN_CTX_start(ctx);
	A = BN_CTX_get(ctx);
	B = BN_CTX_get(ctx);
	X = BN_CTX_get(ctx);
	D = BN_CTX_get(ctx);
	M = BN_CTX_get(ctx);
	Y = BN_CTX_get(ctx);
	if (Y == NULL) goto err;

	if (in == NULL)
		R=BN_new();
	else
		R=in;
	if (R == NULL) goto err;

	BN_zero(X);
	BN_one(Y);
	if (BN_copy(A,a) == NULL) goto err;
	if (BN_copy(B,n) == NULL) goto err;
	sign=1;

	while (!BN_is_zero(B))
		{
		if (!BN_div(D,M,A,B,ctx)) goto err;
		T=A;
		A=B;
		B=M;
		/* T has a struct, M does not */

		if (!BN_mul(T,D,X,ctx)) goto err;
		if (!BN_add(T,T,Y)) goto err;
		M=Y;
		Y=X;
		X=T;
		sign= -sign;
		}
	if (sign < 0)
		{
		if (!BN_sub(Y,n,Y)) goto err;
		}

	if (BN_is_one(A))
		{ if (!BN_mod(R,Y,n,ctx)) goto err; }
	else
		{
		BNerr(BN_F_BN_MOD_INVERSE,BN_R_NO_INVERSE);
		goto err;
		}
	ret=R;
err:
	if ((ret == NULL) && (in == NULL)) BN_free(R);
	BN_CTX_end(ctx);
	return(ret);
	}
Commit	Line	Data
b1ab9ed8 A	1	/*
	2	* Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
	3	*
	4	* The contents of this file constitute Original Code as defined in and are
	5	* subject to the Apple Public Source License Version 1.2 (the 'License').
	6	* You may not use this file except in compliance with the License. Please obtain
	7	* a copy of the License at http://www.apple.com/publicsource and read it before
	8	* using this file.
	9	*
	10	* This Original Code and all software distributed under the License are
	11	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
	12	* OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
	13	* LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
	14	* PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
	15	* specific language governing rights and limitations under the License.
	16	*/
	17
	18
	19	/* crypto/bn/bn_gcd.c */
	20	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
	21	* All rights reserved.
	22	*
	23	* This package is an SSL implementation written
	24	* by Eric Young (eay@cryptsoft.com).
	25	* The implementation was written so as to conform with Netscapes SSL.
	26	*
	27	* This library is free for commercial and non-commercial use as long as
	28	* the following conditions are aheared to. The following conditions
	29	* apply to all code found in this distribution, be it the RC4, RSA,
	30	* lhash, DES, etc., code; not just the SSL code. The SSL documentation
	31	* included with this distribution is covered by the same copyright terms
	32	* except that the holder is Tim Hudson (tjh@cryptsoft.com).
	33	*
	34	* Copyright remains Eric Young's, and as such any Copyright notices in
	35	* the code are not to be removed.
	36	* If this package is used in a product, Eric Young should be given attribution
	37	* as the author of the parts of the library used.
	38	* This can be in the form of a textual message at program startup or
	39	* in documentation (online or textual) provided with the package.
	40	*
	41	* Redistribution and use in source and binary forms, with or without
	42	* modification, are permitted provided that the following conditions
	43	* are met:
	44	* 1. Redistributions of source code must retain the copyright
	45	* notice, this list of conditions and the following disclaimer.
	46	* 2. Redistributions in binary form must reproduce the above copyright
	47	* notice, this list of conditions and the following disclaimer in the
	48	* documentation and/or other materials provided with the distribution.
	49	* 3. All advertising materials mentioning features or use of this software
	50	* must display the following acknowledgement:
	51	* "This product includes cryptographic software written by
	52	* Eric Young (eay@cryptsoft.com)"
	53	* The word 'cryptographic' can be left out if the rouines from the library
	54	* being used are not cryptographic related :-).
	55	* 4. If you include any Windows specific code (or a derivative thereof) from
	56	* the apps directory (application code) you must include an acknowledgement:
	57	* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
	58	*
	59	* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
	60	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	61	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	62	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	63	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	64	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69	* SUCH DAMAGE.
70	*
71	* The licence and distribution terms for any publically available version or
72	* derivative of this code cannot be changed. i.e. this code cannot simply be
73	* copied and put under another distribution licence
74	* [including the GNU Public Licence.]
75	*/
76
77	#include <stdio.h>
78	#include "cryptlib.h"
79	#include "bn_lcl.h"
80
81	static BIGNUM euclid(BIGNUM a, BIGNUM *b);
82
83	int BN_gcd(BIGNUM r, BIGNUM in_a, BIGNUM in_b, BN_CTX ctx)
84	{
85	BIGNUM a,b,*t;
86	int ret=0;
87
88	bn_check_top(in_a);
89	bn_check_top(in_b);
90
91	BN_CTX_start(ctx);
92	a = BN_CTX_get(ctx);
93	b = BN_CTX_get(ctx);
94	if (a == NULL \|\| b == NULL) goto err;
95
96	if (BN_copy(a,in_a) == NULL) goto err;
97	if (BN_copy(b,in_b) == NULL) goto err;
98
99	if (BN_cmp(a,b) < 0) { t=a; a=b; b=t; }
100	t=euclid(a,b);
101	if (t == NULL) goto err;
102
103	if (BN_copy(r,t) == NULL) goto err;
104	ret=1;
105	err:
106	BN_CTX_end(ctx);
107	return(ret);
108	}
109
110	static BIGNUM euclid(BIGNUM a, BIGNUM *b)
111	{
112	BIGNUM *t;
113	int shifts=0;
114
115	bn_check_top(a);
116	bn_check_top(b);
117
118	for (;;)
119	{
120	if (BN_is_zero(b))
121	break;
122
123	if (BN_is_odd(a))
124	{
125	if (BN_is_odd(b))
126	{
127	if (!BN_sub(a,a,b)) goto err;
128	if (!BN_rshift1(a,a)) goto err;
129	if (BN_cmp(a,b) < 0)
130	{ t=a; a=b; b=t; }
131	}
132	else /* a odd - b even */
133	{
134	if (!BN_rshift1(b,b)) goto err;
135	if (BN_cmp(a,b) < 0)
136	{ t=a; a=b; b=t; }
137	}
138	}
139	else /* a is even */
140	{
141	if (BN_is_odd(b))
142	{
143	if (!BN_rshift1(a,a)) goto err;
144	if (BN_cmp(a,b) < 0)
145	{ t=a; a=b; b=t; }
146	}
147	else /* a even - b even */
148	{
149	if (!BN_rshift1(a,a)) goto err;
150	if (!BN_rshift1(b,b)) goto err;
151	shifts++;
152	}
153	}
154	}
155	if (shifts)
156	{
157	if (!BN_lshift(a,a,shifts)) goto err;
158	}
159	return(a);
160	err:
161	return(NULL);
162	}
163
164	/* solves ax == 1 (mod n) */
165	BIGNUM BN_mod_inverse(BIGNUM in, BIGNUM a, const BIGNUM n, BN_CTX *ctx)
166	{
167	BIGNUM A,B,X,Y,M,D,*R=NULL;
168	BIGNUM T,ret=NULL;
169	int sign;
170
171	bn_check_top(a);
172	bn_check_top(n);
173
174	BN_CTX_start(ctx);
175	A = BN_CTX_get(ctx);
176	B = BN_CTX_get(ctx);
177	X = BN_CTX_get(ctx);
178	D = BN_CTX_get(ctx);
179	M = BN_CTX_get(ctx);
180	Y = BN_CTX_get(ctx);
181	if (Y == NULL) goto err;
182
183	if (in == NULL)
184	R=BN_new();
185	else
186	R=in;
187	if (R == NULL) goto err;
188
189	BN_zero(X);
190	BN_one(Y);
191	if (BN_copy(A,a) == NULL) goto err;
192	if (BN_copy(B,n) == NULL) goto err;
193	sign=1;
194
195	while (!BN_is_zero(B))
196	{
197	if (!BN_div(D,M,A,B,ctx)) goto err;
198	T=A;
199	A=B;
200	B=M;
201	/* T has a struct, M does not */
202
203	if (!BN_mul(T,D,X,ctx)) goto err;
204	if (!BN_add(T,T,Y)) goto err;
205	M=Y;
206	Y=X;
207	X=T;
208	sign= -sign;
209	}
210	if (sign < 0)
211	{
212	if (!BN_sub(Y,n,Y)) goto err;
213	}
214
215	if (BN_is_one(A))
216	{ if (!BN_mod(R,Y,n,ctx)) goto err; }
217	else
218	{
219	BNerr(BN_F_BN_MOD_INVERSE,BN_R_NO_INVERSE);
220	goto err;
221	}
222	ret=R;
223	err:
224	if ((ret == NULL) && (in == NULL)) BN_free(R);
225	BN_CTX_end(ctx);
226	return(ret);
227	}
228