xref: /openbsd-src/lib/libcrypto/asn1/a_int.c (revision db3296cf5c1dd9058ceecc3a29fe4aaa0bd26000)
1 /* crypto/asn1/a_int.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 <openssl/asn1.h>
62 
63 ASN1_INTEGER *ASN1_INTEGER_dup(ASN1_INTEGER *x)
64 { return M_ASN1_INTEGER_dup(x);}
65 
66 int ASN1_INTEGER_cmp(ASN1_INTEGER *x, ASN1_INTEGER *y)
67 { return M_ASN1_INTEGER_cmp(x,y);}
68 
69 /*
70  * This converts an ASN1 INTEGER into its content encoding.
71  * The internal representation is an ASN1_STRING whose data is a big endian
72  * representation of the value, ignoring the sign. The sign is determined by
73  * the type: V_ASN1_INTEGER for positive and V_ASN1_NEG_INTEGER for negative.
74  *
75  * Positive integers are no problem: they are almost the same as the DER
76  * encoding, except if the first byte is >= 0x80 we need to add a zero pad.
77  *
78  * Negative integers are a bit trickier...
79  * The DER representation of negative integers is in 2s complement form.
80  * The internal form is converted by complementing each octet and finally
81  * adding one to the result. This can be done less messily with a little trick.
82  * If the internal form has trailing zeroes then they will become FF by the
83  * complement and 0 by the add one (due to carry) so just copy as many trailing
84  * zeros to the destination as there are in the source. The carry will add one
85  * to the last none zero octet: so complement this octet and add one and finally
86  * complement any left over until you get to the start of the string.
87  *
88  * Padding is a little trickier too. If the first bytes is > 0x80 then we pad
89  * with 0xff. However if the first byte is 0x80 and one of the following bytes
90  * is non-zero we pad with 0xff. The reason for this distinction is that 0x80
91  * followed by optional zeros isn't padded.
92  */
93 
94 int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
95 	{
96 	int pad=0,ret,i,neg;
97 	unsigned char *p,*n,pb=0;
98 
99 	if ((a == NULL) || (a->data == NULL)) return(0);
100 	neg=a->type & V_ASN1_NEG;
101 	if (a->length == 0)
102 		ret=1;
103 	else
104 		{
105 		ret=a->length;
106 		i=a->data[0];
107 		if (!neg && (i > 127)) {
108 			pad=1;
109 			pb=0;
110 		} else if(neg) {
111 			if(i>128) {
112 				pad=1;
113 				pb=0xFF;
114 			} else if(i == 128) {
115 			/*
116 			 * Special case: if any other bytes non zero we pad:
117 			 * otherwise we don't.
118 			 */
119 				for(i = 1; i < a->length; i++) if(a->data[i]) {
120 						pad=1;
121 						pb=0xFF;
122 						break;
123 				}
124 			}
125 		}
126 		ret+=pad;
127 		}
128 	if (pp == NULL) return(ret);
129 	p= *pp;
130 
131 	if (pad) *(p++)=pb;
132 	if (a->length == 0) *(p++)=0;
133 	else if (!neg) memcpy(p,a->data,(unsigned int)a->length);
134 	else {
135 		/* Begin at the end of the encoding */
136 		n=a->data + a->length - 1;
137 		p += a->length - 1;
138 		i = a->length;
139 		/* Copy zeros to destination as long as source is zero */
140 		while(!*n) {
141 			*(p--) = 0;
142 			n--;
143 			i--;
144 		}
145 		/* Complement and increment next octet */
146 		*(p--) = ((*(n--)) ^ 0xff) + 1;
147 		i--;
148 		/* Complement any octets left */
149 		for(;i > 0; i--) *(p--) = *(n--) ^ 0xff;
150 	}
151 
152 	*pp+=ret;
153 	return(ret);
154 	}
155 
156 /* Convert just ASN1 INTEGER content octets to ASN1_INTEGER structure */
157 
158 ASN1_INTEGER *c2i_ASN1_INTEGER(ASN1_INTEGER **a, unsigned char **pp,
159 	     long len)
160 	{
161 	ASN1_INTEGER *ret=NULL;
162 	unsigned char *p,*to,*s, *pend;
163 	int i;
164 
165 	if ((a == NULL) || ((*a) == NULL))
166 		{
167 		if ((ret=M_ASN1_INTEGER_new()) == NULL) return(NULL);
168 		ret->type=V_ASN1_INTEGER;
169 		}
170 	else
171 		ret=(*a);
172 
173 	p= *pp;
174 	pend = p + len;
175 
176 	/* We must OPENSSL_malloc stuff, even for 0 bytes otherwise it
177 	 * signifies a missing NULL parameter. */
178 	s=(unsigned char *)OPENSSL_malloc((int)len+1);
179 	if (s == NULL)
180 		{
181 		i=ERR_R_MALLOC_FAILURE;
182 		goto err;
183 		}
184 	to=s;
185 	if(!len) {
186 		/* Strictly speaking this is an illegal INTEGER but we
187 		 * tolerate it.
188 		 */
189 		ret->type=V_ASN1_INTEGER;
190 	} else if (*p & 0x80) /* a negative number */
191 		{
192 		ret->type=V_ASN1_NEG_INTEGER;
193 		if ((*p == 0xff) && (len != 1)) {
194 			p++;
195 			len--;
196 		}
197 		i = len;
198 		p += i - 1;
199 		to += i - 1;
200 		while((!*p) && i) {
201 			*(to--) = 0;
202 			i--;
203 			p--;
204 		}
205 		/* Special case: if all zeros then the number will be of
206 		 * the form FF followed by n zero bytes: this corresponds to
207 		 * 1 followed by n zero bytes. We've already written n zeros
208 		 * so we just append an extra one and set the first byte to
209 		 * a 1. This is treated separately because it is the only case
210 		 * where the number of bytes is larger than len.
211 		 */
212 		if(!i) {
213 			*s = 1;
214 			s[len] = 0;
215 			len++;
216 		} else {
217 			*(to--) = (*(p--) ^ 0xff) + 1;
218 			i--;
219 			for(;i > 0; i--) *(to--) = *(p--) ^ 0xff;
220 		}
221 	} else {
222 		ret->type=V_ASN1_INTEGER;
223 		if ((*p == 0) && (len != 1))
224 			{
225 			p++;
226 			len--;
227 			}
228 		memcpy(s,p,(int)len);
229 	}
230 
231 	if (ret->data != NULL) OPENSSL_free(ret->data);
232 	ret->data=s;
233 	ret->length=(int)len;
234 	if (a != NULL) (*a)=ret;
235 	*pp=pend;
236 	return(ret);
237 err:
238 	ASN1err(ASN1_F_D2I_ASN1_INTEGER,i);
239 	if ((ret != NULL) && ((a == NULL) || (*a != ret)))
240 		M_ASN1_INTEGER_free(ret);
241 	return(NULL);
242 	}
243 
244 
245 /* This is a version of d2i_ASN1_INTEGER that ignores the sign bit of
246  * ASN1 integers: some broken software can encode a positive INTEGER
247  * with its MSB set as negative (it doesn't add a padding zero).
248  */
249 
250 ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, unsigned char **pp,
251 	     long length)
252 	{
253 	ASN1_INTEGER *ret=NULL;
254 	unsigned char *p,*to,*s;
255 	long len;
256 	int inf,tag,xclass;
257 	int i;
258 
259 	if ((a == NULL) || ((*a) == NULL))
260 		{
261 		if ((ret=M_ASN1_INTEGER_new()) == NULL) return(NULL);
262 		ret->type=V_ASN1_INTEGER;
263 		}
264 	else
265 		ret=(*a);
266 
267 	p= *pp;
268 	inf=ASN1_get_object(&p,&len,&tag,&xclass,length);
269 	if (inf & 0x80)
270 		{
271 		i=ASN1_R_BAD_OBJECT_HEADER;
272 		goto err;
273 		}
274 
275 	if (tag != V_ASN1_INTEGER)
276 		{
277 		i=ASN1_R_EXPECTING_AN_INTEGER;
278 		goto err;
279 		}
280 
281 	/* We must OPENSSL_malloc stuff, even for 0 bytes otherwise it
282 	 * signifies a missing NULL parameter. */
283 	s=(unsigned char *)OPENSSL_malloc((int)len+1);
284 	if (s == NULL)
285 		{
286 		i=ERR_R_MALLOC_FAILURE;
287 		goto err;
288 		}
289 	to=s;
290 	ret->type=V_ASN1_INTEGER;
291 	if(len) {
292 		if ((*p == 0) && (len != 1))
293 			{
294 			p++;
295 			len--;
296 			}
297 		memcpy(s,p,(int)len);
298 		p+=len;
299 	}
300 
301 	if (ret->data != NULL) OPENSSL_free(ret->data);
302 	ret->data=s;
303 	ret->length=(int)len;
304 	if (a != NULL) (*a)=ret;
305 	*pp=p;
306 	return(ret);
307 err:
308 	ASN1err(ASN1_F_D2I_ASN1_UINTEGER,i);
309 	if ((ret != NULL) && ((a == NULL) || (*a != ret)))
310 		M_ASN1_INTEGER_free(ret);
311 	return(NULL);
312 	}
313 
314 int ASN1_INTEGER_set(ASN1_INTEGER *a, long v)
315 	{
316 	int i,j,k;
317 	unsigned char buf[sizeof(long)+1];
318 	long d;
319 
320 	a->type=V_ASN1_INTEGER;
321 	if (a->length < (sizeof(long)+1))
322 		{
323 		if (a->data != NULL)
324 			OPENSSL_free(a->data);
325 		if ((a->data=(unsigned char *)OPENSSL_malloc(sizeof(long)+1)) != NULL)
326 			memset((char *)a->data,0,sizeof(long)+1);
327 		}
328 	if (a->data == NULL)
329 		{
330 		ASN1err(ASN1_F_ASN1_INTEGER_SET,ERR_R_MALLOC_FAILURE);
331 		return(0);
332 		}
333 	d=v;
334 	if (d < 0)
335 		{
336 		d= -d;
337 		a->type=V_ASN1_NEG_INTEGER;
338 		}
339 
340 	for (i=0; i<sizeof(long); i++)
341 		{
342 		if (d == 0) break;
343 		buf[i]=(int)d&0xff;
344 		d>>=8;
345 		}
346 	j=0;
347 	for (k=i-1; k >=0; k--)
348 		a->data[j++]=buf[k];
349 	a->length=j;
350 	return(1);
351 	}
352 
353 long ASN1_INTEGER_get(ASN1_INTEGER *a)
354 	{
355 	int neg=0,i;
356 	long r=0;
357 
358 	if (a == NULL) return(0L);
359 	i=a->type;
360 	if (i == V_ASN1_NEG_INTEGER)
361 		neg=1;
362 	else if (i != V_ASN1_INTEGER)
363 		return -1;
364 
365 	if (a->length > sizeof(long))
366 		{
367 		/* hmm... a bit ugly */
368 		return(0xffffffffL);
369 		}
370 	if (a->data == NULL)
371 		return 0;
372 
373 	for (i=0; i<a->length; i++)
374 		{
375 		r<<=8;
376 		r|=(unsigned char)a->data[i];
377 		}
378 	if (neg) r= -r;
379 	return(r);
380 	}
381 
382 ASN1_INTEGER *BN_to_ASN1_INTEGER(BIGNUM *bn, ASN1_INTEGER *ai)
383 	{
384 	ASN1_INTEGER *ret;
385 	int len,j;
386 
387 	if (ai == NULL)
388 		ret=M_ASN1_INTEGER_new();
389 	else
390 		ret=ai;
391 	if (ret == NULL)
392 		{
393 		ASN1err(ASN1_F_BN_TO_ASN1_INTEGER,ERR_R_NESTED_ASN1_ERROR);
394 		goto err;
395 		}
396 	if(bn->neg) ret->type = V_ASN1_NEG_INTEGER;
397 	else ret->type=V_ASN1_INTEGER;
398 	j=BN_num_bits(bn);
399 	len=((j == 0)?0:((j/8)+1));
400 	if (ret->length < len+4)
401 		{
402 		unsigned char *new_data=OPENSSL_realloc(ret->data, len+4);
403 		if (!new_data)
404 			{
405 			ASN1err(ASN1_F_BN_TO_ASN1_INTEGER,ERR_R_MALLOC_FAILURE);
406 			goto err;
407 			}
408 		ret->data=new_data;
409 		}
410 	ret->length=BN_bn2bin(bn,ret->data);
411 	/* Correct zero case */
412 	if(!ret->length)
413 		{
414 		ret->data[0] = 0;
415 		ret->length = 1;
416 		}
417 	return(ret);
418 err:
419 	if (ret != ai) M_ASN1_INTEGER_free(ret);
420 	return(NULL);
421 	}
422 
423 BIGNUM *ASN1_INTEGER_to_BN(ASN1_INTEGER *ai, BIGNUM *bn)
424 	{
425 	BIGNUM *ret;
426 
427 	if ((ret=BN_bin2bn(ai->data,ai->length,bn)) == NULL)
428 		ASN1err(ASN1_F_ASN1_INTEGER_TO_BN,ASN1_R_BN_LIB);
429 	else if(ai->type == V_ASN1_NEG_INTEGER) ret->neg = 1;
430 	return(ret);
431 	}
432 
433 IMPLEMENT_STACK_OF(ASN1_INTEGER)
434 IMPLEMENT_ASN1_SET_OF(ASN1_INTEGER)
435