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      1 /* crypto/asn1/a_int.c */
      2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      3  * All rights reserved.
      4  *
      5  * This package is an SSL implementation written
      6  * by Eric Young (eay (at) 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 (at) 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 (at) 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 (at) 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 #include <openssl/bn.h>
     63 
     64 ASN1_INTEGER *ASN1_INTEGER_dup(const ASN1_INTEGER *x)
     65 { return M_ASN1_INTEGER_dup(x);}
     66 
     67 int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y)
     68 	{
     69 	int neg, ret;
     70 	/* Compare signs */
     71 	neg = x->type & V_ASN1_NEG;
     72 	if (neg != (y->type & V_ASN1_NEG))
     73 		{
     74 		if (neg)
     75 			return -1;
     76 		else
     77 			return 1;
     78 		}
     79 
     80 	ret = ASN1_STRING_cmp(x, y);
     81 
     82 	if (neg)
     83 		return -ret;
     84 	else
     85 		return ret;
     86 	}
     87 
     88 
     89 /*
     90  * This converts an ASN1 INTEGER into its content encoding.
     91  * The internal representation is an ASN1_STRING whose data is a big endian
     92  * representation of the value, ignoring the sign. The sign is determined by
     93  * the type: V_ASN1_INTEGER for positive and V_ASN1_NEG_INTEGER for negative.
     94  *
     95  * Positive integers are no problem: they are almost the same as the DER
     96  * encoding, except if the first byte is >= 0x80 we need to add a zero pad.
     97  *
     98  * Negative integers are a bit trickier...
     99  * The DER representation of negative integers is in 2s complement form.
    100  * The internal form is converted by complementing each octet and finally
    101  * adding one to the result. This can be done less messily with a little trick.
    102  * If the internal form has trailing zeroes then they will become FF by the
    103  * complement and 0 by the add one (due to carry) so just copy as many trailing
    104  * zeros to the destination as there are in the source. The carry will add one
    105  * to the last none zero octet: so complement this octet and add one and finally
    106  * complement any left over until you get to the start of the string.
    107  *
    108  * Padding is a little trickier too. If the first bytes is > 0x80 then we pad
    109  * with 0xff. However if the first byte is 0x80 and one of the following bytes
    110  * is non-zero we pad with 0xff. The reason for this distinction is that 0x80
    111  * followed by optional zeros isn't padded.
    112  */
    113 
    114 int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
    115 	{
    116 	int pad=0,ret,i,neg;
    117 	unsigned char *p,*n,pb=0;
    118 
    119 	if ((a == NULL) || (a->data == NULL)) return(0);
    120 	neg=a->type & V_ASN1_NEG;
    121 	if (a->length == 0)
    122 		ret=1;
    123 	else
    124 		{
    125 		ret=a->length;
    126 		i=a->data[0];
    127 		if (!neg && (i > 127)) {
    128 			pad=1;
    129 			pb=0;
    130 		} else if(neg) {
    131 			if(i>128) {
    132 				pad=1;
    133 				pb=0xFF;
    134 			} else if(i == 128) {
    135 			/*
    136 			 * Special case: if any other bytes non zero we pad:
    137 			 * otherwise we don't.
    138 			 */
    139 				for(i = 1; i < a->length; i++) if(a->data[i]) {
    140 						pad=1;
    141 						pb=0xFF;
    142 						break;
    143 				}
    144 			}
    145 		}
    146 		ret+=pad;
    147 		}
    148 	if (pp == NULL) return(ret);
    149 	p= *pp;
    150 
    151 	if (pad) *(p++)=pb;
    152 	if (a->length == 0) *(p++)=0;
    153 	else if (!neg) memcpy(p,a->data,(unsigned int)a->length);
    154 	else {
    155 		/* Begin at the end of the encoding */
    156 		n=a->data + a->length - 1;
    157 		p += a->length - 1;
    158 		i = a->length;
    159 		/* Copy zeros to destination as long as source is zero */
    160 		while(!*n) {
    161 			*(p--) = 0;
    162 			n--;
    163 			i--;
    164 		}
    165 		/* Complement and increment next octet */
    166 		*(p--) = ((*(n--)) ^ 0xff) + 1;
    167 		i--;
    168 		/* Complement any octets left */
    169 		for(;i > 0; i--) *(p--) = *(n--) ^ 0xff;
    170 	}
    171 
    172 	*pp+=ret;
    173 	return(ret);
    174 	}
    175 
    176 /* Convert just ASN1 INTEGER content octets to ASN1_INTEGER structure */
    177 
    178 ASN1_INTEGER *c2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **pp,
    179 	     long len)
    180 	{
    181 	ASN1_INTEGER *ret=NULL;
    182 	const unsigned char *p, *pend;
    183 	unsigned char *to,*s;
    184 	int i;
    185 
    186 	if ((a == NULL) || ((*a) == NULL))
    187 		{
    188 		if ((ret=M_ASN1_INTEGER_new()) == NULL) return(NULL);
    189 		ret->type=V_ASN1_INTEGER;
    190 		}
    191 	else
    192 		ret=(*a);
    193 
    194 	p= *pp;
    195 	pend = p + len;
    196 
    197 	/* We must OPENSSL_malloc stuff, even for 0 bytes otherwise it
    198 	 * signifies a missing NULL parameter. */
    199 	s=(unsigned char *)OPENSSL_malloc((int)len+1);
    200 	if (s == NULL)
    201 		{
    202 		i=ERR_R_MALLOC_FAILURE;
    203 		goto err;
    204 		}
    205 	to=s;
    206 	if(!len) {
    207 		/* Strictly speaking this is an illegal INTEGER but we
    208 		 * tolerate it.
    209 		 */
    210 		ret->type=V_ASN1_INTEGER;
    211 	} else if (*p & 0x80) /* a negative number */
    212 		{
    213 		ret->type=V_ASN1_NEG_INTEGER;
    214 		if ((*p == 0xff) && (len != 1)) {
    215 			p++;
    216 			len--;
    217 		}
    218 		i = len;
    219 		p += i - 1;
    220 		to += i - 1;
    221 		while((!*p) && i) {
    222 			*(to--) = 0;
    223 			i--;
    224 			p--;
    225 		}
    226 		/* Special case: if all zeros then the number will be of
    227 		 * the form FF followed by n zero bytes: this corresponds to
    228 		 * 1 followed by n zero bytes. We've already written n zeros
    229 		 * so we just append an extra one and set the first byte to
    230 		 * a 1. This is treated separately because it is the only case
    231 		 * where the number of bytes is larger than len.
    232 		 */
    233 		if(!i) {
    234 			*s = 1;
    235 			s[len] = 0;
    236 			len++;
    237 		} else {
    238 			*(to--) = (*(p--) ^ 0xff) + 1;
    239 			i--;
    240 			for(;i > 0; i--) *(to--) = *(p--) ^ 0xff;
    241 		}
    242 	} else {
    243 		ret->type=V_ASN1_INTEGER;
    244 		if ((*p == 0) && (len != 1))
    245 			{
    246 			p++;
    247 			len--;
    248 			}
    249 		memcpy(s,p,(int)len);
    250 	}
    251 
    252 	if (ret->data != NULL) OPENSSL_free(ret->data);
    253 	ret->data=s;
    254 	ret->length=(int)len;
    255 	if (a != NULL) (*a)=ret;
    256 	*pp=pend;
    257 	return(ret);
    258 err:
    259 	ASN1err(ASN1_F_C2I_ASN1_INTEGER,i);
    260 	if ((ret != NULL) && ((a == NULL) || (*a != ret)))
    261 		M_ASN1_INTEGER_free(ret);
    262 	return(NULL);
    263 	}
    264 
    265 
    266 /* This is a version of d2i_ASN1_INTEGER that ignores the sign bit of
    267  * ASN1 integers: some broken software can encode a positive INTEGER
    268  * with its MSB set as negative (it doesn't add a padding zero).
    269  */
    270 
    271 ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp,
    272 	     long length)
    273 	{
    274 	ASN1_INTEGER *ret=NULL;
    275 	const unsigned char *p;
    276 	unsigned char *to,*s;
    277 	long len;
    278 	int inf,tag,xclass;
    279 	int i;
    280 
    281 	if ((a == NULL) || ((*a) == NULL))
    282 		{
    283 		if ((ret=M_ASN1_INTEGER_new()) == NULL) return(NULL);
    284 		ret->type=V_ASN1_INTEGER;
    285 		}
    286 	else
    287 		ret=(*a);
    288 
    289 	p= *pp;
    290 	inf=ASN1_get_object(&p,&len,&tag,&xclass,length);
    291 	if (inf & 0x80)
    292 		{
    293 		i=ASN1_R_BAD_OBJECT_HEADER;
    294 		goto err;
    295 		}
    296 
    297 	if (tag != V_ASN1_INTEGER)
    298 		{
    299 		i=ASN1_R_EXPECTING_AN_INTEGER;
    300 		goto err;
    301 		}
    302 
    303 	/* We must OPENSSL_malloc stuff, even for 0 bytes otherwise it
    304 	 * signifies a missing NULL parameter. */
    305 	s=(unsigned char *)OPENSSL_malloc((int)len+1);
    306 	if (s == NULL)
    307 		{
    308 		i=ERR_R_MALLOC_FAILURE;
    309 		goto err;
    310 		}
    311 	to=s;
    312 	ret->type=V_ASN1_INTEGER;
    313 	if(len) {
    314 		if ((*p == 0) && (len != 1))
    315 			{
    316 			p++;
    317 			len--;
    318 			}
    319 		memcpy(s,p,(int)len);
    320 		p+=len;
    321 	}
    322 
    323 	if (ret->data != NULL) OPENSSL_free(ret->data);
    324 	ret->data=s;
    325 	ret->length=(int)len;
    326 	if (a != NULL) (*a)=ret;
    327 	*pp=p;
    328 	return(ret);
    329 err:
    330 	ASN1err(ASN1_F_D2I_ASN1_UINTEGER,i);
    331 	if ((ret != NULL) && ((a == NULL) || (*a != ret)))
    332 		M_ASN1_INTEGER_free(ret);
    333 	return(NULL);
    334 	}
    335 
    336 int ASN1_INTEGER_set(ASN1_INTEGER *a, long v)
    337 	{
    338 	int j,k;
    339 	unsigned int i;
    340 	unsigned char buf[sizeof(long)+1];
    341 	long d;
    342 
    343 	a->type=V_ASN1_INTEGER;
    344 	if (a->length < (int)(sizeof(long)+1))
    345 		{
    346 		if (a->data != NULL)
    347 			OPENSSL_free(a->data);
    348 		if ((a->data=(unsigned char *)OPENSSL_malloc(sizeof(long)+1)) != NULL)
    349 			memset((char *)a->data,0,sizeof(long)+1);
    350 		}
    351 	if (a->data == NULL)
    352 		{
    353 		ASN1err(ASN1_F_ASN1_INTEGER_SET,ERR_R_MALLOC_FAILURE);
    354 		return(0);
    355 		}
    356 	d=v;
    357 	if (d < 0)
    358 		{
    359 		d= -d;
    360 		a->type=V_ASN1_NEG_INTEGER;
    361 		}
    362 
    363 	for (i=0; i<sizeof(long); i++)
    364 		{
    365 		if (d == 0) break;
    366 		buf[i]=(int)d&0xff;
    367 		d>>=8;
    368 		}
    369 	j=0;
    370 	for (k=i-1; k >=0; k--)
    371 		a->data[j++]=buf[k];
    372 	a->length=j;
    373 	return(1);
    374 	}
    375 
    376 long ASN1_INTEGER_get(const ASN1_INTEGER *a)
    377 	{
    378 	int neg=0,i;
    379 	long r=0;
    380 
    381 	if (a == NULL) return(0L);
    382 	i=a->type;
    383 	if (i == V_ASN1_NEG_INTEGER)
    384 		neg=1;
    385 	else if (i != V_ASN1_INTEGER)
    386 		return -1;
    387 
    388 	if (a->length > (int)sizeof(long))
    389 		{
    390 		/* hmm... a bit ugly */
    391 		return(0xffffffffL);
    392 		}
    393 	if (a->data == NULL)
    394 		return 0;
    395 
    396 	for (i=0; i<a->length; i++)
    397 		{
    398 		r<<=8;
    399 		r|=(unsigned char)a->data[i];
    400 		}
    401 	if (neg) r= -r;
    402 	return(r);
    403 	}
    404 
    405 ASN1_INTEGER *BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai)
    406 	{
    407 	ASN1_INTEGER *ret;
    408 	int len,j;
    409 
    410 	if (ai == NULL)
    411 		ret=M_ASN1_INTEGER_new();
    412 	else
    413 		ret=ai;
    414 	if (ret == NULL)
    415 		{
    416 		ASN1err(ASN1_F_BN_TO_ASN1_INTEGER,ERR_R_NESTED_ASN1_ERROR);
    417 		goto err;
    418 		}
    419 	if (BN_is_negative(bn))
    420 		ret->type = V_ASN1_NEG_INTEGER;
    421 	else ret->type=V_ASN1_INTEGER;
    422 	j=BN_num_bits(bn);
    423 	len=((j == 0)?0:((j/8)+1));
    424 	if (ret->length < len+4)
    425 		{
    426 		unsigned char *new_data=OPENSSL_realloc(ret->data, len+4);
    427 		if (!new_data)
    428 			{
    429 			ASN1err(ASN1_F_BN_TO_ASN1_INTEGER,ERR_R_MALLOC_FAILURE);
    430 			goto err;
    431 			}
    432 		ret->data=new_data;
    433 		}
    434 	ret->length=BN_bn2bin(bn,ret->data);
    435 	/* Correct zero case */
    436 	if(!ret->length)
    437 		{
    438 		ret->data[0] = 0;
    439 		ret->length = 1;
    440 		}
    441 	return(ret);
    442 err:
    443 	if (ret != ai) M_ASN1_INTEGER_free(ret);
    444 	return(NULL);
    445 	}
    446 
    447 BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn)
    448 	{
    449 	BIGNUM *ret;
    450 
    451 	if ((ret=BN_bin2bn(ai->data,ai->length,bn)) == NULL)
    452 		ASN1err(ASN1_F_ASN1_INTEGER_TO_BN,ASN1_R_BN_LIB);
    453 	else if(ai->type == V_ASN1_NEG_INTEGER)
    454 		BN_set_negative(ret, 1);
    455 	return(ret);
    456 	}
    457 
    458 IMPLEMENT_STACK_OF(ASN1_INTEGER)
    459 IMPLEMENT_ASN1_SET_OF(ASN1_INTEGER)
    460