crypto/asn1/a_int.c

   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 /*
  64  * This converts an ASN1 INTEGER into its DER encoding.
  65  * The internal representation is an ASN1_STRING whose data is a big endian
  66  * representation of the value, ignoring the sign. The sign is determined by
  67  * the type: V_ASN1_INTEGER for positive and V_ASN1_NEG_INTEGER for negative.
  68  *
  69  * Positive integers are no problem: they are almost the same as the DER
  70  * encoding, except if the first byte is >= 0x80 we need to add a zero pad.
  71  *
  72  * Negative integers are a bit trickier...
  73  * The DER representation of negative integers is in 2s complement form.
  74  * The internal form is converted by complementing each octet and finally
  75  * adding one to the result. This can be done less messily with a little trick.
  76  * If the internal form has trailing zeroes then they will become FF by the
  77  * complement and 0 by the add one (due to carry) so just copy as many trailing
  78  * zeros to the destination as there are in the source. The carry will add one
  79  * to the last none zero octet: so complement this octet and add one and finally
  80  * complement any left over until you get to the start of the string.
  81  *
  82  * Padding is a little trickier too. If the first bytes is > 0x80 then we pad
  83  * with 0xff. However if the first byte is 0x80 and one of the following bytes
  84  * is non-zero we pad with 0xff. The reason for this distinction is that 0x80
  85  * followed by optional zeros isn't padded.
  86  */
  87
  88 int i2d_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
  89         {
  90         int pad=0,ret,r,i,t;
  91         unsigned char *p,*n,pb=0;
  92
  93         if ((a == NULL) || (a->data == NULL)) return(0);
  94         t=a->type;
  95         if (a->length == 0)
  96                 ret=1;
  97         else
  98                 {
  99                 ret=a->length;
 100                 i=a->data[0];
 101                 if ((t == V_ASN1_INTEGER) && (i > 127)) {
 102                         pad=1;
 103                         pb=0;
 104                 } else if(t == V_ASN1_NEG_INTEGER) {
 105                         if(i>128) {
 106                                 pad=1;
 107                                 pb=0xFF;
 108                         } else if(i == 128) {
 109                         /*
 110                          * Special case: if any other bytes non zero we pad:
 111                          * otherwise we don't.
 112                          */
 113                                 for(i = 1; i < a->length; i++) if(a->data[i]) {
 114                                                 pad=1;
 115                                                 pb=0xFF;
 116                                                 break;
 117                                 }
 118                         }
 119                 }
 120                 ret+=pad;
 121                 }
 122         r=ASN1_object_size(0,ret,V_ASN1_INTEGER);
 123         if (pp == NULL) return(r);
 124         p= *pp;
 125
 126         ASN1_put_object(&p,0,ret,V_ASN1_INTEGER,V_ASN1_UNIVERSAL);
 127         if (pad) *(p++)=pb;
 128         if (a->length == 0)
 129                 *(p++)=0;
 130         else if (t == V_ASN1_INTEGER)
 131                 {
 132                 memcpy(p,a->data,(unsigned int)a->length);
 133                 p+=a->length;
 134                 }
 135         else {
 136                 /* Begin at the end of the encoding */
 137                 n=a->data + a->length - 1;
 138                 p += a->length - 1;
 139                 i = a->length;
 140                 /* Copy zeros to destination as long as source is zero */
 141                 while(!*n) {
 142                         *(p--) = 0;
 143                         n--;
 144                         i--;
 145                 }
 146                 /* Complement and increment next octet */
 147                 *(p--) = ((*(n--)) ^ 0xff) + 1;
 148                 i--;
 149                 /* Complement any octets left */
 150                 for(;i > 0; i--) *(p--) = *(n--) ^ 0xff;
 151                 p += a->length;
 152         }
 153
 154         *pp=p;
 155         return(r);
 156         }
 157
 158 ASN1_INTEGER *d2i_ASN1_INTEGER(ASN1_INTEGER **a, unsigned char **pp,
 159              long length)
 160         {
 161         ASN1_INTEGER *ret=NULL;
 162         unsigned char *p,*to,*s;
 163         long len;
 164         int inf,tag,xclass;
 165         int i;
 166
 167         if ((a == NULL) || ((*a) == NULL))
 168                 {
 169                 if ((ret=ASN1_INTEGER_new()) == NULL) return(NULL);
 170                 ret->type=V_ASN1_INTEGER;
 171                 }
 172         else
 173                 ret=(*a);
 174
 175         p= *pp;
 176         inf=ASN1_get_object(&p,&len,&tag,&xclass,length);
 177         if (inf & 0x80)
 178                 {
 179                 i=ASN1_R_BAD_OBJECT_HEADER;
 180                 goto err;
 181                 }
 182
 183         if (tag != V_ASN1_INTEGER)
 184                 {
 185                 i=ASN1_R_EXPECTING_AN_INTEGER;
 186                 goto err;
 187                 }
 188
 189         /* We must Malloc stuff, even for 0 bytes otherwise it
 190          * signifies a missing NULL parameter. */
 191         s=(unsigned char *)Malloc((int)len+1);
 192         if (s == NULL)
 193                 {
 194                 i=ERR_R_MALLOC_FAILURE;
 195                 goto err;
 196                 }
 197         to=s;
 198         if (*p & 0x80) /* a negative number */
 199                 {
 200                 ret->type=V_ASN1_NEG_INTEGER;
 201                 if ((*p == 0xff) && (len != 1)) {
 202                         p++;
 203                         len--;
 204                 }
 205                 i = len;
 206                 p += i - 1;
 207                 to += i - 1;
 208                 while((!*p) && i) {
 209                         *(to--) = 0;
 210                         i--;
 211                         p--;
 212                 }
 213                 /* Special case: if all zeros then the number will be of
 214                  * the form FF followed by n zero bytes: this corresponds to
 215                  * 1 followed by n zero bytes. We've already written n zeros
 216                  * so we just append an extra one and set the first byte to
 217                  * a 1. This is treated separately because it is the only case
 218                  * where the number of bytes is larger than len.
 219                  */
 220                 if(!i) {
 221                         *s = 1;
 222                         s[len] = 0;
 223                         p += len;
 224                         len++;
 225                 } else {
 226                         *(to--) = (*(p--) ^ 0xff) + 1;
 227                         i--;
 228                         for(;i > 0; i--) *(to--) = *(p--) ^ 0xff;
 229                         p += len;
 230                 }
 231         } else {
 232                 ret->type=V_ASN1_INTEGER;
 233                 if ((*p == 0) && (len != 1))
 234                         {
 235                         p++;
 236                         len--;
 237                         }
 238                 memcpy(s,p,(int)len);
 239                 p+=len;
 240         }
 241
 242         if (ret->data != NULL) Free((char *)ret->data);
 243         ret->data=s;
 244         ret->length=(int)len;
 245         if (a != NULL) (*a)=ret;
 246         *pp=p;
 247         return(ret);
 248 err:
 249         ASN1err(ASN1_F_D2I_ASN1_INTEGER,i);
 250         if ((ret != NULL) && ((a == NULL) || (*a != ret)))
 251                 ASN1_INTEGER_free(ret);
 252         return(NULL);
 253         }
 254
 255 /* This is a version of d2i_ASN1_INTEGER that ignores the sign bit of
 256  * ASN1 integers: some broken software can encode a positive INTEGER
 257  * with its MSB set as negative (it doesn't add a padding zero).
 258  */
 259
 260 ASN1_INTEGER *d2i_ASN1_UINTEGER(ASN1_INTEGER **a, unsigned char **pp,
 261              long length)
 262         {
 263         ASN1_INTEGER *ret=NULL;
 264         unsigned char *p,*to,*s;
 265         long len;
 266         int inf,tag,xclass;
 267         int i;
 268
 269         if ((a == NULL) || ((*a) == NULL))
 270                 {
 271                 if ((ret=ASN1_INTEGER_new()) == NULL) return(NULL);
 272                 ret->type=V_ASN1_INTEGER;
 273                 }
 274         else
 275                 ret=(*a);
 276
 277         p= *pp;
 278         inf=ASN1_get_object(&p,&len,&tag,&xclass,length);
 279         if (inf & 0x80)
 280                 {
 281                 i=ASN1_R_BAD_OBJECT_HEADER;
 282                 goto err;
 283                 }
 284
 285         if (tag != V_ASN1_INTEGER)
 286                 {
 287                 i=ASN1_R_EXPECTING_AN_INTEGER;
 288                 goto err;
 289                 }
 290
 291         /* We must Malloc stuff, even for 0 bytes otherwise it
 292          * signifies a missing NULL parameter. */
 293         s=(unsigned char *)Malloc((int)len+1);
 294         if (s == NULL)
 295                 {
 296                 i=ERR_R_MALLOC_FAILURE;
 297                 goto err;
 298                 }
 299         to=s;
 300                 ret->type=V_ASN1_INTEGER;
 301                 if ((*p == 0) && (len != 1))
 302                         {
 303                         p++;
 304                         len--;
 305                         }
 306                 memcpy(s,p,(int)len);
 307                 p+=len;
 308
 309         if (ret->data != NULL) Free((char *)ret->data);
 310         ret->data=s;
 311         ret->length=(int)len;
 312         if (a != NULL) (*a)=ret;
 313         *pp=p;
 314         return(ret);
 315 err:
 316         ASN1err(ASN1_F_D2I_ASN1_UINTEGER,i);
 317         if ((ret != NULL) && ((a == NULL) || (*a != ret)))
 318                 ASN1_INTEGER_free(ret);
 319         return(NULL);
 320         }
 321
 322 int ASN1_INTEGER_set(ASN1_INTEGER *a, long v)
 323         {
 324         int i,j,k;
 325         unsigned char buf[sizeof(long)+1];
 326         long d;
 327
 328         a->type=V_ASN1_INTEGER;
 329         if (a->length < (sizeof(long)+1))
 330                 {
 331                 if (a->data != NULL)
 332                         Free((char *)a->data);
 333                 if ((a->data=(unsigned char *)Malloc(sizeof(long)+1)) != NULL)
 334                         memset((char *)a->data,0,sizeof(long)+1);
 335                 }
 336         if (a->data == NULL)
 337                 {
 338                 ASN1err(ASN1_F_ASN1_INTEGER_SET,ERR_R_MALLOC_FAILURE);
 339                 return(0);
 340                 }
 341         d=v;
 342         if (d < 0)
 343                 {
 344                 d= -d;
 345                 a->type=V_ASN1_NEG_INTEGER;
 346                 }
 347
 348         for (i=0; i<sizeof(long); i++)
 349                 {
 350                 if (d == 0) break;
 351                 buf[i]=(int)d&0xff;
 352                 d>>=8;
 353                 }
 354         j=0;
 355         for (k=i-1; k >=0; k--)
 356                 a->data[j++]=buf[k];
 357         a->length=j;
 358         return(1);
 359         }
 360
 361 long ASN1_INTEGER_get(ASN1_INTEGER *a)
 362         {
 363         int neg=0,i;
 364         long r=0;
 365
 366         if (a == NULL) return(0L);
 367         i=a->type;
 368         if (i == V_ASN1_NEG_INTEGER)
 369                 neg=1;
 370         else if (i != V_ASN1_INTEGER)
 371                 return(0);
 372
 373         if (a->length > sizeof(long))
 374                 {
 375                 /* hmm... a bit ugly */
 376                 return(0xffffffffL);
 377                 }
 378         if (a->data == NULL)
 379                 return(0);
 380
 381         for (i=0; i<a->length; i++)
 382                 {
 383                 r<<=8;
 384                 r|=(unsigned char)a->data[i];
 385                 }
 386         if (neg) r= -r;
 387         return(r);
 388         }
 389
 390 ASN1_INTEGER *BN_to_ASN1_INTEGER(BIGNUM *bn, ASN1_INTEGER *ai)
 391         {
 392         ASN1_INTEGER *ret;
 393         int len,j;
 394
 395         if (ai == NULL)
 396                 ret=ASN1_INTEGER_new();
 397         else
 398                 ret=ai;
 399         if (ret == NULL)
 400                 {
 401                 ASN1err(ASN1_F_BN_TO_ASN1_INTEGER,ERR_R_NESTED_ASN1_ERROR);
 402                 goto err;
 403                 }
 404         if(bn->neg) ret->type = V_ASN1_NEG_INTEGER;
 405         else ret->type=V_ASN1_INTEGER;
 406         j=BN_num_bits(bn);
 407         len=((j == 0)?0:((j/8)+1));
 408         ret->data=(unsigned char *)Malloc(len+4);
 409         ret->length=BN_bn2bin(bn,ret->data);
 410         return(ret);
 411 err:
 412         if (ret != ai) ASN1_INTEGER_free(ret);
 413         return(NULL);
 414         }
 415
 416 BIGNUM *ASN1_INTEGER_to_BN(ASN1_INTEGER *ai, BIGNUM *bn)
 417         {
 418         BIGNUM *ret;
 419
 420         if ((ret=BN_bin2bn(ai->data,ai->length,bn)) == NULL)
 421                 ASN1err(ASN1_F_ASN1_INTEGER_TO_BN,ASN1_R_BN_LIB);
 422         if(ai->type == V_ASN1_NEG_INTEGER) bn->neg = 1;
 423         return(ret);
 424         }