tomcrypt/src/pk/asn1/der/sequence/der_encode_sequence.c

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
 */
#include "tomcrypt.h"
#include <stdarg.h>


/**
  @file der_encode_sequence.c
  ASN.1 DER, encode a SEQUENCE, Tom St Denis
*/

#ifdef LTC_DER

/**
   Encode a SEQUENCE
   @param list      The list of items to encode
   @param inlen     The number of items in the list
   @param out       [out] The destination 
   @param outlen    [in/out] The size of the output
   @return CRYPT_OK on success
*/
int der_encode_sequence(ltc_asn1_list *list, unsigned long inlen,
                        unsigned char *out,  unsigned long *outlen) 
{
   int           err, type;
   unsigned long size, x, y, z, i;
   void          *data;

   LTC_ARGCHK(list    != NULL);
   LTC_ARGCHK(out     != NULL);
   LTC_ARGCHK(outlen  != NULL);

   /* get size of output that will be required */
   y = 0;
   for (i = 0; i < inlen; i++) {
       type = list[i].type;
       size = list[i].size;
       data = list[i].data;

       if (type == LTC_ASN1_EOL) { 
          break;
       }

       switch (type) {
           case LTC_ASN1_INTEGER:
               if ((err = der_length_integer(data, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_SHORT_INTEGER:
               if ((err = der_length_short_integer(*((unsigned long*)data), &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_BIT_STRING:
               if ((err = der_length_bit_string(size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_OCTET_STRING:
               if ((err = der_length_octet_string(size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_NULL:
               y += 2;
               break;

           case LTC_ASN1_OBJECT_IDENTIFIER:
               if ((err = der_length_object_identifier(data, size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_IA5_STRING:
               if ((err = der_length_ia5_string(data, size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_PRINTABLE_STRING:
               if ((err = der_length_printable_string(data, size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_SEQUENCE:
               if ((err = der_length_sequence(data, size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

          
           default:
               err = CRYPT_INVALID_ARG;
               goto LBL_ERR;
       }
   }

   /* calc header size */
   z = y;
   if (y < 128) {
      y += 2;
   } else if (y < 256) {
      /* 0x30 0x81 LL */
      y += 3;
   } else if (y < 65536UL) {
      /* 0x30 0x82 LL LL */
      y += 4;
   } else if (y < 16777216UL) {
      /* 0x30 0x83 LL LL LL */
      y += 5;
   } else {
      err = CRYPT_INVALID_ARG;
      goto LBL_ERR;
   }

   /* too big ? */
   if (*outlen < y) {
      err = CRYPT_BUFFER_OVERFLOW;
      goto LBL_ERR;
   }

   /* store header */
   x = 0;
   out[x++] = 0x30;
   if (z < 128) {
      out[x++] = z;
   } else if (z < 256) {
      out[x++] = 0x81;
      out[x++] = z;
   } else if (z < 65536UL) {
      out[x++] = 0x82;
      out[x++] = (z>>8UL)&255;
      out[x++] = z&255;
   } else if (z < 16777216UL) {
      out[x++] = 0x83;
      out[x++] = (z>>16UL)&255;
      out[x++] = (z>>8UL)&255;
      out[x++] = z&255;
   }

   /* store data */
   *outlen -= x;
   for (i = 0; i < inlen; i++) {
       type = list[i].type;
       size = list[i].size;
       data = list[i].data;

       if (type == LTC_ASN1_EOL) { 
          break;
       }

       switch (type) {
           case LTC_ASN1_INTEGER:
               z = *outlen;
               if ((err = der_encode_integer(data, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_SHORT_INTEGER:
               z = *outlen;
               if ((err = der_encode_short_integer(*((unsigned long*)data), out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_BIT_STRING:
               z = *outlen;
               if ((err = der_encode_bit_string(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_OCTET_STRING:
               z = *outlen;
               if ((err = der_encode_octet_string(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_NULL:
               out[x++] = 0x05;
               out[x++] = 0x00;
               *outlen -= 2;
               break;

           case LTC_ASN1_OBJECT_IDENTIFIER:
               z = *outlen;
               if ((err = der_encode_object_identifier(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_IA5_STRING:
               z = *outlen;
               if ((err = der_encode_ia5_string(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;
          
           case LTC_ASN1_PRINTABLE_STRING:
               z = *outlen;
               if ((err = der_encode_printable_string(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_SEQUENCE:
               z = *outlen;
               if ((err = der_encode_sequence(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           default:
               err = CRYPT_INVALID_ARG;
               goto LBL_ERR;
       }
   }
   *outlen = x;
   err = CRYPT_OK;   

LBL_ERR:
   return err;
}

#endif