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view libtomcrypt/src/pk/asn1/der/sequence/der_encode_sequence_ex.c @ 994:5c5ade336926

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Prefer stronger algorithms in algorithm negotiation. Prefer diffie-hellman-group14-sha1 (2048 bit) over diffie-hellman-group1-sha1 (1024 bit). Due to meet-in-the-middle attacks the effective key length of three key 3DES is 112 bits. AES is stronger and faster then 3DES. Prefer to delay the start of compression until after authentication has completed. This avoids exposing compression code to attacks from unauthenticated users. (github pull request #9)
author Fedor Brunner <fedor.brunner@azet.sk>
date Fri, 23 Jan 2015 23:00:25 +0800
parents 0cbe8f6dbf9e
children f849a5ca2efc
line wrap: on
line source

/* 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, [email protected], http://libtomcrypt.com
 */
#include "tomcrypt.h"
#include <stdarg.h>


/**
  @file der_encode_sequence_ex.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
   @param type_of   LTC_ASN1_SEQUENCE or LTC_ASN1_SET/LTC_ASN1_SETOF
   @return CRYPT_OK on success
*/
int der_encode_sequence_ex(ltc_asn1_list *list, unsigned long inlen,
                           unsigned char *out,  unsigned long *outlen, int type_of) 
{
   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_BOOLEAN:
               if ((err = der_length_boolean(&x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           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_UTF8_STRING:
               if ((err = der_length_utf8_string(data, size, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_UTCTIME:
               if ((err = der_length_utctime(data, &x)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               y += x;
               break;

           case LTC_ASN1_SET:
           case LTC_ASN1_SETOF:
           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) {
      *outlen = y;
      err = CRYPT_BUFFER_OVERFLOW;
      goto LBL_ERR;
   }

   /* store header */
   x = 0;
   out[x++] = (type_of == LTC_ASN1_SEQUENCE) ? 0x30 : 0x31;
      
   if (z < 128) {
      out[x++] = (unsigned char)z;
   } else if (z < 256) {
      out[x++] = 0x81;
      out[x++] = (unsigned char)z;
   } else if (z < 65536UL) {
      out[x++] = 0x82;
      out[x++] = (unsigned char)((z>>8UL)&255);
      out[x++] = (unsigned char)(z&255);
   } else if (z < 16777216UL) {
      out[x++] = 0x83;
      out[x++] = (unsigned char)((z>>16UL)&255);
      out[x++] = (unsigned char)((z>>8UL)&255);
      out[x++] = (unsigned char)(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_BOOLEAN:
               z = *outlen;
               if ((err = der_encode_boolean(*((int *)data), out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;
          
           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_UTF8_STRING:
               z = *outlen;
               if ((err = der_encode_utf8_string(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_UTCTIME:
               z = *outlen;
               if ((err = der_encode_utctime(data, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_SET:
               z = *outlen;
               if ((err = der_encode_set(data, size, out + x, &z)) != CRYPT_OK) {
                  goto LBL_ERR;
               }
               x       += z;
               *outlen -= z;
               break;

           case LTC_ASN1_SETOF:
               z = *outlen;
               if ((err = der_encode_setof(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_ex(data, size, out + x, &z, type)) != 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