/* 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.com */#include "tomcrypt.h"/**  @file der_encode_object_identifier.c  ASN.1 DER, Encode Object Identifier, Tom St Denis*/#ifdef LTC_DER/**  Encode an OID  @param words   The words to encode  (upto 32-bits each)  @param nwords  The number of words in the OID  @param out     [out] Destination of OID data  @param outlen  [in/out] The max and resulting size of the OID  @return CRYPT_OK if successful*/int der_encode_object_identifier(unsigned long *words, unsigned long  nwords,                                 unsigned char *out,   unsigned long *outlen){   unsigned long i, x, y, z, t, mask, wordbuf;   int           err;   LTC_ARGCHK(words  != NULL);   LTC_ARGCHK(out    != NULL);   LTC_ARGCHK(outlen != NULL);   /* check length */   if ((err = der_length_object_identifier(words, nwords, &x)) != CRYPT_OK) {      return err;   }   if (x > *outlen) {      *outlen = x;      return CRYPT_BUFFER_OVERFLOW;   }   /* compute length to store OID data */   z = 0;   wordbuf = words[0] * 40 + words[1];   for (y = 1; y < nwords; y++) {       t = der_object_identifier_bits(wordbuf);       z += t/7 + ((t%7) ? 1 : 0) + (wordbuf == 0 ? 1 : 0);       if (y < nwords - 1) {          wordbuf = words[y + 1];       }   }   /* store header + length */   x = 0;    out[x++] = 0x06;   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>>8)&255);      out[x++] = (unsigned char)(z&255);   } else {      return CRYPT_INVALID_ARG;   }   /* store first byte */    wordbuf = words[0] * 40 + words[1];       for (i = 1; i < nwords; i++) {        /* store 7 bit words in little endian */        t    = wordbuf & 0xFFFFFFFF;        if (t) {           y    = x;           mask = 0;           while (t) {               out[x++] = (unsigned char)((t & 0x7F) | mask);               t    >>= 7;               mask  |= 0x80;  /* upper bit is set on all but the last byte */           }           /* now swap bytes y...x-1 */           z = x - 1;           while (y < z) {               t = out[y]; out[y] = out[z]; out[z] = (unsigned char)t;               ++y;                --z;           }       } else {          /* zero word */          out[x++] = 0x00;       }              if (i < nwords - 1) {          wordbuf = words[i + 1];       }   }   *outlen = x;   return CRYPT_OK;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/object_identifier/der_encode_object_identifier.c,v $ *//* $Revision: 1.6 $ *//* $Date: 2006/12/04 21:34:03 $ */