Home | History | Annotate | Download | only in object_identifier 
      1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
      2  *
      3  * LibTomCrypt is a library that provides various cryptographic
      4  * algorithms in a highly modular and flexible manner.
      5  *
      6  * The library is free for all purposes without any express
      7  * guarantee it works.
      8  *
      9  * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com
     10  */
     11 #include "tomcrypt.h"
     12 
     13 /**
     14   @file der_decode_object_identifier.c
     15   ASN.1 DER, Decode Object Identifier, Tom St Denis
     16 */
     17 
     18 #ifdef LTC_DER
     19 /**
     20   Decode OID data and store the array of integers in words
     21   @param in      The OID DER encoded data
     22   @param inlen   The length of the OID data
     23   @param words   [out] The destination of the OID words
     24   @param outlen  [in/out] The number of OID words
     25   @return CRYPT_OK if successful
     26 */
     27 int der_decode_object_identifier(const unsigned char *in,    unsigned long  inlen,
     28                                        unsigned long *words, unsigned long *outlen)
     29 {
     30    unsigned long x, y, t, len;
     31 
     32    LTC_ARGCHK(in     != NULL);
     33    LTC_ARGCHK(words  != NULL);
     34    LTC_ARGCHK(outlen != NULL);
     35 
     36    /* header is at least 3 bytes */
     37    if (inlen < 3) {
     38       return CRYPT_INVALID_PACKET;
     39    }
     40 
     41    /* must be room for at least two words */
     42    if (*outlen < 2) {
     43       return CRYPT_BUFFER_OVERFLOW;
     44    }
     45 
     46    /* decode the packet header */
     47    x = 0;
     48    if ((in[x++] & 0x1F) != 0x06) {
     49       return CRYPT_INVALID_PACKET;
     50    }
     51 
     52    /* get the length */
     53    if (in[x] < 128) {
     54       len = in[x++];
     55    } else {
     56        if (in[x] < 0x81 || in[x] > 0x82) {
     57           return CRYPT_INVALID_PACKET;
     58        }
     59        y   = in[x++] & 0x7F;
     60        len = 0;
     61        while (y--) {
     62           len = (len << 8) | (unsigned long)in[x++];
     63        }
     64    }
     65 
     66    if (len < 1 || (len + x) > inlen) {
     67       return CRYPT_INVALID_PACKET;
     68    }
     69 
     70    /* decode words */
     71    y = 0;
     72    t = 0;
     73    while (len--) {
     74        t = (t << 7) | (in[x] & 0x7F);
     75        if (!(in[x++] & 0x80)) {
     76            /* store t */
     77            if (y >= *outlen) {
     78               return CRYPT_BUFFER_OVERFLOW;
     79            }
     80       if (y == 0) {
     81          words[0] = t / 40;
     82          words[1] = t % 40;
     83          y = 2;
     84       } else {
     85               words[y++] = t;
     86       }
     87            t          = 0;
     88        }
     89    }
     90 
     91    *outlen = y;
     92    return CRYPT_OK;
     93 }
     94 
     95 #endif
     96 
     97 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/object_identifier/der_decode_object_identifier.c,v $ */
     98 /* $Revision: 1.5 $ */
     99 /* $Date: 2006/11/21 00:18:23 $ */
    100