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      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_utf8_string.c
     15   ASN.1 DER, encode a UTF8 STRING, Tom St Denis
     16 */
     17 
     18 
     19 #ifdef LTC_DER
     20 
     21 /**
     22   Store a UTF8 STRING
     23   @param in      The DER encoded UTF8 STRING
     24   @param inlen   The size of the DER UTF8 STRING
     25   @param out     [out] The array of utf8s stored (one per char)
     26   @param outlen  [in/out] The number of utf8s stored
     27   @return CRYPT_OK if successful
     28 */
     29 int der_decode_utf8_string(const unsigned char *in,  unsigned long inlen,
     30                                        wchar_t *out, unsigned long *outlen)
     31 {
     32    wchar_t       tmp;
     33    unsigned long x, y, z, len;
     34 
     35    LTC_ARGCHK(in     != NULL);
     36    LTC_ARGCHK(out    != NULL);
     37    LTC_ARGCHK(outlen != NULL);
     38 
     39    /* must have header at least */
     40    if (inlen < 2) {
     41       return CRYPT_INVALID_PACKET;
     42    }
     43 
     44    /* check for 0x0C */
     45    if ((in[0] & 0x1F) != 0x0C) {
     46       return CRYPT_INVALID_PACKET;
     47    }
     48    x = 1;
     49 
     50    /* decode the length */
     51    if (in[x] & 0x80) {
     52       /* valid # of bytes in length are 1,2,3 */
     53       y = in[x] & 0x7F;
     54       if ((y == 0) || (y > 3) || ((x + y) > inlen)) {
     55          return CRYPT_INVALID_PACKET;
     56       }
     57 
     58       /* read the length in */
     59       len = 0;
     60       ++x;
     61       while (y--) {
     62          len = (len << 8) | in[x++];
     63       }
     64    } else {
     65       len = in[x++] & 0x7F;
     66    }
     67 
     68    if (len + x > inlen) {
     69       return CRYPT_INVALID_PACKET;
     70    }
     71 
     72    /* proceed to decode */
     73    for (y = 0; x < inlen; ) {
     74       /* get first byte */
     75       tmp = in[x++];
     76 
     77       /* count number of bytes */
     78       for (z = 0; (tmp & 0x80) && (z <= 4); z++, tmp = (tmp << 1) & 0xFF);
     79 
     80       if (z > 4 || (x + (z - 1) > inlen)) {
     81          return CRYPT_INVALID_PACKET;
     82       }
     83 
     84       /* decode, grab upper bits */
     85       tmp >>= z;
     86 
     87       /* grab remaining bytes */
     88       if (z > 1) { --z; }
     89       while (z-- != 0) {
     90          if ((in[x] & 0xC0) != 0x80) {
     91             return CRYPT_INVALID_PACKET;
     92          }
     93          tmp = (tmp << 6) | ((wchar_t)in[x++] & 0x3F);
     94       }
     95 
     96       if (y > *outlen) {
     97          *outlen = y;
     98          return CRYPT_BUFFER_OVERFLOW;
     99       }
    100       out[y++] = tmp;
    101    }
    102    *outlen = y;
    103 
    104    return CRYPT_OK;
    105 }
    106 
    107 #endif
    108 
    109 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/utf8/der_decode_utf8_string.c,v $ */
    110 /* $Revision: 1.7 $ */
    111 /* $Date: 2006/11/26 02:27:37 $ */
    112