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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_encode_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 an UTF8 STRING
     23   @param in       The array of UTF8 to store (one per wchar_t)
     24   @param inlen    The number of UTF8 to store
     25   @param out      [out] The destination for the DER encoded UTF8 STRING
     26   @param outlen   [in/out] The max size and resulting size of the DER UTF8 STRING
     27   @return CRYPT_OK if successful
     28 */
     29 int der_encode_utf8_string(const wchar_t *in,  unsigned long inlen,
     30                            unsigned char *out, unsigned long *outlen)
     31 {
     32    unsigned long x, y, len;
     33 
     34    LTC_ARGCHK(in     != NULL);
     35    LTC_ARGCHK(out    != NULL);
     36    LTC_ARGCHK(outlen != NULL);
     37 
     38    /* get the size */
     39    for (x = len = 0; x < inlen; x++) {
     40        if (in[x] < 0 || in[x] > 0x1FFFF) {
     41           return CRYPT_INVALID_ARG;
     42        }
     43        len += der_utf8_charsize(in[x]);
     44    }
     45 
     46    if (len < 128) {
     47       y = 2 + len;
     48    } else if (len < 256) {
     49       y = 3 + len;
     50    } else if (len < 65536UL) {
     51       y = 4 + len;
     52    } else if (len < 16777216UL) {
     53       y = 5 + len;
     54    } else {
     55       return CRYPT_INVALID_ARG;
     56    }
     57 
     58    /* too big? */
     59    if (y > *outlen) {
     60       *outlen = len;
     61       return CRYPT_BUFFER_OVERFLOW;
     62    }
     63 
     64    /* encode the header+len */
     65    x = 0;
     66    out[x++] = 0x0C;
     67    if (len < 128) {
     68       out[x++] = len;
     69    } else if (len < 256) {
     70       out[x++] = 0x81;
     71       out[x++] = len;
     72    } else if (len < 65536UL) {
     73       out[x++] = 0x82;
     74       out[x++] = (len>>8)&255;
     75       out[x++] = len&255;
     76    } else if (len < 16777216UL) {
     77       out[x++] = 0x83;
     78       out[x++] = (len>>16)&255;
     79       out[x++] = (len>>8)&255;
     80       out[x++] = len&255;
     81    } else {
     82       return CRYPT_INVALID_ARG;
     83    }
     84 
     85    /* store UTF8 */
     86    for (y = 0; y < inlen; y++) {
     87        switch (der_utf8_charsize(in[y])) {
     88           case 1: out[x++] = in[y]; break;
     89           case 2: out[x++] = 0xC0 | ((in[y] >> 6) & 0x1F);  out[x++] = 0x80 | (in[y] & 0x3F); break;
     90           case 3: out[x++] = 0xE0 | ((in[y] >> 12) & 0x0F); out[x++] = 0x80 | ((in[y] >> 6) & 0x3F); out[x++] = 0x80 | (in[y] & 0x3F); break;
     91           case 4: out[x++] = 0xF0 | ((in[y] >> 18) & 0x07); out[x++] = 0x80 | ((in[y] >> 12) & 0x3F); out[x++] = 0x80 | ((in[y] >> 6) & 0x3F); out[x++] = 0x80 | (in[y] & 0x3F); break;
     92        }
     93    }
     94 
     95    /* retun length */
     96    *outlen = x;
     97 
     98    return CRYPT_OK;
     99 }
    100 
    101 #endif
    102 
    103 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/utf8/der_encode_utf8_string.c,v $ */
    104 /* $Revision: 1.7 $ */
    105 /* $Date: 2006/12/16 17:41:21 $ */
    106