Home | History | Annotate | Download | only in octet 
      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_octet_string.c
     15   ASN.1 DER, encode a OCTET STRING, Tom St Denis
     16 */
     17 
     18 
     19 #ifdef LTC_DER
     20 
     21 /**
     22   Store an OCTET STRING
     23   @param in       The array of OCTETS to store (one per char)
     24   @param inlen    The number of OCTETS to store
     25   @param out      [out] The destination for the DER encoded OCTET STRING
     26   @param outlen   [in/out] The max size and resulting size of the DER OCTET STRING
     27   @return CRYPT_OK if successful
     28 */
     29 int der_encode_octet_string(const unsigned char *in, unsigned long inlen,
     30                                   unsigned char *out, unsigned long *outlen)
     31 {
     32    unsigned long x, y, len;
     33    int           err;
     34 
     35    LTC_ARGCHK(in     != NULL);
     36    LTC_ARGCHK(out    != NULL);
     37    LTC_ARGCHK(outlen != NULL);
     38 
     39    /* get the size */
     40    if ((err = der_length_octet_string(inlen, &len)) != CRYPT_OK) {
     41       return err;
     42    }
     43 
     44    /* too big? */
     45    if (len > *outlen) {
     46       *outlen = len;
     47       return CRYPT_BUFFER_OVERFLOW;
     48    }
     49 
     50    /* encode the header+len */
     51    x = 0;
     52    out[x++] = 0x04;
     53    if (inlen < 128) {
     54       out[x++] = (unsigned char)inlen;
     55    } else if (inlen < 256) {
     56       out[x++] = 0x81;
     57       out[x++] = (unsigned char)inlen;
     58    } else if (inlen < 65536UL) {
     59       out[x++] = 0x82;
     60       out[x++] = (unsigned char)((inlen>>8)&255);
     61       out[x++] = (unsigned char)(inlen&255);
     62    } else if (inlen < 16777216UL) {
     63       out[x++] = 0x83;
     64       out[x++] = (unsigned char)((inlen>>16)&255);
     65       out[x++] = (unsigned char)((inlen>>8)&255);
     66       out[x++] = (unsigned char)(inlen&255);
     67    } else {
     68       return CRYPT_INVALID_ARG;
     69    }
     70 
     71    /* store octets */
     72    for (y = 0; y < inlen; y++) {
     73        out[x++] = in[y];
     74    }
     75 
     76    /* retun length */
     77    *outlen = x;
     78 
     79    return CRYPT_OK;
     80 }
     81 
     82 #endif
     83 
     84 /* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/octet/der_encode_octet_string.c,v $ */
     85 /* $Revision: 1.4 $ */
     86 /* $Date: 2006/12/04 21:34:03 $ */
     87