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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 
     12 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
     13  *
     14  * All curves taken from NIST recommendation paper of July 1999
     15  * Available at http://csrc.nist.gov/cryptval/dss.htm
     16  */
     17 #include "tomcrypt.h"
     18 
     19 /**
     20   @file ecc_ansi_x963_import.c
     21   ECC Crypto, Tom St Denis
     22 */
     23 
     24 #ifdef MECC
     25 
     26 /** Import an ANSI X9.63 format public key
     27   @param in      The input data to read
     28   @param inlen   The length of the input data
     29   @param key     [out] destination to store imported key \
     30 */
     31 int ecc_ansi_x963_import(const unsigned char *in, unsigned long inlen, ecc_key *key)
     32 {
     33    return ecc_ansi_x963_import_ex(in, inlen, key, NULL);
     34 }
     35 
     36 int ecc_ansi_x963_import_ex(const unsigned char *in, unsigned long inlen, ecc_key *key, ltc_ecc_set_type *dp)
     37 {
     38    int x, err;
     39 
     40    LTC_ARGCHK(in  != NULL);
     41    LTC_ARGCHK(key != NULL);
     42 
     43    /* must be odd */
     44    if ((inlen & 1) == 0) {
     45       return CRYPT_INVALID_ARG;
     46    }
     47 
     48    /* init key */
     49    if (mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL) != CRYPT_OK) {
     50       return CRYPT_MEM;
     51    }
     52 
     53    /* check for 4, 6 or 7 */
     54    if (in[0] != 4 && in[0] != 6 && in[0] != 7) {
     55       err = CRYPT_INVALID_PACKET;
     56       goto error;
     57    }
     58 
     59    /* read data */
     60    if ((err = mp_read_unsigned_bin(key->pubkey.x, (unsigned char *)in+1, (inlen-1)>>1)) != CRYPT_OK) {
     61       goto error;
     62    }
     63 
     64    if ((err = mp_read_unsigned_bin(key->pubkey.y, (unsigned char *)in+1+((inlen-1)>>1), (inlen-1)>>1)) != CRYPT_OK) {
     65       goto error;
     66    }
     67    if ((err = mp_set(key->pubkey.z, 1)) != CRYPT_OK) { goto error; }
     68 
     69    if (dp == NULL) {
     70      /* determine the idx */
     71       for (x = 0; ltc_ecc_sets[x].size != 0; x++) {
     72          if ((unsigned)ltc_ecc_sets[x].size >= ((inlen-1)>>1)) {
     73             break;
     74          }
     75       }
     76       if (ltc_ecc_sets[x].size == 0) {
     77          err = CRYPT_INVALID_PACKET;
     78          goto error;
     79       }
     80       /* set the idx */
     81       key->idx  = x;
     82       key->dp = &ltc_ecc_sets[x];
     83    } else {
     84       if (((inlen-1)>>1) != (unsigned long) dp->size) {
     85          err = CRYPT_INVALID_PACKET;
     86          goto error;
     87       }
     88       key->idx = -1;
     89       key->dp  = dp;
     90    }
     91    key->type = PK_PUBLIC;
     92 
     93    /* we're done */
     94    return CRYPT_OK;
     95 error:
     96    mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL);
     97    return err;
     98 }
     99 
    100 #endif
    101 
    102 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_ansi_x963_import.c,v $ */
    103 /* $Revision: 1.9 $ */
    104 /* $Date: 2006/12/04 22:17:46 $ */
    105