view libtomcrypt/src/pk/ecc/ecc_import.c @ 447:278805938dcf

Patch from Nicolai Ehemann to try binding before going to the background, so that if it exits early (because something's already listening etc) then it will return an exitcode of 1.
author Matt Johnston <matt@ucc.asn.au>
date Thu, 19 Jul 2007 15:54:18 +0000
parents 0cbe8f6dbf9e
children ac2158e3e403
line wrap: on
line source

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, [email protected], http://libtomcrypt.com
 */

/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
 *
 * All curves taken from NIST recommendation paper of July 1999
 * Available at http://csrc.nist.gov/cryptval/dss.htm
 */
#include "tomcrypt.h"

/**
  @file ecc_import.c
  ECC Crypto, Tom St Denis
*/  

#ifdef MECC

static int is_point(ecc_key *key)
{
   void *prime, *b, *t1, *t2;
   int err;
   
   if ((err = mp_init_multi(&prime, &b, &t1, &t2, NULL)) != CRYPT_OK) {
      return err;
   }
   
   /* load prime and b */
   if ((err = mp_read_radix(prime, key->dp->prime, 16)) != CRYPT_OK)                          { goto error; }
   if ((err = mp_read_radix(b, key->dp->B, 16)) != CRYPT_OK)                                  { goto error; }
   
   /* compute y^2 */
   if ((err = mp_sqr(key->pubkey.y, t1)) != CRYPT_OK)                                         { goto error; }
   
   /* compute x^3 */
   if ((err = mp_sqr(key->pubkey.x, t2)) != CRYPT_OK)                                         { goto error; }
   if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK)                                             { goto error; }
   if ((err = mp_mul(key->pubkey.x, t2, t2)) != CRYPT_OK)                                     { goto error; }
   
   /* compute y^2 - x^3 */
   if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK)                                                { goto error; }
   
   /* compute y^2 - x^3 + 3x */
   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
   if ((err = mp_mod(t1, prime, t1)) != CRYPT_OK)                                             { goto error; }
   while (mp_cmp_d(t1, 0) == LTC_MP_LT) {
      if ((err = mp_add(t1, prime, t1)) != CRYPT_OK)                                          { goto error; }
   }
   while (mp_cmp(t1, prime) != LTC_MP_LT) {
      if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK)                                          { goto error; }
   }
   
   /* compare to b */
   if (mp_cmp(t1, b) != LTC_MP_EQ) {
      err = CRYPT_INVALID_PACKET;
   } else {
      err = CRYPT_OK;
   }
   
error:
   mp_clear_multi(prime, b, t1, t2, NULL);
   return err;
}

/**
  Import an ECC key from a binary packet
  @param in      The packet to import
  @param inlen   The length of the packet
  @param key     [out] The destination of the import
  @return CRYPT_OK if successful, upon error all allocated memory will be freed
*/
int ecc_import(const unsigned char *in, unsigned long inlen, ecc_key *key)
{
   return ecc_import_ex(in, inlen, key, NULL);
}

/**
  Import an ECC key from a binary packet, using user supplied domain params rather than one of the NIST ones
  @param in      The packet to import
  @param inlen   The length of the packet
  @param key     [out] The destination of the import
  @param dp      pointer to user supplied params; must be the same as the params used when exporting
  @return CRYPT_OK if successful, upon error all allocated memory will be freed
*/
int ecc_import_ex(const unsigned char *in, unsigned long inlen, ecc_key *key, const ltc_ecc_set_type *dp)
{
   unsigned long key_size;
   unsigned char flags[1];
   int           err;

   LTC_ARGCHK(in  != NULL);
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(ltc_mp.name != NULL);

   /* init key */
   if (mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL) != CRYPT_OK) {
      return CRYPT_MEM;
   }

   /* find out what type of key it is */
   if ((err = der_decode_sequence_multi(in, inlen, 
                                  LTC_ASN1_BIT_STRING, 1UL, &flags,
                                  LTC_ASN1_EOL,        0UL, NULL)) != CRYPT_OK) {
      goto done;
   }


   if (flags[0] == 1) {
      /* private key */
      key->type = PK_PRIVATE;
      if ((err = der_decode_sequence_multi(in, inlen,
                                     LTC_ASN1_BIT_STRING,      1UL, flags,
                                     LTC_ASN1_SHORT_INTEGER,   1UL, &key_size,
                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.x,
                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.y,
                                     LTC_ASN1_INTEGER,         1UL, key->k,
                                     LTC_ASN1_EOL,             0UL, NULL)) != CRYPT_OK) {
         goto done;
      }
   } else {
      /* public key */
      key->type = PK_PUBLIC;
      if ((err = der_decode_sequence_multi(in, inlen,
                                     LTC_ASN1_BIT_STRING,      1UL, flags,
                                     LTC_ASN1_SHORT_INTEGER,   1UL, &key_size,
                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.x,
                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.y,
                                     LTC_ASN1_EOL,             0UL, NULL)) != CRYPT_OK) {
         goto done;
      }
   }

   if (dp == NULL) {
     /* find the idx */
     for (key->idx = 0; ltc_ecc_sets[key->idx].size && (unsigned long)ltc_ecc_sets[key->idx].size != key_size; ++key->idx);
     if (ltc_ecc_sets[key->idx].size == 0) {
       err = CRYPT_INVALID_PACKET;
       goto done;
     }
     key->dp = &ltc_ecc_sets[key->idx];
   } else {
     key->idx = -1;
     key->dp = dp;
   }
   /* set z */
   if ((err = mp_set(key->pubkey.z, 1)) != CRYPT_OK) { goto done; }
   
   /* is it a point on the curve?  */
   if ((err = is_point(key)) != CRYPT_OK) {
      goto done;
   }

   /* we're good */
   return CRYPT_OK;
done:
   mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL);
   return err;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_import.c,v $ */
/* $Revision: 1.11 $ */
/* $Date: 2006/12/04 02:19:48 $ */