ecc.c

这是由Rinick编写的加解密函数库。最近找了不少关于加解密的C源码

   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
      return err;
   }

   /* find key size */
   for (x = 0; (keysize > ecc_sets[x].size) && (ecc_sets[x].size != 0); x++);
   keysize = ecc_sets[x].size;

   if (keysize > ECC_MAXSIZE || ecc_sets[x].size == 0) {
      return CRYPT_INVALID_KEYSIZE;
   }
   key->idx = x;

   /* allocate ram */
   base = NULL;
   buf  = XMALLOC(ECC_MAXSIZE);
   if (buf == NULL) {
      return CRYPT_MEM;
   }

   /* make up random string */
   if (prng_descriptor[wprng].read(buf, (unsigned long)keysize, prng) != (unsigned long)keysize) {
      err = CRYPT_ERROR_READPRNG;
      goto LBL_ERR2;
   }

   /* setup the key variables */
   if ((err = mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, &prime, NULL)) != MP_OKAY) {
      err = mpi_to_ltc_error(err);
      goto LBL_ERR;
   }
   base = ecc_new_point();
   if (base == NULL) {
      mp_clear_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, &prime, NULL);
      err = CRYPT_MEM;
      goto LBL_ERR;
   }

   /* read in the specs for this key */
   if ((err = mp_read_radix(&prime, (char *)ecc_sets[key->idx].prime, 64)) != MP_OKAY)      { goto error; }
   if ((err = mp_read_radix(&base->x, (char *)ecc_sets[key->idx].Gx, 64)) != MP_OKAY)       { goto error; }
   if ((err = mp_read_radix(&base->y, (char *)ecc_sets[key->idx].Gy, 64)) != MP_OKAY)       { goto error; }
   mp_set(&base->z, 1);
   if ((err = mp_read_unsigned_bin(&key->k, (unsigned char *)buf, keysize)) != MP_OKAY) { goto error; }

   /* make the public key */
   if ((err = ecc_mulmod(&key->k, base, &key->pubkey, &prime, 1)) != CRYPT_OK)          { goto LBL_ERR; }
   key->type = PK_PRIVATE;

   /* shrink key */
   if ((err = mp_shrink(&key->k)) != MP_OKAY)                                           { goto error; }
   if ((err = mp_shrink(&key->pubkey.x)) != MP_OKAY)                                    { goto error; }
   if ((err = mp_shrink(&key->pubkey.y)) != MP_OKAY)                                    { goto error; }
   if ((err = mp_shrink(&key->pubkey.z)) != MP_OKAY)                                    { goto error; }

   /* free up ram */
   err = CRYPT_OK;
   goto LBL_ERR;
error:
   err = mpi_to_ltc_error(err);
LBL_ERR:
   ecc_del(base);
   mp_clear(&prime);
LBL_ERR2:
#ifdef LTC_CLEAN_STACK
   zeromem(buf, ECC_MAXSIZE);
#endif

   XFREE(buf);

   return err;
}

/**
  Free an ECC key from memory
  @param key   The key you wish to free
*/
void ecc_free(ecc_key *key)
{
   LTC_ARGCHK(key != NULL);
   mp_clear_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL);
}

/**
  Export an ECC key as a binary packet
  @param out     [out] Destination for the key
  @param outlen  [in/out] Max size and resulting size of the exported key
  @param type    The type of key you want to export (PK_PRIVATE or PK_PUBLIC)
  @param key     The key to export
  @return CRYPT_OK if successful
*/
int ecc_export(unsigned char *out, unsigned long *outlen, int type, ecc_key *key)
{
   int           err;
   unsigned char flags[1];
   unsigned long key_size;

   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);
   LTC_ARGCHK(key    != NULL);
   
   /* type valid? */
   if (key->type != PK_PRIVATE && type == PK_PRIVATE) {
      return CRYPT_PK_TYPE_MISMATCH;
   }

   if (is_valid_idx(key->idx) == 0) {
      return CRYPT_INVALID_ARG;
   }

   /* we store the NIST byte size */
   key_size = ecc_sets[key->idx].size;

   if (type == PK_PRIVATE) {
       flags[0] = 1;
       err = der_encode_sequence_multi(out, outlen,
                                 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);
   } else {
       flags[0] = 0;
       err = der_encode_sequence_multi(out, outlen,
                                 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);
   }

   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)
{
   unsigned long key_size;
   unsigned char flags[1];
   int           err;

   LTC_ARGCHK(in  != NULL);
   LTC_ARGCHK(key != NULL);

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


   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 error;
      }
   } else {
      /* public key */
      /* private 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 error;
      }
   }

   /* find the idx */
   for (key->idx = 0; ecc_sets[key->idx].size && (unsigned long)ecc_sets[key->idx].size != key_size; ++key->idx);
   if (ecc_sets[key->idx].size == 0) {
      err = CRYPT_INVALID_PACKET;
      goto error;
   }

   /* set z */
   mp_set(&key->pubkey.z, 1);

   /* we're good */
   return CRYPT_OK;
error:
   mp_clear_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL);
   return err;
}

/**
  Create an ECC shared secret between two keys
  @param private_key      The private ECC key
  @param public_key       The public key
  @param out              [out] Destination of the shared secret (Conforms to EC-DH from ANSI X9.63)
  @param outlen           [in/out] The max size and resulting size of the shared secret
  @return CRYPT_OK if successful
*/
int ecc_shared_secret(ecc_key *private_key, ecc_key *public_key,
                      unsigned char *out, unsigned long *outlen)
{
   unsigned long x;
   ecc_point *result;
   mp_int prime;
   int err;

   LTC_ARGCHK(private_key != NULL);
   LTC_ARGCHK(public_key  != NULL);
   LTC_ARGCHK(out         != NULL);
   LTC_ARGCHK(outlen      != NULL);

   /* type valid? */
   if (private_key->type != PK_PRIVATE) {
      return CRYPT_PK_NOT_PRIVATE;
   }

   if (is_valid_idx(private_key->idx) == 0) {
      return CRYPT_INVALID_ARG;
   }

   if (private_key->idx != public_key->idx) {
      return CRYPT_PK_TYPE_MISMATCH;
   }

   /* make new point */
   result = ecc_new_point();
   if (result == NULL) {
      return CRYPT_MEM;
   }

   if ((err = mp_init(&prime)) != MP_OKAY) {
      ecc_del(result);
      return mpi_to_ltc_error(err);
   }

   if ((err = mp_read_radix(&prime, (char *)ecc_sets[private_key->idx].prime, 64)) != MP_OKAY)            { goto error; }
   if ((err = ecc_mulmod(&private_key->k, &public_key->pubkey, result, &prime, 1)) != CRYPT_OK)       { goto done1; }

   x = (unsigned long)mp_unsigned_bin_size(&prime);
   if (*outlen < x) {
      err = CRYPT_BUFFER_OVERFLOW;
      goto done1;
   }
   zeromem(out, x);
   if ((err = mp_to_unsigned_bin(&result->x, out + (x - mp_unsigned_bin_size(&result->x))))   != MP_OKAY)          { goto error; }

   err     = CRYPT_OK;
   *outlen = x;
   goto done1;
error:
   err = mpi_to_ltc_error(err);
done1:
   mp_clear(&prime);
   ecc_del(result);
   return err;
}

/**
  Get the size of an ECC key
  @param key    The key to get the size of 
  @return The size (octets) of the key or INT_MAX on error
*/
int ecc_get_size(ecc_key *key)
{
   LTC_ARGCHK(key != NULL);
   if (is_valid_idx(key->idx))
      return ecc_sets[key->idx].size;
   else
      return INT_MAX; /* large value known to cause it to fail when passed to ecc_make_key() */
}

/**
  Rinick's  R = P
*/
int ecc_copy(ecc_point *P, ecc_point *R)
{
   int err;
   if ((err = mp_copy(&P->x, &R->x)) != MP_OKAY)                         { goto error; }
   if ((err = mp_copy(&P->y, &R->y)) != MP_OKAY)                         { goto error; }
   if ((err = mp_copy(&P->z, &R->z)) != MP_OKAY)                         { goto error; }
   err = CRYPT_OK;
   goto done;
error:
   err = mpi_to_ltc_error(err);
done:
   return err;
}

/**
  read base point 

  @return CRYPT_OK if successful, upon error all allocated memory will be freed
*/
int ecc_read_base(int keysize, ecc_point *base, mp_int *prime, mp_int *order)
{
   int            x, err;

   LTC_ARGCHK(base != NULL);

   /* find key size */
   for (x = 0; (keysize > ecc_sets[x].size) && (ecc_sets[x].size != 0); x++);
   keysize = ecc_sets[x].size;

   if (keysize > ECC_MAXSIZE || ecc_sets[x].size == 0) {
      return CRYPT_INVALID_KEYSIZE;
   }

   
   if (base == NULL) {
      base = ecc_new_point();
   }

   /* read in the specs for this key */
   
   if ((err = mp_read_radix(&base->x, (char *)ecc_sets[x].Gx, 64)) != MP_OKAY)       { goto error; }
   if ((err = mp_read_radix(&base->y, (char *)ecc_sets[x].Gy, 64)) != MP_OKAY)       { goto error; }
   mp_set(&base->z, 1);

	 if ((err = mp_read_radix(prime, (char *)ecc_sets[x].prime, 64)) != MP_OKAY)      { goto error; }
	 if ((err = mp_read_radix(order, (char *)ecc_sets[x].order, 64)) != MP_OKAY)      { goto error; }


   /* shrink key */
   if ((err = mp_shrink(prime)) != MP_OKAY)                                           { goto error; }
   if ((err = mp_shrink(order)) != MP_OKAY)                                           { goto error; }
   if ((err = mp_shrink(&base->x)) != MP_OKAY)                                    { goto error; }
   if ((err = mp_shrink(&base->y)) != MP_OKAY)                                    { goto error; }
   if ((err = mp_shrink(&base->z)) != MP_OKAY)                                    { goto error; }

   /* free up ram */
   err = CRYPT_OK;
   goto LBL_ERR;
error:
   err = mpi_to_ltc_error(err);
LBL_ERR:
   return err;
}


#include "ecc_sys.c"

#endif



/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc.c,v $ */
/* $Revision: 1.20 $ */
/* $Date: 2005/06/14 20:42:28 $ */