Ejemplo n.º 1
0
int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
{
   mp_int u1,u2,u3,v1,v2,v3,t1,t2,t3,q,tmp;
   int err;

   if ((err = mp_init_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL)) != MP_OKAY) {
      return err;
   }

   /* initialize, (u1,u2,u3) = (1,0,a) */
   mp_set(&u1, 1);
   if ((err = mp_copy(a, &u3)) != MP_OKAY)                                        { goto _ERR; }

   /* initialize, (v1,v2,v3) = (0,1,b) */
   mp_set(&v2, 1);
   if ((err = mp_copy(b, &v3)) != MP_OKAY)                                        { goto _ERR; }

   /* loop while v3 != 0 */
   while (mp_iszero(&v3) == MP_NO) {
       /* q = u3/v3 */
       if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY)                         { goto _ERR; }

       /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */
       if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
       if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY)                             { goto _ERR; }
       if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
       if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY)                             { goto _ERR; }
       if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
       if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY)                             { goto _ERR; }

       /* (u1,u2,u3) = (v1,v2,v3) */
       if ((err = mp_copy(&v1, &u1)) != MP_OKAY)                                  { goto _ERR; }
       if ((err = mp_copy(&v2, &u2)) != MP_OKAY)                                  { goto _ERR; }
       if ((err = mp_copy(&v3, &u3)) != MP_OKAY)                                  { goto _ERR; }

       /* (v1,v2,v3) = (t1,t2,t3) */
       if ((err = mp_copy(&t1, &v1)) != MP_OKAY)                                  { goto _ERR; }
       if ((err = mp_copy(&t2, &v2)) != MP_OKAY)                                  { goto _ERR; }
       if ((err = mp_copy(&t3, &v3)) != MP_OKAY)                                  { goto _ERR; }
   }

   /* make sure U3 >= 0 */
   if (u3.sign == MP_NEG) {
      mp_neg(&u1, &u1);
      mp_neg(&u2, &u2);
      mp_neg(&u3, &u3);
   }

   /* copy result out */
   if (U1 != NULL) { mp_exch(U1, &u1); }
   if (U2 != NULL) { mp_exch(U2, &u2); }
   if (U3 != NULL) { mp_exch(U3, &u3); }

   err = MP_OKAY;
_ERR: mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
   return err;
}
Ejemplo n.º 2
0
int ltc_ecc_is_point(const ltc_ecc_set_type *dp, void *x, void *y)
{
  void *prime, *a, *b, *t1, *t2;
  int err;

  if ((err = mp_init_multi(&prime, &a, &b, &t1, &t2, NULL)) != CRYPT_OK) {
     return err;
  }

  /* load prime, a and b */
  if ((err = mp_read_radix(prime, dp->prime, 16)) != CRYPT_OK)         goto cleanup;
  if ((err = mp_read_radix(b, dp->B, 16)) != CRYPT_OK)                 goto cleanup;
  if ((err = mp_read_radix(a, dp->A, 16)) != CRYPT_OK)                 goto cleanup;

  /* compute y^2 */
  if ((err = mp_sqr(y, t1)) != CRYPT_OK)                               goto cleanup;

  /* compute x^3 */
  if ((err = mp_sqr(x, t2)) != CRYPT_OK)                               goto cleanup;
  if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK)                       goto cleanup;
  if ((err = mp_mul(x, t2, t2)) != CRYPT_OK)                           goto cleanup;

  /* compute y^2 - x^3 */
  if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK)                          goto cleanup;

  /* compute y^2 - x^3 - a*x */
  if ((err = mp_submod(prime, a, prime, t2)) != CRYPT_OK)              goto cleanup;
  if ((err = mp_mulmod(t2, x, prime, t2)) != CRYPT_OK)                 goto cleanup;
  if ((err = mp_addmod(t1, t2, prime, t1)) != CRYPT_OK)                goto cleanup;

  /* adjust range (0, prime) */
  while (mp_cmp_d(t1, 0) == LTC_MP_LT) {
     if ((err = mp_add(t1, prime, t1)) != CRYPT_OK)                    goto cleanup;
  }
  while (mp_cmp(t1, prime) != LTC_MP_LT) {
     if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK)                    goto cleanup;
  }

  /* compare to b */
  if (mp_cmp(t1, b) != LTC_MP_EQ) {
     err = CRYPT_INVALID_PACKET;
  } else {
     err = CRYPT_OK;
  }

cleanup:
  mp_clear_multi(prime, b, t1, t2, NULL);
  return err;
}
Ejemplo n.º 3
0
static int
ltm_rsa_private_calculate(mp_int * in, mp_int * p,  mp_int * q,
			  mp_int * dmp1, mp_int * dmq1, mp_int * iqmp,
			  mp_int * out)
{
    mp_int vp, vq, u;

    mp_init_multi(&vp, &vq, &u, NULL);

    /* vq = c ^ (d mod (q - 1)) mod q */
    /* vp = c ^ (d mod (p - 1)) mod p */
    mp_mod(in, p, &u);
    mp_exptmod(&u, dmp1, p, &vp);
    mp_mod(in, q, &u);
    mp_exptmod(&u, dmq1, q, &vq);

    /* C2 = 1/q mod p  (iqmp) */
    /* u = (vp - vq)C2 mod p. */
    mp_sub(&vp, &vq, &u);
    if (mp_isneg(&u))
	mp_add(&u, p, &u);
    mp_mul(&u, iqmp, &u);
    mp_mod(&u, p, &u);

    /* c ^ d mod n = vq + u q */
    mp_mul(&u, q, &u);
    mp_add(&u, &vq, out);

    mp_clear_multi(&vp, &vq, &u, NULL);

    return 0;
}
Ejemplo n.º 4
0
/* sub */
static int sub(void *a, void *b, void *c)
{
   LTC_ARGCHK(a != NULL);
   LTC_ARGCHK(b != NULL);
   LTC_ARGCHK(c != NULL);
   return mpi_to_ltc_error(mp_sub(a, b, c));
}
Ejemplo n.º 5
0
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;
}
Ejemplo n.º 6
0
/**
 * bignum_sub - c = a - b
 * @a: Bignum from bignum_init()
 * @b: Bignum from bignum_init()
 * @c: Bignum from bignum_init(); used to store the result of a - b
 * Returns: 0 on success, -1 on failure
 */
int bignum_sub(const struct bignum *a, const struct bignum *b,
        struct bignum *c) {
    if (mp_sub((mp_int *) a, (mp_int *) b, (mp_int *) c) != MP_OKAY) {
        wpa_printf(MSG_DEBUG, "BIGNUM: %s failed", __func__);
        return -1;
    }
    return 0;
}
Ejemplo n.º 7
0
static void getp(dss_key *key, unsigned int size) {

	DEF_MP_INT(tempX);
	DEF_MP_INT(tempC);
	DEF_MP_INT(tempP);
	DEF_MP_INT(temp2q);
	int result;
	unsigned char *buf;

	m_mp_init_multi(&tempX, &tempC, &tempP, &temp2q, NULL);


	/* 2*q */
	if (mp_mul_d(key->q, 2, &temp2q) != MP_OKAY) {
		fprintf(stderr, "dss key generation failed\n");
		exit(1);
	}
	
	buf = (unsigned char*)m_malloc(size);

	result = 0;
	do {
		
		genrandom(buf, size);
		buf[0] |= 0x80; /* set the top bit high */

		/* X is a random mp_int */
		bytes_to_mp(&tempX, buf, size);

		/* C = X mod 2q */
		if (mp_mod(&tempX, &temp2q, &tempC) != MP_OKAY) {
			fprintf(stderr, "dss key generation failed\n");
			exit(1);
		}

		/* P = X - (C - 1) = X - C + 1*/
		if (mp_sub(&tempX, &tempC, &tempP) != MP_OKAY) {
			fprintf(stderr, "dss key generation failed\n");
			exit(1);
		}
		
		if (mp_add_d(&tempP, 1, key->p) != MP_OKAY) {
			fprintf(stderr, "dss key generation failed\n");
			exit(1);
		}

		/* now check for prime, 5 rounds is enough according to HAC */
		/* result == 1  =>  p is prime */
		if (mp_prime_is_prime(key->p, 5, &result) != MP_OKAY) {
			fprintf(stderr, "dss key generation failed\n");
			exit(1);
		}
	} while (!result);

	mp_clear_multi(&tempX, &tempC, &tempP, &temp2q, NULL);
	m_burn(buf, size);
	m_free(buf);
}
Ejemplo n.º 8
0
/*-------------------------------------------------------------------*/
static void convert_to_integer(gmp_poly_t *alg_sqrt, mp_t *n,
				mp_t *c, signed_mp_t *m1, 
				signed_mp_t *m0, mp_t *res) {

	/* given the completed square root, apply the homomorphism
	   to convert the polynomial to an integer. We do this
	   by evaluating alg_sqrt at c*m0/m1, with all calculations
	   performed mod n */

	uint32 i;
	mpz_t gmp_n;
	mp_t m1_pow;
	mp_t m1_tmp;
	mp_t m0_tmp;
	mp_t next_coeff;

	mpz_init(gmp_n); 
	mp2gmp(n, gmp_n);
	gmp_poly_mod_q(alg_sqrt, gmp_n, alg_sqrt);
	mpz_clear(gmp_n);

	mp_copy(&m1->num, &m1_tmp);
	if (m1->sign == NEGATIVE)
		mp_sub(n, &m1_tmp, &m1_tmp);
	mp_copy(&m1_tmp, &m1_pow);

	mp_modmul(&m0->num, c, n, &m0_tmp);
	if (m0->sign == POSITIVE)
		mp_sub(n, &m0_tmp, &m0_tmp);

	i = alg_sqrt->degree;
	gmp2mp(alg_sqrt->coeff[i], res);

	for (i--; (int32)i >= 0; i--) {
		mp_modmul(res, &m0_tmp, n, res);
		gmp2mp(alg_sqrt->coeff[i], &next_coeff);
		mp_modmul(&next_coeff, &m1_pow, n, &next_coeff);
		mp_add(res, &next_coeff, res);
		if (i > 0)
			mp_modmul(&m1_pow, &m1_tmp, n, &m1_pow);
	}
	if (mp_cmp(res, n) > 0)
		mp_sub(res, n, res);
}
Ejemplo n.º 9
0
static void
mpi_addsub(mpi *rop, mpi *op1, mpi *op2, int sub)
{
    long xlen;				/* maximum result size */

    if (sub ^ (op1->sign == op2->sign)) {
	/* plus one for possible carry */
	xlen = MAX(op1->size, op2->size) + 1;
	if (rop->alloc < xlen) {
	    rop->digs = mp_realloc(rop->digs, sizeof(BNS) * xlen);
	    rop->alloc = xlen;
	}
	rop->size = mp_add(rop->digs, op1->digs, op2->digs,
			   op1->size, op2->size);
	rop->sign = op1->sign;
    }
    else {
	long cmp;			/* check for larger operator */

	cmp = mpi_cmpabs(op1, op2);
	if (cmp == 0) {
	    rop->digs[0] = 0;
	    rop->size = 1;
	    rop->sign = 0;
	}
	else {
	    xlen = MAX(op1->size, op2->size);
	    if (rop->alloc < xlen) {
		rop->digs = mp_realloc(rop->digs, sizeof(BNS) * xlen);
		rop->alloc = xlen;
	    }
	    if (cmp > 0) {
		rop->size = mp_sub(rop->digs, op1->digs, op2->digs,
				   op1->size, op2->size);
		rop->sign = op1->sign;
	    }
	    else {
		rop->size = mp_sub(rop->digs, op2->digs, op1->digs,
				   op2->size, op1->size);
		rop->sign = sub ^ op2->sign;
	    }
	}
    }
}
Ejemplo n.º 10
0
/* Negates a field element.  Assumes that 0 <= a < meth->irr */
mp_err
ec_GFp_neg(const mp_int *a, mp_int *r, const GFMethod *meth)
{
    /* PRE: 0 <= a < p = meth->irr POST: 0 <= r < p, r = -a (mod p) */

    if (mp_cmp_z(a) == 0) {
        mp_zero(r);
        return MP_OKAY;
    }
    return mp_sub(&meth->irr, a, r);
}
Ejemplo n.º 11
0
Archivo: ec.c Proyecto: txazo/hotspot
/* Generate a random private key using the algorithm A.4.1 of ANSI X9.62,
 * modified a la FIPS 186-2 Change Notice 1 to eliminate the bias in the
 * random number generator.
 *
 * Parameters
 * - order: a buffer that holds the curve's group order
 * - len: the length in octets of the order buffer
 * - random: a buffer of 2 * len random bytes
 * - randomlen: the length in octets of the random buffer
 *
 * Return Value
 * Returns a buffer of len octets that holds the private key. The caller
 * is responsible for freeing the buffer with PORT_ZFree.
 */
static unsigned char *
ec_GenerateRandomPrivateKey(const unsigned char *order, int len,
    const unsigned char *random, int randomlen, int kmflag)
{
    SECStatus rv = SECSuccess;
    mp_err err;
    unsigned char *privKeyBytes = NULL;
    mp_int privKeyVal, order_1, one;

    MP_DIGITS(&privKeyVal) = 0;
    MP_DIGITS(&order_1) = 0;
    MP_DIGITS(&one) = 0;
    CHECK_MPI_OK( mp_init(&privKeyVal, kmflag) );
    CHECK_MPI_OK( mp_init(&order_1, kmflag) );
    CHECK_MPI_OK( mp_init(&one, kmflag) );

    /*
     * Reduces the 2*len buffer of random bytes modulo the group order.
     */
    if ((privKeyBytes = PORT_Alloc(2*len, kmflag)) == NULL) goto cleanup;
    if (randomlen != 2 * len) {
        randomlen = 2 * len;
    }
    /* No need to generate - random bytes are now supplied */
    /* CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(privKeyBytes, 2*len) );*/
    memcpy(privKeyBytes, random, randomlen);

    CHECK_MPI_OK( mp_read_unsigned_octets(&privKeyVal, privKeyBytes, 2*len) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&order_1, order, len) );
    CHECK_MPI_OK( mp_set_int(&one, 1) );
    CHECK_MPI_OK( mp_sub(&order_1, &one, &order_1) );
    CHECK_MPI_OK( mp_mod(&privKeyVal, &order_1, &privKeyVal) );
    CHECK_MPI_OK( mp_add(&privKeyVal, &one, &privKeyVal) );
    CHECK_MPI_OK( mp_to_fixlen_octets(&privKeyVal, privKeyBytes, len) );
    memset(privKeyBytes+len, 0, len);
cleanup:
    mp_clear(&privKeyVal);
    mp_clear(&order_1);
    mp_clear(&one);
    if (err < MP_OKAY) {
        MP_TO_SEC_ERROR(err);
        rv = SECFailure;
    }
    if (rv != SECSuccess && privKeyBytes) {
#ifdef _KERNEL
        kmem_free(privKeyBytes, 2*len);
#else
        free(privKeyBytes);
#endif
        privKeyBytes = NULL;
    }
    return privKeyBytes;
}
Ejemplo n.º 12
0
/* Subtracts two field elements.  Assumes that 0 <= a, b < meth->irr */
mp_err
ec_GFp_sub(const mp_int *a, const mp_int *b, mp_int *r,
           const GFMethod *meth)
{
    mp_err res = MP_OKAY;

    /* PRE: 0 <= a, b < p = meth->irr POST: 0 <= r < p, r = a - b (mod p) */
    res = mp_sub(a, b, r);
    if (res == MP_RANGE) {
        MP_CHECKOK(mp_sub(b, a, r));
        if (mp_cmp_z(r) < 0) {
            MP_CHECKOK(mp_add(r, &meth->irr, r));
        }
        MP_CHECKOK(ec_GFp_neg(r, r, meth));
    }
    if (mp_cmp_z(r) < 0) {
        MP_CHECKOK(mp_add(r, &meth->irr, r));
    }
CLEANUP:
    return res;
}
Ejemplo n.º 13
0
/* Add two field elements.  Assumes that 0 <= a, b < meth->irr */
mp_err
ec_GFp_add(const mp_int *a, const mp_int *b, mp_int *r,
           const GFMethod *meth)
{
    /* PRE: 0 <= a, b < p = meth->irr POST: 0 <= r < p, r = a + b (mod p) */
    mp_err res;

    if ((res = mp_add(a, b, r)) != MP_OKAY) {
        return res;
    }
    if (mp_cmp(r, &meth->irr) >= 0) {
        return mp_sub(r, &meth->irr, r);
    }
    return res;
}
Ejemplo n.º 14
0
/* single digit subtraction */
int
mp_sub_d (mp_int * a, mp_digit b, mp_int * c)
{
  mp_int  t;
  int     res;


  if ((res = mp_init (&t)) != MP_OKAY) {
    return res;
  }
  mp_set (&t, b);
  res = mp_sub (a, &t, c);

  mp_clear (&t);
  return res;
}
Ejemplo n.º 15
0
/* Generate a random private key using the algorithm A.4.1 of ANSI X9.62,
 * modified a la FIPS 186-2 Change Notice 1 to eliminate the bias in the
 * random number generator.
 *
 * Parameters
 * - order: a buffer that holds the curve's group order
 * - len: the length in octets of the order buffer
 *
 * Return Value
 * Returns a buffer of len octets that holds the private key. The caller
 * is responsible for freeing the buffer with PORT_ZFree.
 */
static unsigned char *
ec_GenerateRandomPrivateKey(const unsigned char *order, int len, int kmflag)
{
    SECStatus rv = SECSuccess;
    mp_err err;
    unsigned char *privKeyBytes = NULL;
    mp_int privKeyVal, order_1, one;

    MP_DIGITS(&privKeyVal) = 0;
    MP_DIGITS(&order_1) = 0;
    MP_DIGITS(&one) = 0;
    CHECK_MPI_OK( mp_init(&privKeyVal) );
    CHECK_MPI_OK( mp_init(&order_1) );
    CHECK_MPI_OK( mp_init(&one) );

    /* Generates 2*len random bytes using the global random bit generator
     * (which implements Algorithm 1 of FIPS 186-2 Change Notice 1) then
     * reduces modulo the group order.
     */
    if ((privKeyBytes = PORT_Alloc(2*len, kmflag)) == NULL) goto cleanup;
    CHECK_SEC_OK( RNG_GenerateGlobalRandomBytes(privKeyBytes, 2*len) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&privKeyVal, privKeyBytes, 2*len) );
    CHECK_MPI_OK( mp_read_unsigned_octets(&order_1, order, len) );
    CHECK_MPI_OK( mp_set_int(&one, 1) );
    CHECK_MPI_OK( mp_sub(&order_1, &one, &order_1) );
    CHECK_MPI_OK( mp_mod(&privKeyVal, &order_1, &privKeyVal) );
    CHECK_MPI_OK( mp_add(&privKeyVal, &one, &privKeyVal) );
    CHECK_MPI_OK( mp_to_fixlen_octets(&privKeyVal, privKeyBytes, len) );
    memset(privKeyBytes+len, 0, len);
cleanup:
    mp_clear(&privKeyVal);
    mp_clear(&order_1);
    mp_clear(&one);
    if (err < MP_OKAY) {
	MP_TO_SEC_ERROR(err);
	rv = SECFailure;
    }
    if (rv != SECSuccess && privKeyBytes) {
#ifdef _KERNEL
	kmem_free(privKeyBytes, 2*len);
#else
	free(privKeyBytes);
#endif
	privKeyBytes = NULL;
    }
    return privKeyBytes;
}
Ejemplo n.º 16
0
/* d = a - b (mod c) */
int
mp_submod (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
{
  int     res;
  mp_int  t;

  if ((res = mp_init (&t)) != MP_OKAY) {
    return res;
  }

  if ((res = mp_sub (a, b, &t)) != MP_OKAY) {
    mp_clear (&t);
    return res;
  }
  res = mp_mod (&t, c, d);
  mp_clear (&t);
  return res;
}
/**
   Double an ECC point
   @param P   The point to double
   @param R   [out] The destination of the double
   @param modulus  The modulus of the field the ECC curve is in
   @param mp       The "b" value from montgomery_setup()
   @return CRYPT_OK on success
*/
int ltc_ecc_projective_dbl_point(ecc_point *P, ecc_point *R, void *modulus, void *mp)
{
   void *t1, *t2;
   int   err;

   LTC_ARGCHK(P       != NULL);
   LTC_ARGCHK(R       != NULL);
   LTC_ARGCHK(modulus != NULL);
   LTC_ARGCHK(mp      != NULL);

   if ((err = mp_init_multi(&t1, &t2, NULL)) != CRYPT_OK) {
      return err;
   }

   if (P != R) {
      if ((err = mp_copy(P->x, R->x)) != CRYPT_OK)                                { goto done; }
      if ((err = mp_copy(P->y, R->y)) != CRYPT_OK)                                { goto done; }
      if ((err = mp_copy(P->z, R->z)) != CRYPT_OK)                                { goto done; }
   }

   /* t1 = Z * Z */
   if ((err = mp_sqr(R->z, t1)) != CRYPT_OK)                                      { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)                 { goto done; }
   /* Z = Y * Z */
   if ((err = mp_mul(R->z, R->y, R->z)) != CRYPT_OK)                              { goto done; }
   if ((err = mp_montgomery_reduce(R->z, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* Z = 2Z */
   if ((err = mp_add(R->z, R->z, R->z)) != CRYPT_OK)                              { goto done; }
   if (mp_cmp(R->z, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(R->z, modulus, R->z)) != CRYPT_OK)                        { goto done; }
   }

   /* T2 = X - T1 */
   if ((err = mp_sub(R->x, t1, t2)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp_d(t2, 0) == LTC_MP_LT) {
      if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK)                            { goto done; }
   }
   /* T1 = X + T1 */
   if ((err = mp_add(t1, R->x, t1)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp(t1, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK)                            { goto done; }
   }
   /* T2 = T1 * T2 */
   if ((err = mp_mul(t1, t2, t2)) != CRYPT_OK)                                    { goto done; }
   if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK)                 { goto done; }
   /* T1 = 2T2 */
   if ((err = mp_add(t2, t2, t1)) != CRYPT_OK)                                    { goto done; }
   if (mp_cmp(t1, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK)                            { goto done; }
   }
   /* T1 = T1 + T2 */
   if ((err = mp_add(t1, t2, t1)) != CRYPT_OK)                                    { goto done; }
   if (mp_cmp(t1, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK)                            { goto done; }
   }

   /* Y = 2Y */
   if ((err = mp_add(R->y, R->y, R->y)) != CRYPT_OK)                              { goto done; }
   if (mp_cmp(R->y, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(R->y, modulus, R->y)) != CRYPT_OK)                        { goto done; }
   }
   /* Y = Y * Y */
   if ((err = mp_sqr(R->y, R->y)) != CRYPT_OK)                                    { goto done; }
   if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* T2 = Y * Y */
   if ((err = mp_sqr(R->y, t2)) != CRYPT_OK)                                      { goto done; }
   if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK)                 { goto done; }
   /* T2 = T2/2 */
   if (mp_isodd(t2)) {
      if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK)                            { goto done; }
   }
   if ((err = mp_div_2(t2, t2)) != CRYPT_OK)                                      { goto done; }
   /* Y = Y * X */
   if ((err = mp_mul(R->y, R->x, R->y)) != CRYPT_OK)                              { goto done; }
   if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK)               { goto done; }

   /* X  = T1 * T1 */
   if ((err = mp_sqr(t1, R->x)) != CRYPT_OK)                                      { goto done; }
   if ((err = mp_montgomery_reduce(R->x, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* X = X - Y */
   if ((err = mp_sub(R->x, R->y, R->x)) != CRYPT_OK)                              { goto done; }
   if (mp_cmp_d(R->x, 0) == LTC_MP_LT) {
      if ((err = mp_add(R->x, modulus, R->x)) != CRYPT_OK)                        { goto done; }
   }
   /* X = X - Y */
   if ((err = mp_sub(R->x, R->y, R->x)) != CRYPT_OK)                              { goto done; }
   if (mp_cmp_d(R->x, 0) == LTC_MP_LT) {
      if ((err = mp_add(R->x, modulus, R->x)) != CRYPT_OK)                        { goto done; }
   }

   /* Y = Y - X */
   if ((err = mp_sub(R->y, R->x, R->y)) != CRYPT_OK)                              { goto done; }
   if (mp_cmp_d(R->y, 0) == LTC_MP_LT) {
      if ((err = mp_add(R->y, modulus, R->y)) != CRYPT_OK)                        { goto done; }
   }
   /* Y = Y * T1 */
   if ((err = mp_mul(R->y, t1, R->y)) != CRYPT_OK)                                { goto done; }
   if ((err = mp_montgomery_reduce(R->y, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* Y = Y - T2 */
   if ((err = mp_sub(R->y, t2, R->y)) != CRYPT_OK)                                { goto done; }
   if (mp_cmp_d(R->y, 0) == LTC_MP_LT) {
      if ((err = mp_add(R->y, modulus, R->y)) != CRYPT_OK)                        { goto done; }
   }

   err = CRYPT_OK;
done:
   mp_clear_multi(t1, t2, NULL);
   return err;
}
Ejemplo n.º 18
0
/* multiplication using the Toom-Cook 3-way algorithm 
 *
 * Much more complicated than Karatsuba but has a lower 
 * asymptotic running time of O(N**1.464).  This algorithm is 
 * only particularly useful on VERY large inputs 
 * (we're talking 1000s of digits here...).
*/
int mp_toom_mul(mp_int *a, mp_int *b, mp_int *c)
{
    mp_int w0, w1, w2, w3, w4, tmp1, tmp2, a0, a1, a2, b0, b1, b2;
    int res, B;
        
    /* init temps */
    if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4, 
                             &a0, &a1, &a2, &b0, &b1, 
                             &b2, &tmp1, &tmp2, NULL)) != MP_OKAY) {
       return res;
    }
    
    /* B */
    B = MIN(a->used, b->used) / 3;
    
    /* a = a2 * B**2 + a1 * B + a0 */
    if ((res = mp_mod_2d(a, DIGIT_BIT * B, &a0)) != MP_OKAY) {
       goto ERR;
    }

    if ((res = mp_copy(a, &a1)) != MP_OKAY) {
       goto ERR;
    }
    mp_rshd(&a1, B);
    mp_mod_2d(&a1, DIGIT_BIT * B, &a1);

    if ((res = mp_copy(a, &a2)) != MP_OKAY) {
       goto ERR;
    }
    mp_rshd(&a2, B*2);
    
    /* b = b2 * B**2 + b1 * B + b0 */
    if ((res = mp_mod_2d(b, DIGIT_BIT * B, &b0)) != MP_OKAY) {
       goto ERR;
    }

    if ((res = mp_copy(b, &b1)) != MP_OKAY) {
       goto ERR;
    }
    mp_rshd(&b1, B);
    mp_mod_2d(&b1, DIGIT_BIT * B, &b1);

    if ((res = mp_copy(b, &b2)) != MP_OKAY) {
       goto ERR;
    }
    mp_rshd(&b2, B*2);
    
    /* w0 = a0*b0 */
    if ((res = mp_mul(&a0, &b0, &w0)) != MP_OKAY) {
       goto ERR;
    }
    
    /* w4 = a2 * b2 */
    if ((res = mp_mul(&a2, &b2, &w4)) != MP_OKAY) {
       goto ERR;
    }
    
    /* w1 = (a2 + 2(a1 + 2a0))(b2 + 2(b1 + 2b0)) */
    if ((res = mp_mul_2(&a0, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp1, &a2, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    
    if ((res = mp_mul_2(&b0, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp2, &b1, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_mul_2(&tmp2, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp2, &b2, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    
    if ((res = mp_mul(&tmp1, &tmp2, &w1)) != MP_OKAY) {
       goto ERR;
    }
    
    /* w3 = (a0 + 2(a1 + 2a2))(b0 + 2(b1 + 2b2)) */
    if ((res = mp_mul_2(&a2, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    
    if ((res = mp_mul_2(&b2, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp2, &b1, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_mul_2(&tmp2, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp2, &b0, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    
    if ((res = mp_mul(&tmp1, &tmp2, &w3)) != MP_OKAY) {
       goto ERR;
    }
    

    /* w2 = (a2 + a1 + a0)(b2 + b1 + b0) */
    if ((res = mp_add(&a2, &a1, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&b2, &b1, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_add(&tmp2, &b0, &tmp2)) != MP_OKAY) {
       goto ERR;
    }
    if ((res = mp_mul(&tmp1, &tmp2, &w2)) != MP_OKAY) {
       goto ERR;
    }
    
    /* now solve the matrix 
    
       0  0  0  0  1
       1  2  4  8  16
       1  1  1  1  1
       16 8  4  2  1
       1  0  0  0  0
       
       using 12 subtractions, 4 shifts, 
              2 small divisions and 1 small multiplication 
     */
     
     /* r1 - r4 */
     if ((res = mp_sub(&w1, &w4, &w1)) != MP_OKAY) {
        goto ERR;
     }
     /* r3 - r0 */
     if ((res = mp_sub(&w3, &w0, &w3)) != MP_OKAY) {
        goto ERR;
     }
     /* r1/2 */
     if ((res = mp_div_2(&w1, &w1)) != MP_OKAY) {
        goto ERR;
     }
     /* r3/2 */
     if ((res = mp_div_2(&w3, &w3)) != MP_OKAY) {
        goto ERR;
     }
     /* r2 - r0 - r4 */
     if ((res = mp_sub(&w2, &w0, &w2)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_sub(&w2, &w4, &w2)) != MP_OKAY) {
        goto ERR;
     }
     /* r1 - r2 */
     if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
        goto ERR;
     }
     /* r3 - r2 */
     if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
        goto ERR;
     }
     /* r1 - 8r0 */
     if ((res = mp_mul_2d(&w0, 3, &tmp1)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_sub(&w1, &tmp1, &w1)) != MP_OKAY) {
        goto ERR;
     }
     /* r3 - 8r4 */
     if ((res = mp_mul_2d(&w4, 3, &tmp1)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_sub(&w3, &tmp1, &w3)) != MP_OKAY) {
        goto ERR;
     }
     /* 3r2 - r1 - r3 */
     if ((res = mp_mul_d(&w2, 3, &w2)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_sub(&w2, &w1, &w2)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_sub(&w2, &w3, &w2)) != MP_OKAY) {
        goto ERR;
     }
     /* r1 - r2 */
     if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
        goto ERR;
     }
     /* r3 - r2 */
     if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
        goto ERR;
     }
     /* r1/3 */
     if ((res = mp_div_3(&w1, &w1, NULL)) != MP_OKAY) {
        goto ERR;
     }
     /* r3/3 */
     if ((res = mp_div_3(&w3, &w3, NULL)) != MP_OKAY) {
        goto ERR;
     }
     
     /* at this point shift W[n] by B*n */
     if ((res = mp_lshd(&w1, 1*B)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_lshd(&w2, 2*B)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_lshd(&w3, 3*B)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_lshd(&w4, 4*B)) != MP_OKAY) {
        goto ERR;
     }     
     
     if ((res = mp_add(&w0, &w1, c)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_add(&w2, &w3, &tmp1)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_add(&w4, &tmp1, &tmp1)) != MP_OKAY) {
        goto ERR;
     }
     if ((res = mp_add(&tmp1, c, c)) != MP_OKAY) {
        goto ERR;
     }     
     
ERR:
     mp_clear_multi(&w0, &w1, &w2, &w3, &w4, 
                    &a0, &a1, &a2, &b0, &b1, 
                    &b2, &tmp1, &tmp2, NULL);
     return res;
}     
Ejemplo n.º 19
0
	BigInteger& BigInteger::operator-= (const BigInteger& val)
	{
		CHECK_MP(mp_sub(&t, const_cast<mp_int*>(&val.t), &t));
		return *this;
	}
Ejemplo n.º 20
0
	BigInteger BigInteger::operator- (const BigInteger& val) const
	{
		BigInteger rc;
		CHECK_MP(mp_sub(const_cast<mp_int*>(&t), const_cast<mp_int*>(&val.t), &rc.t));
		return rc;
	}
/* find the n'th root of an integer 
 *
 * Result found such that (c)**b <= a and (c+1)**b > a 
 *
 * This algorithm uses Newton's approximation 
 * x[i+1] = x[i] - f(x[i])/f'(x[i]) 
 * which will find the root in log(N) time where 
 * each step involves a fair bit.  This is not meant to 
 * find huge roots [square and cube, etc].
 */
int mp_n_root (mp_int * a, mp_digit b, mp_int * c)
{
  mp_int  t1, t2, t3;
  int     res, neg;

  /* input must be positive if b is even */
  if ((b & 1) == 0 && a->sign == MP_NEG) {
    return MP_VAL;
  }

  if ((res = mp_init (&t1)) != MP_OKAY) {
    return res;
  }

  if ((res = mp_init (&t2)) != MP_OKAY) {
    goto LBL_T1;
  }

  if ((res = mp_init (&t3)) != MP_OKAY) {
    goto LBL_T2;
  }

  /* if a is negative fudge the sign but keep track */
  neg     = a->sign;
  a->sign = MP_ZPOS;

  /* t2 = 2 */
  mp_set (&t2, 2);

  do {
    /* t1 = t2 */
    if ((res = mp_copy (&t2, &t1)) != MP_OKAY) {
      goto LBL_T3;
    }

    /* t2 = t1 - ((t1**b - a) / (b * t1**(b-1))) */
    
    /* t3 = t1**(b-1) */
    if ((res = mp_expt_d (&t1, b - 1, &t3)) != MP_OKAY) {   
      goto LBL_T3;
    }

    /* numerator */
    /* t2 = t1**b */
    if ((res = mp_mul (&t3, &t1, &t2)) != MP_OKAY) {    
      goto LBL_T3;
    }

    /* t2 = t1**b - a */
    if ((res = mp_sub (&t2, a, &t2)) != MP_OKAY) {  
      goto LBL_T3;
    }

    /* denominator */
    /* t3 = t1**(b-1) * b  */
    if ((res = mp_mul_d (&t3, b, &t3)) != MP_OKAY) {    
      goto LBL_T3;
    }

    /* t3 = (t1**b - a)/(b * t1**(b-1)) */
    if ((res = mp_div (&t2, &t3, &t3, NULL)) != MP_OKAY) {  
      goto LBL_T3;
    }

    if ((res = mp_sub (&t1, &t3, &t2)) != MP_OKAY) {
      goto LBL_T3;
    }
  }  while (mp_cmp (&t1, &t2) != MP_EQ);

  /* result can be off by a few so check */
  for (;;) {
    if ((res = mp_expt_d (&t1, b, &t2)) != MP_OKAY) {
      goto LBL_T3;
    }

    if (mp_cmp (&t2, a) == MP_GT) {
      if ((res = mp_sub_d (&t1, 1, &t1)) != MP_OKAY) {
         goto LBL_T3;
      }
    } else {
      break;
    }
  }

  /* reset the sign of a first */
  a->sign = neg;

  /* set the result */
  mp_exch (&t1, c);

  /* set the sign of the result */
  c->sign = neg;

  res = MP_OKAY;

LBL_T3:mp_clear (&t3);
LBL_T2:mp_clear (&t2);
LBL_T1:mp_clear (&t1);
  return res;
}
Ejemplo n.º 22
0
/* hac 14.61, pp608 */
int mp_invmod_slow (mp_int * a, mp_int * b, mp_int * c)
{
  mp_int  x, y, u, v, A, B, C, D;
  int     res;

  /* b cannot be negative */
  if (b->sign == MP_NEG || mp_iszero(b) == 1) {
    return MP_VAL;
  }

  /* init temps */
  if ((res = mp_init_multi(&x, &y, &u, &v, 
                           &A, &B, &C, &D, NULL)) != MP_OKAY) {
     return res;
  }

  /* x = a, y = b */
  if ((res = mp_mod(a, b, &x)) != MP_OKAY) {
      goto LBL_ERR;
  }
  if ((res = mp_copy (b, &y)) != MP_OKAY) {
    goto LBL_ERR;
  }

  /* 2. [modified] if x,y are both even then return an error! */
  if (mp_iseven (&x) == 1 && mp_iseven (&y) == 1) {
    res = MP_VAL;
    goto LBL_ERR;
  }

  /* 3. u=x, v=y, A=1, B=0, C=0,D=1 */
  if ((res = mp_copy (&x, &u)) != MP_OKAY) {
    goto LBL_ERR;
  }
  if ((res = mp_copy (&y, &v)) != MP_OKAY) {
    goto LBL_ERR;
  }
  mp_set (&A, 1);
  mp_set (&D, 1);

top:
  /* 4.  while u is even do */
  while (mp_iseven (&u) == 1) {
    /* 4.1 u = u/2 */
    if ((res = mp_div_2 (&u, &u)) != MP_OKAY) {
      goto LBL_ERR;
    }
    /* 4.2 if A or B is odd then */
    if (mp_isodd (&A) == 1 || mp_isodd (&B) == 1) {
      /* A = (A+y)/2, B = (B-x)/2 */
      if ((res = mp_add (&A, &y, &A)) != MP_OKAY) {
         goto LBL_ERR;
      }
      if ((res = mp_sub (&B, &x, &B)) != MP_OKAY) {
         goto LBL_ERR;
      }
    }
    /* A = A/2, B = B/2 */
    if ((res = mp_div_2 (&A, &A)) != MP_OKAY) {
      goto LBL_ERR;
    }
    if ((res = mp_div_2 (&B, &B)) != MP_OKAY) {
      goto LBL_ERR;
    }
  }

  /* 5.  while v is even do */
  while (mp_iseven (&v) == 1) {
    /* 5.1 v = v/2 */
    if ((res = mp_div_2 (&v, &v)) != MP_OKAY) {
      goto LBL_ERR;
    }
    /* 5.2 if C or D is odd then */
    if (mp_isodd (&C) == 1 || mp_isodd (&D) == 1) {
      /* C = (C+y)/2, D = (D-x)/2 */
      if ((res = mp_add (&C, &y, &C)) != MP_OKAY) {
         goto LBL_ERR;
      }
      if ((res = mp_sub (&D, &x, &D)) != MP_OKAY) {
         goto LBL_ERR;
      }
    }
    /* C = C/2, D = D/2 */
    if ((res = mp_div_2 (&C, &C)) != MP_OKAY) {
      goto LBL_ERR;
    }
    if ((res = mp_div_2 (&D, &D)) != MP_OKAY) {
      goto LBL_ERR;
    }
  }

  /* 6.  if u >= v then */
  if (mp_cmp (&u, &v) != MP_LT) {
    /* u = u - v, A = A - C, B = B - D */
    if ((res = mp_sub (&u, &v, &u)) != MP_OKAY) {
      goto LBL_ERR;
    }

    if ((res = mp_sub (&A, &C, &A)) != MP_OKAY) {
      goto LBL_ERR;
    }

    if ((res = mp_sub (&B, &D, &B)) != MP_OKAY) {
      goto LBL_ERR;
    }
  } else {
    /* v - v - u, C = C - A, D = D - B */
    if ((res = mp_sub (&v, &u, &v)) != MP_OKAY) {
      goto LBL_ERR;
    }

    if ((res = mp_sub (&C, &A, &C)) != MP_OKAY) {
      goto LBL_ERR;
    }

    if ((res = mp_sub (&D, &B, &D)) != MP_OKAY) {
      goto LBL_ERR;
    }
  }

  /* if not zero goto step 4 */
  if (mp_iszero (&u) == 0)
    goto top;

  /* now a = C, b = D, gcd == g*v */

  /* if v != 1 then there is no inverse */
  if (mp_cmp_d (&v, 1) != MP_EQ) {
    res = MP_VAL;
    goto LBL_ERR;
  }

  /* if its too low */
  while (mp_cmp_d(&C, 0) == MP_LT) {
      if ((res = mp_add(&C, b, &C)) != MP_OKAY) {
         goto LBL_ERR;
      }
  }
  
  /* too big */
  while (mp_cmp_mag(&C, b) != MP_LT) {
      if ((res = mp_sub(&C, b, &C)) != MP_OKAY) {
         goto LBL_ERR;
      }
  }
  
  /* C is now the inverse */
  mp_exch (&C, c);
  res = MP_OKAY;
LBL_ERR:mp_clear_multi (&x, &y, &u, &v, &A, &B, &C, &D, NULL);
  return res;
}
Ejemplo n.º 23
0
Archivo: mpi.c Proyecto: ifzz/weecrypt
void
mpi_add(const mpi *a, const mpi *b, mpi *c)
{
    if (a->size == 0) {
        if (b->size == 0)
            c->size = 0;
        else
            mpi_set_mpi(c, b);
        return;
    } else if (b->size == 0) {
        mpi_set_mpi(c, a);
        return;
    }

    if (a == b) {
        mp_digit cy;
        if (a == c) {
            cy = mp_lshifti(c->digits, c->size, 1);
        } else {
            MPI_SIZE(c, a->size);
            cy = mp_lshift(a->digits, a->size, 1, c->digits);
        }
        if (cy) {
            MPI_MIN_ALLOC(c, c->size + 1);
            c->digits[c->size++] = cy;
        }
        return;
    }

    /* Note: this code is careful so it works for A == C or B == C!! */
    mp_size size;
    if (a->sign == b->sign) {	/* Both positive or negative. */
        size = MAX(a->size, b->size);
        MPI_MIN_ALLOC(c, size + 1);
        mp_digit cy = mp_add(a->digits, a->size, b->digits, b->size, c->digits);
        if (cy)
            c->digits[size++] = cy;
        else
            MP_NORMALIZE(c->digits, size);
        c->sign = a->sign;
    } else {					/* Differing signs. */
        if (a->sign)
            SWAP(a, b, const mpi *);
        ASSERT(a->sign == 0);
        ASSERT(b->sign == 1);

        int cmp = mp_cmp(a->digits, a->size, b->digits, b->size);
        if (cmp > 0) {							/* |A| > |B| */
            /* If B < 0 and |A| > |B|, then C = A - |B| */
            MPI_MIN_ALLOC(c, a->size);
            ASSERT(mp_sub(a->digits, a->size,
                          b->digits, b->size, c->digits) == 0);
            c->sign = 0;
            size = mp_rsize(c->digits, a->size);
        } else if (cmp < 0) {					/* |A| < |B| */
            /* If B < 0 and |A| < |B|, then C = -(|B| - |A|) */
            MPI_MIN_ALLOC(c, b->size);
            ASSERT(mp_sub(b->digits, b->size,
                          a->digits, a->size, c->digits) == 0);
            c->sign = 1;
            size = mp_rsize(c->digits, b->size);
        } else {								/* |A| = |B| */
            c->sign = 0;
            size = 0;
        }
    }
    c->size = size;
}
Ejemplo n.º 24
0
/* Tests a point multiplication (various algorithms) */
mp_err
testPointMul(ECGroup *ecgroup)
{
	mp_err res;
	char s[1000];
	mp_int rx, ry, order_1;

	/* Init */
	MP_DIGITS(&rx) = 0;
	MP_DIGITS(&ry) = 0;
	MP_DIGITS(&order_1) = 0;

	MP_CHECKOK(mp_init(&rx));
	MP_CHECKOK(mp_init(&ry));
	MP_CHECKOK(mp_init(&order_1));

	MP_CHECKOK(mp_set_int(&order_1, 1));
	MP_CHECKOK(mp_sub(&ecgroup->order, &order_1, &order_1));

	/* Test Algorithm 1: Jacobian-Affine Double & Add */
	ec_GFp_pt_mul_jac_fp(&order_1, &ecgroup->genx, &ecgroup->geny, &rx,
						 &ry, ecgroup);
	MP_CHECKOK(ecgroup->meth->field_neg(&ry, &ry, ecgroup->meth));
	if ((mp_cmp(&rx, &ecgroup->genx) != 0)
		|| (mp_cmp(&ry, &ecgroup->geny) != 0)) {
		printf
			("  Error: ec_GFp_pt_mul_jac_fp invalid result (expected (- base point)).\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

	ec_GFp_pt_mul_jac_fp(&ecgroup->order, &ecgroup->genx, &ecgroup->geny,
						 &rx, &ry, ecgroup);
	if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
		printf
			("  Error: ec_GFp_pt_mul_jac_fp invalid result (expected point at infinity.\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

	/* Test Algorithm 2: 4-bit Window in Jacobian */
	ec_GFp_point_mul_jac_4w_fp(&order_1, &ecgroup->genx, &ecgroup->geny,
							   &rx, &ry, ecgroup);
	MP_CHECKOK(ecgroup->meth->field_neg(&ry, &ry, ecgroup->meth));
	if ((mp_cmp(&rx, &ecgroup->genx) != 0)
		|| (mp_cmp(&ry, &ecgroup->geny) != 0)) {
		printf
			("  Error: ec_GFp_point_mul_jac_4w_fp invalid result (expected (- base point)).\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

	ec_GFp_point_mul_jac_4w_fp(&ecgroup->order, &ecgroup->genx,
							   &ecgroup->geny, &rx, &ry, ecgroup);
	if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
		printf
			("  Error: ec_GFp_point_mul_jac_4w_fp invalid result (expected point at infinity.\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

	/* Test Algorithm 3: wNAF with modified Jacobian coordinates */
	ec_GFp_point_mul_wNAF_fp(&order_1, &ecgroup->genx, &ecgroup->geny, &rx,
							 &ry, ecgroup);
	MP_CHECKOK(ecgroup->meth->field_neg(&ry, &ry, ecgroup->meth));
	if ((mp_cmp(&rx, &ecgroup->genx) != 0)
		|| (mp_cmp(&ry, &ecgroup->geny) != 0)) {
		printf
			("  Error: ec_GFp_pt_mul_wNAF_fp invalid result (expected (- base point)).\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

	ec_GFp_point_mul_wNAF_fp(&ecgroup->order, &ecgroup->genx,
							 &ecgroup->geny, &rx, &ry, ecgroup);
	if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
		printf
			("  Error: ec_GFp_pt_mul_wNAF_fp invalid result (expected point at infinity.\n");
		MP_CHECKOK(mp_toradix(&rx, s, 16));
		printf("rx   %s\n", s);
		MP_CHECKOK(mp_toradix(&ry, s, 16));
		printf("ry   %s\n", s);
		res = MP_NO;
		goto CLEANUP;
	}

  CLEANUP:
	if (res == MP_OKAY)
		printf("  Test Passed - Point Multiplication\n");
	else
		printf("TEST FAILED - Point Multiplication\n");
	mp_clear(&rx);
	mp_clear(&ry);
	mp_clear(&order_1);

	return res;
}
Ejemplo n.º 25
0
/**
   Compute an RSA modular exponentiation
   @param in         The input data to send into RSA
   @param inlen      The length of the input (octets)
   @param out        [out] The destination
   @param outlen     [in/out] The max size and resulting size of the output
   @param which      Which exponent to use, e.g. PK_PRIVATE or PK_PUBLIC
   @param key        The RSA key to use
   @return CRYPT_OK if successful
*/
int rsa_exptmod(const unsigned char *in,  unsigned long inlen,
                unsigned char *out, unsigned long *outlen, int which,
                rsa_key *key)
{
    void         *tmp, *tmpa, *tmpb;
    unsigned long x;
    int           err;

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

    /* is the key of the right type for the operation? */
    if (which == PK_PRIVATE && (key->type != PK_PRIVATE)) {
        return CRYPT_PK_NOT_PRIVATE;
    }

    /* must be a private or public operation */
    if (which != PK_PRIVATE && which != PK_PUBLIC) {
        return CRYPT_PK_INVALID_TYPE;
    }

    /* init and copy into tmp */
    if ((err = mp_init_multi(&tmp, &tmpa, &tmpb, NULL)) != CRYPT_OK)                                    {
        return err;
    }
    if ((err = mp_read_unsigned_bin(tmp, (unsigned char *)in, (int)inlen)) != CRYPT_OK)                 {
        goto error;
    }

    /* sanity check on the input */
    if (mp_cmp(key->N, tmp) == LTC_MP_LT) {
        err = CRYPT_PK_INVALID_SIZE;
        goto error;
    }

    /* are we using the private exponent and is the key optimized? */
    if (which == PK_PRIVATE) {
        /* tmpa = tmp^dP mod p */
        if ((err = mp_exptmod(tmp, key->dP, key->p, tmpa)) != CRYPT_OK)                               {
            goto error;
        }

        /* tmpb = tmp^dQ mod q */
        if ((err = mp_exptmod(tmp, key->dQ, key->q, tmpb)) != CRYPT_OK)                               {
            goto error;
        }

        /* tmp = (tmpa - tmpb) * qInv (mod p) */
        if ((err = mp_sub(tmpa, tmpb, tmp)) != CRYPT_OK)                                              {
            goto error;
        }
        if ((err = mp_mulmod(tmp, key->qP, key->p, tmp)) != CRYPT_OK)                                {
            goto error;
        }

        /* tmp = tmpb + q * tmp */
        if ((err = mp_mul(tmp, key->q, tmp)) != CRYPT_OK)                                             {
            goto error;
        }
        if ((err = mp_add(tmp, tmpb, tmp)) != CRYPT_OK)                                               {
            goto error;
        }
    } else {
        /* exptmod it */
        if ((err = mp_exptmod(tmp, key->e, key->N, tmp)) != CRYPT_OK)                                {
            goto error;
        }
    }

    /* read it back */
    x = (unsigned long)mp_unsigned_bin_size(key->N);
    if (x > *outlen) {
        *outlen = x;
        err = CRYPT_BUFFER_OVERFLOW;
        goto error;
    }

    /* this should never happen ... */
    if (mp_unsigned_bin_size(tmp) > mp_unsigned_bin_size(key->N)) {
        err = CRYPT_ERROR;
        goto error;
    }
    *outlen = x;

    /* convert it */
    zeromem(out, x);
    if ((err = mp_to_unsigned_bin(tmp, out+(x-mp_unsigned_bin_size(tmp)))) != CRYPT_OK)               {
        goto error;
    }

    /* clean up and return */
    err = CRYPT_OK;
error:
    mp_clear_multi(tmp, tmpa, tmpb, NULL);
    return err;
}
Ejemplo n.º 26
0
/* reduces x mod m, assumes 0 < x < m**2, mu is 
 * precomputed via mp_reduce_setup.
 * From HAC pp.604 Algorithm 14.42
 */
int mp_reduce (mp_int * x, mp_int * m, mp_int * mu)
{
  mp_int  q;
  int     res, um = USED(m);

  /* q = x */
  if ((res = mp_init_copy (&q, x)) != MP_OKAY) {
    return res;
  }

  /* q1 = x / b**(k-1)  */
  mp_rshd (&q, um - 1);         

  /* according to HAC this optimization is ok */
  if (((unsigned long) um) > (((mp_digit)1) << (DIGIT_BIT - 1))) {
    if ((res = mp_mul (&q, mu, &q)) != MP_OKAY) {
      goto CLEANUP;
    }
  } else {
#ifdef BN_S_MP_MUL_HIGH_DIGS_C
    if ((res = s_mp_mul_high_digs (&q, mu, &q, um)) != MP_OKAY) {
      goto CLEANUP;
    }
#elif defined(BN_FAST_S_MP_MUL_HIGH_DIGS_C)
    if ((res = fast_s_mp_mul_high_digs (&q, mu, &q, um)) != MP_OKAY) {
      goto CLEANUP;
    }
#else 
    { 
      res = MP_VAL;
      goto CLEANUP;
    }
#endif
  }

  /* q3 = q2 / b**(k+1) */
  mp_rshd (&q, um + 1);         

  /* x = x mod b**(k+1), quick (no division) */
  if ((res = mp_mod_2d (x, DIGIT_BIT * (um + 1), x)) != MP_OKAY) {
    goto CLEANUP;
  }

  /* q = q * m mod b**(k+1), quick (no division) */
  if ((res = s_mp_mul_digs (&q, m, &q, um + 1)) != MP_OKAY) {
    goto CLEANUP;
  }

  /* x = x - q */
  if ((res = mp_sub (x, &q, x)) != MP_OKAY) {
    goto CLEANUP;
  }

  /* If x < 0, add b**(k+1) to it */
  if (mp_cmp_d (x, 0) == MP_LT) {
    mp_set (&q, 1);
    if ((res = mp_lshd (&q, um + 1)) != MP_OKAY)
      goto CLEANUP;
    if ((res = mp_add (x, &q, x)) != MP_OKAY)
      goto CLEANUP;
  }

  /* Back off if it's too big */
  while (mp_cmp (x, m) != MP_LT) {
    if ((res = s_mp_sub (x, m, x)) != MP_OKAY) {
      goto CLEANUP;
    }
  }
  
CLEANUP:
  mp_clear (&q);

  return res;
}
Ejemplo n.º 27
0
/* integer signed division. 
 * c*b + d == a [e.g. a/b, c=quotient, d=remainder]
 * HAC pp.598 Algorithm 14.20
 *
 * Note that the description in HAC is horribly 
 * incomplete.  For example, it doesn't consider 
 * the case where digits are removed from 'x' in 
 * the inner loop.  It also doesn't consider the 
 * case that y has fewer than three digits, etc..
 *
 * The overall algorithm is as described as 
 * 14.20 from HAC but fixed to treat these cases.
*/
int mp_div MPA(mp_int * a, mp_int * b, mp_int * c, mp_int * d)
{
  mp_int  q, x, y, t1, t2;
  int     res, n, t, i, norm, neg;

  /* is divisor zero ? */
  if (mp_iszero (b) == 1) {
    return MP_VAL;
  }

  /* if a < b then q=0, r = a */
  if (mp_cmp_mag (a, b) == MP_LT) {
    if (d != NULL) {
      res = mp_copy (MPST, a, d);
    } else {
      res = MP_OKAY;
    }
    if (c != NULL) {
      mp_zero (c);
    }
    return res;
  }

  if ((res = mp_init_size (&q, a->used + 2)) != MP_OKAY) {
    return res;
  }
  q.used = a->used + 2;

  if ((res = mp_init (&t1)) != MP_OKAY) {
    goto LBL_Q;
  }

  if ((res = mp_init (&t2)) != MP_OKAY) {
    goto LBL_T1;
  }

  if ((res = mp_init_copy (MPST, &x, a)) != MP_OKAY) {
    goto LBL_T2;
  }

  if ((res = mp_init_copy (MPST, &y, b)) != MP_OKAY) {
    goto LBL_X;
  }

  /* fix the sign */
  neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
  x.sign = y.sign = MP_ZPOS;

  /* normalize both x and y, ensure that y >= b/2, [b == 2**DIGIT_BIT] */
  norm = mp_count_bits(&y) % DIGIT_BIT;
  if (norm < (int)(DIGIT_BIT-1)) {
     norm = (DIGIT_BIT-1) - norm;
     if ((res = mp_mul_2d (MPST, &x, norm, &x)) != MP_OKAY) {
       goto LBL_Y;
     }
     if ((res = mp_mul_2d (MPST, &y, norm, &y)) != MP_OKAY) {
       goto LBL_Y;
     }
  } else {
     norm = 0;
  }

  /* note hac does 0 based, so if used==5 then its 0,1,2,3,4, e.g. use 4 */
  n = x.used - 1;
  t = y.used - 1;

  /* while (x >= y*b**n-t) do { q[n-t] += 1; x -= y*b**{n-t} } */
  if ((res = mp_lshd (MPST, &y, n - t)) != MP_OKAY) { /* y = y*b**{n-t} */
    goto LBL_Y;
  }

  while (mp_cmp (&x, &y) != MP_LT) {
    ++(q.dp[n - t]);
    if ((res = mp_sub (MPST, &x, &y, &x)) != MP_OKAY) {
      goto LBL_Y;
    }
  }

  /* reset y by shifting it back down */
  mp_rshd (&y, n - t);

  /* step 3. for i from n down to (t + 1) */
  for (i = n; i >= (t + 1); i--) {
    if (i > x.used) {
      continue;
    }

    /* step 3.1 if xi == yt then set q{i-t-1} to b-1, 
     * otherwise set q{i-t-1} to (xi*b + x{i-1})/yt */
    if (x.dp[i] == y.dp[t]) {
      q.dp[i - t - 1] = ((((mp_digit)1) << DIGIT_BIT) - 1);
    } else {
      mp_word tmp;
      tmp = ((mp_word) x.dp[i]) << ((mp_word) DIGIT_BIT);
      tmp |= ((mp_word) x.dp[i - 1]);
      tmp /= ((mp_word) y.dp[t]);
      if (tmp > (mp_word) MP_MASK)
        tmp = MP_MASK;
      q.dp[i - t - 1] = (mp_digit) (tmp & (mp_word) (MP_MASK));
    }

    /* while (q{i-t-1} * (yt * b + y{t-1})) > 
             xi * b**2 + xi-1 * b + xi-2 
     
       do q{i-t-1} -= 1; 
    */
    q.dp[i - t - 1] = (q.dp[i - t - 1] + 1) & MP_MASK;
    do {
      q.dp[i - t - 1] = (q.dp[i - t - 1] - 1) & MP_MASK;

      /* find left hand */
      mp_zero (&t1);
      t1.dp[0] = (t - 1 < 0) ? 0 : y.dp[t - 1];
      t1.dp[1] = y.dp[t];
      t1.used = 2;
      if ((res = mp_mul_d (MPST, &t1, q.dp[i - t - 1], &t1)) != MP_OKAY) {
        goto LBL_Y;
      }

      /* find right hand */
      t2.dp[0] = (i - 2 < 0) ? 0 : x.dp[i - 2];
      t2.dp[1] = (i - 1 < 0) ? 0 : x.dp[i - 1];
      t2.dp[2] = x.dp[i];
      t2.used = 3;
    } while (mp_cmp_mag(&t1, &t2) == MP_GT);

    /* step 3.3 x = x - q{i-t-1} * y * b**{i-t-1} */
    if ((res = mp_mul_d (MPST, &y, q.dp[i - t - 1], &t1)) != MP_OKAY) {
      goto LBL_Y;
    }

    if ((res = mp_lshd (MPST, &t1, i - t - 1)) != MP_OKAY) {
      goto LBL_Y;
    }

    if ((res = mp_sub (MPST, &x, &t1, &x)) != MP_OKAY) {
      goto LBL_Y;
    }

    /* if x < 0 then { x = x + y*b**{i-t-1}; q{i-t-1} -= 1; } */
    if (x.sign == MP_NEG) {
      if ((res = mp_copy (MPST, &y, &t1)) != MP_OKAY) {
        goto LBL_Y;
      }
      if ((res = mp_lshd (MPST, &t1, i - t - 1)) != MP_OKAY) {
        goto LBL_Y;
      }
      if ((res = mp_add (MPST, &x, &t1, &x)) != MP_OKAY) {
        goto LBL_Y;
      }

      q.dp[i - t - 1] = (q.dp[i - t - 1] - 1UL) & MP_MASK;
    }
  }

  /* now q is the quotient and x is the remainder 
   * [which we have to normalize] 
   */
  
  /* get sign before writing to c */
  x.sign = x.used == 0 ? MP_ZPOS : a->sign;

  if (c != NULL) {
    mp_clamp (&q);
    mp_managed_copy (MPST, &q, c);
    c->sign = neg;
  }

  if (d != NULL) {
    mp_div_2d (MPST, &x, norm, &x, NULL);
    mp_managed_copy (MPST, &x, d);
  }

  res = MP_OKAY;

LBL_Y:mp_clear (&y);
LBL_X:mp_clear (&x);
LBL_T2:mp_clear (&t2);
LBL_T1:mp_clear (&t1);
LBL_Q:mp_clear (&q);
  return res;
}
Ejemplo n.º 28
0
static int RsaFunction(const byte* in, word32 inLen, byte* out, word32* outLen,
                       int type, RsaKey* key)
{
    #define ERROR_OUT(x) { ret = x; goto done;}

    mp_int tmp;
    int    ret = 0;
    word32 keyLen, len;

    if (mp_init(&tmp) != MP_OKAY)
        return MP_INIT_E;

    if (mp_read_unsigned_bin(&tmp, (byte*)in, inLen) != MP_OKAY)
        ERROR_OUT(MP_READ_E);

    if (type == RSA_PRIVATE_DECRYPT || type == RSA_PRIVATE_ENCRYPT) {
        #ifdef RSA_LOW_MEM      /* half as much memory but twice as slow */
            if (mp_exptmod(&tmp, &key->d, &key->n, &tmp) != MP_OKAY)
                ERROR_OUT(MP_EXPTMOD_E);
        #else
            #define INNER_ERROR_OUT(x) { ret = x; goto inner_done; }

            mp_int tmpa, tmpb;

            if (mp_init(&tmpa) != MP_OKAY)
                ERROR_OUT(MP_INIT_E);

            if (mp_init(&tmpb) != MP_OKAY) {
                mp_clear(&tmpa);
                ERROR_OUT(MP_INIT_E);
            }

            /* tmpa = tmp^dP mod p */
            if (mp_exptmod(&tmp, &key->dP, &key->p, &tmpa) != MP_OKAY)
                INNER_ERROR_OUT(MP_EXPTMOD_E);

            /* tmpb = tmp^dQ mod q */
            if (mp_exptmod(&tmp, &key->dQ, &key->q, &tmpb) != MP_OKAY)
                INNER_ERROR_OUT(MP_EXPTMOD_E);

            /* tmp = (tmpa - tmpb) * qInv (mod p) */
            if (mp_sub(&tmpa, &tmpb, &tmp) != MP_OKAY)
                INNER_ERROR_OUT(MP_SUB_E);

            if (mp_mulmod(&tmp, &key->u, &key->p, &tmp) != MP_OKAY)
                INNER_ERROR_OUT(MP_MULMOD_E);

            /* tmp = tmpb + q * tmp */
            if (mp_mul(&tmp, &key->q, &tmp) != MP_OKAY)
                INNER_ERROR_OUT(MP_MUL_E);

            if (mp_add(&tmp, &tmpb, &tmp) != MP_OKAY)
                INNER_ERROR_OUT(MP_ADD_E);

        inner_done:
            mp_clear(&tmpa);
            mp_clear(&tmpb);

            if (ret != 0) return ret;

        #endif   /* RSA_LOW_MEM */
    }
    else if (type == RSA_PUBLIC_ENCRYPT || type == RSA_PUBLIC_DECRYPT) {
        if (mp_exptmod(&tmp, &key->e, &key->n, &tmp) != MP_OKAY)
            ERROR_OUT(MP_EXPTMOD_E);
    }
    else
        ERROR_OUT(RSA_WRONG_TYPE_E);

    keyLen = mp_unsigned_bin_size(&key->n);
    if (keyLen > *outLen)
        ERROR_OUT(RSA_BUFFER_E);

    len = mp_unsigned_bin_size(&tmp);

    /* pad front w/ zeros to match key length */
    while (len < keyLen) {
        *out++ = 0x00;
        len++;
    }

    *outLen = keyLen;

    /* convert */
    if (mp_to_unsigned_bin(&tmp, out) != MP_OKAY)
        ERROR_OUT(MP_TO_E);
   
done: 
    mp_clear(&tmp);
    return ret;
}
Ejemplo n.º 29
0
/* slower bit-bang division... also smaller */
int mp_div MPA(mp_int * a, mp_int * b, mp_int * c, mp_int * d)
{
   mp_int ta, tb, tq, q;
   int    res, n, n2;

  /* is divisor zero ? */
  if (mp_iszero (b) == 1) {
    return MP_VAL;
  }

  /* if a < b then q=0, r = a */
  if (mp_cmp_mag (a, b) == MP_LT) {
    if (d != NULL) {
      res = mp_copy (a, d);
    } else {
      res = MP_OKAY;
    }
    if (c != NULL) {
      mp_zero (c);
    }
    return res;
  }
	
  /* init our temps */
  if ((res = mp_init_multi(&ta, &tb, &tq, &q, NULL) != MP_OKAY)) {
     return res;
  }


  mp_set(&tq, 1);
  n = mp_count_bits(a) - mp_count_bits(b);
  if (((res = mp_abs(a, &ta)) != MP_OKAY) ||
      ((res = mp_abs(b, &tb)) != MP_OKAY) || 
      ((res = mp_mul_2d(&tb, n, &tb)) != MP_OKAY) ||
      ((res = mp_mul_2d(&tq, n, &tq)) != MP_OKAY)) {
      goto LBL_ERR;
  }

  while (n-- >= 0) {
     if (mp_cmp(&tb, &ta) != MP_GT) {
        if (((res = mp_sub(&ta, &tb, &ta)) != MP_OKAY) ||
            ((res = mp_add(&q, &tq, &q)) != MP_OKAY)) {
           goto LBL_ERR;
        }
     }
     if (((res = mp_div_2d(&tb, 1, &tb, NULL)) != MP_OKAY) ||
         ((res = mp_div_2d(&tq, 1, &tq, NULL)) != MP_OKAY)) {
           goto LBL_ERR;
     }
  }

  /* now q == quotient and ta == remainder */
  n  = a->sign;
  n2 = (a->sign == b->sign ? MP_ZPOS : MP_NEG);
  if (c != NULL) {
     mp_exch(c, &q);
     c->sign  = (mp_iszero(c) == MP_YES) ? MP_ZPOS : n2;
  }
  if (d != NULL) {
     mp_exch(d, &ta);
     d->sign = (mp_iszero(d) == MP_YES) ? MP_ZPOS : n;
  }
LBL_ERR:
   mp_clear_multi(&ta, &tb, &tq, &q, NULL);
   return res;
}
Ejemplo n.º 30
0
/**
  Read a mp_int integer
  @param in       The DER encoded data
  @param inlen    Size of DER encoded data
  @param num      The first mp_int to decode
  @return CRYPT_OK if successful
*/
int der_decode_integer(const unsigned char *in, unsigned long inlen, void *num)
{
   unsigned long x, y, z;
   int           err;

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

   /* min DER INTEGER is 0x02 01 00 == 0 */
   if (inlen < (1 + 1 + 1)) {
      return CRYPT_INVALID_PACKET;
   }

   /* ok expect 0x02 when we AND with 0001 1111 [1F] */
   x = 0;
   if ((in[x++] & 0x1F) != 0x02) {
      return CRYPT_INVALID_PACKET;
   }

   /* now decode the len stuff */
   z = in[x++];

   if ((z & 0x80) == 0x00) {
      /* short form */

      /* will it overflow? */
      if (x + z > inlen) {
         return CRYPT_INVALID_PACKET;
      }
     
      /* no so read it */
      if ((err = mp_read_unsigned_bin(num, (unsigned char *)in + x, z)) != CRYPT_OK) {
         return err;
      }
   } else {
      /* long form */
      z &= 0x7F;
      
      /* will number of length bytes overflow? (or > 4) */
      if (((x + z) > inlen) || (z > 4) || (z == 0)) {
         return CRYPT_INVALID_PACKET;
      }

      /* now read it in */
      y = 0;
      while (z--) {
         y = ((unsigned long)(in[x++])) | (y << 8);
      }

      /* now will reading y bytes overrun? */
      if ((x + y) > inlen) {
         return CRYPT_INVALID_PACKET;
      }

      /* no so read it */
      if ((err = mp_read_unsigned_bin(num, (unsigned char *)in + x, y)) != CRYPT_OK) {
         return err;
      }
   }

   /* see if it's negative */
   if (in[x] & 0x80) {
      void *tmp;
      if (mp_init(&tmp) != CRYPT_OK) {
         return CRYPT_MEM;
      }

      if (mp_2expt(tmp, mp_count_bits(num)) != CRYPT_OK || mp_sub(num, tmp, num) != CRYPT_OK) {
         mp_clear(tmp);
         return CRYPT_MEM;
      }
      mp_clear(tmp);
   } 

   return CRYPT_OK;

}