示例#1
0
文件: mpl_gcd.c 项目: knikulov/libmpl
int
mpl_gcd(mpl_int *c, const mpl_int *a, const mpl_int *b)
{
    mpl_int x, y, u, v;
    int rc, k;

    if ((rc = mpl_initv(&u, &v, NULL)) != MPL_OK)
        return rc;

    x.dig = a->dig;
    x.alloc = a->alloc;
    x.top = a->top;
    x.sign = MPL_SIGN_POS;

    y.dig = b->dig;
    y.alloc = b->alloc;
    y.top = b->top;
    y.sign = MPL_SIGN_POS;

    rc = mpl_copy(&u, &x);
    if (rc != MPL_OK)
        goto err;

    rc = mpl_copy(&v, &y);
    if (rc != MPL_OK)
        goto err;

    k = 0;
    while (mpl_iseven(&v) && mpl_iseven(&u)) {
        rc = mpl_shr(&u, 1);
        if (rc != MPL_OK)
            goto err;
        rc = mpl_shr(&v, 1);
        if (rc != MPL_OK)
            goto err;
        ++k;
    }

    do {
        /* Reduce u by factor of two. */
        while (mpl_iseven(&u)) {
            rc = mpl_shr(&u, 1);
            if (rc != MPL_OK)
                goto err;
        }

        /* Reduce v by factor of two. */
        while (mpl_iseven(&v)) {
            rc = mpl_shr(&v, 1);
            if (rc != MPL_OK)
                goto err;
        }

        /* Reduce greatest of u or v. */
        if (mpl_cmp(&u, &v) != MPL_CMP_LT) {
            /* u = (u - v) / 2 */
            rc = mpl_sub(&u, &u, &v);
            if (rc != MPL_OK)
                goto err;
            rc = mpl_shr(&u, 1);
            if (rc != MPL_OK)
                goto err;
        } else {
            /* v = (v - u) / 2 */
            rc = mpl_sub(&v, &v, &u);
            if (rc != MPL_OK)
                goto err;
            rc = mpl_shr(&v, 1);
            if (rc != MPL_OK)
                goto err;
        }

    } while (!mpl_iszero(&u) && !mpl_iszero(&v));

    if (mpl_iszero(&u)) {
        rc = mpl_copy(c, &v);
        if (rc != MPL_OK)
            goto err;
    } else {
        rc = mpl_copy(c, &u);
        if (rc != MPL_OK)
            goto err;
    }

    if (k > 0) {
        rc = mpl_shl(c, k);
        if (rc != MPL_OK)
            goto err;
    }

    rc = MPL_OK;
err:
    mpl_clearv(&u, &v, NULL);
    return rc;
}
示例#2
0
int
mpl_primality_miller_rabin(const mpl_int *m, int r,
			  int (*rnd)(void *buf, size_t size, void *rndctx),
			  void *rndctx)
{
	mpl_int m_minus_one, one;
	mpl_int m_mod, a, t, x, mu;
	int i, rc, s, n;

	if (rnd == NULL || r == 0 || mpl_iszero(m))
		return MPL_ERR;

	rc = mpl_initv(&m_minus_one, &one, &a, &t, &x, &mu, NULL);
	if (rc != MPL_OK)
		return rc;
	/* m_mod = |m| */
	m_mod.dig = m->dig;
	m_mod.top = m->top;
	m_mod.sign = MPL_SIGN_POS;
	m_mod.alloc = 0;

	/* one = 1, m_minus_one = |m| - 1 */
	mpl_set_one(&one);

	rc = mpl_sub(&m_minus_one, &m_mod, &one);
	if (rc != MPL_OK)
		goto out;

	/* Prepare Barrett reduction precalculated constant. */
	rc = mpl_reduce_barrett_setup(&mu, &m_mod);
	if (rc != MPL_OK)
		goto out;

	/* Determine power of two used to construct |m|-1 = 2^s * t. */
	s = 0;
	n = m_minus_one.top + 1;

	for (i = 0; i < n; i++) {
		_mpl_int_t dig;
		int cnt;

		dig = m_minus_one.dig[i];

		for (cnt = 0; cnt < MPL_INT_BITS; cnt++) {
			if (dig & 0x1)
				goto brk_loop;
			dig >>= 1;
			++s;
		}
	}

brk_loop:

	/* The following condition is a paranoidal check. */
	if (i >= n) {
		rc = MPL_ERR;
		goto out;
	}

	/* m_minus_one = 2^s * t */
	rc = mpl_copy(&t, &m_minus_one);
	if (rc != MPL_OK)
		goto out;

	if (s > 0) {
		rc = mpl_shr(&t, s);
		if (rc != MPL_OK)
			goto out;
	}

	/* Number of random bytes one digit less than m. */
	n = (m->top * MPL_INT_BITS) / CHAR_BIT;

	for (i = 0; i < r; i++) {
		int j;

		//rc = mpl_random(&a, n, rnd, rndctx);
		rc = mpl_rand_below(&a, &m_minus_one, rnd, rndctx);
		if (rc != MPL_OK)
			goto out;

		rc = mpl_mod_exp(&x, &a, &t, &m_mod);
		if (rc != MPL_OK)
			goto out;

		if (mpl_cmp(&x, &one) == MPL_CMP_EQ)
			continue;

		if (mpl_cmp(&x, &m_minus_one) == MPL_CMP_EQ)
			continue;

		for (j = 1; j < s; j++) {
			
			rc = mpl_sqr(&x, &x);
			if (rc != MPL_OK)
				goto out;

			rc = mpl_reduce_barrett(&x, &x, &m_mod, &mu);
			if (rc != MPL_OK)
				goto out;

			if (mpl_isone(&x)) {
				rc = MPL_COMPOSITE;
				goto out;
			}

			if (mpl_cmp(&x, &m_minus_one) == MPL_CMP_EQ)
				break;
		}

		if (j >= s) {
			rc = MPL_COMPOSITE;
			goto out;
		}
	}

	rc = MPL_OK;
out:
	mpl_clearv(&m_minus_one, &one, &a, &t, &x, &mu, NULL);
	return rc;
}