cf783db152
$FreeBSD$ tags and man page dates. Add a post-merge script which reapplies these changes. Run both scripts to normalize the existing code base. As a result, many files which should have had $FreeBSD$ tags but didn't now have them. Partly rewrite the upgrade instructions and remove the now outdated list of tricks.
674 lines
17 KiB
C
674 lines
17 KiB
C
/* $OpenBSD: schnorr.c,v 1.9 2014/01/09 23:20:00 djm Exp $ */
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/* $FreeBSD$ */
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/*
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* Copyright (c) 2008 Damien Miller. All rights reserved.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Implementation of Schnorr signatures / zero-knowledge proofs, based on
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* description in:
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*
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* F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
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* 16th Workshop on Security Protocols, Cambridge, April 2008
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*
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* http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
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*/
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#include "includes.h"
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__RCSID("$FreeBSD$");
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#include <sys/types.h>
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#include <string.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <openssl/evp.h>
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#include <openssl/bn.h>
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#include "xmalloc.h"
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#include "buffer.h"
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#include "log.h"
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#include "schnorr.h"
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#include "digest.h"
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#ifdef JPAKE
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#include "openbsd-compat/openssl-compat.h"
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/* #define SCHNORR_DEBUG */ /* Privacy-violating debugging */
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/* #define SCHNORR_MAIN */ /* Include main() selftest */
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#ifndef SCHNORR_DEBUG
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# define SCHNORR_DEBUG_BN(a)
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# define SCHNORR_DEBUG_BUF(a)
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#else
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# define SCHNORR_DEBUG_BN(a) debug3_bn a
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# define SCHNORR_DEBUG_BUF(a) debug3_buf a
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#endif /* SCHNORR_DEBUG */
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/*
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* Calculate hash component of Schnorr signature H(g || g^v || g^x || id)
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* using the hash function defined by "hash_alg". Returns signature as
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* bignum or NULL on error.
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*/
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static BIGNUM *
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schnorr_hash(const BIGNUM *p, const BIGNUM *q, const BIGNUM *g,
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int hash_alg, const BIGNUM *g_v, const BIGNUM *g_x,
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const u_char *id, u_int idlen)
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{
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u_char *digest;
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u_int digest_len;
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BIGNUM *h;
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Buffer b;
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int success = -1;
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if ((h = BN_new()) == NULL) {
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error("%s: BN_new", __func__);
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return NULL;
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}
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buffer_init(&b);
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/* h = H(g || p || q || g^v || g^x || id) */
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buffer_put_bignum2(&b, g);
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buffer_put_bignum2(&b, p);
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buffer_put_bignum2(&b, q);
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buffer_put_bignum2(&b, g_v);
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buffer_put_bignum2(&b, g_x);
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buffer_put_string(&b, id, idlen);
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SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
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"%s: hashblob", __func__));
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if (hash_buffer(buffer_ptr(&b), buffer_len(&b), hash_alg,
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&digest, &digest_len) != 0) {
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error("%s: hash_buffer", __func__);
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goto out;
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}
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if (BN_bin2bn(digest, (int)digest_len, h) == NULL) {
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error("%s: BN_bin2bn", __func__);
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goto out;
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}
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success = 0;
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SCHNORR_DEBUG_BN((h, "%s: h = ", __func__));
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out:
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buffer_free(&b);
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bzero(digest, digest_len);
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free(digest);
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digest_len = 0;
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if (success == 0)
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return h;
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BN_clear_free(h);
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return NULL;
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}
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/*
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* Generate Schnorr signature to prove knowledge of private value 'x' used
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* in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g'
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* using the hash function "hash_alg".
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* 'idlen' bytes from 'id' will be included in the signature hash as an anti-
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* replay salt.
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*
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* On success, 0 is returned. The signature values are returned as *e_p
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* (g^v mod p) and *r_p (v - xh mod q). The caller must free these values.
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* On failure, -1 is returned.
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*/
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int
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schnorr_sign(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
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int hash_alg, const BIGNUM *x, const BIGNUM *g_x,
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const u_char *id, u_int idlen, BIGNUM **r_p, BIGNUM **e_p)
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{
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int success = -1;
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BIGNUM *h, *tmp, *v, *g_v, *r;
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BN_CTX *bn_ctx;
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SCHNORR_DEBUG_BN((x, "%s: x = ", __func__));
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SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
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/* Avoid degenerate cases: g^0 yields a spoofable signature */
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if (BN_cmp(g_x, BN_value_one()) <= 0) {
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error("%s: g_x < 1", __func__);
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return -1;
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}
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if (BN_cmp(g_x, grp_p) >= 0) {
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error("%s: g_x > g", __func__);
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return -1;
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}
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h = g_v = r = tmp = v = NULL;
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if ((bn_ctx = BN_CTX_new()) == NULL) {
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error("%s: BN_CTX_new", __func__);
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goto out;
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}
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if ((g_v = BN_new()) == NULL ||
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(r = BN_new()) == NULL ||
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(tmp = BN_new()) == NULL) {
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error("%s: BN_new", __func__);
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goto out;
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}
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/*
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* v must be a random element of Zq, so 1 <= v < q
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* we also exclude v = 1, since g^1 looks dangerous
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*/
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if ((v = bn_rand_range_gt_one(grp_p)) == NULL) {
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error("%s: bn_rand_range2", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((v, "%s: v = ", __func__));
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/* g_v = g^v mod p */
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if (BN_mod_exp(g_v, grp_g, v, grp_p, bn_ctx) == -1) {
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error("%s: BN_mod_exp (g^v mod p)", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__));
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/* h = H(g || g^v || g^x || id) */
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if ((h = schnorr_hash(grp_p, grp_q, grp_g, hash_alg, g_v, g_x,
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id, idlen)) == NULL) {
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error("%s: schnorr_hash failed", __func__);
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goto out;
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}
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/* r = v - xh mod q */
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if (BN_mod_mul(tmp, x, h, grp_q, bn_ctx) == -1) {
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error("%s: BN_mod_mul (tmp = xv mod q)", __func__);
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goto out;
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}
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if (BN_mod_sub(r, v, tmp, grp_q, bn_ctx) == -1) {
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error("%s: BN_mod_mul (r = v - tmp)", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((g_v, "%s: e = ", __func__));
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SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
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*e_p = g_v;
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*r_p = r;
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success = 0;
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out:
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BN_CTX_free(bn_ctx);
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if (h != NULL)
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BN_clear_free(h);
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if (v != NULL)
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BN_clear_free(v);
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BN_clear_free(tmp);
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return success;
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}
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/*
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* Generate Schnorr signature to prove knowledge of private value 'x' used
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* in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g'
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* using a SHA256 hash.
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* 'idlen' bytes from 'id' will be included in the signature hash as an anti-
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* replay salt.
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* On success, 0 is returned and *siglen bytes of signature are returned in
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* *sig (caller to free). Returns -1 on failure.
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*/
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int
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schnorr_sign_buf(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
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const BIGNUM *x, const BIGNUM *g_x, const u_char *id, u_int idlen,
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u_char **sig, u_int *siglen)
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{
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Buffer b;
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BIGNUM *r, *e;
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if (schnorr_sign(grp_p, grp_q, grp_g, SSH_DIGEST_SHA256,
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x, g_x, id, idlen, &r, &e) != 0)
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return -1;
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/* Signature is (e, r) */
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buffer_init(&b);
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/* XXX sigtype-hash as string? */
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buffer_put_bignum2(&b, e);
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buffer_put_bignum2(&b, r);
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*siglen = buffer_len(&b);
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*sig = xmalloc(*siglen);
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memcpy(*sig, buffer_ptr(&b), *siglen);
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SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
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"%s: sigblob", __func__));
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buffer_free(&b);
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BN_clear_free(r);
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BN_clear_free(e);
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return 0;
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}
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/*
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* Verify Schnorr signature { r (v - xh mod q), e (g^v mod p) } against
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* public exponent g_x (g^x) under group defined by 'grp_p', 'grp_q' and
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* 'grp_g' using hash "hash_alg".
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* Signature hash will be salted with 'idlen' bytes from 'id'.
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* Returns -1 on failure, 0 on incorrect signature or 1 on matching signature.
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*/
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int
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schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
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int hash_alg, const BIGNUM *g_x, const u_char *id, u_int idlen,
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const BIGNUM *r, const BIGNUM *e)
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{
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int success = -1;
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BIGNUM *h = NULL, *g_xh = NULL, *g_r = NULL, *gx_q = NULL;
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BIGNUM *expected = NULL;
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BN_CTX *bn_ctx;
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SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
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/* Avoid degenerate cases: g^0 yields a spoofable signature */
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if (BN_cmp(g_x, BN_value_one()) <= 0) {
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error("%s: g_x <= 1", __func__);
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return -1;
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}
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if (BN_cmp(g_x, grp_p) >= 0) {
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error("%s: g_x >= p", __func__);
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return -1;
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}
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h = g_xh = g_r = expected = NULL;
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if ((bn_ctx = BN_CTX_new()) == NULL) {
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error("%s: BN_CTX_new", __func__);
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goto out;
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}
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if ((g_xh = BN_new()) == NULL ||
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(g_r = BN_new()) == NULL ||
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(gx_q = BN_new()) == NULL ||
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(expected = BN_new()) == NULL) {
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error("%s: BN_new", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((e, "%s: e = ", __func__));
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SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
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/* gx_q = (g^x)^q must === 1 mod p */
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if (BN_mod_exp(gx_q, g_x, grp_q, grp_p, bn_ctx) == -1) {
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error("%s: BN_mod_exp (g_x^q mod p)", __func__);
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goto out;
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}
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if (BN_cmp(gx_q, BN_value_one()) != 0) {
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error("%s: Invalid signature (g^x)^q != 1 mod p", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__));
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/* h = H(g || g^v || g^x || id) */
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if ((h = schnorr_hash(grp_p, grp_q, grp_g, hash_alg, e, g_x,
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id, idlen)) == NULL) {
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error("%s: schnorr_hash failed", __func__);
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goto out;
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}
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/* g_xh = (g^x)^h */
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if (BN_mod_exp(g_xh, g_x, h, grp_p, bn_ctx) == -1) {
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error("%s: BN_mod_exp (g_x^h mod p)", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__));
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/* g_r = g^r */
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if (BN_mod_exp(g_r, grp_g, r, grp_p, bn_ctx) == -1) {
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error("%s: BN_mod_exp (g_x^h mod p)", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((g_r, "%s: g_r = ", __func__));
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/* expected = g^r * g_xh */
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if (BN_mod_mul(expected, g_r, g_xh, grp_p, bn_ctx) == -1) {
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error("%s: BN_mod_mul (expected = g_r mod p)", __func__);
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goto out;
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}
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SCHNORR_DEBUG_BN((expected, "%s: expected = ", __func__));
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/* Check e == expected */
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success = BN_cmp(expected, e) == 0;
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out:
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BN_CTX_free(bn_ctx);
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if (h != NULL)
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BN_clear_free(h);
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if (gx_q != NULL)
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BN_clear_free(gx_q);
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if (g_xh != NULL)
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BN_clear_free(g_xh);
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if (g_r != NULL)
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BN_clear_free(g_r);
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if (expected != NULL)
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BN_clear_free(expected);
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return success;
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}
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/*
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* Verify Schnorr signature 'sig' of length 'siglen' against public exponent
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* g_x (g^x) under group defined by 'grp_p', 'grp_q' and 'grp_g' using a
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* SHA256 hash.
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* Signature hash will be salted with 'idlen' bytes from 'id'.
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* Returns -1 on failure, 0 on incorrect signature or 1 on matching signature.
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*/
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int
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schnorr_verify_buf(const BIGNUM *grp_p, const BIGNUM *grp_q,
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const BIGNUM *grp_g,
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const BIGNUM *g_x, const u_char *id, u_int idlen,
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const u_char *sig, u_int siglen)
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{
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Buffer b;
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int ret = -1;
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u_int rlen;
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BIGNUM *r, *e;
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e = r = NULL;
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if ((e = BN_new()) == NULL ||
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(r = BN_new()) == NULL) {
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error("%s: BN_new", __func__);
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goto out;
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}
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/* Extract g^v and r from signature blob */
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buffer_init(&b);
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buffer_append(&b, sig, siglen);
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SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
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"%s: sigblob", __func__));
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buffer_get_bignum2(&b, e);
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buffer_get_bignum2(&b, r);
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rlen = buffer_len(&b);
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buffer_free(&b);
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if (rlen != 0) {
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error("%s: remaining bytes in signature %d", __func__, rlen);
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goto out;
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}
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ret = schnorr_verify(grp_p, grp_q, grp_g, SSH_DIGEST_SHA256,
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g_x, id, idlen, r, e);
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out:
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BN_clear_free(e);
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BN_clear_free(r);
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return ret;
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}
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/* Helper functions */
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/*
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* Generate uniformly distributed random number in range (1, high).
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* Return number on success, NULL on failure.
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*/
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BIGNUM *
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bn_rand_range_gt_one(const BIGNUM *high)
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{
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BIGNUM *r, *tmp;
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int success = -1;
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if ((tmp = BN_new()) == NULL) {
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error("%s: BN_new", __func__);
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return NULL;
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}
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if ((r = BN_new()) == NULL) {
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error("%s: BN_new failed", __func__);
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goto out;
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}
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if (BN_set_word(tmp, 2) != 1) {
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error("%s: BN_set_word(tmp, 2)", __func__);
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goto out;
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}
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if (BN_sub(tmp, high, tmp) == -1) {
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error("%s: BN_sub failed (tmp = high - 2)", __func__);
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goto out;
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}
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if (BN_rand_range(r, tmp) == -1) {
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error("%s: BN_rand_range failed", __func__);
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goto out;
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}
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if (BN_set_word(tmp, 2) != 1) {
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error("%s: BN_set_word(tmp, 2)", __func__);
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goto out;
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}
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if (BN_add(r, r, tmp) == -1) {
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error("%s: BN_add failed (r = r + 2)", __func__);
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goto out;
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}
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success = 0;
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out:
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BN_clear_free(tmp);
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if (success == 0)
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return r;
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BN_clear_free(r);
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return NULL;
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}
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/* XXX convert all callers of this to use ssh_digest_memory() directly */
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/*
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* Hash contents of buffer 'b' with hash 'md'. Returns 0 on success,
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* with digest via 'digestp' (caller to free) and length via 'lenp'.
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* Returns -1 on failure.
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*/
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int
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hash_buffer(const u_char *buf, u_int len, int hash_alg,
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u_char **digestp, u_int *lenp)
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{
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u_char digest[SSH_DIGEST_MAX_LENGTH];
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u_int digest_len = ssh_digest_bytes(hash_alg);
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if (digest_len == 0) {
|
|
error("%s: invalid hash", __func__);
|
|
return -1;
|
|
}
|
|
if (ssh_digest_memory(hash_alg, buf, len, digest, digest_len) != 0) {
|
|
error("%s: digest_memory failed", __func__);
|
|
return -1;
|
|
}
|
|
*digestp = xmalloc(digest_len);
|
|
*lenp = digest_len;
|
|
memcpy(*digestp, digest, *lenp);
|
|
bzero(digest, sizeof(digest));
|
|
digest_len = 0;
|
|
return 0;
|
|
}
|
|
|
|
/* print formatted string followed by bignum */
|
|
void
|
|
debug3_bn(const BIGNUM *n, const char *fmt, ...)
|
|
{
|
|
char *out, *h;
|
|
va_list args;
|
|
int ret;
|
|
|
|
out = NULL;
|
|
va_start(args, fmt);
|
|
ret = vasprintf(&out, fmt, args);
|
|
va_end(args);
|
|
if (ret == -1 || out == NULL)
|
|
fatal("%s: vasprintf failed", __func__);
|
|
|
|
if (n == NULL)
|
|
debug3("%s(null)", out);
|
|
else {
|
|
h = BN_bn2hex(n);
|
|
debug3("%s0x%s", out, h);
|
|
free(h);
|
|
}
|
|
free(out);
|
|
}
|
|
|
|
/* print formatted string followed by buffer contents in hex */
|
|
void
|
|
debug3_buf(const u_char *buf, u_int len, const char *fmt, ...)
|
|
{
|
|
char *out, h[65];
|
|
u_int i, j;
|
|
va_list args;
|
|
int ret;
|
|
|
|
out = NULL;
|
|
va_start(args, fmt);
|
|
ret = vasprintf(&out, fmt, args);
|
|
va_end(args);
|
|
if (ret == -1 || out == NULL)
|
|
fatal("%s: vasprintf failed", __func__);
|
|
|
|
debug3("%s length %u%s", out, len, buf == NULL ? " (null)" : "");
|
|
free(out);
|
|
if (buf == NULL)
|
|
return;
|
|
|
|
*h = '\0';
|
|
for (i = j = 0; i < len; i++) {
|
|
snprintf(h + j, sizeof(h) - j, "%02x", buf[i]);
|
|
j += 2;
|
|
if (j >= sizeof(h) - 1 || i == len - 1) {
|
|
debug3(" %s", h);
|
|
*h = '\0';
|
|
j = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Construct a MODP group from hex strings p (which must be a safe
|
|
* prime) and g, automatically calculating subgroup q as (p / 2)
|
|
*/
|
|
struct modp_group *
|
|
modp_group_from_g_and_safe_p(const char *grp_g, const char *grp_p)
|
|
{
|
|
struct modp_group *ret;
|
|
|
|
ret = xcalloc(1, sizeof(*ret));
|
|
ret->p = ret->q = ret->g = NULL;
|
|
if (BN_hex2bn(&ret->p, grp_p) == 0 ||
|
|
BN_hex2bn(&ret->g, grp_g) == 0)
|
|
fatal("%s: BN_hex2bn", __func__);
|
|
/* Subgroup order is p/2 (p is a safe prime) */
|
|
if ((ret->q = BN_new()) == NULL)
|
|
fatal("%s: BN_new", __func__);
|
|
if (BN_rshift1(ret->q, ret->p) != 1)
|
|
fatal("%s: BN_rshift1", __func__);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void
|
|
modp_group_free(struct modp_group *grp)
|
|
{
|
|
if (grp->g != NULL)
|
|
BN_clear_free(grp->g);
|
|
if (grp->p != NULL)
|
|
BN_clear_free(grp->p);
|
|
if (grp->q != NULL)
|
|
BN_clear_free(grp->q);
|
|
bzero(grp, sizeof(*grp));
|
|
free(grp);
|
|
}
|
|
|
|
/* main() function for self-test */
|
|
|
|
#ifdef SCHNORR_MAIN
|
|
static void
|
|
schnorr_selftest_one(const BIGNUM *grp_p, const BIGNUM *grp_q,
|
|
const BIGNUM *grp_g, const BIGNUM *x)
|
|
{
|
|
BIGNUM *g_x;
|
|
u_char *sig;
|
|
u_int siglen;
|
|
BN_CTX *bn_ctx;
|
|
|
|
if ((bn_ctx = BN_CTX_new()) == NULL)
|
|
fatal("%s: BN_CTX_new", __func__);
|
|
if ((g_x = BN_new()) == NULL)
|
|
fatal("%s: BN_new", __func__);
|
|
|
|
if (BN_mod_exp(g_x, grp_g, x, grp_p, bn_ctx) == -1)
|
|
fatal("%s: g_x", __func__);
|
|
if (schnorr_sign_buf(grp_p, grp_q, grp_g, x, g_x, "junk", 4,
|
|
&sig, &siglen))
|
|
fatal("%s: schnorr_sign", __func__);
|
|
if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "junk", 4,
|
|
sig, siglen) != 1)
|
|
fatal("%s: verify fail", __func__);
|
|
if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "JUNK", 4,
|
|
sig, siglen) != 0)
|
|
fatal("%s: verify should have failed (bad ID)", __func__);
|
|
sig[4] ^= 1;
|
|
if (schnorr_verify_buf(grp_p, grp_q, grp_g, g_x, "junk", 4,
|
|
sig, siglen) != 0)
|
|
fatal("%s: verify should have failed (bit error)", __func__);
|
|
free(sig);
|
|
BN_free(g_x);
|
|
BN_CTX_free(bn_ctx);
|
|
}
|
|
|
|
static void
|
|
schnorr_selftest(void)
|
|
{
|
|
BIGNUM *x;
|
|
struct modp_group *grp;
|
|
u_int i;
|
|
char *hh;
|
|
|
|
grp = jpake_default_group();
|
|
if ((x = BN_new()) == NULL)
|
|
fatal("%s: BN_new", __func__);
|
|
SCHNORR_DEBUG_BN((grp->p, "%s: grp->p = ", __func__));
|
|
SCHNORR_DEBUG_BN((grp->q, "%s: grp->q = ", __func__));
|
|
SCHNORR_DEBUG_BN((grp->g, "%s: grp->g = ", __func__));
|
|
|
|
/* [1, 20) */
|
|
for (i = 1; i < 20; i++) {
|
|
printf("x = %u\n", i);
|
|
fflush(stdout);
|
|
if (BN_set_word(x, i) != 1)
|
|
fatal("%s: set x word", __func__);
|
|
schnorr_selftest_one(grp->p, grp->q, grp->g, x);
|
|
}
|
|
|
|
/* 100 x random [0, p) */
|
|
for (i = 0; i < 100; i++) {
|
|
if (BN_rand_range(x, grp->p) != 1)
|
|
fatal("%s: BN_rand_range", __func__);
|
|
hh = BN_bn2hex(x);
|
|
printf("x = (random) 0x%s\n", hh);
|
|
free(hh);
|
|
fflush(stdout);
|
|
schnorr_selftest_one(grp->p, grp->q, grp->g, x);
|
|
}
|
|
|
|
/* [q-20, q) */
|
|
if (BN_set_word(x, 20) != 1)
|
|
fatal("%s: BN_set_word (x = 20)", __func__);
|
|
if (BN_sub(x, grp->q, x) != 1)
|
|
fatal("%s: BN_sub (q - x)", __func__);
|
|
for (i = 0; i < 19; i++) {
|
|
hh = BN_bn2hex(x);
|
|
printf("x = (q - %d) 0x%s\n", 20 - i, hh);
|
|
free(hh);
|
|
fflush(stdout);
|
|
schnorr_selftest_one(grp->p, grp->q, grp->g, x);
|
|
if (BN_add(x, x, BN_value_one()) != 1)
|
|
fatal("%s: BN_add (x + 1)", __func__);
|
|
}
|
|
BN_free(x);
|
|
}
|
|
|
|
int
|
|
main(int argc, char **argv)
|
|
{
|
|
log_init(argv[0], SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_USER, 1);
|
|
|
|
schnorr_selftest();
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#endif
|