Implement DH using imath.

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@17472 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/des/dh-imath.c

@@ -0,0 +1,213 @@
+/*
+ * Copyright (c) 2006 Kungliga Tekniska H<>gskolan
+ * (Royal Institute of Technology, Stockholm, Sweden). 
+ * All rights reserved. 
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * modification, are permitted provided that the following conditions 
+ * are met: 
+ *
+ * 1. Redistributions of source code must retain the above copyright 
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright 
+ *    notice, this list of conditions and the following disclaimer in the 
+ *    documentation and/or other materials provided with the distribution. 
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors 
+ *    may be used to endorse or promote products derived from this software 
+ *    without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
+ * SUCH DAMAGE. 
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <dh.h>
+
+#include <roken.h>
+
+#include "imath/imath.h"
+
+RCSID("$Id$");
+
+static void
+BN2mpz(mpz_t *s, const BIGNUM *bn)
+{
+    size_t len;
+    void *p;
+
+    len = BN_num_bytes(bn);
+    p = malloc(len);
+    BN_bn2bin(bn, p);
+    mp_int_read_unsigned(s, p, len);
+    free(p);
+}
+
+
+static BIGNUM *
+mpz2BN(mpz_t *s)
+{
+    size_t size;
+    BIGNUM *bn;
+    void *p;
+
+    size = mp_int_unsigned_len(s);
+    p = malloc(size);
+    if (p == NULL && size != 0)
+	return NULL;
+    mp_int_to_unsigned(s, p, size);
+
+    bn = BN_bin2bn(p, size, NULL);
+    free(p);
+    return bn;
+}
+
+/*
+ *
+ */
+
+static int
+dh_generate_key(DH *dh)
+{
+    mpz_t pub, priv_key, g, p;
+
+    if (dh->p == NULL || dh->g == NULL)
+	return 0;
+
+    if (dh->priv_key == NULL) {
+	size_t bits = BN_num_bits(dh->p);
+	dh->priv_key = BN_new();
+	if (dh->priv_key == NULL)
+	    return 0;
+	if (!BN_rand(dh->priv_key, bits - 1, 0, 0)) {
+	    BN_clear_free(dh->priv_key);
+	    dh->priv_key = NULL;
+	    return 0;
+	}
+    }
+    if (dh->pub_key)
+	BN_free(dh->pub_key);
+
+    mp_int_init(&pub);
+    mp_int_init(&priv_key);
+    mp_int_init(&g);
+    mp_int_init(&p);
+
+    BN2mpz(&priv_key, dh->priv_key);
+    BN2mpz(&g, dh->g);
+    BN2mpz(&p, dh->p);
+
+    mp_int_exptmod(&g, &priv_key, &p, &pub);
+
+    mp_int_clear(&priv_key);
+    mp_int_clear(&g);
+    mp_int_clear(&p);
+
+    dh->pub_key = mpz2BN(&pub);
+    mp_int_clear(&pub);
+    if (dh->pub_key == NULL)
+	return 0;
+
+    return 1;
+}
+
+static int 
+dh_compute_key(unsigned char *shared, const BIGNUM * pub, DH *dh)
+{
+    mpz_t s, priv_key, p, peer_pub;
+    size_t size = 0;
+    mp_result res;
+
+    if (dh->pub_key == NULL || dh->g == NULL || dh->priv_key == NULL)
+	return 0;
+
+    mp_int_init(&p);
+    BN2mpz(&p, dh->p);
+
+    mp_int_init(&peer_pub);
+    BN2mpz(&peer_pub, pub);
+
+    /* check if peers pubkey is reasonable */
+    if (MP_SIGN(&peer_pub) != 1
+	|| mp_int_compare(&peer_pub, &p) >= 0
+	|| mp_int_compare_value(&peer_pub, 1) <= 0)
+    {
+	mp_int_clear(&p);
+	mp_int_clear(&peer_pub);
+	return 0;
+    }
+
+    mp_int_init(&priv_key);
+    BN2mpz(&priv_key, dh->priv_key);
+
+    mp_int_init(&s);
+
+    mp_int_exptmod(&peer_pub, &priv_key, &p, &s);
+
+    mp_int_clear(&p);
+    mp_int_clear(&peer_pub);
+    mp_int_clear(&priv_key);
+
+    size = mp_int_unsigned_len(&s);
+    res = mp_int_to_unsigned(&s, shared, size);
+    mp_int_clear(&s);
+
+    return (res == MP_OK) ? size : -1;
+}
+
+static int
+dh_generate_params(DH *dh, int a, int b, BN_GENCB *callback)
+{
+    /* groups should already be known, we don't care about this */
+    return 0;
+}
+
+static int
+dh_init(DH *dh)
+{
+    return 1;
+}
+
+static int
+dh_finish(DH *dh)
+{
+    return 1;
+}
+
+
+/*
+ *
+ */
+
+const DH_METHOD hc_dh_imath_method = {
+    "hx509 imath DH",
+    dh_generate_key,
+    dh_compute_key,
+    NULL,
+    dh_init,
+    dh_finish,
+    0,
+    NULL,
+    dh_generate_params
+};
+
+const DH_METHOD *
+DH_imath_method(void)
+{
+    return &hc_dh_imath_method;
+}