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authorMatt Johnston <matt@ucc.asn.au>2004-06-01 02:46:09 +0000
committerMatt Johnston <matt@ucc.asn.au>2004-06-01 02:46:09 +0000
commitd53c6e53ee09a98198f57c5dfa18416040d3ce99 (patch)
tree3b5a173c356f867b94df3873b57ff36d33129ea7 /gendss.c
downloaddropbear-d53c6e53ee09a98198f57c5dfa18416040d3ce99.tar.gz
Makefile.in contains updated files required
Diffstat (limited to 'gendss.c')
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1 files changed, 215 insertions, 0 deletions
diff --git a/gendss.c b/gendss.c
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+/*
+ * Dropbear - a SSH2 server
+ *
+ * Copyright (c) 2002,2003 Matt Johnston
+ * All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE. */
+
+#include "includes.h"
+#include "dbutil.h"
+#include "signkey.h"
+#include "bignum.h"
+#include "random.h"
+#include "buffer.h"
+#include "gendss.h"
+#include "dss.h"
+
+#define PSIZE 128 /* 1024 bit*/
+#define QSIZE 20 /* 160 bit */
+
+#ifdef DROPBEAR_DSS
+
+static void getq(dss_key *key);
+static void getp(dss_key *key, unsigned int size);
+static void getg(dss_key *key);
+static void getx(dss_key *key);
+static void gety(dss_key *key);
+
+dss_key * gen_dss_priv_key(unsigned int size) {
+
+ dss_key *key;
+
+ key = (dss_key*)m_malloc(sizeof(dss_key));
+
+ key->p = (mp_int*)m_malloc(sizeof(mp_int));
+ key->q = (mp_int*)m_malloc(sizeof(mp_int));
+ key->g = (mp_int*)m_malloc(sizeof(mp_int));
+ key->y = (mp_int*)m_malloc(sizeof(mp_int));
+ key->x = (mp_int*)m_malloc(sizeof(mp_int));
+ m_mp_init_multi(key->p, key->q, key->g, key->y, key->x, NULL);
+
+ seedrandom();
+
+ getq(key);
+ getp(key, size);
+ getg(key);
+ getx(key);
+ gety(key);
+
+ return key;
+
+}
+
+static void getq(dss_key *key) {
+
+ char buf[QSIZE];
+
+ /* 160 bit prime */
+ genrandom(buf, QSIZE);
+ buf[0] |= 0x80; /* top bit high */
+ buf[QSIZE-1] |= 0x01; /* bottom bit high */
+
+ if (mp_read_unsigned_bin(key->q, buf, QSIZE) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+
+ /* 18 rounds are required according to HAC */
+ if (mp_prime_next_prime(key->q, 18, 0) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+}
+
+static void getp(dss_key *key, unsigned int size) {
+
+ mp_int tempX, tempC, tempP, 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 */
+ if (mp_read_unsigned_bin(&tempX, buf, size) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+
+ /* 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_free(buf);
+}
+
+static void getg(dss_key * key) {
+
+ char printbuf[1000];
+ mp_int div, h, val;
+
+ m_mp_init_multi(&div, &h, &val, NULL);
+
+ /* get div=(p-1)/q */
+ if (mp_sub_d(key->p, 1, &val) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+ if (mp_div(&val, key->q, &div, NULL) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+
+ /* initialise h=1 */
+ mp_set(&h, 1);
+ do {
+ /* now keep going with g=h^div mod p, until g > 1 */
+ if (mp_exptmod(&h, &div, key->p, key->g) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+
+ if (mp_add_d(&h, 1, &h) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+
+ } while (mp_cmp_d(key->g, 1) != MP_GT);
+
+ mp_toradix(key->g, printbuf, 10);
+
+ mp_clear_multi(&div, &h, &val, NULL);
+}
+
+static void getx(dss_key *key) {
+
+ mp_int val;
+ char buf[QSIZE];
+
+ m_mp_init(&val);
+
+ do {
+ genrandom(buf, QSIZE);
+
+ if (mp_read_unsigned_bin(&val, buf, QSIZE) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ }
+ } while ((mp_cmp_d(&val, 1) == MP_GT) && (mp_cmp(&val, key->q) == MP_LT));
+
+ mp_copy(&val, key->x);
+ mp_clear(&val);
+
+}
+
+static void gety(dss_key *key) {
+
+ if (mp_exptmod(key->g, key->x, key->p, key->y) != MP_OKAY) {
+ fprintf(stderr, "dss key generation failed\n");
+ exit(1);
+ }
+}
+
+#endif /* DROPBEAR_DSS */