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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
commit674a60748884dc55ee7091b7c23a41240e75f73c (patch)
tree3b5a173c356f867b94df3873b57ff36d33129ea7 /genrsa.c
Makefile.in contains updated files required
--HG-- extra : convert_revision : cc8a8c49dc70e632c352853a39801089b08149be
Diffstat (limited to 'genrsa.c')
-rw-r--r--genrsa.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/genrsa.c b/genrsa.c
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+++ b/genrsa.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 "bignum.h"
+#include "random.h"
+#include "rsa.h"
+#include "genrsa.h"
+
+#define RSA_E 65537
+
+#ifdef DROPBEAR_RSA
+
+static void getrsaprime(mp_int* prime, mp_int *primeminus,
+ mp_int* rsa_e, unsigned int size);
+
+/* mostly taken from libtomcrypt's rsa key generation routine */
+rsa_key * gen_rsa_priv_key(unsigned int size) {
+
+ rsa_key * key;
+ mp_int pminus, qminus, lcm;
+
+ key = (rsa_key*)m_malloc(sizeof(rsa_key));
+
+ key->e = (mp_int*)m_malloc(sizeof(mp_int));
+ key->n = (mp_int*)m_malloc(sizeof(mp_int));
+ key->d = (mp_int*)m_malloc(sizeof(mp_int));
+ key->p = (mp_int*)m_malloc(sizeof(mp_int));
+ key->q = (mp_int*)m_malloc(sizeof(mp_int));
+
+ m_mp_init_multi(key->e, key->n, key->d, key->p, key->q,
+ &pminus, &lcm, &qminus, NULL);
+
+ seedrandom();
+
+ if (mp_set_int(key->e, RSA_E) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+
+ /* PuTTY doesn't like it if the modulus isn't a multiple of 8 bits,
+ * so we just generate them until we get one which is OK */
+ getrsaprime(key->p, &pminus, key->e, size/2);
+ do {
+ getrsaprime(key->q, &qminus, key->e, size/2);
+
+ if (mp_mul(key->p, key->q, key->n) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+ } while (mp_count_bits(key->n) % 8 != 0);
+
+ /* lcm(p-1, q-1) */
+ if (mp_lcm(&pminus, &qminus, &lcm) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+
+ /* de = 1 mod lcm(p-1,q-1) */
+ /* therefore d = (e^-1) mod lcm(p-1,q-1) */
+ if (mp_invmod(key->e, &lcm, key->d) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+
+ mp_clear_multi(&pminus, &qminus, &lcm, NULL);
+
+ return key;
+}
+
+/* return a prime suitable for p or q */
+static void getrsaprime(mp_int* prime, mp_int *primeminus,
+ mp_int* rsa_e, unsigned int size) {
+
+ unsigned char *buf;
+ mp_int temp_gcd;
+
+ buf = (unsigned char*)m_malloc(size+1);
+
+ m_mp_init(&temp_gcd);
+ do {
+ /* generate a random odd number with MSB set, then find the
+ the next prime above it */
+ genrandom(buf, size+1);
+ buf[0] |= 0x80; /* MSB set */
+
+ if (mp_read_unsigned_bin(prime, buf, size+1) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+
+ /* find the next integer which is prime, 8 round of miller-rabin */
+ if (mp_prime_next_prime(prime, 8, 0) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+
+ /* subtract one to get p-1 */
+ if (mp_sub_d(prime, 1, primeminus) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+ /* check relative primality to e */
+ if (mp_gcd(primeminus, rsa_e, &temp_gcd) != MP_OKAY) {
+ fprintf(stderr, "rsa generation failed\n");
+ exit(1);
+ }
+ } while (mp_cmp_d(&temp_gcd, 1) != MP_EQ); /* while gcd(p-1, e) != 1 */
+
+ /* now we have a good value for result */
+ mp_clear(&temp_gcd);
+ m_burn(buf, size+1);
+ m_free(buf);
+}
+
+#endif /* DROPBEAR_RSA */