X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/c8682232940ff590d349f4783399f5c8f5761262..ec1f12d364f648cd11a7baa785963a15a4d0b872:/dh.c

diff --git a/dh.c b/dh.c
index 636758fa..575522dd 100644
--- a/dh.c
+++ b/dh.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: dh.c,v 1.10 2001/03/28 22:04:57 provos Exp $");
+RCSID("$OpenBSD: dh.c,v 1.14 2001/04/15 08:43:45 markus Exp $");
 
 #include "xmalloc.h"
 
@@ -80,10 +80,10 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg)
 
 	dhg->g = BN_new();
 	dhg->p = BN_new();
-	if (BN_hex2bn(&dhg->g, gen) < 0)
+	if (BN_hex2bn(&dhg->g, gen) == 0)
 		goto failclean;
 
-	if (BN_hex2bn(&dhg->p, prime) < 0)
+	if (BN_hex2bn(&dhg->p, prime) == 0)
 		goto failclean;
 
 	if (BN_num_bits(dhg->p) != dhg->size)
@@ -151,11 +151,9 @@ choose_dh(int min, int wantbits, int max)
 	while (fgets(line, sizeof(line), f)) {
 		if (!parse_prime(linenum, line, &dhg))
 			continue;
-		if (dhg.size > max || dhg.size < min)
-			continue;
-		if (dhg.size != best)
-			continue;
-		if (linenum++ != which) {
+		if ((dhg.size > max || dhg.size < min) ||
+		    dhg.size != best ||
+		    linenum++ != which) {
 			BN_free(dhg.g);
 			BN_free(dhg.p);
 			continue;
@@ -163,6 +161,134 @@ choose_dh(int min, int wantbits, int max)
 		break;
 	}
 	fclose(f);
+	if (linenum != which+1)
+		fatal("WARNING: line %d disappeared in %s, giving up",
+		    which, _PATH_DH_PRIMES);
 
 	return (dh_new_group(dhg.g, dhg.p));
 }
+
+/* diffie-hellman-group1-sha1 */
+
+int
+dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
+{
+	int i;
+	int n = BN_num_bits(dh_pub);
+	int bits_set = 0;
+
+	if (dh_pub->neg) {
+		log("invalid public DH value: negativ");
+		return 0;
+	}
+	for (i = 0; i <= n; i++)
+		if (BN_is_bit_set(dh_pub, i))
+			bits_set++;
+	debug("bits set: %d/%d", bits_set, BN_num_bits(dh->p));
+
+	/* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */
+	if (bits_set > 1 && (BN_cmp(dh_pub, dh->p) == -1))
+		return 1;
+	log("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p));
+	return 0;
+}
+
+void
+dh_gen_key(DH *dh, int need)
+{
+	int i, bits_set = 0, tries = 0;
+
+	if (dh->p == NULL)
+		fatal("dh_gen_key: dh->p == NULL");
+	if (2*need >= BN_num_bits(dh->p))
+		fatal("dh_gen_key: group too small: %d (2*need %d)",
+		    BN_num_bits(dh->p), 2*need);
+	do {
+		if (dh->priv_key != NULL)
+			BN_free(dh->priv_key);
+		dh->priv_key = BN_new();
+		if (dh->priv_key == NULL)
+			fatal("dh_gen_key: BN_new failed");
+		/* generate a 2*need bits random private exponent */
+		if (!BN_rand(dh->priv_key, 2*need, 0, 0))
+			fatal("dh_gen_key: BN_rand failed");
+		if (DH_generate_key(dh) == 0)
+			fatal("DH_generate_key");
+		for (i = 0; i <= BN_num_bits(dh->priv_key); i++)
+			if (BN_is_bit_set(dh->priv_key, i))
+				bits_set++;
+		debug("dh_gen_key: priv key bits set: %d/%d",
+		    bits_set, BN_num_bits(dh->priv_key));
+		if (tries++ > 10)
+			fatal("dh_gen_key: too many bad keys: giving up");
+	} while (!dh_pub_is_valid(dh, dh->pub_key));
+}
+
+DH *
+dh_new_group_asc(const char *gen, const char *modulus)
+{
+	DH *dh;
+
+	dh = DH_new();
+	if (dh == NULL)
+		fatal("DH_new");
+
+	if (BN_hex2bn(&dh->p, modulus) == 0)
+		fatal("BN_hex2bn p");
+	if (BN_hex2bn(&dh->g, gen) == 0)
+		fatal("BN_hex2bn g");
+
+	return (dh);
+}
+
+/*
+ * This just returns the group, we still need to generate the exchange
+ * value.
+ */
+
+DH *
+dh_new_group(BIGNUM *gen, BIGNUM *modulus)
+{
+	DH *dh;
+
+	dh = DH_new();
+	if (dh == NULL)
+		fatal("DH_new");
+	dh->p = modulus;
+	dh->g = gen;
+
+	return (dh);
+}
+
+DH *
+dh_new_group1(void)
+{
+	static char *gen = "2", *group1 =
+	    "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
+	    "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
+	    "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
+	    "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
+	    "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
+	    "FFFFFFFF" "FFFFFFFF";
+
+	return (dh_new_group_asc(gen, group1));
+}
+
+/*
+ * Estimates the group order for a Diffie-Hellman group that has an
+ * attack complexity approximately the same as O(2**bits).  Estimate
+ * with:  O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3)))
+ */
+
+int
+dh_estimate(int bits)
+{
+
+	if (bits < 64)
+		return (512);	/* O(2**63) */
+	if (bits < 128)
+		return (1024);	/* O(2**86) */
+	if (bits < 192)
+		return (2048);	/* O(2**116) */
+	return (4096);		/* O(2**156) */
+}