X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/03b8f8be75466e67c22ef6ac36e1cc76f997921c..c9ecc3c71562790fd69d7d595322e9eca55b875b:/dh.c

diff --git a/dh.c b/dh.c
index 6c53b003..044d869f 100644
--- a/dh.c
+++ b/dh.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: dh.c,v 1.11 2001/03/29 21:17:39 markus Exp $");
+RCSID("$OpenBSD: dh.c,v 1.31 2004/08/04 10:37:52 djm Exp $");
 
 #include "xmalloc.h"
 
@@ -39,7 +39,7 @@ RCSID("$OpenBSD: dh.c,v 1.11 2001/03/29 21:17:39 markus Exp $");
 #include "log.h"
 #include "misc.h"
 
-int
+static int
 parse_prime(int linenum, char *line, struct dhgroup *dhg)
 {
 	char *cp, *arg;
@@ -50,7 +50,7 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg)
 	/* Ignore leading whitespace */
 	if (*arg == '\0')
 		arg = strdelim(&cp);
-	if (!*arg || *arg == '#')
+	if (!arg || !*arg || *arg == '#')
 		return 0;
 
 	/* time */
@@ -78,22 +78,27 @@ parse_prime(int linenum, char *line, struct dhgroup *dhg)
 	if (cp != NULL || *prime == '\0')
 		goto fail;
 
-	dhg->g = BN_new();
-	dhg->p = BN_new();
-	if (BN_hex2bn(&dhg->g, gen) < 0)
+	if ((dhg->g = BN_new()) == NULL)
+		fatal("parse_prime: BN_new failed");
+	if ((dhg->p = BN_new()) == NULL)
+		fatal("parse_prime: BN_new failed");
+	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)
 		goto failclean;
 
+	if (BN_is_zero(dhg->g) || BN_is_one(dhg->g))
+		goto failclean;
+
 	return (1);
 
  failclean:
-	BN_free(dhg->g);
-	BN_free(dhg->p);
+	BN_clear_free(dhg->g);
+	BN_clear_free(dhg->p);
  fail:
 	error("Bad prime description in line %d", linenum);
 	return (0);
@@ -103,15 +108,16 @@ DH *
 choose_dh(int min, int wantbits, int max)
 {
 	FILE *f;
-	char line[1024];
+	char line[4096];
 	int best, bestcount, which;
 	int linenum;
 	struct dhgroup dhg;
 
-	f = fopen(_PATH_DH_PRIMES, "r");
-	if (!f) {
-		log("WARNING: %s does not exist, using old prime", _PATH_DH_PRIMES);
-		return (dh_new_group1());
+	if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL &&
+	    (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) {
+		logit("WARNING: %s does not exist, using fixed modulus",
+		    _PATH_DH_MODULI);
+		return (dh_new_group14());
 	}
 
 	linenum = 0;
@@ -120,8 +126,8 @@ choose_dh(int min, int wantbits, int max)
 		linenum++;
 		if (!parse_prime(linenum, line, &dhg))
 			continue;
-		BN_free(dhg.g);
-		BN_free(dhg.p);
+		BN_clear_free(dhg.g);
+		BN_clear_free(dhg.p);
 
 		if (dhg.size > max || dhg.size < min)
 			continue;
@@ -134,16 +140,12 @@ choose_dh(int min, int wantbits, int max)
 		if (dhg.size == best)
 			bestcount++;
 	}
-	fclose (f);
+	rewind(f);
 
 	if (bestcount == 0) {
-		log("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
-		return (NULL);
-	}
-
-	f = fopen(_PATH_DH_PRIMES, "r");
-	if (!f) {
-		fatal("WARNING: %s disappeared, giving up", _PATH_DH_PRIMES);
+		fclose(f);
+		logit("WARNING: no suitable primes in %s", _PATH_DH_PRIMES);
+		return (dh_new_group14());
 	}
 
 	linenum = 0;
@@ -151,23 +153,24 @@ 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) {
-			BN_free(dhg.g);
-			BN_free(dhg.p);
+		if ((dhg.size > max || dhg.size < min) ||
+		    dhg.size != best ||
+		    linenum++ != which) {
+			BN_clear_free(dhg.g);
+			BN_clear_free(dhg.p);
 			continue;
 		}
 		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 */
+/* diffie-hellman-groupN-sha1 */
 
 int
 dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
@@ -177,46 +180,45 @@ dh_pub_is_valid(DH *dh, BIGNUM *dh_pub)
 	int bits_set = 0;
 
 	if (dh_pub->neg) {
-		log("invalid public DH value: negativ");
+		logit("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));
+	debug2("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));
+	logit("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;
+	int i, bits_set, tries = 0;
 
 	if (dh->p == NULL)
 		fatal("dh_gen_key: dh->p == NULL");
-	if (2*need >= BN_num_bits(dh->p))
+	if (need > INT_MAX / 2 || 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)
+			BN_clear_free(dh->priv_key);
+		if ((dh->priv_key = BN_new()) == 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++)
+		for (i = 0, bits_set = 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",
+		debug2("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");
@@ -227,15 +229,13 @@ DH *
 dh_new_group_asc(const char *gen, const char *modulus)
 {
 	DH *dh;
-	int ret;
 
-	dh = DH_new();
-	if (dh == NULL)
-		fatal("DH_new");
+	if ((dh = DH_new()) == NULL)
+		fatal("dh_new_group_asc: DH_new");
 
-	if ((ret = BN_hex2bn(&dh->p, modulus)) < 0)
+	if (BN_hex2bn(&dh->p, modulus) == 0)
 		fatal("BN_hex2bn p");
-	if ((ret = BN_hex2bn(&dh->g, gen)) < 0)
+	if (BN_hex2bn(&dh->g, gen) == 0)
 		fatal("BN_hex2bn g");
 
 	return (dh);
@@ -251,9 +251,8 @@ dh_new_group(BIGNUM *gen, BIGNUM *modulus)
 {
 	DH *dh;
 
-	dh = DH_new();
-	if (dh == NULL)
-		fatal("DH_new");
+	if ((dh = DH_new()) == NULL)
+		fatal("dh_new_group: DH_new");
 	dh->p = modulus;
 	dh->g = gen;
 
@@ -273,3 +272,39 @@ dh_new_group1(void)
 
 	return (dh_new_group_asc(gen, group1));
 }
+
+DH *
+dh_new_group14(void)
+{
+	static char *gen = "2", *group14 =
+	    "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" "ECE45B3D"
+	    "C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
+	    "83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
+	    "670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
+	    "E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
+	    "DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
+	    "15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF";
+
+	return (dh_new_group_asc(gen, group14));
+}
+
+/*
+ * 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 <= 128)
+		return (1024);	/* O(2**86) */
+	if (bits <= 192)
+		return (2048);	/* O(2**116) */
+	return (4096);		/* O(2**156) */
+}