- OpenBSD CVS Sync

   - markus@cvs.openbsd.org 2001/03/29 21:17:40
     [dh.c dh.h kex.c kex.h]
     prepare for rekeying: move DH code to dh.c

1 files changed, 108 insertions, 1 deletions

diff --git a/dh.c b/dh.c
index 636758fa8..6c53b0038 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 1.11 2001/03/29 21:17:39 markus Exp $");
 
 #include "xmalloc.h"
 
@@ -166,3 +166,110 @@ choose_dh(int min, int wantbits, int max)
 
         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;
+        int ret;
+
+        dh = DH_new();
+        if (dh == NULL)
+                fatal("DH_new");
+
+        if ((ret = BN_hex2bn(&dh->p, modulus)) < 0)
+                fatal("BN_hex2bn p");
+        if ((ret = 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));
+}