Support diffie-hellman-group14-sha1 group exchange. Tested against

locally built OpenSSH 3.9, and seems to work fine.

[originally from svn r5018]

ssh.c

@@ -104,7 +104,7 @@
  * Packet type contexts, so that ssh2_pkt_type can correctly decode
  * the ambiguous type numbers back into the correct type strings.
  */
-#define SSH2_PKTCTX_DHGROUP1         0x0001
+#define SSH2_PKTCTX_DHGROUP          0x0001
 #define SSH2_PKTCTX_DHGEX            0x0002
 #define SSH2_PKTCTX_PUBLICKEY        0x0010
 #define SSH2_PKTCTX_PASSWORD         0x0020
@@ -222,8 +222,8 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
     translate(SSH2_MSG_SERVICE_ACCEPT);
     translate(SSH2_MSG_KEXINIT);
     translate(SSH2_MSG_NEWKEYS);
-    translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP1);
+    translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
-    translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP1);
+    translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
     translatec(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
@@ -362,7 +362,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
 const static struct ssh_kex *kex_algs[] = {
     &ssh_diffiehellman_gex,
-    &ssh_diffiehellman
+    &ssh_diffiehellman_group14,
+    &ssh_diffiehellman_group1,
 };
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
@@ -4650,7 +4651,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      * If we're doing Diffie-Hellman group exchange, start by
      * requesting a group.
      */
-    if (ssh->kex == &ssh_diffiehellman_gex) {
+    if (!ssh->kex->pdata) {
 	logevent("Doing Diffie-Hellman group exchange");
 	ssh->pkt_ctx |= SSH2_PKTCTX_DHGEX;
 	/*
@@ -4673,14 +4674,16 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
 	    bombout(("unable to read mp-ints from incoming group packet"));
 	    crStop(0);
 	}
-	ssh->kex_ctx = dh_setup_group(s->p, s->g);
+	ssh->kex_ctx = dh_setup_gex(s->p, s->g);
 	s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
 	s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
     } else {
-	ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP1;
+	ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP;
-	ssh->kex_ctx = dh_setup_group1();
+	ssh->kex_ctx = dh_setup_group(ssh->kex);
 	s->kex_init_value = SSH2_MSG_KEXDH_INIT;
 	s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
+	logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
+		  ssh->kex->groupname);
     }
 
     logevent("Doing Diffie-Hellman key exchange");

ssh.h

@@ -177,11 +177,13 @@ struct ssh_kex {
     /*
      * Plugging in another KEX algorithm requires structural chaos,
      * so it's hard to abstract them into nice little structures
-     * like this. Hence, for the moment, this is just a
+     * like this. Fortunately, all our KEXes are basically
-     * placeholder. I claim justification in the fact that OpenSSH
+     * Diffie-Hellman at the moment, so in this structure I simply
-     * does this too :-)
+     * parametrise the DH exchange a bit.
      */
-    char *name;
+    char *name, *groupname;
+    const unsigned char *pdata, *gdata;/* NULL means use group exchange */
+    int plen, glen;
 };
 
 struct ssh_signkey {
@@ -231,7 +233,8 @@ extern const struct ssh2_ciphers ssh2_3des;
 extern const struct ssh2_ciphers ssh2_des;
 extern const struct ssh2_ciphers ssh2_aes;
 extern const struct ssh2_ciphers ssh2_blowfish;
-extern const struct ssh_kex ssh_diffiehellman;
+extern const struct ssh_kex ssh_diffiehellman_group1;
+extern const struct ssh_kex ssh_diffiehellman_group14;
 extern const struct ssh_kex ssh_diffiehellman_gex;
 extern const struct ssh_signkey ssh_dss;
 extern const struct ssh_signkey ssh_rsa;
@@ -336,8 +339,8 @@ char *bignum_decimal(Bignum x);
 void diagbn(char *prefix, Bignum md);
 #endif
 
-void *dh_setup_group1(void);
+void *dh_setup_group(const struct ssh_kex *kex);
-void *dh_setup_group(Bignum pval, Bignum gval);
+void *dh_setup_gex(Bignum pval, Bignum gval);
 void dh_cleanup(void *);
 Bignum dh_create_e(void *, int nbits);
 Bignum dh_find_K(void *, Bignum f);

sshdh.c

@@ -1,17 +1,9 @@
 #include "ssh.h"
 
-const struct ssh_kex ssh_diffiehellman = {
-    "diffie-hellman-group1-sha1"
-};
-
-const struct ssh_kex ssh_diffiehellman_gex = {
-    "diffie-hellman-group-exchange-sha1"
-};
-
 /*
- * The prime p used in the key exchange. 
+ * The primes used in the group1 and group14 key exchange.
  */
-static const unsigned char P[] = {
+static const unsigned char P1[] = {
     0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
     0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
     0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
@@ -24,12 +16,51 @@ static const unsigned char P[] = {
     0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
     0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
 };
+static const unsigned char P14[] = {
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
+    0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+    0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
+    0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
+    0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
+    0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
+    0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
+    0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
+    0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
+    0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
+    0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
+    0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
+    0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
+    0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
+    0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
+    0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
+    0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
+    0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
+    0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
+    0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
+    0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF
+};
 
 /*
- * The generator g = 2.
+ * The generator g = 2 (used for both group1 and group14).
  */
 static const unsigned char G[] = { 2 };
 
+const struct ssh_kex ssh_diffiehellman_group1 = {
+    "diffie-hellman-group1-sha1", "group1",
+    P1, G, lenof(P1), lenof(G)
+};
+
+const struct ssh_kex ssh_diffiehellman_group14 = {
+    "diffie-hellman-group14-sha1", "group14",
+    P14, G, lenof(P14), lenof(G)
+};
+
+const struct ssh_kex ssh_diffiehellman_gex = {
+    "diffie-hellman-group-exchange-sha1", NULL,
+    NULL, NULL, 0, 0
+};
+
 /*
  * Variables.
  */
@@ -48,21 +79,21 @@ static void dh_init(struct dh_ctx *ctx)
 }
 
 /*
- * Initialise DH for the standard group1.
+ * Initialise DH for a standard group.
  */
-void *dh_setup_group1(void)
+void *dh_setup_group(const struct ssh_kex *kex)
 {
     struct dh_ctx *ctx = snew(struct dh_ctx);
-    ctx->p = bignum_from_bytes(P, sizeof(P));
+    ctx->p = bignum_from_bytes(kex->pdata, kex->plen);
-    ctx->g = bignum_from_bytes(G, sizeof(G));
+    ctx->g = bignum_from_bytes(kex->gdata, kex->glen);
     dh_init(ctx);
     return ctx;
 }
 
 /*
- * Initialise DH for an alternative group.
+ * Initialise DH for a server-supplied group.
  */
-void *dh_setup_group(Bignum pval, Bignum gval)
+void *dh_setup_gex(Bignum pval, Bignum gval)
 {
     struct dh_ctx *ctx = snew(struct dh_ctx);
     ctx->p = copybn(pval);