1 files changed, 106 insertions, 0 deletions
diff --git a/svr-kex.c b/svr-kex.c
new file mode 100644
index 0000000..75cb090
--- /dev/null
+++ b/svr-kex.c
@@ -0,0 +1,106 @@
+/*
+ * Dropbear - a SSH2 server
+ * 
+ * Copyright (c) 2002,2003 Matt Johnston
+ * Copyright (c) 2004 by Mihnea Stoenescu
+ * 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 "algo.h"
+#include "buffer.h"
+#include "session.h"
+#include "kex.h"
+#include "ssh.h"
+#include "packet.h"
+#include "bignum.h"
+#include "random.h"
+#include "runopts.h"
+
+
+static void send_msg_kexdh_reply(mp_int *dh_e);
+
+/* Handle a diffie-hellman key exchange initialisation. This involves
+ * calculating a session key reply value, and corresponding hash. These
+ * are carried out by send_msg_kexdh_reply(). recv_msg_kexdh_init() calls
+ * that function, then brings the new keys into use */
+void recv_msg_kexdh_init() {
+
+	DEF_MP_INT(dh_e);
+
+	TRACE(("enter recv_msg_kexdh_init"))
+	if (!ses.kexstate.recvkexinit) {
+		dropbear_exit("Premature kexdh_init message received");
+	}
+
+	m_mp_init(&dh_e);
+	if (buf_getmpint(ses.payload, &dh_e) != DROPBEAR_SUCCESS) {
+		dropbear_exit("Failed to get kex value");
+	}
+
+	send_msg_kexdh_reply(&dh_e);
+
+	mp_clear(&dh_e);
+
+	send_msg_newkeys();
+	ses.requirenext = SSH_MSG_NEWKEYS;
+	TRACE(("leave recv_msg_kexdh_init"))
+}
+	
+/* Generate our side of the diffie-hellman key exchange value (dh_f), and
+ * calculate the session key using the diffie-hellman algorithm. Following
+ * that, the session hash is calculated, and signed with RSA or DSS. The
+ * result is sent to the client. 
+ *
+ * See the ietf-secsh-transport draft, section 6, for details */
+static void send_msg_kexdh_reply(mp_int *dh_e) {
+
+	DEF_MP_INT(dh_y);
+	DEF_MP_INT(dh_f);
+
+	TRACE(("enter send_msg_kexdh_reply"))
+	m_mp_init_multi(&dh_y, &dh_f, NULL);
+	
+	gen_kexdh_vals(&dh_f, &dh_y);
+
+	kexdh_comb_key(&dh_f, &dh_y, dh_e, svr_opts.hostkey);
+	mp_clear(&dh_y);
+
+	/* we can start creating the kexdh_reply packet */
+	CHECKCLEARTOWRITE();
+	buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY);
+	buf_put_pub_key(ses.writepayload, svr_opts.hostkey,
+			ses.newkeys->algo_hostkey);
+
+	/* put f */
+	buf_putmpint(ses.writepayload, &dh_f);
+	mp_clear(&dh_f);
+
+	/* calc the signature */
+	buf_put_sign(ses.writepayload, svr_opts.hostkey, 
+			ses.newkeys->algo_hostkey, ses.hash, SHA1_HASH_SIZE);
+
+	/* the SSH_MSG_KEXDH_REPLY is done */
+	encrypt_packet();
+
+	TRACE(("leave send_msg_kexdh_reply"))
+}
+