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/*
* 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);
buf_getmpint(ses.payload, &dh_e);
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"));
}
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