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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, buffer *ecdh_qs);
/* 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);
buffer *ecdh_qs = NULL;
TRACE(("enter recv_msg_kexdh_init"))
if (!ses.kexstate.recvkexinit) {
dropbear_exit("Premature kexdh_init message received");
}
if (IS_NORMAL_DH(ses.newkeys->algo_kex)) {
m_mp_init(&dh_e);
if (buf_getmpint(ses.payload, &dh_e) != DROPBEAR_SUCCESS) {
dropbear_exit("Failed to get kex value");
}
} else {
#ifdef DROPBEAR_ECDH
buffer *ecdh_qs = buf_getstringbuf(ses.payload);
#endif
}
send_msg_kexdh_reply(&dh_e, ecdh_qs);
mp_clear(&dh_e);
if (ecdh_qs) {
buf_free(ecdh_qs);
}
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 transport RFC4253 section 8 for details
* or RFC5656 section 4 for elliptic curve variant. */
static void send_msg_kexdh_reply(mp_int *dh_e, buffer *ecdh_qs) {
TRACE(("enter send_msg_kexdh_reply"))
/* 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);
if (IS_NORMAL_DH(ses.newkeys->algo_kex)) {
// Normal diffie-hellman
struct kex_dh_param * dh_param = gen_kexdh_param();
kexdh_comb_key(dh_param, dh_e, svr_opts.hostkey);
/* put f */
buf_putmpint(ses.writepayload, &dh_param->pub);
free_kexdh_param(dh_param);
} else {
#ifdef DROPBEAR_ECDH
struct kex_ecdh_param *ecdh_param = gen_kexecdh_param();
kexecdh_comb_key(ecdh_param, ecdh_qs, svr_opts.hostkey);
buf_put_ecc_pub(ses.writepayload, &ecdh_param->key);
free_kexecdh_param(ecdh_param);
#endif
}
/* 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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