1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/***************************************************************************
* fqterm, a terminal emulator for both BBS and *nix. *
* Copyright (C) 2008 fqterm development group. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. *
***************************************************************************/
#include "fqterm_ssh_kex.h"
#include "fqterm_ssh_md5.h"
#include "fqterm_trace.h"
namespace FQTerm {
FQTermSSHKex::FQTermSSHKex(const char *V_C, const char *V_S) {
V_C_ = new char[strlen(V_C) + 1];
V_S_ = new char[strlen(V_S) + 1];
strcpy(V_C_, V_C);
strcpy(V_S_, V_S);
}
FQTermSSHKex::~FQTermSSHKex() {
delete[] V_C_;
delete[] V_S_;
}
//==============================================================================
//FQTermSSH1Kex
//==============================================================================
FQTermSSH1Kex::FQTermSSH1Kex(const char *V_C, const char *V_S)
: FQTermSSHKex(V_C, V_S) {
is_first_kex_ = true;
kex_state_ = FQTermSSH1Kex::BEFORE_PUBLICKEY;
}
FQTermSSH1Kex::~FQTermSSH1Kex(){}
void FQTermSSH1Kex::initKex(FQTermSSHPacketReceiver *packetReceiver,
FQTermSSHPacketSender *packetSender) {
packet_receiver_ = packetReceiver;
packet_sender_ = packetSender;
packet_receiver_->disconnect(this);
FQ_VERIFY(connect(packet_receiver_, SIGNAL(packetAvaliable(int)),
this, SLOT(handlePacket(int))));
kex_state_ = FQTermSSH1Kex::BEFORE_PUBLICKEY;
emit reKex();
}
void FQTermSSH1Kex::handlePacket(int type) {
switch (kex_state_) {
case FQTermSSH1Kex::BEFORE_PUBLICKEY:
makeSessionKey();
kex_state_ = FQTermSSH1Kex::SESSIONKEY_SENT;
break;
case FQTermSSH1Kex::SESSIONKEY_SENT:
if (type != SSH1_SMSG_SUCCESS) {
emit kexError(tr("Kex exchange failed!"));
break;
}
emit kexOK();
kex_state_ = FQTermSSH1Kex::KEYEX_OK;
break;
case FQTermSSH1Kex::KEYEX_OK:
break;
}
}
void FQTermSSH1Kex::makeSessionKey() {
int i;
BIGNUM *key = BN_new();
BIGNUM *host_rsa_e = BN_new();
BIGNUM *host_rsa_n = BN_new();
BIGNUM *server_rsa_e = BN_new();
BIGNUM *server_rsa_n = BN_new();
u_int32_t rand_val;
int bits;
int rbits;
if (packet_receiver_->packetType() != SSH1_SMSG_PUBLIC_KEY) {
emit kexError(tr("startKex: First packet is not public key"));
return ;
}
packet_receiver_->getRawData((char*)cookie_, 8);
// Get the public key.
server_key_ = ssh_pubkey_new(SSH_RSA);
bits = packet_receiver_->getInt();
packet_receiver_->getBN(server_rsa_e);
packet_receiver_->getBN(server_rsa_n);
ssh_pubkey_setrsa(server_key_, server_rsa_n, server_rsa_e, NULL);
rbits = BN_num_bits(server_rsa_n);
if (bits != rbits) {
FQ_TRACE("sshkex", 0) << "Warning: Server lies about "
<< "size of server public key: "
<< "actual size: " << rbits
<< " vs. anounced: " << bits;
FQ_TRACE("sshkex", 0) << "Warning: This may be due to "
<< "an old implementation of ssh.";
}
// Get the host key.
host_key_ = ssh_pubkey_new(SSH_RSA);
bits = packet_receiver_->getInt();
packet_receiver_->getBN(host_rsa_e);
packet_receiver_->getBN(host_rsa_n);
ssh_pubkey_setrsa(host_key_, host_rsa_n, host_rsa_e, NULL);
rbits = BN_num_bits(host_rsa_n);
if (bits != rbits) {
FQ_TRACE("sshkex", 0) << "Warning: Server lies about "
<< "size of server public key: "
<< "actual size: " << rbits
<< " vs. anounced: " << bits;
FQ_TRACE("sshkex", 0) << "Warning: This may be due to "
<< "an old implementation of ssh.";
}
// Get protocol flags.
server_flag_ = packet_receiver_->getInt();
ciphers_ = packet_receiver_->getInt();
auth_ = packet_receiver_->getInt();
if ((ciphers_ &(1 << SSH_CIPHER_3DES)) == 0) {
FQ_VERIFY(false); // server do not support my cipher
}
makeSessionId();
// Generate an encryption key for the session. The key is a 256 bit
// random number, interpreted as a 32-byte key, with the least
// significant 8 bits being the first byte of the key.
for (i = 0; i < 32; i++) {
if (i % 4 == 0) {
rand_val = rand();
}
session_key_[i] = (rand_val &0xff);
rand_val >>= 8;
}
BN_set_word(key, 0);
for (i = 0; i < 32; i++) {
BN_lshift(key, key, 8);
if (i < 16) {
BN_add_word(key, session_key_[i] ^ session_id_[i]);
} else {
BN_add_word(key, session_key_[i]);
}
}
if (BN_cmp(server_rsa_n, host_rsa_n) < 0) {
ssh_pubkey_encrypt(server_key_, key, key);
ssh_pubkey_encrypt(host_key_, key, key);
} else {
ssh_pubkey_encrypt(host_key_, key, key);
ssh_pubkey_encrypt(server_key_, key, key);
}
ssh_pubkey_free(host_key_);
ssh_pubkey_free(server_key_);
packet_sender_->startPacket(SSH1_CMSG_SESSION_KEY);
packet_sender_->putByte(SSH_CIPHER_3DES);
packet_sender_->putRawData((const char*)cookie_, 8);
packet_sender_->putBN(key);
BN_free(key);
packet_sender_->putInt(1);
packet_sender_->write();
emit startEncryption(session_key_);
}
void FQTermSSH1Kex::makeSessionId() {
u_char *p;
FQTermSSHMD5 *md5;
int servlen, hostlen;
const BIGNUM *host_n;
const BIGNUM *server_n;
const BIGNUM *e, *d;
md5 = new FQTermSSHMD5;
ssh_pubkey_getrsa(server_key_, &server_n, &e, &d);
ssh_pubkey_getrsa(host_key_, &host_n, &e, &d);
servlen = BN_num_bytes(server_n);
hostlen = BN_num_bytes(host_n);
p = new u_char[servlen + hostlen];
BN_bn2bin(host_n, p);
BN_bn2bin(server_n, p+hostlen);
md5->update(p, servlen + hostlen);
md5->update(cookie_, 8);
md5->final(session_id_);
delete md5;
delete [] p;
}
} // namespace FQTerm
#include "fqterm_ssh_kex.moc"
|
