Mercurial > dropbear

comparison svr-kex.c @ 26:0969767bca0d

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snapshot of stuff
author Matt Johnston <matt@ucc.asn.au>
date Mon, 26 Jul 2004 02:44:20 +0000
parents 469950e86d0f
children e3adf4cf5465
comparison
equal deleted inserted replaced
25:e4b6e2d569b2 26:0969767bca0d
68 * result is sent to the client. 68 * result is sent to the client.
69 * 69 *
70 * See the ietf-secsh-transport draft, section 6, for details */ 70 * See the ietf-secsh-transport draft, section 6, for details */
71 static void send_msg_kexdh_reply(mp_int *dh_e) { 71 static void send_msg_kexdh_reply(mp_int *dh_e) {
72 72
73 mp_int dh_p, dh_q, dh_g, dh_y, dh_f; 73 mp_int dh_y, dh_f;
74 unsigned char randbuf[DH_P_LEN];
75 int dh_q_len;
76 hash_state hs;
77 74
78 TRACE(("enter send_msg_kexdh_reply")); 75 TRACE(("enter send_msg_kexdh_reply"));
79 76
80 m_mp_init_multi(&dh_g, &dh_p, &dh_q, &dh_y, &dh_f, NULL); 77 gen_kexdh_vals(&dh_f, &dh_y);
81 78
82 /* read the prime and generator*/ 79 kexdh_comb_key(&dh_f, &dh_y, dh_e, svr_opts.hostkey);
83 if (mp_read_unsigned_bin(&dh_p, (unsigned char*)dh_p_val, DH_P_LEN) 80 mp_clear(&dh_y);
84 != MP_OKAY) {
85 dropbear_exit("Diffie-Hellman error");
86 }
87
88 if (mp_set_int(&dh_g, DH_G_VAL) != MP_OKAY) {
89 dropbear_exit("Diffie-Hellman error");
90 }
91 81
92 /* calculate q = (p-1)/2 */
93 if (mp_sub_d(&dh_p, 1, &dh_y) != MP_OKAY) { /*dh_y is just a temp var here*/
94 dropbear_exit("Diffie-Hellman error");
95 }
96 if (mp_div_2(&dh_y, &dh_q) != MP_OKAY) {
97 dropbear_exit("Diffie-Hellman error");
98 }
99
100 dh_q_len = mp_unsigned_bin_size(&dh_q);
101
102 /* calculate our random value dh_y */
103 do {
104 assert((unsigned int)dh_q_len <= sizeof(randbuf));
105 genrandom(randbuf, dh_q_len);
106 if (mp_read_unsigned_bin(&dh_y, randbuf, dh_q_len) != MP_OKAY) {
107 dropbear_exit("Diffie-Hellman error");
108 }
109 } while (mp_cmp(&dh_y, &dh_q) == MP_GT || mp_cmp_d(&dh_y, 0) != MP_GT);
110
111 /* f = g^y mod p */
112 if (mp_exptmod(&dh_g, &dh_y, &dh_p, &dh_f) != MP_OKAY) {
113 dropbear_exit("Diffie-Hellman error");
114 }
115 mp_clear(&dh_g);
116
117 /* K = e^y mod p */
118 ses.dh_K = (mp_int*)m_malloc(sizeof(mp_int));
119 m_mp_init(ses.dh_K);
120 if (mp_exptmod(dh_e, &dh_y, &dh_p, ses.dh_K) != MP_OKAY) {
121 dropbear_exit("Diffie-Hellman error");
122 }
123
124 /* clear no longer needed vars */
125 mp_clear_multi(&dh_y, &dh_p, &dh_q, NULL);
126
127 /* Create the remainder of the hash buffer, to generate the exchange hash */
128 /* K_S, the host key */
129 buf_put_pub_key(ses.kexhashbuf, svr_opts.hostkey,
130 ses.newkeys->algo_hostkey);
131 /* e, exchange value sent by the client */
132 buf_putmpint(ses.kexhashbuf, dh_e);
133 /* f, exchange value sent by the server */
134 buf_putmpint(ses.kexhashbuf, &dh_f);
135 /* K, the shared secret */
136 buf_putmpint(ses.kexhashbuf, ses.dh_K);
137
138 /* calculate the hash H to sign */
139 sha1_init(&hs);
140 buf_setpos(ses.kexhashbuf, 0);
141 sha1_process(&hs, buf_getptr(ses.kexhashbuf, ses.kexhashbuf->len),
142 ses.kexhashbuf->len);
143 sha1_done(&hs, ses.hash);
144 buf_free(ses.kexhashbuf);
145 ses.kexhashbuf = NULL;
146
147 /* first time around, we set the session_id to H */
148 if (ses.session_id == NULL) {
149 /* create the session_id, this never needs freeing */
150 ses.session_id = (unsigned char*)m_malloc(SHA1_HASH_SIZE);
151 memcpy(ses.session_id, ses.hash, SHA1_HASH_SIZE);
152 }
153
154 /* we can start creating the kexdh_reply packet */ 82 /* we can start creating the kexdh_reply packet */
155 CHECKCLEARTOWRITE(); 83 CHECKCLEARTOWRITE();
156 buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY); 84 buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY);
157 buf_put_pub_key(ses.writepayload, svr_opts.hostkey, 85 buf_put_pub_key(ses.writepayload, svr_opts.hostkey,
158 ses.newkeys->algo_hostkey); 86 ses.newkeys->algo_hostkey);
169 encrypt_packet(); 97 encrypt_packet();
170 98
171 TRACE(("leave send_msg_kexdh_reply")); 99 TRACE(("leave send_msg_kexdh_reply"));
172 } 100 }
173 101
174 /* read the client's choice of algorithms */
175 void svr_read_kex() {
176
177 algo_type * algo;
178 char * erralgo = NULL;
179
180 int goodguess = 0;
181 int allgood = 1; /* we AND this with each goodguess and see if its still
182 true after */
183
184 buf_incrpos(ses.payload, 16); /* start after the cookie */
185
186 ses.newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
187
188 /* kex_algorithms */
189 algo = svr_buf_match_algo(ses.payload, sshkex, &goodguess);
190 allgood &= goodguess;
191 if (algo == NULL) {
192 erralgo = "kex";
193 goto error;
194 }
195 ses.newkeys->algo_kex = algo->val;
196
197 /* server_host_key_algorithms */
198 algo = svr_buf_match_algo(ses.payload, sshhostkey, &goodguess);
199 allgood &= goodguess;
200 if (algo == NULL) {
201 erralgo = "hostkey";
202 goto error;
203 }
204 ses.newkeys->algo_hostkey = algo->val;
205
206 /* encryption_algorithms_client_to_server */
207 algo = svr_buf_match_algo(ses.payload, sshciphers, &goodguess);
208 if (algo == NULL) {
209 erralgo = "enc c->s";
210 goto error;
211 }
212 ses.newkeys->recv_algo_crypt = (struct dropbear_cipher*)algo->data;
213
214 /* encryption_algorithms_server_to_client */
215 algo = svr_buf_match_algo(ses.payload, sshciphers, &goodguess);
216 if (algo == NULL) {
217 erralgo = "enc s->c";
218 goto error;
219 }
220 ses.newkeys->trans_algo_crypt = (struct dropbear_cipher*)algo->data;
221
222 /* mac_algorithms_client_to_server */
223 algo = svr_buf_match_algo(ses.payload, sshhashes, &goodguess);
224 if (algo == NULL) {
225 erralgo = "mac c->s";
226 goto error;
227 }
228 ses.newkeys->recv_algo_mac = (struct dropbear_hash*)algo->data;
229
230 /* mac_algorithms_server_to_client */
231 algo = svr_buf_match_algo(ses.payload, sshhashes, &goodguess);
232 if (algo == NULL) {
233 erralgo = "mac s->c";
234 goto error;
235 }
236 ses.newkeys->trans_algo_mac = (struct dropbear_hash*)algo->data;
237
238 /* compression_algorithms_client_to_server */
239 algo = svr_buf_match_algo(ses.payload, sshcompress, &goodguess);
240 if (algo == NULL) {
241 erralgo = "comp c->s";
242 goto error;
243 }
244 ses.newkeys->recv_algo_comp = algo->val;
245
246 /* compression_algorithms_server_to_client */
247 algo = svr_buf_match_algo(ses.payload, sshcompress, &goodguess);
248 if (algo == NULL) {
249 erralgo = "comp s->c";
250 goto error;
251 }
252 ses.newkeys->trans_algo_comp = algo->val;
253
254 /* languages_client_to_server */
255 buf_eatstring(ses.payload);
256
257 /* languages_server_to_client */
258 buf_eatstring(ses.payload);
259
260 /* first_kex_packet_follows */
261 if (buf_getbyte(ses.payload)) {
262 ses.kexstate.firstfollows = 1;
263 /* if the guess wasn't good, we ignore the packet sent */
264 if (!allgood) {
265 ses.ignorenext = 1;
266 }
267 }
268
269 /* reserved for future extensions */
270 buf_getint(ses.payload);
271 return;
272
273 error:
274 dropbear_exit("no matching algo %s", erralgo);
275 }