Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| 3 | * |
| 4 | * Redistribution and use in source and binary forms, with or without |
| 5 | * modification, are permitted provided that the following conditions |
| 6 | * are met: |
| 7 | * 1. Redistributions of source code must retain the above copyright |
| 8 | * notice, this list of conditions and the following disclaimer. |
| 9 | * 2. Redistributions in binary form must reproduce the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer in the |
| 11 | * documentation and/or other materials provided with the distribution. |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 12 | * |
| 13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 23 | */ |
| 24 | |
| 25 | #include "includes.h" |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 26 | RCSID("$OpenBSD: kex.c,v 1.26 2001/04/03 19:53:29 markus Exp $"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 27 | |
| 28 | #include <openssl/crypto.h> |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 29 | |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 30 | #include "ssh2.h" |
| 31 | #include "xmalloc.h" |
| 32 | #include "buffer.h" |
| 33 | #include "bufaux.h" |
| 34 | #include "packet.h" |
| 35 | #include "compat.h" |
| 36 | #include "cipher.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 37 | #include "kex.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 38 | #include "key.h" |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 39 | #include "log.h" |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 40 | #include "mac.h" |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 41 | #include "match.h" |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 42 | #include "dispatch.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 43 | |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 44 | #define KEX_COOKIE_LEN 16 |
| 45 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 46 | void kex_kexinit_finish(Kex *kex); |
| 47 | void kex_choose_conf(Kex *k); |
| 48 | |
| 49 | /* put algorithm proposal into buffer */ |
| 50 | void |
| 51 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 52 | { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 53 | u_int32_t rand = 0; |
| 54 | int i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 55 | |
| 56 | buffer_clear(b); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 57 | for (i = 0; i < KEX_COOKIE_LEN; i++) { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 58 | if (i % 4 == 0) |
| 59 | rand = arc4random(); |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 60 | buffer_put_char(b, rand & 0xff); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 61 | rand >>= 8; |
| 62 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 63 | for (i = 0; i < PROPOSAL_MAX; i++) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 64 | buffer_put_cstring(b, proposal[i]); |
| 65 | buffer_put_char(b, 0); /* first_kex_packet_follows */ |
| 66 | buffer_put_int(b, 0); /* uint32 reserved */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 67 | } |
| 68 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 69 | /* parse buffer and return algorithm proposal */ |
| 70 | char ** |
| 71 | kex_buf2prop(Buffer *raw) |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 72 | { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 73 | Buffer b; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 74 | int i; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 75 | char **proposal; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 76 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 77 | proposal = xmalloc(PROPOSAL_MAX * sizeof(char *)); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 78 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 79 | buffer_init(&b); |
| 80 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 81 | /* skip cookie */ |
| 82 | for (i = 0; i < KEX_COOKIE_LEN; i++) |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 83 | buffer_get_char(&b); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 84 | /* extract kex init proposal strings */ |
| 85 | for (i = 0; i < PROPOSAL_MAX; i++) { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 86 | proposal[i] = buffer_get_string(&b,NULL); |
| 87 | debug2("kex_parse_kexinit: %s", proposal[i]); |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 88 | } |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 89 | /* first kex follows / reserved */ |
| 90 | i = buffer_get_char(&b); |
| 91 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
| 92 | i = buffer_get_int(&b); |
| 93 | debug2("kex_parse_kexinit: reserved %d ", i); |
| 94 | buffer_free(&b); |
| 95 | return proposal; |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 96 | } |
| 97 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 98 | void |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 99 | kex_prop_free(char **proposal) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 100 | { |
| 101 | int i; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 102 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 103 | for (i = 0; i < PROPOSAL_MAX; i++) |
| 104 | xfree(proposal[i]); |
| 105 | xfree(proposal); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 106 | } |
| 107 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 108 | void |
| 109 | kex_protocol_error(int type, int plen, void *ctxt) |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 110 | { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 111 | error("Hm, kex protocol error: type %d plen %d", type, plen); |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 112 | } |
| 113 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 114 | void |
| 115 | kex_send_newkeys(void) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 116 | { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 117 | packet_start(SSH2_MSG_NEWKEYS); |
| 118 | packet_send(); |
| 119 | /* packet_write_wait(); */ |
| 120 | debug("SSH2_MSG_NEWKEYS sent"); |
| 121 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 122 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 123 | void |
| 124 | kex_input_newkeys(int type, int plen, void *ctxt) |
| 125 | { |
| 126 | Kex *kex = ctxt; |
| 127 | int i; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 128 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 129 | debug("SSH2_MSG_NEWKEYS received"); |
| 130 | kex->newkeys = 1; |
| 131 | for (i = 30; i <= 49; i++) |
| 132 | dispatch_set(i, &kex_protocol_error); |
| 133 | buffer_clear(&kex->peer); |
| 134 | buffer_clear(&kex->my); |
| 135 | kex->flags &= ~KEX_INIT_SENT; |
| 136 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 137 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 138 | void |
| 139 | kex_send_kexinit(Kex *kex) |
| 140 | { |
| 141 | packet_start(SSH2_MSG_KEXINIT); |
| 142 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); |
| 143 | packet_send(); |
| 144 | debug("SSH2_MSG_KEXINIT sent"); |
| 145 | kex->flags |= KEX_INIT_SENT; |
| 146 | } |
| 147 | |
| 148 | void |
| 149 | kex_input_kexinit(int type, int plen, void *ctxt) |
| 150 | { |
| 151 | char *ptr; |
| 152 | int dlen; |
| 153 | Kex *kex = (Kex *)ctxt; |
| 154 | |
| 155 | dispatch_set(SSH2_MSG_KEXINIT, &kex_protocol_error); |
| 156 | debug("SSH2_MSG_KEXINIT received"); |
| 157 | |
| 158 | ptr = packet_get_raw(&dlen); |
| 159 | buffer_append(&kex->peer, ptr, dlen); |
| 160 | |
| 161 | kex_kexinit_finish(kex); |
| 162 | } |
| 163 | |
| 164 | Kex * |
| 165 | kex_start(char *proposal[PROPOSAL_MAX]) |
| 166 | { |
| 167 | Kex *kex; |
| 168 | int i; |
| 169 | |
| 170 | kex = xmalloc(sizeof(*kex)); |
| 171 | memset(kex, 0, sizeof(*kex)); |
| 172 | buffer_init(&kex->peer); |
| 173 | buffer_init(&kex->my); |
| 174 | kex_prop2buf(&kex->my, proposal); |
| 175 | kex->newkeys = 0; |
| 176 | |
| 177 | kex_send_kexinit(kex); /* we start */ |
| 178 | /* Numbers 30-49 are used for kex packets */ |
| 179 | for (i = 30; i <= 49; i++) |
| 180 | dispatch_set(i, kex_protocol_error); |
| 181 | |
| 182 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); |
| 183 | dispatch_set(SSH2_MSG_NEWKEYS, &kex_input_newkeys); |
| 184 | return kex; |
| 185 | } |
| 186 | |
| 187 | void |
| 188 | kex_kexinit_finish(Kex *kex) |
| 189 | { |
| 190 | if (!(kex->flags & KEX_INIT_SENT)) |
| 191 | kex_send_kexinit(kex); |
| 192 | |
| 193 | kex_choose_conf(kex); |
| 194 | |
| 195 | switch(kex->kex_type) { |
| 196 | case DH_GRP1_SHA1: |
| 197 | kexdh(kex); |
| 198 | break; |
| 199 | case DH_GEX_SHA1: |
| 200 | kexgex(kex); |
| 201 | break; |
| 202 | default: |
| 203 | fatal("Unsupported key exchange %d", kex->kex_type); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 204 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 205 | } |
| 206 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 207 | void |
| 208 | choose_enc(Enc *enc, char *client, char *server) |
| 209 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 210 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 211 | if (name == NULL) |
| 212 | fatal("no matching cipher found: client %s server %s", client, server); |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 213 | enc->cipher = cipher_by_name(name); |
| 214 | if (enc->cipher == NULL) |
| 215 | fatal("matching cipher is not supported: %s", name); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 216 | enc->name = name; |
| 217 | enc->enabled = 0; |
| 218 | enc->iv = NULL; |
| 219 | enc->key = NULL; |
| 220 | } |
| 221 | void |
| 222 | choose_mac(Mac *mac, char *client, char *server) |
| 223 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 224 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 225 | if (name == NULL) |
| 226 | fatal("no matching mac found: client %s server %s", client, server); |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 227 | if (mac_init(mac, name) < 0) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 228 | fatal("unsupported mac %s", name); |
Ben Lindstrom | 06b33aa | 2001-02-15 03:01:59 +0000 | [diff] [blame] | 229 | /* truncate the key */ |
| 230 | if (datafellows & SSH_BUG_HMAC) |
| 231 | mac->key_len = 16; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 232 | mac->name = name; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 233 | mac->key = NULL; |
| 234 | mac->enabled = 0; |
| 235 | } |
| 236 | void |
| 237 | choose_comp(Comp *comp, char *client, char *server) |
| 238 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 239 | char *name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 240 | if (name == NULL) |
| 241 | fatal("no matching comp found: client %s server %s", client, server); |
| 242 | if (strcmp(name, "zlib") == 0) { |
| 243 | comp->type = 1; |
| 244 | } else if (strcmp(name, "none") == 0) { |
| 245 | comp->type = 0; |
| 246 | } else { |
| 247 | fatal("unsupported comp %s", name); |
| 248 | } |
| 249 | comp->name = name; |
| 250 | } |
| 251 | void |
| 252 | choose_kex(Kex *k, char *client, char *server) |
| 253 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 254 | k->name = match_list(client, server, NULL); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 255 | if (k->name == NULL) |
| 256 | fatal("no kex alg"); |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 257 | if (strcmp(k->name, KEX_DH1) == 0) { |
| 258 | k->kex_type = DH_GRP1_SHA1; |
| 259 | } else if (strcmp(k->name, KEX_DHGEX) == 0) { |
| 260 | k->kex_type = DH_GEX_SHA1; |
| 261 | } else |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 262 | fatal("bad kex alg %s", k->name); |
| 263 | } |
| 264 | void |
| 265 | choose_hostkeyalg(Kex *k, char *client, char *server) |
| 266 | { |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 267 | char *hostkeyalg = match_list(client, server, NULL); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 268 | if (hostkeyalg == NULL) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 269 | fatal("no hostkey alg"); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 270 | k->hostkey_type = key_type_from_name(hostkeyalg); |
| 271 | if (k->hostkey_type == KEY_UNSPEC) |
| 272 | fatal("bad hostkey alg '%s'", hostkeyalg); |
Ben Lindstrom | 48bd7c1 | 2001-01-09 00:35:42 +0000 | [diff] [blame] | 273 | xfree(hostkeyalg); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 274 | } |
| 275 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 276 | void |
| 277 | kex_choose_conf(Kex *k) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 278 | { |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 279 | char **my, **peer; |
| 280 | char **cprop, **sprop; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 281 | int mode; |
| 282 | int ctos; /* direction: if true client-to-server */ |
| 283 | int need; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 284 | |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 285 | my = kex_buf2prop(&k->my); |
| 286 | peer = kex_buf2prop(&k->peer); |
| 287 | |
| 288 | if (k->server) { |
| 289 | cprop=peer; |
| 290 | sprop=my; |
| 291 | } else { |
| 292 | cprop=my; |
| 293 | sprop=peer; |
| 294 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 295 | |
| 296 | for (mode = 0; mode < MODE_MAX; mode++) { |
| 297 | int nenc, nmac, ncomp; |
| 298 | ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN); |
| 299 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
| 300 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; |
| 301 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; |
| 302 | choose_enc (&k->enc [mode], cprop[nenc], sprop[nenc]); |
| 303 | choose_mac (&k->mac [mode], cprop[nmac], sprop[nmac]); |
| 304 | choose_comp(&k->comp[mode], cprop[ncomp], sprop[ncomp]); |
| 305 | debug("kex: %s %s %s %s", |
| 306 | ctos ? "client->server" : "server->client", |
| 307 | k->enc[mode].name, |
| 308 | k->mac[mode].name, |
| 309 | k->comp[mode].name); |
| 310 | } |
| 311 | choose_kex(k, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); |
| 312 | choose_hostkeyalg(k, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], |
| 313 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 314 | need = 0; |
| 315 | for (mode = 0; mode < MODE_MAX; mode++) { |
Damien Miller | 874d77b | 2000-10-14 16:23:11 +1100 | [diff] [blame] | 316 | if (need < k->enc[mode].cipher->key_len) |
| 317 | need = k->enc[mode].cipher->key_len; |
| 318 | if (need < k->enc[mode].cipher->block_size) |
| 319 | need = k->enc[mode].cipher->block_size; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 320 | if (need < k->mac[mode].key_len) |
| 321 | need = k->mac[mode].key_len; |
| 322 | } |
Damien Miller | b1715dc | 2000-05-30 13:44:51 +1000 | [diff] [blame] | 323 | /* XXX need runden? */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 324 | k->we_need = need; |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 325 | |
| 326 | kex_prop_free(my); |
| 327 | kex_prop_free(peer); |
| 328 | |
| 329 | } |
| 330 | |
| 331 | u_char * |
| 332 | derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret) |
| 333 | { |
| 334 | Buffer b; |
| 335 | EVP_MD *evp_md = EVP_sha1(); |
| 336 | EVP_MD_CTX md; |
| 337 | char c = id; |
| 338 | int have; |
| 339 | int mdsz = evp_md->md_size; |
| 340 | u_char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz); |
| 341 | |
| 342 | buffer_init(&b); |
| 343 | buffer_put_bignum2(&b, shared_secret); |
| 344 | |
| 345 | EVP_DigestInit(&md, evp_md); |
| 346 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); /* shared_secret K */ |
| 347 | EVP_DigestUpdate(&md, hash, mdsz); /* transport-06 */ |
| 348 | EVP_DigestUpdate(&md, &c, 1); /* key id */ |
| 349 | EVP_DigestUpdate(&md, hash, mdsz); /* session id */ |
| 350 | EVP_DigestFinal(&md, digest, NULL); |
| 351 | |
| 352 | /* expand */ |
| 353 | for (have = mdsz; need > have; have += mdsz) { |
| 354 | EVP_DigestInit(&md, evp_md); |
| 355 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); |
| 356 | EVP_DigestUpdate(&md, hash, mdsz); |
| 357 | EVP_DigestUpdate(&md, digest, have); |
| 358 | EVP_DigestFinal(&md, digest + have, NULL); |
| 359 | } |
| 360 | buffer_free(&b); |
| 361 | #ifdef DEBUG_KEX |
| 362 | fprintf(stderr, "key '%c'== ", c); |
| 363 | dump_digest("key", digest, need); |
| 364 | #endif |
| 365 | return digest; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 366 | } |
| 367 | |
Ben Lindstrom | b9be60a | 2001-03-11 01:49:19 +0000 | [diff] [blame] | 368 | #define NKEYS 6 |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 369 | void |
Ben Lindstrom | 46c1622 | 2000-12-22 01:43:59 +0000 | [diff] [blame] | 370 | kex_derive_keys(Kex *k, u_char *hash, BIGNUM *shared_secret) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 371 | { |
| 372 | int i; |
| 373 | int mode; |
| 374 | int ctos; |
Ben Lindstrom | 46c1622 | 2000-12-22 01:43:59 +0000 | [diff] [blame] | 375 | u_char *keys[NKEYS]; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 376 | |
| 377 | for (i = 0; i < NKEYS; i++) |
| 378 | keys[i] = derive_key('A'+i, k->we_need, hash, shared_secret); |
| 379 | |
| 380 | for (mode = 0; mode < MODE_MAX; mode++) { |
| 381 | ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN); |
| 382 | k->enc[mode].iv = keys[ctos ? 0 : 1]; |
| 383 | k->enc[mode].key = keys[ctos ? 2 : 3]; |
| 384 | k->mac[mode].key = keys[ctos ? 4 : 5]; |
| 385 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 386 | } |
Ben Lindstrom | 20d7c7b | 2001-04-04 01:56:17 +0000 | [diff] [blame^] | 387 | |
| 388 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
| 389 | void |
| 390 | dump_digest(char *msg, u_char *digest, int len) |
| 391 | { |
| 392 | int i; |
| 393 | |
| 394 | fprintf(stderr, "%s\n", msg); |
| 395 | for (i = 0; i< len; i++){ |
| 396 | fprintf(stderr, "%02x", digest[i]); |
| 397 | if (i%32 == 31) |
| 398 | fprintf(stderr, "\n"); |
| 399 | else if (i%8 == 7) |
| 400 | fprintf(stderr, " "); |
| 401 | } |
| 402 | fprintf(stderr, "\n"); |
| 403 | } |
| 404 | #endif |