Annotation of src/usr.bin/ssh/kex.c, Revision 1.82
1.82 ! andreas 1: /* $OpenBSD: kex.c,v 1.81 2009/05/27 06:34:36 andreas Exp $ */
1.1 markus 2: /*
1.36 markus 3: * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
1.1 markus 4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.73 stevesk 26: #include <sys/param.h>
1.18 markus 27:
1.76 deraadt 28: #include <signal.h>
1.75 stevesk 29: #include <stdio.h>
1.74 stevesk 30: #include <stdlib.h>
1.72 stevesk 31: #include <string.h>
1.1 markus 32:
1.76 deraadt 33: #include <openssl/crypto.h>
34:
35: #include "xmalloc.h"
1.1 markus 36: #include "ssh2.h"
37: #include "buffer.h"
1.7 markus 38: #include "packet.h"
1.1 markus 39: #include "compat.h"
1.18 markus 40: #include "cipher.h"
1.76 deraadt 41: #include "key.h"
1.1 markus 42: #include "kex.h"
1.18 markus 43: #include "log.h"
1.21 markus 44: #include "mac.h"
1.23 markus 45: #include "match.h"
1.26 markus 46: #include "dispatch.h"
1.48 provos 47: #include "monitor.h"
1.82 ! andreas 48: #include "roaming.h"
1.48 provos 49:
1.35 itojun 50: /* prototype */
51: static void kex_kexinit_finish(Kex *);
52: static void kex_choose_conf(Kex *);
1.26 markus 53:
54: /* put algorithm proposal into buffer */
1.35 itojun 55: static void
1.26 markus 56: kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
1.1 markus 57: {
1.61 djm 58: u_int i;
1.26 markus 59:
60: buffer_clear(b);
1.49 markus 61: /*
62: * add a dummy cookie, the cookie will be overwritten by
63: * kex_send_kexinit(), each time a kexinit is set
64: */
65: for (i = 0; i < KEX_COOKIE_LEN; i++)
66: buffer_put_char(b, 0);
1.1 markus 67: for (i = 0; i < PROPOSAL_MAX; i++)
1.26 markus 68: buffer_put_cstring(b, proposal[i]);
69: buffer_put_char(b, 0); /* first_kex_packet_follows */
70: buffer_put_int(b, 0); /* uint32 reserved */
1.1 markus 71: }
72:
1.26 markus 73: /* parse buffer and return algorithm proposal */
1.35 itojun 74: static char **
1.53 markus 75: kex_buf2prop(Buffer *raw, int *first_kex_follows)
1.7 markus 76: {
1.26 markus 77: Buffer b;
1.78 djm 78: u_int i;
1.26 markus 79: char **proposal;
1.7 markus 80:
1.70 djm 81: proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
1.7 markus 82:
1.26 markus 83: buffer_init(&b);
84: buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
1.7 markus 85: /* skip cookie */
86: for (i = 0; i < KEX_COOKIE_LEN; i++)
1.26 markus 87: buffer_get_char(&b);
1.7 markus 88: /* extract kex init proposal strings */
89: for (i = 0; i < PROPOSAL_MAX; i++) {
1.26 markus 90: proposal[i] = buffer_get_string(&b,NULL);
91: debug2("kex_parse_kexinit: %s", proposal[i]);
1.7 markus 92: }
1.26 markus 93: /* first kex follows / reserved */
94: i = buffer_get_char(&b);
1.53 markus 95: if (first_kex_follows != NULL)
96: *first_kex_follows = i;
1.26 markus 97: debug2("kex_parse_kexinit: first_kex_follows %d ", i);
98: i = buffer_get_int(&b);
1.78 djm 99: debug2("kex_parse_kexinit: reserved %u ", i);
1.26 markus 100: buffer_free(&b);
101: return proposal;
1.1 markus 102: }
103:
1.35 itojun 104: static void
1.26 markus 105: kex_prop_free(char **proposal)
1.1 markus 106: {
1.61 djm 107: u_int i;
1.26 markus 108:
109: for (i = 0; i < PROPOSAL_MAX; i++)
110: xfree(proposal[i]);
111: xfree(proposal);
1.1 markus 112: }
113:
1.78 djm 114: /* ARGSUSED */
1.35 itojun 115: static void
1.41 markus 116: kex_protocol_error(int type, u_int32_t seq, void *ctxt)
1.1 markus 117: {
1.41 markus 118: error("Hm, kex protocol error: type %d seq %u", type, seq);
1.26 markus 119: }
1.1 markus 120:
1.35 itojun 121: static void
1.44 markus 122: kex_reset_dispatch(void)
1.29 markus 123: {
1.42 markus 124: dispatch_range(SSH2_MSG_TRANSPORT_MIN,
125: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.44 markus 126: dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.29 markus 127: }
128:
129: void
1.28 markus 130: kex_finish(Kex *kex)
1.26 markus 131: {
1.44 markus 132: kex_reset_dispatch();
1.28 markus 133:
1.26 markus 134: packet_start(SSH2_MSG_NEWKEYS);
135: packet_send();
136: /* packet_write_wait(); */
137: debug("SSH2_MSG_NEWKEYS sent");
1.19 stevesk 138:
1.52 markus 139: debug("expecting SSH2_MSG_NEWKEYS");
1.40 markus 140: packet_read_expect(SSH2_MSG_NEWKEYS);
1.46 markus 141: packet_check_eom();
1.26 markus 142: debug("SSH2_MSG_NEWKEYS received");
1.32 markus 143:
1.30 markus 144: kex->done = 1;
1.26 markus 145: buffer_clear(&kex->peer);
1.27 markus 146: /* buffer_clear(&kex->my); */
1.26 markus 147: kex->flags &= ~KEX_INIT_SENT;
1.32 markus 148: xfree(kex->name);
149: kex->name = NULL;
1.26 markus 150: }
1.1 markus 151:
1.26 markus 152: void
153: kex_send_kexinit(Kex *kex)
154: {
1.60 avsm 155: u_int32_t rnd = 0;
1.49 markus 156: u_char *cookie;
1.61 djm 157: u_int i;
1.49 markus 158:
1.29 markus 159: if (kex == NULL) {
160: error("kex_send_kexinit: no kex, cannot rekey");
161: return;
162: }
1.28 markus 163: if (kex->flags & KEX_INIT_SENT) {
164: debug("KEX_INIT_SENT");
165: return;
166: }
1.30 markus 167: kex->done = 0;
1.49 markus 168:
169: /* generate a random cookie */
170: if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
171: fatal("kex_send_kexinit: kex proposal too short");
172: cookie = buffer_ptr(&kex->my);
173: for (i = 0; i < KEX_COOKIE_LEN; i++) {
174: if (i % 4 == 0)
1.60 avsm 175: rnd = arc4random();
176: cookie[i] = rnd;
177: rnd >>= 8;
1.49 markus 178: }
1.26 markus 179: packet_start(SSH2_MSG_KEXINIT);
180: packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
181: packet_send();
182: debug("SSH2_MSG_KEXINIT sent");
183: kex->flags |= KEX_INIT_SENT;
1.1 markus 184: }
185:
1.78 djm 186: /* ARGSUSED */
1.26 markus 187: void
1.41 markus 188: kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1.11 provos 189: {
1.26 markus 190: char *ptr;
1.61 djm 191: u_int i, dlen;
1.26 markus 192: Kex *kex = (Kex *)ctxt;
1.11 provos 193:
1.26 markus 194: debug("SSH2_MSG_KEXINIT received");
1.29 markus 195: if (kex == NULL)
196: fatal("kex_input_kexinit: no kex, cannot rekey");
1.11 provos 197:
1.26 markus 198: ptr = packet_get_raw(&dlen);
199: buffer_append(&kex->peer, ptr, dlen);
1.31 markus 200:
201: /* discard packet */
202: for (i = 0; i < KEX_COOKIE_LEN; i++)
203: packet_get_char();
204: for (i = 0; i < PROPOSAL_MAX; i++)
205: xfree(packet_get_string(NULL));
1.51 markus 206: (void) packet_get_char();
207: (void) packet_get_int();
1.39 markus 208: packet_check_eom();
1.19 stevesk 209:
1.26 markus 210: kex_kexinit_finish(kex);
211: }
1.11 provos 212:
1.26 markus 213: Kex *
1.28 markus 214: kex_setup(char *proposal[PROPOSAL_MAX])
1.26 markus 215: {
216: Kex *kex;
1.11 provos 217:
1.70 djm 218: kex = xcalloc(1, sizeof(*kex));
1.26 markus 219: buffer_init(&kex->peer);
220: buffer_init(&kex->my);
221: kex_prop2buf(&kex->my, proposal);
1.30 markus 222: kex->done = 0;
1.26 markus 223:
224: kex_send_kexinit(kex); /* we start */
1.44 markus 225: kex_reset_dispatch();
1.26 markus 226:
227: return kex;
1.11 provos 228: }
229:
1.35 itojun 230: static void
1.26 markus 231: kex_kexinit_finish(Kex *kex)
1.1 markus 232: {
1.26 markus 233: if (!(kex->flags & KEX_INIT_SENT))
234: kex_send_kexinit(kex);
1.1 markus 235:
1.26 markus 236: kex_choose_conf(kex);
1.1 markus 237:
1.54 markus 238: if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
239: kex->kex[kex->kex_type] != NULL) {
240: (kex->kex[kex->kex_type])(kex);
241: } else {
1.26 markus 242: fatal("Unsupported key exchange %d", kex->kex_type);
1.1 markus 243: }
244: }
245:
1.35 itojun 246: static void
1.1 markus 247: choose_enc(Enc *enc, char *client, char *server)
248: {
1.23 markus 249: char *name = match_list(client, server, NULL);
1.1 markus 250: if (name == NULL)
1.78 djm 251: fatal("no matching cipher found: client %s server %s",
252: client, server);
1.45 markus 253: if ((enc->cipher = cipher_by_name(name)) == NULL)
1.12 markus 254: fatal("matching cipher is not supported: %s", name);
1.1 markus 255: enc->name = name;
256: enc->enabled = 0;
257: enc->iv = NULL;
258: enc->key = NULL;
1.45 markus 259: enc->key_len = cipher_keylen(enc->cipher);
260: enc->block_size = cipher_blocksize(enc->cipher);
1.1 markus 261: }
1.69 deraadt 262:
1.35 itojun 263: static void
1.1 markus 264: choose_mac(Mac *mac, char *client, char *server)
265: {
1.23 markus 266: char *name = match_list(client, server, NULL);
1.1 markus 267: if (name == NULL)
1.78 djm 268: fatal("no matching mac found: client %s server %s",
269: client, server);
1.79 djm 270: if (mac_setup(mac, name) < 0)
1.1 markus 271: fatal("unsupported mac %s", name);
1.21 markus 272: /* truncate the key */
273: if (datafellows & SSH_BUG_HMAC)
274: mac->key_len = 16;
1.1 markus 275: mac->name = name;
276: mac->key = NULL;
277: mac->enabled = 0;
278: }
1.69 deraadt 279:
1.35 itojun 280: static void
1.1 markus 281: choose_comp(Comp *comp, char *client, char *server)
282: {
1.23 markus 283: char *name = match_list(client, server, NULL);
1.1 markus 284: if (name == NULL)
285: fatal("no matching comp found: client %s server %s", client, server);
1.64 markus 286: if (strcmp(name, "zlib@openssh.com") == 0) {
287: comp->type = COMP_DELAYED;
288: } else if (strcmp(name, "zlib") == 0) {
289: comp->type = COMP_ZLIB;
1.1 markus 290: } else if (strcmp(name, "none") == 0) {
1.64 markus 291: comp->type = COMP_NONE;
1.1 markus 292: } else {
293: fatal("unsupported comp %s", name);
294: }
295: comp->name = name;
296: }
1.69 deraadt 297:
1.35 itojun 298: static void
1.1 markus 299: choose_kex(Kex *k, char *client, char *server)
300: {
1.23 markus 301: k->name = match_list(client, server, NULL);
1.1 markus 302: if (k->name == NULL)
1.78 djm 303: fatal("Unable to negotiate a key exchange method");
1.11 provos 304: if (strcmp(k->name, KEX_DH1) == 0) {
1.54 markus 305: k->kex_type = KEX_DH_GRP1_SHA1;
1.65 djm 306: k->evp_md = EVP_sha1();
1.59 djm 307: } else if (strcmp(k->name, KEX_DH14) == 0) {
308: k->kex_type = KEX_DH_GRP14_SHA1;
1.65 djm 309: k->evp_md = EVP_sha1();
310: } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) {
1.54 markus 311: k->kex_type = KEX_DH_GEX_SHA1;
1.65 djm 312: k->evp_md = EVP_sha1();
1.66 djm 313: } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) {
314: k->kex_type = KEX_DH_GEX_SHA256;
1.80 djm 315: k->evp_md = EVP_sha256();
1.11 provos 316: } else
1.1 markus 317: fatal("bad kex alg %s", k->name);
318: }
1.65 djm 319:
1.35 itojun 320: static void
1.1 markus 321: choose_hostkeyalg(Kex *k, char *client, char *server)
322: {
1.23 markus 323: char *hostkeyalg = match_list(client, server, NULL);
1.13 markus 324: if (hostkeyalg == NULL)
1.1 markus 325: fatal("no hostkey alg");
1.13 markus 326: k->hostkey_type = key_type_from_name(hostkeyalg);
327: if (k->hostkey_type == KEY_UNSPEC)
328: fatal("bad hostkey alg '%s'", hostkeyalg);
1.17 markus 329: xfree(hostkeyalg);
1.1 markus 330: }
331:
1.56 djm 332: static int
1.53 markus 333: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
334: {
335: static int check[] = {
336: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
337: };
338: int *idx;
339: char *p;
340:
341: for (idx = &check[0]; *idx != -1; idx++) {
342: if ((p = strchr(my[*idx], ',')) != NULL)
343: *p = '\0';
344: if ((p = strchr(peer[*idx], ',')) != NULL)
345: *p = '\0';
346: if (strcmp(my[*idx], peer[*idx]) != 0) {
347: debug2("proposal mismatch: my %s peer %s",
348: my[*idx], peer[*idx]);
349: return (0);
350: }
351: }
352: debug2("proposals match");
353: return (1);
354: }
355:
1.35 itojun 356: static void
1.27 markus 357: kex_choose_conf(Kex *kex)
1.1 markus 358: {
1.27 markus 359: Newkeys *newkeys;
1.26 markus 360: char **my, **peer;
361: char **cprop, **sprop;
1.27 markus 362: int nenc, nmac, ncomp;
1.61 djm 363: u_int mode, ctos, need;
1.53 markus 364: int first_kex_follows, type;
1.1 markus 365:
1.53 markus 366: my = kex_buf2prop(&kex->my, NULL);
367: peer = kex_buf2prop(&kex->peer, &first_kex_follows);
1.26 markus 368:
1.27 markus 369: if (kex->server) {
1.26 markus 370: cprop=peer;
371: sprop=my;
372: } else {
373: cprop=my;
374: sprop=peer;
1.82 ! andreas 375: }
! 376:
! 377: /* Check whether server offers roaming */
! 378: if (!kex->server) {
! 379: char *roaming;
! 380: roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
! 381: if (roaming) {
! 382: kex->roaming = 1;
! 383: xfree(roaming);
! 384: }
1.26 markus 385: }
1.1 markus 386:
1.30 markus 387: /* Algorithm Negotiation */
1.1 markus 388: for (mode = 0; mode < MODE_MAX; mode++) {
1.70 djm 389: newkeys = xcalloc(1, sizeof(*newkeys));
1.30 markus 390: kex->newkeys[mode] = newkeys;
1.78 djm 391: ctos = (!kex->server && mode == MODE_OUT) ||
392: (kex->server && mode == MODE_IN);
1.1 markus 393: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
394: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
395: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.27 markus 396: choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]);
397: choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]);
398: choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
1.2 markus 399: debug("kex: %s %s %s %s",
1.1 markus 400: ctos ? "client->server" : "server->client",
1.27 markus 401: newkeys->enc.name,
402: newkeys->mac.name,
403: newkeys->comp.name);
1.1 markus 404: }
1.27 markus 405: choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
406: choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1.1 markus 407: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
408: need = 0;
409: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 410: newkeys = kex->newkeys[mode];
1.45 markus 411: if (need < newkeys->enc.key_len)
412: need = newkeys->enc.key_len;
413: if (need < newkeys->enc.block_size)
414: need = newkeys->enc.block_size;
1.27 markus 415: if (need < newkeys->mac.key_len)
416: need = newkeys->mac.key_len;
1.1 markus 417: }
1.7 markus 418: /* XXX need runden? */
1.27 markus 419: kex->we_need = need;
1.53 markus 420:
421: /* ignore the next message if the proposals do not match */
1.56 djm 422: if (first_kex_follows && !proposals_match(my, peer) &&
1.63 djm 423: !(datafellows & SSH_BUG_FIRSTKEX)) {
1.53 markus 424: type = packet_read();
425: debug2("skipping next packet (type %u)", type);
426: }
1.26 markus 427:
428: kex_prop_free(my);
429: kex_prop_free(peer);
430: }
431:
1.35 itojun 432: static u_char *
1.65 djm 433: derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
434: BIGNUM *shared_secret)
1.26 markus 435: {
436: Buffer b;
437: EVP_MD_CTX md;
438: char c = id;
1.61 djm 439: u_int have;
1.65 djm 440: int mdsz;
1.61 djm 441: u_char *digest;
1.62 djm 442:
1.65 djm 443: if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
444: fatal("bad kex md size %d", mdsz);
1.68 deraadt 445: digest = xmalloc(roundup(need, mdsz));
1.26 markus 446:
447: buffer_init(&b);
448: buffer_put_bignum2(&b, shared_secret);
449:
1.30 markus 450: /* K1 = HASH(K || H || "A" || session_id) */
1.65 djm 451: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 452: if (!(datafellows & SSH_BUG_DERIVEKEY))
453: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 454: EVP_DigestUpdate(&md, hash, hashlen);
1.30 markus 455: EVP_DigestUpdate(&md, &c, 1);
1.27 markus 456: EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
1.26 markus 457: EVP_DigestFinal(&md, digest, NULL);
458:
1.30 markus 459: /*
460: * expand key:
461: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
462: * Key = K1 || K2 || ... || Kn
463: */
1.26 markus 464: for (have = mdsz; need > have; have += mdsz) {
1.65 djm 465: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 466: if (!(datafellows & SSH_BUG_DERIVEKEY))
467: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 468: EVP_DigestUpdate(&md, hash, hashlen);
1.26 markus 469: EVP_DigestUpdate(&md, digest, have);
470: EVP_DigestFinal(&md, digest + have, NULL);
471: }
472: buffer_free(&b);
473: #ifdef DEBUG_KEX
474: fprintf(stderr, "key '%c'== ", c);
475: dump_digest("key", digest, need);
476: #endif
477: return digest;
1.1 markus 478: }
479:
1.30 markus 480: Newkeys *current_keys[MODE_MAX];
1.27 markus 481:
1.23 markus 482: #define NKEYS 6
1.26 markus 483: void
1.65 djm 484: kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
1.1 markus 485: {
1.15 markus 486: u_char *keys[NKEYS];
1.61 djm 487: u_int i, mode, ctos;
1.1 markus 488:
1.65 djm 489: for (i = 0; i < NKEYS; i++) {
490: keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
491: shared_secret);
492: }
1.1 markus 493:
1.52 markus 494: debug2("kex_derive_keys");
1.1 markus 495: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 496: current_keys[mode] = kex->newkeys[mode];
497: kex->newkeys[mode] = NULL;
1.69 deraadt 498: ctos = (!kex->server && mode == MODE_OUT) ||
499: (kex->server && mode == MODE_IN);
1.30 markus 500: current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
501: current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
502: current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 503: }
1.27 markus 504: }
505:
506: Newkeys *
507: kex_get_newkeys(int mode)
508: {
1.30 markus 509: Newkeys *ret;
510:
511: ret = current_keys[mode];
512: current_keys[mode] = NULL;
513: return ret;
1.57 djm 514: }
515:
516: void
517: derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
518: u_int8_t cookie[8], u_int8_t id[16])
519: {
520: const EVP_MD *evp_md = EVP_md5();
521: EVP_MD_CTX md;
522: u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
523: int len;
524:
525: EVP_DigestInit(&md, evp_md);
526:
527: len = BN_num_bytes(host_modulus);
1.61 djm 528: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 529: fatal("%s: bad host modulus (len %d)", __func__, len);
530: BN_bn2bin(host_modulus, nbuf);
531: EVP_DigestUpdate(&md, nbuf, len);
532:
533: len = BN_num_bytes(server_modulus);
1.61 djm 534: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 535: fatal("%s: bad server modulus (len %d)", __func__, len);
536: BN_bn2bin(server_modulus, nbuf);
537: EVP_DigestUpdate(&md, nbuf, len);
538:
539: EVP_DigestUpdate(&md, cookie, 8);
540:
1.58 djm 541: EVP_DigestFinal(&md, obuf, NULL);
1.57 djm 542: memcpy(id, obuf, 16);
543:
544: memset(nbuf, 0, sizeof(nbuf));
545: memset(obuf, 0, sizeof(obuf));
546: memset(&md, 0, sizeof(md));
1.1 markus 547: }
1.26 markus 548:
549: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
550: void
551: dump_digest(char *msg, u_char *digest, int len)
552: {
1.61 djm 553: u_int i;
1.26 markus 554:
555: fprintf(stderr, "%s\n", msg);
1.77 stevesk 556: for (i = 0; i < len; i++) {
1.26 markus 557: fprintf(stderr, "%02x", digest[i]);
558: if (i%32 == 31)
559: fprintf(stderr, "\n");
560: else if (i%8 == 7)
561: fprintf(stderr, " ");
562: }
563: fprintf(stderr, "\n");
564: }
565: #endif
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