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Annotation of src/usr.bin/ssh/kex.c, Revision 1.59

1.1       markus      1: /*
1.36      markus      2:  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
1.1       markus      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.
                     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"
1.59    ! djm        26: RCSID("$OpenBSD: kex.c,v 1.58 2004/05/09 01:26:48 djm Exp $");
1.18      markus     27:
                     28: #include <openssl/crypto.h>
1.1       markus     29:
                     30: #include "ssh2.h"
                     31: #include "xmalloc.h"
                     32: #include "buffer.h"
                     33: #include "bufaux.h"
1.7       markus     34: #include "packet.h"
1.1       markus     35: #include "compat.h"
1.18      markus     36: #include "cipher.h"
1.1       markus     37: #include "kex.h"
1.13      markus     38: #include "key.h"
1.18      markus     39: #include "log.h"
1.21      markus     40: #include "mac.h"
1.23      markus     41: #include "match.h"
1.26      markus     42: #include "dispatch.h"
1.48      provos     43: #include "monitor.h"
1.1       markus     44:
1.7       markus     45: #define KEX_COOKIE_LEN 16
1.48      provos     46:
1.35      itojun     47: /* prototype */
                     48: static void kex_kexinit_finish(Kex *);
                     49: static void kex_choose_conf(Kex *);
1.26      markus     50:
                     51: /* put algorithm proposal into buffer */
1.35      itojun     52: static void
1.26      markus     53: kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
1.1       markus     54: {
                     55:        int i;
1.26      markus     56:
                     57:        buffer_clear(b);
1.49      markus     58:        /*
                     59:         * add a dummy cookie, the cookie will be overwritten by
                     60:         * kex_send_kexinit(), each time a kexinit is set
                     61:         */
                     62:        for (i = 0; i < KEX_COOKIE_LEN; i++)
                     63:                buffer_put_char(b, 0);
1.1       markus     64:        for (i = 0; i < PROPOSAL_MAX; i++)
1.26      markus     65:                buffer_put_cstring(b, proposal[i]);
                     66:        buffer_put_char(b, 0);                  /* first_kex_packet_follows */
                     67:        buffer_put_int(b, 0);                   /* uint32 reserved */
1.1       markus     68: }
                     69:
1.26      markus     70: /* parse buffer and return algorithm proposal */
1.35      itojun     71: static char **
1.53      markus     72: kex_buf2prop(Buffer *raw, int *first_kex_follows)
1.7       markus     73: {
1.26      markus     74:        Buffer b;
1.7       markus     75:        int i;
1.26      markus     76:        char **proposal;
1.7       markus     77:
1.26      markus     78:        proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));
1.7       markus     79:
1.26      markus     80:        buffer_init(&b);
                     81:        buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
1.7       markus     82:        /* skip cookie */
                     83:        for (i = 0; i < KEX_COOKIE_LEN; i++)
1.26      markus     84:                buffer_get_char(&b);
1.7       markus     85:        /* extract kex init proposal strings */
                     86:        for (i = 0; i < PROPOSAL_MAX; i++) {
1.26      markus     87:                proposal[i] = buffer_get_string(&b,NULL);
                     88:                debug2("kex_parse_kexinit: %s", proposal[i]);
1.7       markus     89:        }
1.26      markus     90:        /* first kex follows / reserved */
                     91:        i = buffer_get_char(&b);
1.53      markus     92:        if (first_kex_follows != NULL)
                     93:                *first_kex_follows = i;
1.26      markus     94:        debug2("kex_parse_kexinit: first_kex_follows %d ", i);
                     95:        i = buffer_get_int(&b);
                     96:        debug2("kex_parse_kexinit: reserved %d ", i);
                     97:        buffer_free(&b);
                     98:        return proposal;
1.1       markus     99: }
                    100:
1.35      itojun    101: static void
1.26      markus    102: kex_prop_free(char **proposal)
1.1       markus    103: {
                    104:        int i;
1.26      markus    105:
                    106:        for (i = 0; i < PROPOSAL_MAX; i++)
                    107:                xfree(proposal[i]);
                    108:        xfree(proposal);
1.1       markus    109: }
                    110:
1.35      itojun    111: static void
1.41      markus    112: kex_protocol_error(int type, u_int32_t seq, void *ctxt)
1.1       markus    113: {
1.41      markus    114:        error("Hm, kex protocol error: type %d seq %u", type, seq);
1.26      markus    115: }
1.1       markus    116:
1.35      itojun    117: static void
1.44      markus    118: kex_reset_dispatch(void)
1.29      markus    119: {
1.42      markus    120:        dispatch_range(SSH2_MSG_TRANSPORT_MIN,
                    121:            SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.44      markus    122:        dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.29      markus    123: }
                    124:
                    125: void
1.28      markus    126: kex_finish(Kex *kex)
1.26      markus    127: {
1.44      markus    128:        kex_reset_dispatch();
1.28      markus    129:
1.26      markus    130:        packet_start(SSH2_MSG_NEWKEYS);
                    131:        packet_send();
                    132:        /* packet_write_wait(); */
                    133:        debug("SSH2_MSG_NEWKEYS sent");
1.19      stevesk   134:
1.52      markus    135:        debug("expecting SSH2_MSG_NEWKEYS");
1.40      markus    136:        packet_read_expect(SSH2_MSG_NEWKEYS);
1.46      markus    137:        packet_check_eom();
1.26      markus    138:        debug("SSH2_MSG_NEWKEYS received");
1.32      markus    139:
1.30      markus    140:        kex->done = 1;
1.26      markus    141:        buffer_clear(&kex->peer);
1.27      markus    142:        /* buffer_clear(&kex->my); */
1.26      markus    143:        kex->flags &= ~KEX_INIT_SENT;
1.32      markus    144:        xfree(kex->name);
                    145:        kex->name = NULL;
1.26      markus    146: }
1.1       markus    147:
1.26      markus    148: void
                    149: kex_send_kexinit(Kex *kex)
                    150: {
1.49      markus    151:        u_int32_t rand = 0;
                    152:        u_char *cookie;
                    153:        int i;
                    154:
1.29      markus    155:        if (kex == NULL) {
                    156:                error("kex_send_kexinit: no kex, cannot rekey");
                    157:                return;
                    158:        }
1.28      markus    159:        if (kex->flags & KEX_INIT_SENT) {
                    160:                debug("KEX_INIT_SENT");
                    161:                return;
                    162:        }
1.30      markus    163:        kex->done = 0;
1.49      markus    164:
                    165:        /* generate a random cookie */
                    166:        if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
                    167:                fatal("kex_send_kexinit: kex proposal too short");
                    168:        cookie = buffer_ptr(&kex->my);
                    169:        for (i = 0; i < KEX_COOKIE_LEN; i++) {
                    170:                if (i % 4 == 0)
                    171:                        rand = arc4random();
                    172:                cookie[i] = rand;
                    173:                rand >>= 8;
                    174:        }
1.26      markus    175:        packet_start(SSH2_MSG_KEXINIT);
                    176:        packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
                    177:        packet_send();
                    178:        debug("SSH2_MSG_KEXINIT sent");
                    179:        kex->flags |= KEX_INIT_SENT;
1.1       markus    180: }
                    181:
1.26      markus    182: void
1.41      markus    183: kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1.11      provos    184: {
1.26      markus    185:        char *ptr;
                    186:        int dlen;
1.31      markus    187:        int i;
1.26      markus    188:        Kex *kex = (Kex *)ctxt;
1.11      provos    189:
1.26      markus    190:        debug("SSH2_MSG_KEXINIT received");
1.29      markus    191:        if (kex == NULL)
                    192:                fatal("kex_input_kexinit: no kex, cannot rekey");
1.11      provos    193:
1.26      markus    194:        ptr = packet_get_raw(&dlen);
                    195:        buffer_append(&kex->peer, ptr, dlen);
1.31      markus    196:
                    197:        /* discard packet */
                    198:        for (i = 0; i < KEX_COOKIE_LEN; i++)
                    199:                packet_get_char();
                    200:        for (i = 0; i < PROPOSAL_MAX; i++)
                    201:                xfree(packet_get_string(NULL));
1.51      markus    202:        (void) packet_get_char();
                    203:        (void) packet_get_int();
1.39      markus    204:        packet_check_eom();
1.19      stevesk   205:
1.26      markus    206:        kex_kexinit_finish(kex);
                    207: }
1.11      provos    208:
1.26      markus    209: Kex *
1.28      markus    210: kex_setup(char *proposal[PROPOSAL_MAX])
1.26      markus    211: {
                    212:        Kex *kex;
1.11      provos    213:
1.26      markus    214:        kex = xmalloc(sizeof(*kex));
                    215:        memset(kex, 0, sizeof(*kex));
                    216:        buffer_init(&kex->peer);
                    217:        buffer_init(&kex->my);
                    218:        kex_prop2buf(&kex->my, proposal);
1.30      markus    219:        kex->done = 0;
1.26      markus    220:
                    221:        kex_send_kexinit(kex);                                  /* we start */
1.44      markus    222:        kex_reset_dispatch();
1.26      markus    223:
                    224:        return kex;
1.11      provos    225: }
                    226:
1.35      itojun    227: static void
1.26      markus    228: kex_kexinit_finish(Kex *kex)
1.1       markus    229: {
1.26      markus    230:        if (!(kex->flags & KEX_INIT_SENT))
                    231:                kex_send_kexinit(kex);
1.1       markus    232:
1.26      markus    233:        kex_choose_conf(kex);
1.1       markus    234:
1.54      markus    235:        if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
                    236:            kex->kex[kex->kex_type] != NULL) {
                    237:                (kex->kex[kex->kex_type])(kex);
                    238:        } else {
1.26      markus    239:                fatal("Unsupported key exchange %d", kex->kex_type);
1.1       markus    240:        }
                    241: }
                    242:
1.35      itojun    243: static void
1.1       markus    244: choose_enc(Enc *enc, char *client, char *server)
                    245: {
1.23      markus    246:        char *name = match_list(client, server, NULL);
1.1       markus    247:        if (name == NULL)
                    248:                fatal("no matching cipher found: client %s server %s", client, server);
1.45      markus    249:        if ((enc->cipher = cipher_by_name(name)) == NULL)
1.12      markus    250:                fatal("matching cipher is not supported: %s", name);
1.1       markus    251:        enc->name = name;
                    252:        enc->enabled = 0;
                    253:        enc->iv = NULL;
                    254:        enc->key = NULL;
1.45      markus    255:        enc->key_len = cipher_keylen(enc->cipher);
                    256:        enc->block_size = cipher_blocksize(enc->cipher);
1.1       markus    257: }
1.35      itojun    258: static void
1.1       markus    259: choose_mac(Mac *mac, char *client, char *server)
                    260: {
1.23      markus    261:        char *name = match_list(client, server, NULL);
1.1       markus    262:        if (name == NULL)
                    263:                fatal("no matching mac found: client %s server %s", client, server);
1.21      markus    264:        if (mac_init(mac, name) < 0)
1.1       markus    265:                fatal("unsupported mac %s", name);
1.21      markus    266:        /* truncate the key */
                    267:        if (datafellows & SSH_BUG_HMAC)
                    268:                mac->key_len = 16;
1.1       markus    269:        mac->name = name;
                    270:        mac->key = NULL;
                    271:        mac->enabled = 0;
                    272: }
1.35      itojun    273: static void
1.1       markus    274: choose_comp(Comp *comp, char *client, char *server)
                    275: {
1.23      markus    276:        char *name = match_list(client, server, NULL);
1.1       markus    277:        if (name == NULL)
                    278:                fatal("no matching comp found: client %s server %s", client, server);
                    279:        if (strcmp(name, "zlib") == 0) {
                    280:                comp->type = 1;
                    281:        } else if (strcmp(name, "none") == 0) {
                    282:                comp->type = 0;
                    283:        } else {
                    284:                fatal("unsupported comp %s", name);
                    285:        }
                    286:        comp->name = name;
                    287: }
1.35      itojun    288: static void
1.1       markus    289: choose_kex(Kex *k, char *client, char *server)
                    290: {
1.23      markus    291:        k->name = match_list(client, server, NULL);
1.1       markus    292:        if (k->name == NULL)
                    293:                fatal("no kex alg");
1.11      provos    294:        if (strcmp(k->name, KEX_DH1) == 0) {
1.54      markus    295:                k->kex_type = KEX_DH_GRP1_SHA1;
1.59    ! djm       296:        } else if (strcmp(k->name, KEX_DH14) == 0) {
        !           297:                k->kex_type = KEX_DH_GRP14_SHA1;
1.11      provos    298:        } else if (strcmp(k->name, KEX_DHGEX) == 0) {
1.54      markus    299:                k->kex_type = KEX_DH_GEX_SHA1;
1.11      provos    300:        } else
1.1       markus    301:                fatal("bad kex alg %s", k->name);
                    302: }
1.35      itojun    303: static void
1.1       markus    304: choose_hostkeyalg(Kex *k, char *client, char *server)
                    305: {
1.23      markus    306:        char *hostkeyalg = match_list(client, server, NULL);
1.13      markus    307:        if (hostkeyalg == NULL)
1.1       markus    308:                fatal("no hostkey alg");
1.13      markus    309:        k->hostkey_type = key_type_from_name(hostkeyalg);
                    310:        if (k->hostkey_type == KEY_UNSPEC)
                    311:                fatal("bad hostkey alg '%s'", hostkeyalg);
1.17      markus    312:        xfree(hostkeyalg);
1.1       markus    313: }
                    314:
1.56      djm       315: static int
1.53      markus    316: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
                    317: {
                    318:        static int check[] = {
                    319:                PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
                    320:        };
                    321:        int *idx;
                    322:        char *p;
                    323:
                    324:        for (idx = &check[0]; *idx != -1; idx++) {
                    325:                if ((p = strchr(my[*idx], ',')) != NULL)
                    326:                        *p = '\0';
                    327:                if ((p = strchr(peer[*idx], ',')) != NULL)
                    328:                        *p = '\0';
                    329:                if (strcmp(my[*idx], peer[*idx]) != 0) {
                    330:                        debug2("proposal mismatch: my %s peer %s",
                    331:                            my[*idx], peer[*idx]);
                    332:                        return (0);
                    333:                }
                    334:        }
                    335:        debug2("proposals match");
                    336:        return (1);
                    337: }
                    338:
1.35      itojun    339: static void
1.27      markus    340: kex_choose_conf(Kex *kex)
1.1       markus    341: {
1.27      markus    342:        Newkeys *newkeys;
1.26      markus    343:        char **my, **peer;
                    344:        char **cprop, **sprop;
1.27      markus    345:        int nenc, nmac, ncomp;
1.1       markus    346:        int mode;
                    347:        int ctos;                               /* direction: if true client-to-server */
                    348:        int need;
1.53      markus    349:        int first_kex_follows, type;
1.1       markus    350:
1.53      markus    351:        my   = kex_buf2prop(&kex->my, NULL);
                    352:        peer = kex_buf2prop(&kex->peer, &first_kex_follows);
1.26      markus    353:
1.27      markus    354:        if (kex->server) {
1.26      markus    355:                cprop=peer;
                    356:                sprop=my;
                    357:        } else {
                    358:                cprop=my;
                    359:                sprop=peer;
                    360:        }
1.1       markus    361:
1.30      markus    362:        /* Algorithm Negotiation */
1.1       markus    363:        for (mode = 0; mode < MODE_MAX; mode++) {
1.27      markus    364:                newkeys = xmalloc(sizeof(*newkeys));
                    365:                memset(newkeys, 0, sizeof(*newkeys));
1.30      markus    366:                kex->newkeys[mode] = newkeys;
1.27      markus    367:                ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
1.1       markus    368:                nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
                    369:                nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
                    370:                ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.27      markus    371:                choose_enc (&newkeys->enc,  cprop[nenc],  sprop[nenc]);
                    372:                choose_mac (&newkeys->mac,  cprop[nmac],  sprop[nmac]);
                    373:                choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
1.2       markus    374:                debug("kex: %s %s %s %s",
1.1       markus    375:                    ctos ? "client->server" : "server->client",
1.27      markus    376:                    newkeys->enc.name,
                    377:                    newkeys->mac.name,
                    378:                    newkeys->comp.name);
1.1       markus    379:        }
1.27      markus    380:        choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
                    381:        choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1.1       markus    382:            sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
                    383:        need = 0;
                    384:        for (mode = 0; mode < MODE_MAX; mode++) {
1.30      markus    385:                newkeys = kex->newkeys[mode];
1.45      markus    386:                if (need < newkeys->enc.key_len)
                    387:                        need = newkeys->enc.key_len;
                    388:                if (need < newkeys->enc.block_size)
                    389:                        need = newkeys->enc.block_size;
1.27      markus    390:                if (need < newkeys->mac.key_len)
                    391:                        need = newkeys->mac.key_len;
1.1       markus    392:        }
1.7       markus    393:        /* XXX need runden? */
1.27      markus    394:        kex->we_need = need;
1.53      markus    395:
                    396:        /* ignore the next message if the proposals do not match */
1.56      djm       397:        if (first_kex_follows && !proposals_match(my, peer) &&
1.55      markus    398:           !(datafellows & SSH_BUG_FIRSTKEX)) {
1.53      markus    399:                type = packet_read();
                    400:                debug2("skipping next packet (type %u)", type);
                    401:        }
1.26      markus    402:
                    403:        kex_prop_free(my);
                    404:        kex_prop_free(peer);
                    405: }
                    406:
1.35      itojun    407: static u_char *
1.27      markus    408: derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
1.26      markus    409: {
                    410:        Buffer b;
1.47      markus    411:        const EVP_MD *evp_md = EVP_sha1();
1.26      markus    412:        EVP_MD_CTX md;
                    413:        char c = id;
                    414:        int have;
1.43      markus    415:        int mdsz = EVP_MD_size(evp_md);
1.30      markus    416:        u_char *digest = xmalloc(roundup(need, mdsz));
1.26      markus    417:
                    418:        buffer_init(&b);
                    419:        buffer_put_bignum2(&b, shared_secret);
                    420:
1.30      markus    421:        /* K1 = HASH(K || H || "A" || session_id) */
1.26      markus    422:        EVP_DigestInit(&md, evp_md);
1.34      markus    423:        if (!(datafellows & SSH_BUG_DERIVEKEY))
                    424:                EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.30      markus    425:        EVP_DigestUpdate(&md, hash, mdsz);
                    426:        EVP_DigestUpdate(&md, &c, 1);
1.27      markus    427:        EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
1.26      markus    428:        EVP_DigestFinal(&md, digest, NULL);
                    429:
1.30      markus    430:        /*
                    431:         * expand key:
                    432:         * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
                    433:         * Key = K1 || K2 || ... || Kn
                    434:         */
1.26      markus    435:        for (have = mdsz; need > have; have += mdsz) {
                    436:                EVP_DigestInit(&md, evp_md);
1.34      markus    437:                if (!(datafellows & SSH_BUG_DERIVEKEY))
                    438:                        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.26      markus    439:                EVP_DigestUpdate(&md, hash, mdsz);
                    440:                EVP_DigestUpdate(&md, digest, have);
                    441:                EVP_DigestFinal(&md, digest + have, NULL);
                    442:        }
                    443:        buffer_free(&b);
                    444: #ifdef DEBUG_KEX
                    445:        fprintf(stderr, "key '%c'== ", c);
                    446:        dump_digest("key", digest, need);
                    447: #endif
                    448:        return digest;
1.1       markus    449: }
                    450:
1.30      markus    451: Newkeys *current_keys[MODE_MAX];
1.27      markus    452:
1.23      markus    453: #define NKEYS  6
1.26      markus    454: void
1.27      markus    455: kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
1.1       markus    456: {
1.15      markus    457:        u_char *keys[NKEYS];
1.27      markus    458:        int i, mode, ctos;
1.1       markus    459:
                    460:        for (i = 0; i < NKEYS; i++)
1.27      markus    461:                keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
1.1       markus    462:
1.52      markus    463:        debug2("kex_derive_keys");
1.1       markus    464:        for (mode = 0; mode < MODE_MAX; mode++) {
1.30      markus    465:                current_keys[mode] = kex->newkeys[mode];
                    466:                kex->newkeys[mode] = NULL;
1.27      markus    467:                ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
1.30      markus    468:                current_keys[mode]->enc.iv  = keys[ctos ? 0 : 1];
                    469:                current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
                    470:                current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1       markus    471:        }
1.27      markus    472: }
                    473:
                    474: Newkeys *
                    475: kex_get_newkeys(int mode)
                    476: {
1.30      markus    477:        Newkeys *ret;
                    478:
                    479:        ret = current_keys[mode];
                    480:        current_keys[mode] = NULL;
                    481:        return ret;
1.57      djm       482: }
                    483:
                    484: void
                    485: derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
                    486:     u_int8_t cookie[8], u_int8_t id[16])
                    487: {
                    488:        const EVP_MD *evp_md = EVP_md5();
                    489:        EVP_MD_CTX md;
                    490:        u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
                    491:        int len;
                    492:
                    493:        EVP_DigestInit(&md, evp_md);
                    494:
                    495:        len = BN_num_bytes(host_modulus);
                    496:        if (len < (512 / 8) || len > sizeof(nbuf))
                    497:                fatal("%s: bad host modulus (len %d)", __func__, len);
                    498:        BN_bn2bin(host_modulus, nbuf);
                    499:        EVP_DigestUpdate(&md, nbuf, len);
                    500:
                    501:        len = BN_num_bytes(server_modulus);
                    502:        if (len < (512 / 8) || len > sizeof(nbuf))
                    503:                fatal("%s: bad server modulus (len %d)", __func__, len);
                    504:        BN_bn2bin(server_modulus, nbuf);
                    505:        EVP_DigestUpdate(&md, nbuf, len);
                    506:
                    507:        EVP_DigestUpdate(&md, cookie, 8);
                    508:
1.58      djm       509:        EVP_DigestFinal(&md, obuf, NULL);
1.57      djm       510:        memcpy(id, obuf, 16);
                    511:
                    512:        memset(nbuf, 0, sizeof(nbuf));
                    513:        memset(obuf, 0, sizeof(obuf));
                    514:        memset(&md, 0, sizeof(md));
1.1       markus    515: }
1.26      markus    516:
                    517: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
                    518: void
                    519: dump_digest(char *msg, u_char *digest, int len)
                    520: {
                    521:        int i;
                    522:
                    523:        fprintf(stderr, "%s\n", msg);
1.37      deraadt   524:        for (i = 0; i< len; i++) {
1.26      markus    525:                fprintf(stderr, "%02x", digest[i]);
                    526:                if (i%32 == 31)
                    527:                        fprintf(stderr, "\n");
                    528:                else if (i%8 == 7)
                    529:                        fprintf(stderr, " ");
                    530:        }
                    531:        fprintf(stderr, "\n");
                    532: }
                    533: #endif