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Annotation of src/usr.bin/ssh/kexecdh.c, Revision 1.3

1.3     ! djm         1: /* $OpenBSD: kexecdh.c,v 1.2 2010/09/09 10:45:45 djm Exp $ */
1.1       djm         2: /*
                      3:  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
                      4:  * Copyright (c) 2010 Damien Miller.  All rights reserved.
                      5:  *
                      6:  * Redistribution and use in source and binary forms, with or without
                      7:  * modification, are permitted provided that the following conditions
                      8:  * are met:
                      9:  * 1. Redistributions of source code must retain the above copyright
                     10:  *    notice, this list of conditions and the following disclaimer.
                     11:  * 2. Redistributions in binary form must reproduce the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer in the
                     13:  *    documentation and/or other materials provided with the distribution.
                     14:  *
                     15:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
                     16:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
                     17:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
                     18:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
                     19:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
                     20:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
                     21:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
                     22:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
                     23:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
                     24:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                     25:  */
                     26:
                     27: #include <sys/types.h>
                     28:
                     29: #include <signal.h>
                     30: #include <string.h>
                     31:
                     32: #include <openssl/bn.h>
                     33: #include <openssl/evp.h>
                     34: #include <openssl/ec.h>
                     35: #include <openssl/ecdh.h>
                     36:
                     37: #include "buffer.h"
                     38: #include "ssh2.h"
                     39: #include "key.h"
                     40: #include "cipher.h"
                     41: #include "kex.h"
                     42: #include "log.h"
                     43:
                     44: int
                     45: kex_ecdh_name_to_nid(const char *kexname)
                     46: {
1.2       djm        47:        if (strlen(kexname) < sizeof(KEX_ECDH_SHA2_STEM) - 1)
1.1       djm        48:                fatal("%s: kexname too short \"%s\"", __func__, kexname);
1.3     ! djm        49:        return key_curve_name_to_nid(kexname + sizeof(KEX_ECDH_SHA2_STEM) - 1);
1.2       djm        50: }
                     51:
                     52: const EVP_MD *
                     53: kex_ecdh_name_to_evpmd(const char *kexname)
                     54: {
                     55:        int nid = kex_ecdh_name_to_nid(kexname);
                     56:
1.3     ! djm        57:        if (nid == -1)
        !            58:                fatal("%s: unsupported ECDH curve \"%s\"", __func__, kexname);
1.2       djm        59:        return key_ec_nid_to_evpmd(nid);
1.1       djm        60: }
                     61:
                     62: void
                     63: kex_ecdh_hash(
                     64:     const EVP_MD *evp_md,
                     65:     const EC_GROUP *ec_group,
                     66:     char *client_version_string,
                     67:     char *server_version_string,
                     68:     char *ckexinit, int ckexinitlen,
                     69:     char *skexinit, int skexinitlen,
                     70:     u_char *serverhostkeyblob, int sbloblen,
                     71:     const EC_POINT *client_dh_pub,
                     72:     const EC_POINT *server_dh_pub,
                     73:     const BIGNUM *shared_secret,
                     74:     u_char **hash, u_int *hashlen)
                     75: {
                     76:        Buffer b;
                     77:        EVP_MD_CTX md;
                     78:        static u_char digest[EVP_MAX_MD_SIZE];
                     79:
                     80:        buffer_init(&b);
                     81:        buffer_put_cstring(&b, client_version_string);
                     82:        buffer_put_cstring(&b, server_version_string);
                     83:
                     84:        /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
                     85:        buffer_put_int(&b, ckexinitlen+1);
                     86:        buffer_put_char(&b, SSH2_MSG_KEXINIT);
                     87:        buffer_append(&b, ckexinit, ckexinitlen);
                     88:        buffer_put_int(&b, skexinitlen+1);
                     89:        buffer_put_char(&b, SSH2_MSG_KEXINIT);
                     90:        buffer_append(&b, skexinit, skexinitlen);
                     91:
                     92:        buffer_put_string(&b, serverhostkeyblob, sbloblen);
                     93:        buffer_put_ecpoint(&b, ec_group, client_dh_pub);
                     94:        buffer_put_ecpoint(&b, ec_group, server_dh_pub);
                     95:        buffer_put_bignum2(&b, shared_secret);
                     96:
                     97: #ifdef DEBUG_KEX
                     98:        buffer_dump(&b);
                     99: #endif
                    100:        EVP_DigestInit(&md, evp_md);
                    101:        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
                    102:        EVP_DigestFinal(&md, digest, NULL);
                    103:
                    104:        buffer_free(&b);
                    105:
                    106: #ifdef DEBUG_KEX
                    107:        dump_digest("hash", digest, EVP_MD_size(evp_md));
                    108: #endif
                    109:        *hash = digest;
                    110:        *hashlen = EVP_MD_size(evp_md);
                    111: }
                    112: