1 /* $OpenBSD: kexecdh.c,v 1.3 2010/09/22 05:01:29 djm Exp $ */ 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 { 47 if (strlen(kexname) < sizeof(KEX_ECDH_SHA2_STEM) - 1) 48 fatal("%s: kexname too short \"%s\"", __func__, kexname); 49 return key_curve_name_to_nid(kexname + sizeof(KEX_ECDH_SHA2_STEM) - 1); 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 57 if (nid == -1) 58 fatal("%s: unsupported ECDH curve \"%s\"", __func__, kexname); 59 return key_ec_nid_to_evpmd(nid); 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 } 112 113