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 "includes.h" 28 29 #ifdef OPENSSL_HAS_ECC 30 31 #include <sys/types.h> 32 33 #include <signal.h> 34 #include <string.h> 35 36 #include <openssl/bn.h> 37 #include <openssl/evp.h> 38 #include <openssl/ec.h> 39 #include <openssl/ecdh.h> 40 41 #include "buffer.h" 42 #include "ssh2.h" 43 #include "key.h" 44 #include "cipher.h" 45 #include "kex.h" 46 #include "log.h" 47 48 int 49 kex_ecdh_name_to_nid(const char *kexname) 50 { 51 if (strlen(kexname) < sizeof(KEX_ECDH_SHA2_STEM) - 1) 52 fatal("%s: kexname too short \"%s\"", __func__, kexname); 53 return key_curve_name_to_nid(kexname + sizeof(KEX_ECDH_SHA2_STEM) - 1); 54 } 55 56 const EVP_MD * 57 kex_ecdh_name_to_evpmd(const char *kexname) 58 { 59 int nid = kex_ecdh_name_to_nid(kexname); 60 61 if (nid == -1) 62 fatal("%s: unsupported ECDH curve \"%s\"", __func__, kexname); 63 return key_ec_nid_to_evpmd(nid); 64 } 65 66 void 67 kex_ecdh_hash( 68 const EVP_MD *evp_md, 69 const EC_GROUP *ec_group, 70 char *client_version_string, 71 char *server_version_string, 72 char *ckexinit, int ckexinitlen, 73 char *skexinit, int skexinitlen, 74 u_char *serverhostkeyblob, int sbloblen, 75 const EC_POINT *client_dh_pub, 76 const EC_POINT *server_dh_pub, 77 const BIGNUM *shared_secret, 78 u_char **hash, u_int *hashlen) 79 { 80 Buffer b; 81 EVP_MD_CTX md; 82 static u_char digest[EVP_MAX_MD_SIZE]; 83 84 buffer_init(&b); 85 buffer_put_cstring(&b, client_version_string); 86 buffer_put_cstring(&b, server_version_string); 87 88 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ 89 buffer_put_int(&b, ckexinitlen+1); 90 buffer_put_char(&b, SSH2_MSG_KEXINIT); 91 buffer_append(&b, ckexinit, ckexinitlen); 92 buffer_put_int(&b, skexinitlen+1); 93 buffer_put_char(&b, SSH2_MSG_KEXINIT); 94 buffer_append(&b, skexinit, skexinitlen); 95 96 buffer_put_string(&b, serverhostkeyblob, sbloblen); 97 buffer_put_ecpoint(&b, ec_group, client_dh_pub); 98 buffer_put_ecpoint(&b, ec_group, server_dh_pub); 99 buffer_put_bignum2(&b, shared_secret); 100 101 #ifdef DEBUG_KEX 102 buffer_dump(&b); 103 #endif 104 EVP_DigestInit(&md, evp_md); 105 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); 106 EVP_DigestFinal(&md, digest, NULL); 107 108 buffer_free(&b); 109 110 #ifdef DEBUG_KEX 111 dump_digest("hash", digest, EVP_MD_size(evp_md)); 112 #endif 113 *hash = digest; 114 *hashlen = EVP_MD_size(evp_md); 115 } 116 117 #endif /* OPENSSL_HAS_ECC */ 118