1 /* $OpenBSD: kexecdh.c,v 1.6 2015/01/19 20:16:15 markus 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 "ssh2.h" 38 #include "sshkey.h" 39 #include "cipher.h" 40 #include "kex.h" 41 #include "sshbuf.h" 42 #include "digest.h" 43 #include "ssherr.h" 44 45 int 46 kex_ecdh_hash( 47 int hash_alg, 48 const EC_GROUP *ec_group, 49 const char *client_version_string, 50 const char *server_version_string, 51 const u_char *ckexinit, size_t ckexinitlen, 52 const u_char *skexinit, size_t skexinitlen, 53 const u_char *serverhostkeyblob, size_t sbloblen, 54 const EC_POINT *client_dh_pub, 55 const EC_POINT *server_dh_pub, 56 const BIGNUM *shared_secret, 57 u_char *hash, size_t *hashlen) 58 { 59 struct sshbuf *b; 60 int r; 61 62 if (*hashlen < ssh_digest_bytes(hash_alg)) 63 return SSH_ERR_INVALID_ARGUMENT; 64 if ((b = sshbuf_new()) == NULL) 65 return SSH_ERR_ALLOC_FAIL; 66 if ((r = sshbuf_put_cstring(b, client_version_string)) != 0 || 67 (r = sshbuf_put_cstring(b, server_version_string)) != 0 || 68 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ 69 (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 || 70 (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || 71 (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 || 72 (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 || 73 (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || 74 (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 || 75 (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 || 76 (r = sshbuf_put_ec(b, client_dh_pub, ec_group)) != 0 || 77 (r = sshbuf_put_ec(b, server_dh_pub, ec_group)) != 0 || 78 (r = sshbuf_put_bignum2(b, shared_secret)) != 0) { 79 sshbuf_free(b); 80 return r; 81 } 82 #ifdef DEBUG_KEX 83 sshbuf_dump(b, stderr); 84 #endif 85 if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) { 86 sshbuf_free(b); 87 return SSH_ERR_LIBCRYPTO_ERROR; 88 } 89 sshbuf_free(b); 90 *hashlen = ssh_digest_bytes(hash_alg); 91 #ifdef DEBUG_KEX 92 dump_digest("hash", hash, *hashlen); 93 #endif 94 return 0; 95 } 96