1 /* $NetBSD: ssh-ecdsa.c,v 1.6 2015/04/03 23:58:19 christos Exp $ */ 2 /* $OpenBSD: ssh-ecdsa.c,v 1.11 2014/06/24 01:13:21 djm Exp $ */ 3 /* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * Copyright (c) 2010 Damien Miller. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: ssh-ecdsa.c,v 1.6 2015/04/03 23:58:19 christos Exp $"); 30 #include <sys/types.h> 31 32 #include <openssl/bn.h> 33 #include <openssl/ec.h> 34 #include <openssl/ecdsa.h> 35 #include <openssl/evp.h> 36 37 #include <string.h> 38 39 #include "sshbuf.h" 40 #include "ssherr.h" 41 #include "digest.h" 42 #define SSHKEY_INTERNAL 43 #include "sshkey.h" 44 45 /* ARGSUSED */ 46 int 47 ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, 48 const u_char *data, size_t datalen, u_int compat) 49 { 50 ECDSA_SIG *sig = NULL; 51 int hash_alg; 52 u_char digest[SSH_DIGEST_MAX_LENGTH]; 53 size_t len, dlen; 54 struct sshbuf *b = NULL, *bb = NULL; 55 int ret = SSH_ERR_INTERNAL_ERROR; 56 57 if (lenp != NULL) 58 *lenp = 0; 59 if (sigp != NULL) 60 *sigp = NULL; 61 62 if (key == NULL || key->ecdsa == NULL || 63 sshkey_type_plain(key->type) != KEY_ECDSA) 64 return SSH_ERR_INVALID_ARGUMENT; 65 66 if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 || 67 (dlen = ssh_digest_bytes(hash_alg)) == 0) 68 return SSH_ERR_INTERNAL_ERROR; 69 if ((ret = ssh_digest_memory(hash_alg, data, datalen, 70 digest, sizeof(digest))) != 0) 71 goto out; 72 73 if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) { 74 ret = SSH_ERR_LIBCRYPTO_ERROR; 75 goto out; 76 } 77 78 if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) { 79 ret = SSH_ERR_ALLOC_FAIL; 80 goto out; 81 } 82 if ((ret = sshbuf_put_bignum2(bb, sig->r)) != 0 || 83 (ret = sshbuf_put_bignum2(bb, sig->s)) != 0) 84 goto out; 85 if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 || 86 (ret = sshbuf_put_stringb(b, bb)) != 0) 87 goto out; 88 len = sshbuf_len(b); 89 if (sigp != NULL) { 90 if ((*sigp = malloc(len)) == NULL) { 91 ret = SSH_ERR_ALLOC_FAIL; 92 goto out; 93 } 94 memcpy(*sigp, sshbuf_ptr(b), len); 95 } 96 if (lenp != NULL) 97 *lenp = len; 98 ret = 0; 99 out: 100 explicit_bzero(digest, sizeof(digest)); 101 if (b != NULL) 102 sshbuf_free(b); 103 if (bb != NULL) 104 sshbuf_free(bb); 105 if (sig != NULL) 106 ECDSA_SIG_free(sig); 107 return ret; 108 } 109 110 /* ARGSUSED */ 111 int 112 ssh_ecdsa_verify(const struct sshkey *key, 113 const u_char *signature, size_t signaturelen, 114 const u_char *data, size_t datalen, u_int compat) 115 { 116 ECDSA_SIG *sig = NULL; 117 int hash_alg; 118 u_char digest[SSH_DIGEST_MAX_LENGTH]; 119 size_t dlen; 120 int ret = SSH_ERR_INTERNAL_ERROR; 121 struct sshbuf *b = NULL, *sigbuf = NULL; 122 char *ktype = NULL; 123 124 if (key == NULL || key->ecdsa == NULL || 125 sshkey_type_plain(key->type) != KEY_ECDSA) 126 return SSH_ERR_INVALID_ARGUMENT; 127 128 if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 || 129 (dlen = ssh_digest_bytes(hash_alg)) == 0) 130 return SSH_ERR_INTERNAL_ERROR; 131 132 /* fetch signature */ 133 if ((b = sshbuf_from(signature, signaturelen)) == NULL) 134 return SSH_ERR_ALLOC_FAIL; 135 if (sshbuf_get_cstring(b, &ktype, NULL) != 0 || 136 sshbuf_froms(b, &sigbuf) != 0) { 137 ret = SSH_ERR_INVALID_FORMAT; 138 goto out; 139 } 140 if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) { 141 ret = SSH_ERR_KEY_TYPE_MISMATCH; 142 goto out; 143 } 144 if (sshbuf_len(b) != 0) { 145 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; 146 goto out; 147 } 148 149 /* parse signature */ 150 if ((sig = ECDSA_SIG_new()) == NULL) { 151 ret = SSH_ERR_ALLOC_FAIL; 152 goto out; 153 } 154 if (sshbuf_get_bignum2(sigbuf, sig->r) != 0 || 155 sshbuf_get_bignum2(sigbuf, sig->s) != 0) { 156 ret = SSH_ERR_INVALID_FORMAT; 157 goto out; 158 } 159 if (sshbuf_len(sigbuf) != 0) { 160 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; 161 goto out; 162 } 163 if ((ret = ssh_digest_memory(hash_alg, data, datalen, 164 digest, sizeof(digest))) != 0) 165 goto out; 166 167 switch (ECDSA_do_verify(digest, dlen, sig, key->ecdsa)) { 168 case 1: 169 ret = 0; 170 break; 171 case 0: 172 ret = SSH_ERR_SIGNATURE_INVALID; 173 goto out; 174 default: 175 ret = SSH_ERR_LIBCRYPTO_ERROR; 176 goto out; 177 } 178 179 out: 180 explicit_bzero(digest, sizeof(digest)); 181 if (sigbuf != NULL) 182 sshbuf_free(sigbuf); 183 if (b != NULL) 184 sshbuf_free(b); 185 if (sig != NULL) 186 ECDSA_SIG_free(sig); 187 free(ktype); 188 return ret; 189 } 190