1 /* $OpenBSD: ssh-ecdsa.c,v 1.13 2016/04/21 06:08:02 djm Exp $ */ 2 /* 3 * Copyright (c) 2000 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 #if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) 30 31 #include <sys/types.h> 32 33 #include <openssl/bn.h> 34 #include <openssl/ec.h> 35 #include <openssl/ecdsa.h> 36 #include <openssl/evp.h> 37 38 #include <string.h> 39 40 #include "sshbuf.h" 41 #include "ssherr.h" 42 #include "digest.h" 43 #define SSHKEY_INTERNAL 44 #include "sshkey.h" 45 46 /* ARGSUSED */ 47 int 48 ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, 49 const u_char *data, size_t datalen, u_int compat) 50 { 51 ECDSA_SIG *sig = NULL; 52 int hash_alg; 53 u_char digest[SSH_DIGEST_MAX_LENGTH]; 54 size_t len, dlen; 55 struct sshbuf *b = NULL, *bb = NULL; 56 int ret = SSH_ERR_INTERNAL_ERROR; 57 58 if (lenp != NULL) 59 *lenp = 0; 60 if (sigp != NULL) 61 *sigp = NULL; 62 63 if (key == NULL || key->ecdsa == NULL || 64 sshkey_type_plain(key->type) != KEY_ECDSA) 65 return SSH_ERR_INVALID_ARGUMENT; 66 67 if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 || 68 (dlen = ssh_digest_bytes(hash_alg)) == 0) 69 return SSH_ERR_INTERNAL_ERROR; 70 if ((ret = ssh_digest_memory(hash_alg, data, datalen, 71 digest, sizeof(digest))) != 0) 72 goto out; 73 74 if ((sig = ECDSA_do_sign(digest, dlen, key->ecdsa)) == NULL) { 75 ret = SSH_ERR_LIBCRYPTO_ERROR; 76 goto out; 77 } 78 79 if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) { 80 ret = SSH_ERR_ALLOC_FAIL; 81 goto out; 82 } 83 if ((ret = sshbuf_put_bignum2(bb, sig->r)) != 0 || 84 (ret = sshbuf_put_bignum2(bb, sig->s)) != 0) 85 goto out; 86 if ((ret = sshbuf_put_cstring(b, sshkey_ssh_name_plain(key))) != 0 || 87 (ret = sshbuf_put_stringb(b, bb)) != 0) 88 goto out; 89 len = sshbuf_len(b); 90 if (sigp != NULL) { 91 if ((*sigp = malloc(len)) == NULL) { 92 ret = SSH_ERR_ALLOC_FAIL; 93 goto out; 94 } 95 memcpy(*sigp, sshbuf_ptr(b), len); 96 } 97 if (lenp != NULL) 98 *lenp = len; 99 ret = 0; 100 out: 101 explicit_bzero(digest, sizeof(digest)); 102 sshbuf_free(b); 103 sshbuf_free(bb); 104 if (sig != NULL) 105 ECDSA_SIG_free(sig); 106 return ret; 107 } 108 109 /* ARGSUSED */ 110 int 111 ssh_ecdsa_verify(const struct sshkey *key, 112 const u_char *signature, size_t signaturelen, 113 const u_char *data, size_t datalen, u_int compat) 114 { 115 ECDSA_SIG *sig = NULL; 116 int hash_alg; 117 u_char digest[SSH_DIGEST_MAX_LENGTH]; 118 size_t dlen; 119 int ret = SSH_ERR_INTERNAL_ERROR; 120 struct sshbuf *b = NULL, *sigbuf = NULL; 121 char *ktype = NULL; 122 123 if (key == NULL || key->ecdsa == NULL || 124 sshkey_type_plain(key->type) != KEY_ECDSA || 125 signature == NULL || signaturelen == 0) 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 sshbuf_free(sigbuf); 182 sshbuf_free(b); 183 if (sig != NULL) 184 ECDSA_SIG_free(sig); 185 free(ktype); 186 return ret; 187 } 188 189 #endif /* WITH_OPENSSL && OPENSSL_HAS_ECC */ 190