Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 1 | /* $OpenBSD: ssh-ecdsa.c,v 1.6 2013/05/17 00:13:14 djm Exp $ */ |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 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 | |
Damien Miller | c79ff07 | 2010-08-31 22:50:48 +1000 | [diff] [blame] | 27 | #include "includes.h" |
| 28 | |
Damien Miller | 6af914a | 2010-09-10 11:39:26 +1000 | [diff] [blame] | 29 | #ifdef OPENSSL_HAS_ECC |
| 30 | |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 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 "xmalloc.h" |
| 41 | #include "buffer.h" |
| 42 | #include "compat.h" |
| 43 | #include "log.h" |
| 44 | #include "key.h" |
| 45 | |
| 46 | int |
| 47 | ssh_ecdsa_sign(const Key *key, u_char **sigp, u_int *lenp, |
| 48 | const u_char *data, u_int datalen) |
| 49 | { |
| 50 | ECDSA_SIG *sig; |
Damien Miller | 041ab7c | 2010-09-10 11:23:34 +1000 | [diff] [blame] | 51 | const EVP_MD *evp_md; |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 52 | EVP_MD_CTX md; |
| 53 | u_char digest[EVP_MAX_MD_SIZE]; |
| 54 | u_int len, dlen; |
| 55 | Buffer b, bb; |
| 56 | |
| 57 | if (key == NULL || key->ecdsa == NULL || |
| 58 | (key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) { |
| 59 | error("%s: no ECDSA key", __func__); |
| 60 | return -1; |
| 61 | } |
Damien Miller | 041ab7c | 2010-09-10 11:23:34 +1000 | [diff] [blame] | 62 | evp_md = key_ec_nid_to_evpmd(key->ecdsa_nid); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 63 | EVP_DigestInit(&md, evp_md); |
| 64 | EVP_DigestUpdate(&md, data, datalen); |
| 65 | EVP_DigestFinal(&md, digest, &dlen); |
| 66 | |
| 67 | sig = ECDSA_do_sign(digest, dlen, key->ecdsa); |
| 68 | memset(digest, 'd', sizeof(digest)); |
| 69 | |
| 70 | if (sig == NULL) { |
| 71 | error("%s: sign failed", __func__); |
| 72 | return -1; |
| 73 | } |
| 74 | |
| 75 | buffer_init(&bb); |
| 76 | buffer_put_bignum2(&bb, sig->r); |
| 77 | buffer_put_bignum2(&bb, sig->s); |
| 78 | ECDSA_SIG_free(sig); |
| 79 | |
| 80 | buffer_init(&b); |
| 81 | buffer_put_cstring(&b, key_ssh_name_plain(key)); |
| 82 | buffer_put_string(&b, buffer_ptr(&bb), buffer_len(&bb)); |
| 83 | buffer_free(&bb); |
| 84 | len = buffer_len(&b); |
| 85 | if (lenp != NULL) |
| 86 | *lenp = len; |
| 87 | if (sigp != NULL) { |
| 88 | *sigp = xmalloc(len); |
| 89 | memcpy(*sigp, buffer_ptr(&b), len); |
| 90 | } |
| 91 | buffer_free(&b); |
| 92 | |
| 93 | return 0; |
| 94 | } |
| 95 | int |
| 96 | ssh_ecdsa_verify(const Key *key, const u_char *signature, u_int signaturelen, |
| 97 | const u_char *data, u_int datalen) |
| 98 | { |
| 99 | ECDSA_SIG *sig; |
Damien Miller | 041ab7c | 2010-09-10 11:23:34 +1000 | [diff] [blame] | 100 | const EVP_MD *evp_md; |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 101 | EVP_MD_CTX md; |
| 102 | u_char digest[EVP_MAX_MD_SIZE], *sigblob; |
| 103 | u_int len, dlen; |
| 104 | int rlen, ret; |
| 105 | Buffer b, bb; |
Damien Miller | 041ab7c | 2010-09-10 11:23:34 +1000 | [diff] [blame] | 106 | char *ktype; |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 107 | |
| 108 | if (key == NULL || key->ecdsa == NULL || |
| 109 | (key->type != KEY_ECDSA && key->type != KEY_ECDSA_CERT)) { |
| 110 | error("%s: no ECDSA key", __func__); |
| 111 | return -1; |
| 112 | } |
Damien Miller | 041ab7c | 2010-09-10 11:23:34 +1000 | [diff] [blame] | 113 | evp_md = key_ec_nid_to_evpmd(key->ecdsa_nid); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 114 | |
| 115 | /* fetch signature */ |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 116 | buffer_init(&b); |
| 117 | buffer_append(&b, signature, signaturelen); |
| 118 | ktype = buffer_get_string(&b, NULL); |
| 119 | if (strcmp(key_ssh_name_plain(key), ktype) != 0) { |
| 120 | error("%s: cannot handle type %s", __func__, ktype); |
| 121 | buffer_free(&b); |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 122 | free(ktype); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 123 | return -1; |
| 124 | } |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 125 | free(ktype); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 126 | sigblob = buffer_get_string(&b, &len); |
| 127 | rlen = buffer_len(&b); |
| 128 | buffer_free(&b); |
| 129 | if (rlen != 0) { |
| 130 | error("%s: remaining bytes in signature %d", __func__, rlen); |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 131 | free(sigblob); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 132 | return -1; |
| 133 | } |
| 134 | |
| 135 | /* parse signature */ |
| 136 | if ((sig = ECDSA_SIG_new()) == NULL) |
| 137 | fatal("%s: ECDSA_SIG_new failed", __func__); |
| 138 | if ((sig->r = BN_new()) == NULL || |
| 139 | (sig->s = BN_new()) == NULL) |
| 140 | fatal("%s: BN_new failed", __func__); |
| 141 | |
| 142 | buffer_init(&bb); |
| 143 | buffer_append(&bb, sigblob, len); |
| 144 | buffer_get_bignum2(&bb, sig->r); |
| 145 | buffer_get_bignum2(&bb, sig->s); |
| 146 | if (buffer_len(&bb) != 0) |
| 147 | fatal("%s: remaining bytes in inner sigblob", __func__); |
Damien Miller | 83ba8e6 | 2012-02-11 08:17:27 +1100 | [diff] [blame] | 148 | buffer_free(&bb); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 149 | |
| 150 | /* clean up */ |
| 151 | memset(sigblob, 0, len); |
Darren Tucker | a627d42 | 2013-06-02 07:31:17 +1000 | [diff] [blame] | 152 | free(sigblob); |
Damien Miller | eb8b60e | 2010-08-31 22:41:14 +1000 | [diff] [blame] | 153 | |
| 154 | /* hash the data */ |
| 155 | EVP_DigestInit(&md, evp_md); |
| 156 | EVP_DigestUpdate(&md, data, datalen); |
| 157 | EVP_DigestFinal(&md, digest, &dlen); |
| 158 | |
| 159 | ret = ECDSA_do_verify(digest, dlen, sig, key->ecdsa); |
| 160 | memset(digest, 'd', sizeof(digest)); |
| 161 | |
| 162 | ECDSA_SIG_free(sig); |
| 163 | |
| 164 | debug("%s: signature %s", __func__, |
| 165 | ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error"); |
| 166 | return ret; |
| 167 | } |
Damien Miller | 6af914a | 2010-09-10 11:39:26 +1000 | [diff] [blame] | 168 | |
| 169 | #endif /* OPENSSL_HAS_ECC */ |