1 /* $OpenBSD: ssh-xmss.c,v 1.4 2020/10/19 22:49:23 dtucker Exp $*/ 2 /* 3 * Copyright (c) 2017 Stefan-Lukas Gazdag. 4 * Copyright (c) 2017 Markus Friedl. 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 #include "includes.h" 19 #ifdef WITH_XMSS 20 21 #define SSHKEY_INTERNAL 22 #include <sys/types.h> 23 #include <limits.h> 24 25 #include <string.h> 26 #include <stdarg.h> 27 #include <unistd.h> 28 29 #include "log.h" 30 #include "sshbuf.h" 31 #include "sshkey.h" 32 #include "sshkey-xmss.h" 33 #include "ssherr.h" 34 #include "ssh.h" 35 36 #include "xmss_fast.h" 37 38 int 39 ssh_xmss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, 40 const u_char *data, size_t datalen, u_int compat) 41 { 42 u_char *sig = NULL; 43 size_t slen = 0, len = 0, required_siglen; 44 unsigned long long smlen; 45 int r, ret; 46 struct sshbuf *b = NULL; 47 48 if (lenp != NULL) 49 *lenp = 0; 50 if (sigp != NULL) 51 *sigp = NULL; 52 53 if (key == NULL || 54 sshkey_type_plain(key->type) != KEY_XMSS || 55 key->xmss_sk == NULL || 56 sshkey_xmss_params(key) == NULL) 57 return SSH_ERR_INVALID_ARGUMENT; 58 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0) 59 return r; 60 if (datalen >= INT_MAX - required_siglen) 61 return SSH_ERR_INVALID_ARGUMENT; 62 smlen = slen = datalen + required_siglen; 63 if ((sig = malloc(slen)) == NULL) 64 return SSH_ERR_ALLOC_FAIL; 65 if ((r = sshkey_xmss_get_state(key, 1)) != 0) 66 goto out; 67 if ((ret = xmss_sign(key->xmss_sk, sshkey_xmss_bds_state(key), sig, &smlen, 68 data, datalen, sshkey_xmss_params(key))) != 0 || smlen <= datalen) { 69 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */ 70 goto out; 71 } 72 /* encode signature */ 73 if ((b = sshbuf_new()) == NULL) { 74 r = SSH_ERR_ALLOC_FAIL; 75 goto out; 76 } 77 if ((r = sshbuf_put_cstring(b, "ssh-xmss@openssh.com")) != 0 || 78 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0) 79 goto out; 80 len = sshbuf_len(b); 81 if (sigp != NULL) { 82 if ((*sigp = malloc(len)) == NULL) { 83 r = SSH_ERR_ALLOC_FAIL; 84 goto out; 85 } 86 memcpy(*sigp, sshbuf_ptr(b), len); 87 } 88 if (lenp != NULL) 89 *lenp = len; 90 /* success */ 91 r = 0; 92 out: 93 if ((ret = sshkey_xmss_update_state(key, 1)) != 0) { 94 /* discard signature since we cannot update the state */ 95 if (r == 0 && sigp != NULL && *sigp != NULL) { 96 explicit_bzero(*sigp, len); 97 free(*sigp); 98 } 99 if (sigp != NULL) 100 *sigp = NULL; 101 if (lenp != NULL) 102 *lenp = 0; 103 r = ret; 104 } 105 sshbuf_free(b); 106 if (sig != NULL) 107 freezero(sig, slen); 108 109 return r; 110 } 111 112 int 113 ssh_xmss_verify(const struct sshkey *key, 114 const u_char *signature, size_t signaturelen, 115 const u_char *data, size_t datalen, u_int compat) 116 { 117 struct sshbuf *b = NULL; 118 char *ktype = NULL; 119 const u_char *sigblob; 120 u_char *sm = NULL, *m = NULL; 121 size_t len, required_siglen; 122 unsigned long long smlen = 0, mlen = 0; 123 int r, ret; 124 125 if (key == NULL || 126 sshkey_type_plain(key->type) != KEY_XMSS || 127 key->xmss_pk == NULL || 128 sshkey_xmss_params(key) == NULL || 129 signature == NULL || signaturelen == 0) 130 return SSH_ERR_INVALID_ARGUMENT; 131 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0) 132 return r; 133 if (datalen >= INT_MAX - required_siglen) 134 return SSH_ERR_INVALID_ARGUMENT; 135 136 if ((b = sshbuf_from(signature, signaturelen)) == NULL) 137 return SSH_ERR_ALLOC_FAIL; 138 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 || 139 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0) 140 goto out; 141 if (strcmp("ssh-xmss@openssh.com", ktype) != 0) { 142 r = SSH_ERR_KEY_TYPE_MISMATCH; 143 goto out; 144 } 145 if (sshbuf_len(b) != 0) { 146 r = SSH_ERR_UNEXPECTED_TRAILING_DATA; 147 goto out; 148 } 149 if (len != required_siglen) { 150 r = SSH_ERR_INVALID_FORMAT; 151 goto out; 152 } 153 if (datalen >= SIZE_MAX - len) { 154 r = SSH_ERR_INVALID_ARGUMENT; 155 goto out; 156 } 157 smlen = len + datalen; 158 mlen = smlen; 159 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) { 160 r = SSH_ERR_ALLOC_FAIL; 161 goto out; 162 } 163 memcpy(sm, sigblob, len); 164 memcpy(sm+len, data, datalen); 165 if ((ret = xmss_sign_open(m, &mlen, sm, smlen, 166 key->xmss_pk, sshkey_xmss_params(key))) != 0) { 167 debug2_f("xmss_sign_open failed: %d", ret); 168 } 169 if (ret != 0 || mlen != datalen) { 170 r = SSH_ERR_SIGNATURE_INVALID; 171 goto out; 172 } 173 /* XXX compare 'm' and 'data' ? */ 174 /* success */ 175 r = 0; 176 out: 177 if (sm != NULL) 178 freezero(sm, smlen); 179 if (m != NULL) 180 freezero(m, smlen); 181 sshbuf_free(b); 182 free(ktype); 183 return r; 184 } 185 #endif /* WITH_XMSS */ 186