1 /* $OpenBSD: ssh-ed25519.c,v 1.4 2014/06/24 01:13:21 djm Exp $ */ 2 /* 3 * Copyright (c) 2013 Markus Friedl <markus@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include "includes.h" 19 20 #include <sys/types.h> 21 #include <limits.h> 22 23 #include "crypto_api.h" 24 25 #include <string.h> 26 #include <stdarg.h> 27 28 #include "xmalloc.h" 29 #include "log.h" 30 #include "buffer.h" 31 #define SSHKEY_INTERNAL 32 #include "sshkey.h" 33 #include "ssherr.h" 34 #include "ssh.h" 35 36 int 37 ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, 38 const u_char *data, size_t datalen, u_int compat) 39 { 40 u_char *sig = NULL; 41 size_t slen = 0, len; 42 unsigned long long smlen; 43 int r, ret; 44 struct sshbuf *b = NULL; 45 46 if (lenp != NULL) 47 *lenp = 0; 48 if (sigp != NULL) 49 *sigp = NULL; 50 51 if (key == NULL || 52 sshkey_type_plain(key->type) != KEY_ED25519 || 53 key->ed25519_sk == NULL || 54 datalen >= INT_MAX - crypto_sign_ed25519_BYTES) 55 return SSH_ERR_INVALID_ARGUMENT; 56 smlen = slen = datalen + crypto_sign_ed25519_BYTES; 57 if ((sig = malloc(slen)) == NULL) 58 return SSH_ERR_ALLOC_FAIL; 59 60 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen, 61 key->ed25519_sk)) != 0 || smlen <= datalen) { 62 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */ 63 goto out; 64 } 65 /* encode signature */ 66 if ((b = sshbuf_new()) == NULL) { 67 r = SSH_ERR_ALLOC_FAIL; 68 goto out; 69 } 70 if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 || 71 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0) 72 goto out; 73 len = sshbuf_len(b); 74 if (sigp != NULL) { 75 if ((*sigp = malloc(len)) == NULL) { 76 r = SSH_ERR_ALLOC_FAIL; 77 goto out; 78 } 79 memcpy(*sigp, sshbuf_ptr(b), len); 80 } 81 if (lenp != NULL) 82 *lenp = len; 83 /* success */ 84 r = 0; 85 out: 86 sshbuf_free(b); 87 if (sig != NULL) { 88 explicit_bzero(sig, slen); 89 free(sig); 90 } 91 92 return r; 93 } 94 95 int 96 ssh_ed25519_verify(const struct sshkey *key, 97 const u_char *signature, size_t signaturelen, 98 const u_char *data, size_t datalen, u_int compat) 99 { 100 struct sshbuf *b = NULL; 101 char *ktype = NULL; 102 const u_char *sigblob; 103 u_char *sm = NULL, *m = NULL; 104 size_t len; 105 unsigned long long smlen = 0, mlen = 0; 106 int r, ret; 107 108 if (key == NULL || 109 sshkey_type_plain(key->type) != KEY_ED25519 || 110 key->ed25519_pk == NULL || 111 datalen >= INT_MAX - crypto_sign_ed25519_BYTES) 112 return SSH_ERR_INVALID_ARGUMENT; 113 114 if ((b = sshbuf_from(signature, signaturelen)) == NULL) 115 return SSH_ERR_ALLOC_FAIL; 116 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 || 117 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0) 118 goto out; 119 if (strcmp("ssh-ed25519", ktype) != 0) { 120 r = SSH_ERR_KEY_TYPE_MISMATCH; 121 goto out; 122 } 123 if (sshbuf_len(b) != 0) { 124 r = SSH_ERR_UNEXPECTED_TRAILING_DATA; 125 goto out; 126 } 127 if (len > crypto_sign_ed25519_BYTES) { 128 r = SSH_ERR_INVALID_FORMAT; 129 goto out; 130 } 131 if (datalen >= SIZE_MAX - len) 132 return SSH_ERR_INVALID_ARGUMENT; 133 smlen = len + datalen; 134 mlen = smlen; 135 if ((sm = malloc(smlen)) == NULL || (m = xmalloc(mlen)) == NULL) { 136 r = SSH_ERR_ALLOC_FAIL; 137 goto out; 138 } 139 memcpy(sm, sigblob, len); 140 memcpy(sm+len, data, datalen); 141 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen, 142 key->ed25519_pk)) != 0) { 143 debug2("%s: crypto_sign_ed25519_open failed: %d", 144 __func__, ret); 145 } 146 if (ret != 0 || mlen != datalen) { 147 r = SSH_ERR_SIGNATURE_INVALID; 148 goto out; 149 } 150 /* XXX compare 'm' and 'data' ? */ 151 /* success */ 152 r = 0; 153 out: 154 if (sm != NULL) { 155 explicit_bzero(sm, smlen); 156 free(sm); 157 } 158 if (m != NULL) { 159 explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */ 160 free(m); 161 } 162 sshbuf_free(b); 163 free(ktype); 164 return r; 165 } 166 167