1 /* $OpenBSD: ssh-ed25519.c,v 1.9 2020/10/18 11:32:02 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 #define SSHKEY_INTERNAL 18 #include <sys/types.h> 19 #include <limits.h> 20 21 #include "crypto_api.h" 22 23 #include <string.h> 24 #include <stdarg.h> 25 26 #include "log.h" 27 #include "sshbuf.h" 28 #include "sshkey.h" 29 #include "ssherr.h" 30 #include "ssh.h" 31 32 int 33 ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp, 34 const u_char *data, size_t datalen, u_int compat) 35 { 36 u_char *sig = NULL; 37 size_t slen = 0, len; 38 unsigned long long smlen; 39 int r, ret; 40 struct sshbuf *b = NULL; 41 42 if (lenp != NULL) 43 *lenp = 0; 44 if (sigp != NULL) 45 *sigp = NULL; 46 47 if (key == NULL || 48 sshkey_type_plain(key->type) != KEY_ED25519 || 49 key->ed25519_sk == NULL || 50 datalen >= INT_MAX - crypto_sign_ed25519_BYTES) 51 return SSH_ERR_INVALID_ARGUMENT; 52 smlen = slen = datalen + crypto_sign_ed25519_BYTES; 53 if ((sig = malloc(slen)) == NULL) 54 return SSH_ERR_ALLOC_FAIL; 55 56 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen, 57 key->ed25519_sk)) != 0 || smlen <= datalen) { 58 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */ 59 goto out; 60 } 61 /* encode signature */ 62 if ((b = sshbuf_new()) == NULL) { 63 r = SSH_ERR_ALLOC_FAIL; 64 goto out; 65 } 66 if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 || 67 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0) 68 goto out; 69 len = sshbuf_len(b); 70 if (sigp != NULL) { 71 if ((*sigp = malloc(len)) == NULL) { 72 r = SSH_ERR_ALLOC_FAIL; 73 goto out; 74 } 75 memcpy(*sigp, sshbuf_ptr(b), len); 76 } 77 if (lenp != NULL) 78 *lenp = len; 79 /* success */ 80 r = 0; 81 out: 82 sshbuf_free(b); 83 if (sig != NULL) 84 freezero(sig, slen); 85 86 return r; 87 } 88 89 int 90 ssh_ed25519_verify(const struct sshkey *key, 91 const u_char *signature, size_t signaturelen, 92 const u_char *data, size_t datalen, u_int compat) 93 { 94 struct sshbuf *b = NULL; 95 char *ktype = NULL; 96 const u_char *sigblob; 97 u_char *sm = NULL, *m = NULL; 98 size_t len; 99 unsigned long long smlen = 0, mlen = 0; 100 int r, ret; 101 102 if (key == NULL || 103 sshkey_type_plain(key->type) != KEY_ED25519 || 104 key->ed25519_pk == NULL || 105 datalen >= INT_MAX - crypto_sign_ed25519_BYTES || 106 signature == NULL || signaturelen == 0) 107 return SSH_ERR_INVALID_ARGUMENT; 108 109 if ((b = sshbuf_from(signature, signaturelen)) == NULL) 110 return SSH_ERR_ALLOC_FAIL; 111 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 || 112 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0) 113 goto out; 114 if (strcmp("ssh-ed25519", ktype) != 0) { 115 r = SSH_ERR_KEY_TYPE_MISMATCH; 116 goto out; 117 } 118 if (sshbuf_len(b) != 0) { 119 r = SSH_ERR_UNEXPECTED_TRAILING_DATA; 120 goto out; 121 } 122 if (len > crypto_sign_ed25519_BYTES) { 123 r = SSH_ERR_INVALID_FORMAT; 124 goto out; 125 } 126 if (datalen >= SIZE_MAX - len) { 127 r = SSH_ERR_INVALID_ARGUMENT; 128 goto out; 129 } 130 smlen = len + datalen; 131 mlen = smlen; 132 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) { 133 r = SSH_ERR_ALLOC_FAIL; 134 goto out; 135 } 136 memcpy(sm, sigblob, len); 137 memcpy(sm+len, data, datalen); 138 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen, 139 key->ed25519_pk)) != 0) { 140 debug2_f("crypto_sign_ed25519_open failed: %d", ret); 141 } 142 if (ret != 0 || mlen != datalen) { 143 r = SSH_ERR_SIGNATURE_INVALID; 144 goto out; 145 } 146 /* XXX compare 'm' and 'data' ? */ 147 /* success */ 148 r = 0; 149 out: 150 if (sm != NULL) 151 freezero(sm, smlen); 152 if (m != NULL) 153 freezero(m, smlen); /* NB mlen may be invalid if r != 0 */ 154 sshbuf_free(b); 155 free(ktype); 156 return r; 157 } 158