crypto/openssh/ssh-ed25519.c

   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
  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 "log.h"
  29 #include "sshbuf.h"
  30 #define SSHKEY_INTERNAL
  31 #include "sshkey.h"
  32 #include "ssherr.h"
  33 #include "ssh.h"
  34
  35 int
  36 ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
  37     const u_char *data, size_t datalen, u_int compat)
  38 {
  39         u_char *sig = NULL;
  40         size_t slen = 0, len;
  41         unsigned long long smlen;
  42         int r, ret;
  43         struct sshbuf *b = NULL;
  44
  45         if (lenp != NULL)
  46                 *lenp = 0;
  47         if (sigp != NULL)
  48                 *sigp = NULL;
  49
  50         if (key == NULL ||
  51             sshkey_type_plain(key->type) != KEY_ED25519 ||
  52             key->ed25519_sk == NULL ||
  53             datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
  54                 return SSH_ERR_INVALID_ARGUMENT;
  55         smlen = slen = datalen + crypto_sign_ed25519_BYTES;
  56         if ((sig = malloc(slen)) == NULL)
  57                 return SSH_ERR_ALLOC_FAIL;
  58
  59         if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
  60             key->ed25519_sk)) != 0 || smlen <= datalen) {
  61                 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
  62                 goto out;
  63         }
  64         /* encode signature */
  65         if ((b = sshbuf_new()) == NULL) {
  66                 r = SSH_ERR_ALLOC_FAIL;
  67                 goto out;
  68         }
  69         if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 ||
  70             (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
  71                 goto out;
  72         len = sshbuf_len(b);
  73         if (sigp != NULL) {
  74                 if ((*sigp = malloc(len)) == NULL) {
  75                         r = SSH_ERR_ALLOC_FAIL;
  76                         goto out;
  77                 }
  78                 memcpy(*sigp, sshbuf_ptr(b), len);
  79         }
  80         if (lenp != NULL)
  81                 *lenp = len;
  82         /* success */
  83         r = 0;
  84  out:
  85         sshbuf_free(b);
  86         if (sig != NULL)
  87                 freezero(sig, slen);
  88
  89         return r;
  90 }
  91
  92 int
  93 ssh_ed25519_verify(const struct sshkey *key,
  94     const u_char *signature, size_t signaturelen,
  95     const u_char *data, size_t datalen, u_int compat)
  96 {
  97         struct sshbuf *b = NULL;
  98         char *ktype = NULL;
  99         const u_char *sigblob;
 100         u_char *sm = NULL, *m = NULL;
 101         size_t len;
 102         unsigned long long smlen = 0, mlen = 0;
 103         int r, ret;
 104
 105         if (key == NULL ||
 106             sshkey_type_plain(key->type) != KEY_ED25519 ||
 107             key->ed25519_pk == NULL ||
 108             datalen >= INT_MAX - crypto_sign_ed25519_BYTES ||
 109             signature == NULL || signaturelen == 0)
 110                 return SSH_ERR_INVALID_ARGUMENT;
 111
 112         if ((b = sshbuf_from(signature, signaturelen)) == NULL)
 113                 return SSH_ERR_ALLOC_FAIL;
 114         if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
 115             (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
 116                 goto out;
 117         if (strcmp("ssh-ed25519", ktype) != 0) {
 118                 r = SSH_ERR_KEY_TYPE_MISMATCH;
 119                 goto out;
 120         }
 121         if (sshbuf_len(b) != 0) {
 122                 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
 123                 goto out;
 124         }
 125         if (len > crypto_sign_ed25519_BYTES) {
 126                 r = SSH_ERR_INVALID_FORMAT;
 127                 goto out;
 128         }
 129         if (datalen >= SIZE_MAX - len) {
 130                 r = SSH_ERR_INVALID_ARGUMENT;
 131                 goto out;
 132         }
 133         smlen = len + datalen;
 134         mlen = smlen;
 135         if ((sm = malloc(smlen)) == NULL || (m = malloc(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_f("crypto_sign_ed25519_open failed: %d", ret);
 144         }
 145         if (ret != 0 || mlen != datalen) {
 146                 r = SSH_ERR_SIGNATURE_INVALID;
 147                 goto out;
 148         }
 149         /* XXX compare 'm' and 'data' ? */
 150         /* success */
 151         r = 0;
 152  out:
 153         if (sm != NULL)
 154                 freezero(sm, smlen);
 155         if (m != NULL)
 156                 freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
 157         sshbuf_free(b);
 158         free(ktype);
 159         return r;
 160 }