crypto/openssh/ssh-ed25519.c

   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