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/* $OpenBSD: ssh-ed25519.c,v 1.13 2022/10/28 00:37:24 djm Exp $ */
/*
* Copyright (c) 2013 Markus Friedl <markus@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <limits.h>
#include "crypto_api.h"
#include <string.h>
#include <stdarg.h>
#include "log.h"
#include "sshbuf.h"
#define SSHKEY_INTERNAL
#include "sshkey.h"
#include "ssherr.h"
#include "ssh.h"
static void
ssh_ed25519_cleanup(struct sshkey *k)
{
freezero(k->ed25519_pk, ED25519_PK_SZ);
freezero(k->ed25519_sk, ED25519_SK_SZ);
k->ed25519_pk = NULL;
k->ed25519_sk = NULL;
}
static int
ssh_ed25519_equal(const struct sshkey *a, const struct sshkey *b)
{
if (a->ed25519_pk == NULL || b->ed25519_pk == NULL)
return 0;
if (memcmp(a->ed25519_pk, b->ed25519_pk, ED25519_PK_SZ) != 0)
return 0;
return 1;
}
static int
ssh_ed25519_serialize_public(const struct sshkey *key, struct sshbuf *b,
const char *typename, enum sshkey_serialize_rep opts)
{
int r;
if (key->ed25519_pk == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_put_cstring(b, typename)) != 0 ||
(r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0)
return r;
return 0;
}
int
ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
const u_char *data, size_t datalen, u_int compat)
{
u_char *sig = NULL;
size_t slen = 0, len;
unsigned long long smlen;
int r, ret;
struct sshbuf *b = NULL;
if (lenp != NULL)
*lenp = 0;
if (sigp != NULL)
*sigp = NULL;
if (key == NULL ||
sshkey_type_plain(key->type) != KEY_ED25519 ||
key->ed25519_sk == NULL ||
datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
return SSH_ERR_INVALID_ARGUMENT;
smlen = slen = datalen + crypto_sign_ed25519_BYTES;
if ((sig = malloc(slen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
key->ed25519_sk)) != 0 || smlen <= datalen) {
r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
goto out;
}
/* encode signature */
if ((b = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 ||
(r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
goto out;
len = sshbuf_len(b);
if (sigp != NULL) {
if ((*sigp = malloc(len)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(*sigp, sshbuf_ptr(b), len);
}
if (lenp != NULL)
*lenp = len;
/* success */
r = 0;
out:
sshbuf_free(b);
if (sig != NULL)
freezero(sig, slen);
return r;
}
int
ssh_ed25519_verify(const struct sshkey *key,
const u_char *signature, size_t signaturelen,
const u_char *data, size_t datalen, u_int compat)
{
struct sshbuf *b = NULL;
char *ktype = NULL;
const u_char *sigblob;
u_char *sm = NULL, *m = NULL;
size_t len;
unsigned long long smlen = 0, mlen = 0;
int r, ret;
if (key == NULL ||
sshkey_type_plain(key->type) != KEY_ED25519 ||
key->ed25519_pk == NULL ||
datalen >= INT_MAX - crypto_sign_ed25519_BYTES ||
signature == NULL || signaturelen == 0)
return SSH_ERR_INVALID_ARGUMENT;
if ((b = sshbuf_from(signature, signaturelen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
(r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
goto out;
if (strcmp("ssh-ed25519", ktype) != 0) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (sshbuf_len(b) != 0) {
r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
goto out;
}
if (len > crypto_sign_ed25519_BYTES) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if (datalen >= SIZE_MAX - len) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
smlen = len + datalen;
mlen = smlen;
if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
memcpy(sm, sigblob, len);
memcpy(sm+len, data, datalen);
if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
key->ed25519_pk)) != 0) {
debug2_f("crypto_sign_ed25519_open failed: %d", ret);
}
if (ret != 0 || mlen != datalen) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* XXX compare 'm' and 'data' ? */
/* success */
r = 0;
out:
if (sm != NULL)
freezero(sm, smlen);
if (m != NULL)
freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
sshbuf_free(b);
free(ktype);
return r;
}
/* NB. not static; used by ED25519-SK */
const struct sshkey_impl_funcs sshkey_ed25519_funcs = {
/* .size = */ NULL,
/* .alloc = */ NULL,
/* .cleanup = */ ssh_ed25519_cleanup,
/* .equal = */ ssh_ed25519_equal,
/* .ssh_serialize_public = */ ssh_ed25519_serialize_public,
};
const struct sshkey_impl sshkey_ed25519_impl = {
/* .name = */ "ssh-ed25519",
/* .shortname = */ "ED25519",
/* .sigalg = */ NULL,
/* .type = */ KEY_ED25519,
/* .nid = */ 0,
/* .cert = */ 0,
/* .sigonly = */ 0,
/* .keybits = */ 256,
/* .funcs = */ &sshkey_ed25519_funcs,
};
const struct sshkey_impl sshkey_ed25519_cert_impl = {
/* .name = */ "ssh-ed25519-cert-v01@openssh.com",
/* .shortname = */ "ED25519-CERT",
/* .sigalg = */ NULL,
/* .type = */ KEY_ED25519_CERT,
/* .nid = */ 0,
/* .cert = */ 1,
/* .sigonly = */ 0,
/* .keybits = */ 256,
/* .funcs = */ &sshkey_ed25519_funcs,
};
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