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/* $OpenBSD: ssh-xmss.c,v 1.1 2018/02/23 15:58:38 markus Exp $*/
/*
* Copyright (c) 2017 Stefan-Lukas Gazdag.
* Copyright (c) 2017 Markus Friedl.
*
* 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"
#define SSHKEY_INTERNAL
#include <sys/types.h>
#include <limits.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include "log.h"
#include "sshbuf.h"
#include "sshkey.h"
#include "sshkey-xmss.h"
#include "ssherr.h"
#include "ssh.h"
#include "xmss_fast.h"
int
ssh_xmss_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 = 0, required_siglen;
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_XMSS ||
key->xmss_sk == NULL ||
sshkey_xmss_params(key) == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
return r;
if (datalen >= INT_MAX - required_siglen)
return SSH_ERR_INVALID_ARGUMENT;
smlen = slen = datalen + required_siglen;
if ((sig = malloc(slen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshkey_xmss_get_state(key, error)) != 0)
goto out;
if ((ret = xmss_sign(key->xmss_sk, sshkey_xmss_bds_state(key), sig, &smlen,
data, datalen, sshkey_xmss_params(key))) != 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-xmss@openssh.com")) != 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:
if ((ret = sshkey_xmss_update_state(key, error)) != 0) {
/* discard signature since we cannot update the state */
if (r == 0 && sigp != NULL && *sigp != NULL) {
explicit_bzero(*sigp, len);
free(*sigp);
}
if (sigp != NULL)
*sigp = NULL;
if (lenp != NULL)
*lenp = 0;
r = ret;
}
sshbuf_free(b);
if (sig != NULL) {
explicit_bzero(sig, slen);
free(sig);
}
return r;
}
int
ssh_xmss_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, required_siglen;
unsigned long long smlen = 0, mlen = 0;
int r, ret;
if (key == NULL ||
sshkey_type_plain(key->type) != KEY_XMSS ||
key->xmss_pk == NULL ||
sshkey_xmss_params(key) == NULL ||
signature == NULL || signaturelen == 0)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
return r;
if (datalen >= INT_MAX - required_siglen)
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-xmss@openssh.com", 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 != required_siglen) {
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 = xmss_sign_open(m, &mlen, sm, smlen,
key->xmss_pk, sshkey_xmss_params(key))) != 0) {
debug2("%s: crypto_sign_xmss_open failed: %d",
__func__, 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) {
explicit_bzero(sm, smlen);
free(sm);
}
if (m != NULL) {
explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */
free(m);
}
sshbuf_free(b);
free(ktype);
return r;
}
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