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openssh-portable/sshkey-xmss.c

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/* $OpenBSD: sshkey-xmss.c,v 1.9 2020/10/19 22:49:23 dtucker Exp $ */
/*
* Copyright (c) 2017 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#ifdef WITH_XMSS
#include <sys/types.h>
#include <sys/uio.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#ifdef HAVE_SYS_FILE_H
# include <sys/file.h>
#endif
#include "ssh2.h"
#include "ssherr.h"
#include "sshbuf.h"
#include "cipher.h"
#include "sshkey.h"
#include "sshkey-xmss.h"
#include "atomicio.h"
#include "log.h"
#include "xmss_fast.h"
/* opaque internal XMSS state */
#define XMSS_MAGIC "xmss-state-v1"
#define XMSS_CIPHERNAME "aes256-gcm@openssh.com"
struct ssh_xmss_state {
xmss_params params;
u_int32_t n, w, h, k;
bds_state bds;
u_char *stack;
u_int32_t stackoffset;
u_char *stacklevels;
u_char *auth;
u_char *keep;
u_char *th_nodes;
u_char *retain;
treehash_inst *treehash;
u_int32_t idx; /* state read from file */
u_int32_t maxidx; /* restricted # of signatures */
int have_state; /* .state file exists */
int lockfd; /* locked in sshkey_xmss_get_state() */
u_char allow_update; /* allow sshkey_xmss_update_state() */
char *enc_ciphername;/* encrypt state with cipher */
u_char *enc_keyiv; /* encrypt state with key */
u_int32_t enc_keyiv_len; /* length of enc_keyiv */
};
int sshkey_xmss_init_bds_state(struct sshkey *);
int sshkey_xmss_init_enc_key(struct sshkey *, const char *);
void sshkey_xmss_free_bds(struct sshkey *);
int sshkey_xmss_get_state_from_file(struct sshkey *, const char *,
int *, int);
int sshkey_xmss_encrypt_state(const struct sshkey *, struct sshbuf *,
struct sshbuf **);
int sshkey_xmss_decrypt_state(const struct sshkey *, struct sshbuf *,
struct sshbuf **);
int sshkey_xmss_serialize_enc_key(const struct sshkey *, struct sshbuf *);
int sshkey_xmss_deserialize_enc_key(struct sshkey *, struct sshbuf *);
#define PRINT(...) do { if (printerror) sshlog(__FILE__, __func__, __LINE__, \
0, SYSLOG_LEVEL_ERROR, __VA_ARGS__); } while (0)
int
sshkey_xmss_init(struct sshkey *key, const char *name)
{
struct ssh_xmss_state *state;
if (key->xmss_state != NULL)
return SSH_ERR_INVALID_FORMAT;
if (name == NULL)
return SSH_ERR_INVALID_FORMAT;
state = calloc(sizeof(struct ssh_xmss_state), 1);
if (state == NULL)
return SSH_ERR_ALLOC_FAIL;
if (strcmp(name, XMSS_SHA2_256_W16_H10_NAME) == 0) {
state->n = 32;
state->w = 16;
state->h = 10;
} else if (strcmp(name, XMSS_SHA2_256_W16_H16_NAME) == 0) {
state->n = 32;
state->w = 16;
state->h = 16;
} else if (strcmp(name, XMSS_SHA2_256_W16_H20_NAME) == 0) {
state->n = 32;
state->w = 16;
state->h = 20;
} else {
free(state);
return SSH_ERR_KEY_TYPE_UNKNOWN;
}
if ((key->xmss_name = strdup(name)) == NULL) {
free(state);
return SSH_ERR_ALLOC_FAIL;
}
state->k = 2; /* XXX hardcoded */
state->lockfd = -1;
if (xmss_set_params(&state->params, state->n, state->h, state->w,
state->k) != 0) {
free(state);
return SSH_ERR_INVALID_FORMAT;
}
key->xmss_state = state;
return 0;
}
void
sshkey_xmss_free_state(struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
sshkey_xmss_free_bds(key);
if (state) {
if (state->enc_keyiv) {
explicit_bzero(state->enc_keyiv, state->enc_keyiv_len);
free(state->enc_keyiv);
}
free(state->enc_ciphername);
free(state);
}
key->xmss_state = NULL;
}
#define SSH_XMSS_K2_MAGIC "k=2"
#define num_stack(x) ((x->h+1)*(x->n))
#define num_stacklevels(x) (x->h+1)
#define num_auth(x) ((x->h)*(x->n))
#define num_keep(x) ((x->h >> 1)*(x->n))
#define num_th_nodes(x) ((x->h - x->k)*(x->n))
#define num_retain(x) (((1ULL << x->k) - x->k - 1) * (x->n))
#define num_treehash(x) ((x->h) - (x->k))
int
sshkey_xmss_init_bds_state(struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
u_int32_t i;
state->stackoffset = 0;
if ((state->stack = calloc(num_stack(state), 1)) == NULL ||
(state->stacklevels = calloc(num_stacklevels(state), 1))== NULL ||
(state->auth = calloc(num_auth(state), 1)) == NULL ||
(state->keep = calloc(num_keep(state), 1)) == NULL ||
(state->th_nodes = calloc(num_th_nodes(state), 1)) == NULL ||
(state->retain = calloc(num_retain(state), 1)) == NULL ||
(state->treehash = calloc(num_treehash(state),
sizeof(treehash_inst))) == NULL) {
sshkey_xmss_free_bds(key);
return SSH_ERR_ALLOC_FAIL;
}
for (i = 0; i < state->h - state->k; i++)
state->treehash[i].node = &state->th_nodes[state->n*i];
xmss_set_bds_state(&state->bds, state->stack, state->stackoffset,
state->stacklevels, state->auth, state->keep, state->treehash,
state->retain, 0);
return 0;
}
void
sshkey_xmss_free_bds(struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
if (state == NULL)
return;
free(state->stack);
free(state->stacklevels);
free(state->auth);
free(state->keep);
free(state->th_nodes);
free(state->retain);
free(state->treehash);
state->stack = NULL;
state->stacklevels = NULL;
state->auth = NULL;
state->keep = NULL;
state->th_nodes = NULL;
state->retain = NULL;
state->treehash = NULL;
}
void *
sshkey_xmss_params(const struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
if (state == NULL)
return NULL;
return &state->params;
}
void *
sshkey_xmss_bds_state(const struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
if (state == NULL)
return NULL;
return &state->bds;
}
int
sshkey_xmss_siglen(const struct sshkey *key, size_t *lenp)
{
struct ssh_xmss_state *state = key->xmss_state;
if (lenp == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if (state == NULL)
return SSH_ERR_INVALID_FORMAT;
*lenp = 4 + state->n +
state->params.wots_par.keysize +
state->h * state->n;
return 0;
}
size_t
sshkey_xmss_pklen(const struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
if (state == NULL)
return 0;
return state->n * 2;
}
size_t
sshkey_xmss_sklen(const struct sshkey *key)
{
struct ssh_xmss_state *state = key->xmss_state;
if (state == NULL)
return 0;
return state->n * 4 + 4;
}
int
sshkey_xmss_init_enc_key(struct sshkey *k, const char *ciphername)
{
struct ssh_xmss_state *state = k->xmss_state;
const struct sshcipher *cipher;
size_t keylen = 0, ivlen = 0;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((cipher = cipher_by_name(ciphername)) == NULL)
return SSH_ERR_INTERNAL_ERROR;
if ((state->enc_ciphername = strdup(ciphername)) == NULL)
return SSH_ERR_ALLOC_FAIL;
keylen = cipher_keylen(cipher);
ivlen = cipher_ivlen(cipher);
state->enc_keyiv_len = keylen + ivlen;
if ((state->enc_keyiv = calloc(state->enc_keyiv_len, 1)) == NULL) {
free(state->enc_ciphername);
state->enc_ciphername = NULL;
return SSH_ERR_ALLOC_FAIL;
}
arc4random_buf(state->enc_keyiv, state->enc_keyiv_len);
return 0;
}
int
sshkey_xmss_serialize_enc_key(const struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
int r;
if (state == NULL || state->enc_keyiv == NULL ||
state->enc_ciphername == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_put_cstring(b, state->enc_ciphername)) != 0 ||
(r = sshbuf_put_string(b, state->enc_keyiv,
state->enc_keyiv_len)) != 0)
return r;
return 0;
}
int
sshkey_xmss_deserialize_enc_key(struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
size_t len;
int r;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_get_cstring(b, &state->enc_ciphername, NULL)) != 0 ||
(r = sshbuf_get_string(b, &state->enc_keyiv, &len)) != 0)
return r;
state->enc_keyiv_len = len;
return 0;
}
int
sshkey_xmss_serialize_pk_info(const struct sshkey *k, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
struct ssh_xmss_state *state = k->xmss_state;
u_char have_info = 1;
u_int32_t idx;
int r;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if (opts != SSHKEY_SERIALIZE_INFO)
return 0;
idx = k->xmss_sk ? PEEK_U32(k->xmss_sk) : state->idx;
if ((r = sshbuf_put_u8(b, have_info)) != 0 ||
(r = sshbuf_put_u32(b, idx)) != 0 ||
(r = sshbuf_put_u32(b, state->maxidx)) != 0)
return r;
return 0;
}
int
sshkey_xmss_deserialize_pk_info(struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
u_char have_info;
int r;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
/* optional */
if (sshbuf_len(b) == 0)
return 0;
if ((r = sshbuf_get_u8(b, &have_info)) != 0)
return r;
if (have_info != 1)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_get_u32(b, &state->idx)) != 0 ||
(r = sshbuf_get_u32(b, &state->maxidx)) != 0)
return r;
return 0;
}
int
sshkey_xmss_generate_private_key(struct sshkey *k, u_int bits)
{
int r;
const char *name;
if (bits == 10) {
name = XMSS_SHA2_256_W16_H10_NAME;
} else if (bits == 16) {
name = XMSS_SHA2_256_W16_H16_NAME;
} else if (bits == 20) {
name = XMSS_SHA2_256_W16_H20_NAME;
} else {
name = XMSS_DEFAULT_NAME;
}
if ((r = sshkey_xmss_init(k, name)) != 0 ||
(r = sshkey_xmss_init_bds_state(k)) != 0 ||
(r = sshkey_xmss_init_enc_key(k, XMSS_CIPHERNAME)) != 0)
return r;
if ((k->xmss_pk = malloc(sshkey_xmss_pklen(k))) == NULL ||
(k->xmss_sk = malloc(sshkey_xmss_sklen(k))) == NULL) {
return SSH_ERR_ALLOC_FAIL;
}
xmss_keypair(k->xmss_pk, k->xmss_sk, sshkey_xmss_bds_state(k),
sshkey_xmss_params(k));
return 0;
}
int
sshkey_xmss_get_state_from_file(struct sshkey *k, const char *filename,
int *have_file, int printerror)
{
struct sshbuf *b = NULL, *enc = NULL;
int ret = SSH_ERR_SYSTEM_ERROR, r, fd = -1;
u_int32_t len;
unsigned char buf[4], *data = NULL;
*have_file = 0;
if ((fd = open(filename, O_RDONLY)) >= 0) {
*have_file = 1;
if (atomicio(read, fd, buf, sizeof(buf)) != sizeof(buf)) {
PRINT("%s: corrupt state file: %s", __func__, filename);
goto done;
}
len = PEEK_U32(buf);
if ((data = calloc(len, 1)) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto done;
}
if (atomicio(read, fd, data, len) != len) {
PRINT("%s: cannot read blob: %s", __func__, filename);
goto done;
}
if ((enc = sshbuf_from(data, len)) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto done;
}
sshkey_xmss_free_bds(k);
if ((r = sshkey_xmss_decrypt_state(k, enc, &b)) != 0) {
ret = r;
goto done;
}
if ((r = sshkey_xmss_deserialize_state(k, b)) != 0) {
ret = r;
goto done;
}
ret = 0;
}
done:
if (fd != -1)
close(fd);
free(data);
sshbuf_free(enc);
sshbuf_free(b);
return ret;
}
int
sshkey_xmss_get_state(const struct sshkey *k, int printerror)
{
struct ssh_xmss_state *state = k->xmss_state;
u_int32_t idx = 0;
char *filename = NULL;
char *statefile = NULL, *ostatefile = NULL, *lockfile = NULL;
int lockfd = -1, have_state = 0, have_ostate, tries = 0;
int ret = SSH_ERR_INVALID_ARGUMENT, r;
if (state == NULL)
goto done;
/*
* If maxidx is set, then we are allowed a limited number
* of signatures, but don't need to access the disk.
* Otherwise we need to deal with the on-disk state.
*/
if (state->maxidx) {
/* xmss_sk always contains the current state */
idx = PEEK_U32(k->xmss_sk);
if (idx < state->maxidx) {
state->allow_update = 1;
return 0;
}
return SSH_ERR_INVALID_ARGUMENT;
}
if ((filename = k->xmss_filename) == NULL)
goto done;
if (asprintf(&lockfile, "%s.lock", filename) == -1 ||
asprintf(&statefile, "%s.state", filename) == -1 ||
asprintf(&ostatefile, "%s.ostate", filename) == -1) {
ret = SSH_ERR_ALLOC_FAIL;
goto done;
}
if ((lockfd = open(lockfile, O_CREAT|O_RDONLY, 0600)) == -1) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: cannot open/create: %s", __func__, lockfile);
goto done;
}
while (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
if (errno != EWOULDBLOCK) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: cannot lock: %s", __func__, lockfile);
goto done;
}
if (++tries > 10) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: giving up on: %s", __func__, lockfile);
goto done;
}
usleep(1000*100*tries);
}
/* XXX no longer const */
if ((r = sshkey_xmss_get_state_from_file((struct sshkey *)k,
statefile, &have_state, printerror)) != 0) {
if ((r = sshkey_xmss_get_state_from_file((struct sshkey *)k,
ostatefile, &have_ostate, printerror)) == 0) {
state->allow_update = 1;
r = sshkey_xmss_forward_state(k, 1);
state->idx = PEEK_U32(k->xmss_sk);
state->allow_update = 0;
}
}
if (!have_state && !have_ostate) {
/* check that bds state is initialized */
if (state->bds.auth == NULL)
goto done;
PRINT("%s: start from scratch idx 0: %u", __func__, state->idx);
} else if (r != 0) {
ret = r;
goto done;
}
if (state->idx + 1 < state->idx) {
PRINT("%s: state wrap: %u", __func__, state->idx);
goto done;
}
state->have_state = have_state;
state->lockfd = lockfd;
state->allow_update = 1;
lockfd = -1;
ret = 0;
done:
if (lockfd != -1)
close(lockfd);
free(lockfile);
free(statefile);
free(ostatefile);
return ret;
}
int
sshkey_xmss_forward_state(const struct sshkey *k, u_int32_t reserve)
{
struct ssh_xmss_state *state = k->xmss_state;
u_char *sig = NULL;
size_t required_siglen;
unsigned long long smlen;
u_char data;
int ret, r;
if (state == NULL || !state->allow_update)
return SSH_ERR_INVALID_ARGUMENT;
if (reserve == 0)
return SSH_ERR_INVALID_ARGUMENT;
if (state->idx + reserve <= state->idx)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshkey_xmss_siglen(k, &required_siglen)) != 0)
return r;
if ((sig = malloc(required_siglen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
while (reserve-- > 0) {
state->idx = PEEK_U32(k->xmss_sk);
smlen = required_siglen;
if ((ret = xmss_sign(k->xmss_sk, sshkey_xmss_bds_state(k),
sig, &smlen, &data, 0, sshkey_xmss_params(k))) != 0) {
r = SSH_ERR_INVALID_ARGUMENT;
break;
}
}
free(sig);
return r;
}
int
sshkey_xmss_update_state(const struct sshkey *k, int printerror)
{
struct ssh_xmss_state *state = k->xmss_state;
struct sshbuf *b = NULL, *enc = NULL;
u_int32_t idx = 0;
unsigned char buf[4];
char *filename = NULL;
char *statefile = NULL, *ostatefile = NULL, *nstatefile = NULL;
int fd = -1;
int ret = SSH_ERR_INVALID_ARGUMENT;
if (state == NULL || !state->allow_update)
return ret;
if (state->maxidx) {
/* no update since the number of signatures is limited */
ret = 0;
goto done;
}
idx = PEEK_U32(k->xmss_sk);
if (idx == state->idx) {
/* no signature happened, no need to update */
ret = 0;
goto done;
} else if (idx != state->idx + 1) {
PRINT("%s: more than one signature happened: idx %u state %u",
__func__, idx, state->idx);
goto done;
}
state->idx = idx;
if ((filename = k->xmss_filename) == NULL)
goto done;
if (asprintf(&statefile, "%s.state", filename) == -1 ||
asprintf(&ostatefile, "%s.ostate", filename) == -1 ||
asprintf(&nstatefile, "%s.nstate", filename) == -1) {
ret = SSH_ERR_ALLOC_FAIL;
goto done;
}
unlink(nstatefile);
if ((b = sshbuf_new()) == NULL) {
ret = SSH_ERR_ALLOC_FAIL;
goto done;
}
if ((ret = sshkey_xmss_serialize_state(k, b)) != 0) {
PRINT("%s: SERLIALIZE FAILED: %d", __func__, ret);
goto done;
}
if ((ret = sshkey_xmss_encrypt_state(k, b, &enc)) != 0) {
PRINT("%s: ENCRYPT FAILED: %d", __func__, ret);
goto done;
}
if ((fd = open(nstatefile, O_CREAT|O_WRONLY|O_EXCL, 0600)) == -1) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: open new state file: %s", __func__, nstatefile);
goto done;
}
POKE_U32(buf, sshbuf_len(enc));
if (atomicio(vwrite, fd, buf, sizeof(buf)) != sizeof(buf)) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: write new state file hdr: %s", __func__, nstatefile);
close(fd);
goto done;
}
if (atomicio(vwrite, fd, sshbuf_mutable_ptr(enc), sshbuf_len(enc)) !=
sshbuf_len(enc)) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: write new state file data: %s", __func__, nstatefile);
close(fd);
goto done;
}
if (fsync(fd) == -1) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: sync new state file: %s", __func__, nstatefile);
close(fd);
goto done;
}
if (close(fd) == -1) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: close new state file: %s", __func__, nstatefile);
goto done;
}
if (state->have_state) {
unlink(ostatefile);
if (link(statefile, ostatefile)) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: backup state %s to %s", __func__, statefile,
ostatefile);
goto done;
}
}
if (rename(nstatefile, statefile) == -1) {
ret = SSH_ERR_SYSTEM_ERROR;
PRINT("%s: rename %s to %s", __func__, nstatefile, statefile);
goto done;
}
ret = 0;
done:
if (state->lockfd != -1) {
close(state->lockfd);
state->lockfd = -1;
}
if (nstatefile)
unlink(nstatefile);
free(statefile);
free(ostatefile);
free(nstatefile);
sshbuf_free(b);
sshbuf_free(enc);
return ret;
}
int
sshkey_xmss_serialize_state(const struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
treehash_inst *th;
u_int32_t i, node;
int r;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if (state->stack == NULL)
return SSH_ERR_INVALID_ARGUMENT;
state->stackoffset = state->bds.stackoffset; /* copy back */
if ((r = sshbuf_put_cstring(b, SSH_XMSS_K2_MAGIC)) != 0 ||
(r = sshbuf_put_u32(b, state->idx)) != 0 ||
(r = sshbuf_put_string(b, state->stack, num_stack(state))) != 0 ||
(r = sshbuf_put_u32(b, state->stackoffset)) != 0 ||
(r = sshbuf_put_string(b, state->stacklevels, num_stacklevels(state))) != 0 ||
(r = sshbuf_put_string(b, state->auth, num_auth(state))) != 0 ||
(r = sshbuf_put_string(b, state->keep, num_keep(state))) != 0 ||
(r = sshbuf_put_string(b, state->th_nodes, num_th_nodes(state))) != 0 ||
(r = sshbuf_put_string(b, state->retain, num_retain(state))) != 0 ||
(r = sshbuf_put_u32(b, num_treehash(state))) != 0)
return r;
for (i = 0; i < num_treehash(state); i++) {
th = &state->treehash[i];
node = th->node - state->th_nodes;
if ((r = sshbuf_put_u32(b, th->h)) != 0 ||
(r = sshbuf_put_u32(b, th->next_idx)) != 0 ||
(r = sshbuf_put_u32(b, th->stackusage)) != 0 ||
(r = sshbuf_put_u8(b, th->completed)) != 0 ||
(r = sshbuf_put_u32(b, node)) != 0)
return r;
}
return 0;
}
int
sshkey_xmss_serialize_state_opt(const struct sshkey *k, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
struct ssh_xmss_state *state = k->xmss_state;
int r = SSH_ERR_INVALID_ARGUMENT;
u_char have_stack, have_filename, have_enc;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((r = sshbuf_put_u8(b, opts)) != 0)
return r;
switch (opts) {
case SSHKEY_SERIALIZE_STATE:
r = sshkey_xmss_serialize_state(k, b);
break;
case SSHKEY_SERIALIZE_FULL:
if ((r = sshkey_xmss_serialize_enc_key(k, b)) != 0)
return r;
r = sshkey_xmss_serialize_state(k, b);
break;
case SSHKEY_SERIALIZE_SHIELD:
/* all of stack/filename/enc are optional */
have_stack = state->stack != NULL;
if ((r = sshbuf_put_u8(b, have_stack)) != 0)
return r;
if (have_stack) {
state->idx = PEEK_U32(k->xmss_sk); /* update */
if ((r = sshkey_xmss_serialize_state(k, b)) != 0)
return r;
}
have_filename = k->xmss_filename != NULL;
if ((r = sshbuf_put_u8(b, have_filename)) != 0)
return r;
if (have_filename &&
(r = sshbuf_put_cstring(b, k->xmss_filename)) != 0)
return r;
have_enc = state->enc_keyiv != NULL;
if ((r = sshbuf_put_u8(b, have_enc)) != 0)
return r;
if (have_enc &&
(r = sshkey_xmss_serialize_enc_key(k, b)) != 0)
return r;
if ((r = sshbuf_put_u32(b, state->maxidx)) != 0 ||
(r = sshbuf_put_u8(b, state->allow_update)) != 0)
return r;
break;
case SSHKEY_SERIALIZE_DEFAULT:
r = 0;
break;
default:
r = SSH_ERR_INVALID_ARGUMENT;
break;
}
return r;
}
int
sshkey_xmss_deserialize_state(struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
treehash_inst *th;
u_int32_t i, lh, node;
size_t ls, lsl, la, lk, ln, lr;
char *magic;
int r = SSH_ERR_INTERNAL_ERROR;
if (state == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if (k->xmss_sk == NULL)
return SSH_ERR_INVALID_ARGUMENT;
if ((state->treehash = calloc(num_treehash(state),
sizeof(treehash_inst))) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_get_cstring(b, &magic, NULL)) != 0 ||
(r = sshbuf_get_u32(b, &state->idx)) != 0 ||
(r = sshbuf_get_string(b, &state->stack, &ls)) != 0 ||
(r = sshbuf_get_u32(b, &state->stackoffset)) != 0 ||
(r = sshbuf_get_string(b, &state->stacklevels, &lsl)) != 0 ||
(r = sshbuf_get_string(b, &state->auth, &la)) != 0 ||
(r = sshbuf_get_string(b, &state->keep, &lk)) != 0 ||
(r = sshbuf_get_string(b, &state->th_nodes, &ln)) != 0 ||
(r = sshbuf_get_string(b, &state->retain, &lr)) != 0 ||
(r = sshbuf_get_u32(b, &lh)) != 0)
goto out;
if (strcmp(magic, SSH_XMSS_K2_MAGIC) != 0) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
/* XXX check stackoffset */
if (ls != num_stack(state) ||
lsl != num_stacklevels(state) ||
la != num_auth(state) ||
lk != num_keep(state) ||
ln != num_th_nodes(state) ||
lr != num_retain(state) ||
lh != num_treehash(state)) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
for (i = 0; i < num_treehash(state); i++) {
th = &state->treehash[i];
if ((r = sshbuf_get_u32(b, &th->h)) != 0 ||
(r = sshbuf_get_u32(b, &th->next_idx)) != 0 ||
(r = sshbuf_get_u32(b, &th->stackusage)) != 0 ||
(r = sshbuf_get_u8(b, &th->completed)) != 0 ||
(r = sshbuf_get_u32(b, &node)) != 0)
goto out;
if (node < num_th_nodes(state))
th->node = &state->th_nodes[node];
}
POKE_U32(k->xmss_sk, state->idx);
xmss_set_bds_state(&state->bds, state->stack, state->stackoffset,
state->stacklevels, state->auth, state->keep, state->treehash,
state->retain, 0);
/* success */
r = 0;
out:
free(magic);
return r;
}
int
sshkey_xmss_deserialize_state_opt(struct sshkey *k, struct sshbuf *b)
{
struct ssh_xmss_state *state = k->xmss_state;
enum sshkey_serialize_rep opts;
u_char have_state, have_stack, have_filename, have_enc;
int r;
if ((r = sshbuf_get_u8(b, &have_state)) != 0)
return r;
opts = have_state;
switch (opts) {
case SSHKEY_SERIALIZE_DEFAULT:
r = 0;
break;
case SSHKEY_SERIALIZE_SHIELD:
if ((r = sshbuf_get_u8(b, &have_stack)) != 0)
return r;
if (have_stack &&
(r = sshkey_xmss_deserialize_state(k, b)) != 0)
return r;
if ((r = sshbuf_get_u8(b, &have_filename)) != 0)
return r;
if (have_filename &&
(r = sshbuf_get_cstring(b, &k->xmss_filename, NULL)) != 0)
return r;
if ((r = sshbuf_get_u8(b, &have_enc)) != 0)
return r;
if (have_enc &&
(r = sshkey_xmss_deserialize_enc_key(k, b)) != 0)
return r;
if ((r = sshbuf_get_u32(b, &state->maxidx)) != 0 ||
(r = sshbuf_get_u8(b, &state->allow_update)) != 0)
return r;
break;
case SSHKEY_SERIALIZE_STATE:
if ((r = sshkey_xmss_deserialize_state(k, b)) != 0)
return r;
break;
case SSHKEY_SERIALIZE_FULL:
if ((r = sshkey_xmss_deserialize_enc_key(k, b)) != 0 ||
(r = sshkey_xmss_deserialize_state(k, b)) != 0)
return r;
break;
default:
r = SSH_ERR_INVALID_FORMAT;
break;
}
return r;
}
int
sshkey_xmss_encrypt_state(const struct sshkey *k, struct sshbuf *b,
struct sshbuf **retp)
{
struct ssh_xmss_state *state = k->xmss_state;
struct sshbuf *encrypted = NULL, *encoded = NULL, *padded = NULL;
struct sshcipher_ctx *ciphercontext = NULL;
const struct sshcipher *cipher;
u_char *cp, *key, *iv = NULL;
size_t i, keylen, ivlen, blocksize, authlen, encrypted_len, aadlen;
int r = SSH_ERR_INTERNAL_ERROR;
if (retp != NULL)
*retp = NULL;
if (state == NULL ||
state->enc_keyiv == NULL ||
state->enc_ciphername == NULL)
return SSH_ERR_INTERNAL_ERROR;
if ((cipher = cipher_by_name(state->enc_ciphername)) == NULL) {
r = SSH_ERR_INTERNAL_ERROR;
goto out;
}
blocksize = cipher_blocksize(cipher);
keylen = cipher_keylen(cipher);
ivlen = cipher_ivlen(cipher);
authlen = cipher_authlen(cipher);
if (state->enc_keyiv_len != keylen + ivlen) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
key = state->enc_keyiv;
if ((encrypted = sshbuf_new()) == NULL ||
(encoded = sshbuf_new()) == NULL ||
(padded = sshbuf_new()) == NULL ||
(iv = malloc(ivlen)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
/* replace first 4 bytes of IV with index to ensure uniqueness */
memcpy(iv, key + keylen, ivlen);
POKE_U32(iv, state->idx);
if ((r = sshbuf_put(encoded, XMSS_MAGIC, sizeof(XMSS_MAGIC))) != 0 ||
(r = sshbuf_put_u32(encoded, state->idx)) != 0)
goto out;
/* padded state will be encrypted */
if ((r = sshbuf_putb(padded, b)) != 0)
goto out;
i = 0;
while (sshbuf_len(padded) % blocksize) {
if ((r = sshbuf_put_u8(padded, ++i & 0xff)) != 0)
goto out;
}
encrypted_len = sshbuf_len(padded);
/* header including the length of state is used as AAD */
if ((r = sshbuf_put_u32(encoded, encrypted_len)) != 0)
goto out;
aadlen = sshbuf_len(encoded);
/* concat header and state */
if ((r = sshbuf_putb(encoded, padded)) != 0)
goto out;
/* reserve space for encryption of encoded data plus auth tag */
/* encrypt at offset addlen */
if ((r = sshbuf_reserve(encrypted,
encrypted_len + aadlen + authlen, &cp)) != 0 ||
(r = cipher_init(&ciphercontext, cipher, key, keylen,
iv, ivlen, 1)) != 0 ||
(r = cipher_crypt(ciphercontext, 0, cp, sshbuf_ptr(encoded),
encrypted_len, aadlen, authlen)) != 0)
goto out;
/* success */
r = 0;
out:
if (retp != NULL) {
*retp = encrypted;
encrypted = NULL;
}
sshbuf_free(padded);
sshbuf_free(encoded);
sshbuf_free(encrypted);
cipher_free(ciphercontext);
free(iv);
return r;
}
int
sshkey_xmss_decrypt_state(const struct sshkey *k, struct sshbuf *encoded,
struct sshbuf **retp)
{
struct ssh_xmss_state *state = k->xmss_state;
struct sshbuf *copy = NULL, *decrypted = NULL;
struct sshcipher_ctx *ciphercontext = NULL;
const struct sshcipher *cipher = NULL;
u_char *key, *iv = NULL, *dp;
size_t keylen, ivlen, authlen, aadlen;
u_int blocksize, encrypted_len, index;
int r = SSH_ERR_INTERNAL_ERROR;
if (retp != NULL)
*retp = NULL;
if (state == NULL ||
state->enc_keyiv == NULL ||
state->enc_ciphername == NULL)
return SSH_ERR_INTERNAL_ERROR;
if ((cipher = cipher_by_name(state->enc_ciphername)) == NULL) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
blocksize = cipher_blocksize(cipher);
keylen = cipher_keylen(cipher);
ivlen = cipher_ivlen(cipher);
authlen = cipher_authlen(cipher);
if (state->enc_keyiv_len != keylen + ivlen) {
r = SSH_ERR_INTERNAL_ERROR;
goto out;
}
key = state->enc_keyiv;
if ((copy = sshbuf_fromb(encoded)) == NULL ||
(decrypted = sshbuf_new()) == NULL ||
(iv = malloc(ivlen)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
/* check magic */
if (sshbuf_len(encoded) < sizeof(XMSS_MAGIC) ||
memcmp(sshbuf_ptr(encoded), XMSS_MAGIC, sizeof(XMSS_MAGIC))) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
/* parse public portion */
if ((r = sshbuf_consume(encoded, sizeof(XMSS_MAGIC))) != 0 ||
(r = sshbuf_get_u32(encoded, &index)) != 0 ||
(r = sshbuf_get_u32(encoded, &encrypted_len)) != 0)
goto out;
/* check size of encrypted key blob */
if (encrypted_len < blocksize || (encrypted_len % blocksize) != 0) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
/* check that an appropriate amount of auth data is present */
if (sshbuf_len(encoded) < authlen ||
sshbuf_len(encoded) - authlen < encrypted_len) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
aadlen = sshbuf_len(copy) - sshbuf_len(encoded);
/* replace first 4 bytes of IV with index to ensure uniqueness */
memcpy(iv, key + keylen, ivlen);
POKE_U32(iv, index);
/* decrypt private state of key */
if ((r = sshbuf_reserve(decrypted, aadlen + encrypted_len, &dp)) != 0 ||
(r = cipher_init(&ciphercontext, cipher, key, keylen,
iv, ivlen, 0)) != 0 ||
(r = cipher_crypt(ciphercontext, 0, dp, sshbuf_ptr(copy),
encrypted_len, aadlen, authlen)) != 0)
goto out;
/* there should be no trailing data */
if ((r = sshbuf_consume(encoded, encrypted_len + authlen)) != 0)
goto out;
if (sshbuf_len(encoded) != 0) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
/* remove AAD */
if ((r = sshbuf_consume(decrypted, aadlen)) != 0)
goto out;
/* XXX encrypted includes unchecked padding */
/* success */
r = 0;
if (retp != NULL) {
*retp = decrypted;
decrypted = NULL;
}
out:
cipher_free(ciphercontext);
sshbuf_free(copy);
sshbuf_free(decrypted);
free(iv);
return r;
}
u_int32_t
sshkey_xmss_signatures_left(const struct sshkey *k)
{
struct ssh_xmss_state *state = k->xmss_state;
u_int32_t idx;
if (sshkey_type_plain(k->type) == KEY_XMSS && state &&
state->maxidx) {
idx = k->xmss_sk ? PEEK_U32(k->xmss_sk) : state->idx;
if (idx < state->maxidx)
return state->maxidx - idx;
}
return 0;
}
int
sshkey_xmss_enable_maxsign(struct sshkey *k, u_int32_t maxsign)
{
struct ssh_xmss_state *state = k->xmss_state;
if (sshkey_type_plain(k->type) != KEY_XMSS)
return SSH_ERR_INVALID_ARGUMENT;
if (maxsign == 0)
return 0;
if (state->idx + maxsign < state->idx)
return SSH_ERR_INVALID_ARGUMENT;
state->maxidx = state->idx + maxsign;
return 0;
}
#endif /* WITH_XMSS */
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