1 files changed, 387 insertions, 0 deletions

diff --git a/ssh-xmss.c b/ssh-xmss.c
new file mode 100644
index 0000000..b3aec0f
--- /dev/null
+++ b/ssh-xmss.c
@@ -0,0 +1,387 @@
+/* $OpenBSD: ssh-xmss.c,v 1.14 2022/10/28 00:44:44 djm 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"
+#ifdef WITH_XMSS
+
+#define SSHKEY_INTERNAL
+#include <sys/types.h>
+#include <limits.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdint.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"
+
+static void
+ssh_xmss_cleanup(struct sshkey *k)
+{
+	freezero(k->xmss_pk, sshkey_xmss_pklen(k));
+	freezero(k->xmss_sk, sshkey_xmss_sklen(k));
+	sshkey_xmss_free_state(k);
+	free(k->xmss_name);
+	free(k->xmss_filename);
+	k->xmss_pk = NULL;
+	k->xmss_sk = NULL;
+	k->xmss_name = NULL;
+	k->xmss_filename = NULL;
+}
+
+static int
+ssh_xmss_equal(const struct sshkey *a, const struct sshkey *b)
+{
+	if (a->xmss_pk == NULL || b->xmss_pk == NULL)
+		return 0;
+	if (sshkey_xmss_pklen(a) != sshkey_xmss_pklen(b))
+		return 0;
+	if (memcmp(a->xmss_pk, b->xmss_pk, sshkey_xmss_pklen(a)) != 0)
+		return 0;
+	return 1;
+}
+
+static int
+ssh_xmss_serialize_public(const struct sshkey *key, struct sshbuf *b,
+    enum sshkey_serialize_rep opts)
+{
+	int r;
+
+	if (key->xmss_name == NULL || key->xmss_pk == NULL ||
+	    sshkey_xmss_pklen(key) == 0)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((r = sshbuf_put_cstring(b, key->xmss_name)) != 0 ||
+	    (r = sshbuf_put_string(b, key->xmss_pk,
+	    sshkey_xmss_pklen(key))) != 0 ||
+	    (r = sshkey_xmss_serialize_pk_info(key, b, opts)) != 0)
+		return r;
+
+	return 0;
+}
+
+static int
+ssh_xmss_serialize_private(const struct sshkey *key, struct sshbuf *b,
+    enum sshkey_serialize_rep opts)
+{
+	int r;
+
+	if (key->xmss_name == NULL)
+		return SSH_ERR_INVALID_ARGUMENT;
+	/* Note: can't reuse ssh_xmss_serialize_public because of sk order */
+	if ((r = sshbuf_put_cstring(b, key->xmss_name)) != 0 ||
+	    (r = sshbuf_put_string(b, key->xmss_pk,
+	    sshkey_xmss_pklen(key))) != 0 ||
+	    (r = sshbuf_put_string(b, key->xmss_sk,
+	    sshkey_xmss_sklen(key))) != 0 ||
+	    (r = sshkey_xmss_serialize_state_opt(key, b, opts)) != 0)
+		return r;
+
+	return 0;
+}
+
+static int
+ssh_xmss_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+	int r = SSH_ERR_INTERNAL_ERROR;
+	u_int32_t left;
+	size_t pklen;
+
+	if ((r = sshkey_xmss_init(to, from->xmss_name)) != 0)
+		return r;
+	if (from->xmss_pk == NULL)
+		return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
+
+	if ((pklen = sshkey_xmss_pklen(from)) == 0 ||
+	    sshkey_xmss_pklen(to) != pklen)
+		return SSH_ERR_INTERNAL_ERROR;
+	if ((to->xmss_pk = malloc(pklen)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	memcpy(to->xmss_pk, from->xmss_pk, pklen);
+	/* simulate number of signatures left on pubkey */
+	left = sshkey_xmss_signatures_left(from);
+	if (left)
+		sshkey_xmss_enable_maxsign(to, left);
+	return 0;
+}
+
+static int
+ssh_xmss_deserialize_public(const char *ktype, struct sshbuf *b,
+    struct sshkey *key)
+{
+	size_t len = 0;
+	char *xmss_name = NULL;
+	u_char *pk = NULL;
+	int ret = SSH_ERR_INTERNAL_ERROR;
+
+	if ((ret = sshbuf_get_cstring(b, &xmss_name, NULL)) != 0)
+		goto out;
+	if ((ret = sshkey_xmss_init(key, xmss_name)) != 0)
+		goto out;
+	if ((ret = sshbuf_get_string(b, &pk, &len)) != 0)
+		goto out;
+	if (len == 0 || len != sshkey_xmss_pklen(key)) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	key->xmss_pk = pk;
+	pk = NULL;
+	if (!sshkey_is_cert(key) &&
+	    (ret = sshkey_xmss_deserialize_pk_info(key, b)) != 0)
+		goto out;
+	/* success */
+	ret = 0;
+ out:
+	free(xmss_name);
+	freezero(pk, len);
+	return ret;
+}
+
+static int
+ssh_xmss_deserialize_private(const char *ktype, struct sshbuf *b,
+    struct sshkey *key)
+{
+	int r;
+	char *xmss_name = NULL;
+	size_t pklen = 0, sklen = 0;
+	u_char *xmss_pk = NULL, *xmss_sk = NULL;
+
+	/* Note: can't reuse ssh_xmss_deserialize_public because of sk order */
+	if ((r = sshbuf_get_cstring(b, &xmss_name, NULL)) != 0 ||
+	    (r = sshbuf_get_string(b, &xmss_pk, &pklen)) != 0 ||
+	    (r = sshbuf_get_string(b, &xmss_sk, &sklen)) != 0)
+		goto out;
+	if (!sshkey_is_cert(key) &&
+	    (r = sshkey_xmss_init(key, xmss_name)) != 0)
+		goto out;
+	if (pklen != sshkey_xmss_pklen(key) ||
+	    sklen != sshkey_xmss_sklen(key)) {
+		r = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	key->xmss_pk = xmss_pk;
+	key->xmss_sk = xmss_sk;
+	xmss_pk = xmss_sk = NULL;
+	/* optional internal state */
+	if ((r = sshkey_xmss_deserialize_state_opt(key, b)) != 0)
+		goto out;
+	/* success */
+	r = 0;
+ out:
+	free(xmss_name);
+	freezero(xmss_pk, pklen);
+	freezero(xmss_sk, sklen);
+	return r;
+}
+
+static int
+ssh_xmss_sign(struct sshkey *key,
+    u_char **sigp, size_t *lenp,
+    const u_char *data, size_t datalen,
+    const char *alg, const char *sk_provider, const char *sk_pin, 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, 1)) != 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, 1)) != 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)
+		freezero(sig, slen);
+
+	return r;
+}
+
+static int
+ssh_xmss_verify(const struct sshkey *key,
+    const u_char *sig, size_t siglen,
+    const u_char *data, size_t dlen, const char *alg, u_int compat,
+    struct sshkey_sig_details **detailsp)
+{
+	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 ||
+	    sig == NULL || siglen == 0)
+		return SSH_ERR_INVALID_ARGUMENT;
+	if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
+		return r;
+	if (dlen >= INT_MAX - required_siglen)
+		return SSH_ERR_INVALID_ARGUMENT;
+
+	if ((b = sshbuf_from(sig, siglen)) == 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 (dlen >= SIZE_MAX - len) {
+		r = SSH_ERR_INVALID_ARGUMENT;
+		goto out;
+	}
+	smlen = len + dlen;
+	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, dlen);
+	if ((ret = xmss_sign_open(m, &mlen, sm, smlen,
+	    key->xmss_pk, sshkey_xmss_params(key))) != 0) {
+		debug2_f("xmss_sign_open failed: %d", ret);
+	}
+	if (ret != 0 || mlen != dlen) {
+		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);
+	sshbuf_free(b);
+	free(ktype);
+	return r;
+}
+
+static const struct sshkey_impl_funcs sshkey_xmss_funcs = {
+	/* .size = */		NULL,
+	/* .alloc = */		NULL,
+	/* .cleanup = */	ssh_xmss_cleanup,
+	/* .equal = */		ssh_xmss_equal,
+	/* .ssh_serialize_public = */ ssh_xmss_serialize_public,
+	/* .ssh_deserialize_public = */ ssh_xmss_deserialize_public,
+	/* .ssh_serialize_private = */ ssh_xmss_serialize_private,
+	/* .ssh_deserialize_private = */ ssh_xmss_deserialize_private,
+	/* .generate = */	sshkey_xmss_generate_private_key,
+	/* .copy_public = */	ssh_xmss_copy_public,
+	/* .sign = */		ssh_xmss_sign,
+	/* .verify = */		ssh_xmss_verify,
+};
+
+const struct sshkey_impl sshkey_xmss_impl = {
+	/* .name = */		"ssh-xmss@openssh.com",
+	/* .shortname = */	"XMSS",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_XMSS,
+	/* .nid = */		0,
+	/* .cert = */		0,
+	/* .sigonly = */	0,
+	/* .keybits = */	256,
+	/* .funcs = */		&sshkey_xmss_funcs,
+};
+
+const struct sshkey_impl sshkey_xmss_cert_impl = {
+	/* .name = */		"ssh-xmss-cert-v01@openssh.com",
+	/* .shortname = */	"XMSS-CERT",
+	/* .sigalg = */		NULL,
+	/* .type = */		KEY_XMSS_CERT,
+	/* .nid = */		0,
+	/* .cert = */		1,
+	/* .sigonly = */	0,
+	/* .keybits = */	256,
+	/* .funcs = */		&sshkey_xmss_funcs,
+};
+#endif /* WITH_XMSS */