/* $NetBSD: ssh-xmss.c,v 1.5.2.1 2023/08/11 15:36:40 martin Exp $ */ /* $OpenBSD: ssh-xmss.c,v 1.14 2022/10/28 00:44:44 djm Exp $*/ /* * Copyright (c) 2017 Stefan-Lukas Gazdag. * Copyright (c) 2017 Markus Friedl. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "includes.h" __RCSID("$NetBSD: ssh-xmss.c,v 1.5.2.1 2023/08/11 15:36:40 martin Exp $"); #define SSHKEY_INTERNAL #include #include #include #include #include #include #include #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, };