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-rw-r--r--ssh-ed25519-sk.c288
1 files changed, 288 insertions, 0 deletions
diff --git a/ssh-ed25519-sk.c b/ssh-ed25519-sk.c
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+++ b/ssh-ed25519-sk.c
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+/* $OpenBSD: ssh-ed25519-sk.c,v 1.15 2022/10/28 00:44:44 djm Exp $ */
+/*
+ * Copyright (c) 2019 Markus Friedl. All rights reserved.
+ *
+ * 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.
+ */
+
+/* #define DEBUG_SK 1 */
+
+#include "includes.h"
+
+#define SSHKEY_INTERNAL
+#include <sys/types.h>
+#include <limits.h>
+
+#include "crypto_api.h"
+
+#include <string.h>
+#include <stdarg.h>
+
+#include "log.h"
+#include "sshbuf.h"
+#include "sshkey.h"
+#include "ssherr.h"
+#include "ssh.h"
+#include "digest.h"
+
+/* Reuse some ED25519 internals */
+extern struct sshkey_impl_funcs sshkey_ed25519_funcs;
+
+static void
+ssh_ed25519_sk_cleanup(struct sshkey *k)
+{
+ sshkey_sk_cleanup(k);
+ sshkey_ed25519_funcs.cleanup(k);
+}
+
+static int
+ssh_ed25519_sk_equal(const struct sshkey *a, const struct sshkey *b)
+{
+ if (!sshkey_sk_fields_equal(a, b))
+ return 0;
+ if (!sshkey_ed25519_funcs.equal(a, b))
+ return 0;
+ return 1;
+}
+
+static int
+ssh_ed25519_sk_serialize_public(const struct sshkey *key, struct sshbuf *b,
+ enum sshkey_serialize_rep opts)
+{
+ int r;
+
+ if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
+ return r;
+ if ((r = sshkey_serialize_sk(key, b)) != 0)
+ return r;
+
+ return 0;
+}
+
+static int
+ssh_ed25519_sk_serialize_private(const struct sshkey *key, struct sshbuf *b,
+ enum sshkey_serialize_rep opts)
+{
+ int r;
+
+ if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
+ return r;
+ if ((r = sshkey_serialize_private_sk(key, b)) != 0)
+ return r;
+
+ return 0;
+}
+
+static int
+ssh_ed25519_sk_copy_public(const struct sshkey *from, struct sshkey *to)
+{
+ int r;
+
+ if ((r = sshkey_ed25519_funcs.copy_public(from, to)) != 0)
+ return r;
+ if ((r = sshkey_copy_public_sk(from, to)) != 0)
+ return r;
+ return 0;
+}
+
+static int
+ssh_ed25519_sk_deserialize_public(const char *ktype, struct sshbuf *b,
+ struct sshkey *key)
+{
+ int r;
+
+ if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
+ return r;
+ if ((r = sshkey_deserialize_sk(b, key)) != 0)
+ return r;
+ return 0;
+}
+
+static int
+ssh_ed25519_sk_deserialize_private(const char *ktype, struct sshbuf *b,
+ struct sshkey *key)
+{
+ int r;
+
+ if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
+ return r;
+ if ((r = sshkey_private_deserialize_sk(b, key)) != 0)
+ return r;
+ return 0;
+}
+
+static int
+ssh_ed25519_sk_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;
+ struct sshbuf *encoded = NULL;
+ char *ktype = NULL;
+ const u_char *sigblob;
+ const u_char *sm;
+ u_char *m = NULL;
+ u_char apphash[32];
+ u_char msghash[32];
+ u_char sig_flags;
+ u_int sig_counter;
+ size_t len;
+ unsigned long long smlen = 0, mlen = 0;
+ int r = SSH_ERR_INTERNAL_ERROR;
+ int ret;
+ struct sshkey_sig_details *details = NULL;
+
+ if (detailsp != NULL)
+ *detailsp = NULL;
+
+ if (key == NULL ||
+ sshkey_type_plain(key->type) != KEY_ED25519_SK ||
+ key->ed25519_pk == NULL ||
+ sig == NULL || siglen == 0)
+ return SSH_ERR_INVALID_ARGUMENT;
+
+ if ((b = sshbuf_from(sig, siglen)) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+ sshbuf_get_string_direct(b, &sigblob, &len) != 0 ||
+ sshbuf_get_u8(b, &sig_flags) != 0 ||
+ sshbuf_get_u32(b, &sig_counter) != 0) {
+ r = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+#ifdef DEBUG_SK
+ fprintf(stderr, "%s: data:\n", __func__);
+ /* sshbuf_dump_data(data, datalen, stderr); */
+ fprintf(stderr, "%s: sigblob:\n", __func__);
+ sshbuf_dump_data(sigblob, len, stderr);
+ fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
+ __func__, sig_flags, sig_counter);
+#endif
+ if (strcmp(sshkey_ssh_name_plain(key), 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 (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
+ strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
+ ssh_digest_memory(SSH_DIGEST_SHA256, data, dlen,
+ msghash, sizeof(msghash)) != 0) {
+ r = SSH_ERR_INVALID_ARGUMENT;
+ goto out;
+ }
+#ifdef DEBUG_SK
+ fprintf(stderr, "%s: hashed application:\n", __func__);
+ sshbuf_dump_data(apphash, sizeof(apphash), stderr);
+ fprintf(stderr, "%s: hashed message:\n", __func__);
+ sshbuf_dump_data(msghash, sizeof(msghash), stderr);
+#endif
+ if ((details = calloc(1, sizeof(*details))) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ details->sk_counter = sig_counter;
+ details->sk_flags = sig_flags;
+ if ((encoded = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if (sshbuf_put(encoded, sigblob, len) != 0 ||
+ sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
+ sshbuf_put_u8(encoded, sig_flags) != 0 ||
+ sshbuf_put_u32(encoded, sig_counter) != 0 ||
+ sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+#ifdef DEBUG_SK
+ fprintf(stderr, "%s: signed buf:\n", __func__);
+ sshbuf_dump(encoded, stderr);
+#endif
+ sm = sshbuf_ptr(encoded);
+ smlen = sshbuf_len(encoded);
+ mlen = smlen;
+ if ((m = malloc(smlen)) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ 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 != smlen - len) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
+ /* XXX compare 'm' and 'sm + len' ? */
+ /* success */
+ r = 0;
+ if (detailsp != NULL) {
+ *detailsp = details;
+ details = NULL;
+ }
+ out:
+ if (m != NULL)
+ freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
+ sshkey_sig_details_free(details);
+ sshbuf_free(b);
+ sshbuf_free(encoded);
+ free(ktype);
+ return r;
+}
+
+static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = {
+ /* .size = */ NULL,
+ /* .alloc = */ NULL,
+ /* .cleanup = */ ssh_ed25519_sk_cleanup,
+ /* .equal = */ ssh_ed25519_sk_equal,
+ /* .ssh_serialize_public = */ ssh_ed25519_sk_serialize_public,
+ /* .ssh_deserialize_public = */ ssh_ed25519_sk_deserialize_public,
+ /* .ssh_serialize_private = */ ssh_ed25519_sk_serialize_private,
+ /* .ssh_deserialize_private = */ ssh_ed25519_sk_deserialize_private,
+ /* .generate = */ NULL,
+ /* .copy_public = */ ssh_ed25519_sk_copy_public,
+ /* .sign = */ NULL,
+ /* .verify = */ ssh_ed25519_sk_verify,
+};
+
+const struct sshkey_impl sshkey_ed25519_sk_impl = {
+ /* .name = */ "sk-ssh-ed25519@openssh.com",
+ /* .shortname = */ "ED25519-SK",
+ /* .sigalg = */ NULL,
+ /* .type = */ KEY_ED25519_SK,
+ /* .nid = */ 0,
+ /* .cert = */ 0,
+ /* .sigonly = */ 0,
+ /* .keybits = */ 256,
+ /* .funcs = */ &sshkey_ed25519_sk_funcs,
+};
+
+const struct sshkey_impl sshkey_ed25519_sk_cert_impl = {
+ /* .name = */ "sk-ssh-ed25519-cert-v01@openssh.com",
+ /* .shortname = */ "ED25519-SK-CERT",
+ /* .sigalg = */ NULL,
+ /* .type = */ KEY_ED25519_SK_CERT,
+ /* .nid = */ 0,
+ /* .cert = */ 1,
+ /* .sigonly = */ 0,
+ /* .keybits = */ 256,
+ /* .funcs = */ &sshkey_ed25519_sk_funcs,
+};