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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:40:04 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:40:04 +0000
commit25505898530a333011f4fd5cbc841ad6b26c089c (patch)
tree333a33fdd60930bcccc3f177ed9467d535e9bac6 /kexc25519.c
parentInitial commit. (diff)
downloadopenssh-upstream.tar.xz
openssh-upstream.zip
Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kexc25519.c')
-rw-r--r--kexc25519.c199
1 files changed, 199 insertions, 0 deletions
diff --git a/kexc25519.c b/kexc25519.c
new file mode 100644
index 0000000..f13d766
--- /dev/null
+++ b/kexc25519.c
@@ -0,0 +1,199 @@
+/* $OpenBSD: kexc25519.c,v 1.17 2019/01/21 10:40:11 djm Exp $ */
+/*
+ * Copyright (c) 2019 Markus Friedl. All rights reserved.
+ * Copyright (c) 2010 Damien Miller. All rights reserved.
+ * Copyright (c) 2013 Aris Adamantiadis. 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"
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+#include "sshkey.h"
+#include "kex.h"
+#include "sshbuf.h"
+#include "digest.h"
+#include "ssherr.h"
+#include "ssh2.h"
+
+extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE],
+ const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE])
+ __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
+ __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)))
+ __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE)));
+
+void
+kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
+{
+ static const u_char basepoint[CURVE25519_SIZE] = {9};
+
+ arc4random_buf(key, CURVE25519_SIZE);
+ crypto_scalarmult_curve25519(pub, key, basepoint);
+}
+
+int
+kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE],
+ const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int raw)
+{
+ u_char shared_key[CURVE25519_SIZE];
+ u_char zero[CURVE25519_SIZE];
+ int r;
+
+ crypto_scalarmult_curve25519(shared_key, key, pub);
+
+ /* Check for all-zero shared secret */
+ explicit_bzero(zero, CURVE25519_SIZE);
+ if (timingsafe_bcmp(zero, shared_key, CURVE25519_SIZE) == 0)
+ return SSH_ERR_KEY_INVALID_EC_VALUE;
+
+#ifdef DEBUG_KEXECDH
+ dump_digest("shared secret", shared_key, CURVE25519_SIZE);
+#endif
+ if (raw)
+ r = sshbuf_put(out, shared_key, CURVE25519_SIZE);
+ else
+ r = sshbuf_put_bignum2_bytes(out, shared_key, CURVE25519_SIZE);
+ explicit_bzero(shared_key, CURVE25519_SIZE);
+ return r;
+}
+
+int
+kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
+ const u_char pub[CURVE25519_SIZE], struct sshbuf *out)
+{
+ return kexc25519_shared_key_ext(key, pub, out, 0);
+}
+
+int
+kex_c25519_keypair(struct kex *kex)
+{
+ struct sshbuf *buf = NULL;
+ u_char *cp = NULL;
+ int r;
+
+ if ((buf = sshbuf_new()) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if ((r = sshbuf_reserve(buf, CURVE25519_SIZE, &cp)) != 0)
+ goto out;
+ kexc25519_keygen(kex->c25519_client_key, cp);
+#ifdef DEBUG_KEXECDH
+ dump_digest("client public key c25519:", cp, CURVE25519_SIZE);
+#endif
+ kex->client_pub = buf;
+ buf = NULL;
+ out:
+ sshbuf_free(buf);
+ return r;
+}
+
+int
+kex_c25519_enc(struct kex *kex, const struct sshbuf *client_blob,
+ struct sshbuf **server_blobp, struct sshbuf **shared_secretp)
+{
+ struct sshbuf *server_blob = NULL;
+ struct sshbuf *buf = NULL;
+ const u_char *client_pub;
+ u_char *server_pub;
+ u_char server_key[CURVE25519_SIZE];
+ int r;
+
+ *server_blobp = NULL;
+ *shared_secretp = NULL;
+
+ if (sshbuf_len(client_blob) != CURVE25519_SIZE) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
+ client_pub = sshbuf_ptr(client_blob);
+#ifdef DEBUG_KEXECDH
+ dump_digest("client public key 25519:", client_pub, CURVE25519_SIZE);
+#endif
+ /* allocate space for encrypted KEM key and ECDH pub key */
+ if ((server_blob = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = sshbuf_reserve(server_blob, CURVE25519_SIZE, &server_pub)) != 0)
+ goto out;
+ kexc25519_keygen(server_key, server_pub);
+ /* allocate shared secret */
+ if ((buf = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = kexc25519_shared_key_ext(server_key, client_pub, buf, 0)) < 0)
+ goto out;
+#ifdef DEBUG_KEXECDH
+ dump_digest("server public key 25519:", server_pub, CURVE25519_SIZE);
+ dump_digest("encoded shared secret:", sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+ *server_blobp = server_blob;
+ *shared_secretp = buf;
+ server_blob = NULL;
+ buf = NULL;
+ out:
+ explicit_bzero(server_key, sizeof(server_key));
+ sshbuf_free(server_blob);
+ sshbuf_free(buf);
+ return r;
+}
+
+int
+kex_c25519_dec(struct kex *kex, const struct sshbuf *server_blob,
+ struct sshbuf **shared_secretp)
+{
+ struct sshbuf *buf = NULL;
+ const u_char *server_pub;
+ int r;
+
+ *shared_secretp = NULL;
+
+ if (sshbuf_len(server_blob) != CURVE25519_SIZE) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
+ server_pub = sshbuf_ptr(server_blob);
+#ifdef DEBUG_KEXECDH
+ dump_digest("server public key c25519:", server_pub, CURVE25519_SIZE);
+#endif
+ /* shared secret */
+ if ((buf = sshbuf_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((r = kexc25519_shared_key_ext(kex->c25519_client_key, server_pub,
+ buf, 0)) < 0)
+ goto out;
+#ifdef DEBUG_KEXECDH
+ dump_digest("encoded shared secret:", sshbuf_ptr(buf), sshbuf_len(buf));
+#endif
+ *shared_secretp = buf;
+ buf = NULL;
+ out:
+ sshbuf_free(buf);
+ return r;
+}