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authordjm@openbsd.org <djm@openbsd.org>2019-01-21 10:24:09 +0000
committerDamien Miller <djm@mindrot.org>2019-01-21 22:08:04 +1100
commit2f6a9ddbbf6ca8623c53c323ff17fb6d68d66970 (patch)
tree2fe3ee7094f85e9f834d69c5d609a1b9fe886930 /kexc25519.c
parentdfd591618cdf2c96727ac0eb65f89cf54af0d97e (diff)
upstream: use KEM API for vanilla c25519 KEX
OpenBSD-Commit-ID: 38d937b85ff770886379dd66a8f32ab0c1c35c1f
Diffstat (limited to 'kexc25519.c')
-rw-r--r--kexc25519.c122
1 files changed, 112 insertions, 10 deletions
diff --git a/kexc25519.c b/kexc25519.c
index 3911baf1..a06c6e44 100644
--- a/kexc25519.c
+++ b/kexc25519.c
@@ -1,6 +1,6 @@
-/* $OpenBSD: kexc25519.c,v 1.13 2019/01/21 10:20:12 djm Exp $ */
+/* $OpenBSD: kexc25519.c,v 1.14 2019/01/21 10:24:09 djm Exp $ */
/*
- * Copyright (c) 2001, 2013 Markus Friedl. All rights reserved.
+ * Copyright (c) 2019 Markus Friedl. All rights reserved.
* Copyright (c) 2010 Damien Miller. All rights reserved.
* Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
*
@@ -29,20 +29,16 @@
#include <sys/types.h>
-#include <signal.h>
+#include <stdio.h>
#include <string.h>
+#include <signal.h>
-#include <openssl/bn.h>
-#include <openssl/evp.h>
-
-#include "sshbuf.h"
-#include "ssh2.h"
#include "sshkey.h"
-#include "cipher.h"
#include "kex.h"
-#include "log.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])
@@ -142,3 +138,109 @@ kex_c25519_hash(
#endif
return 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->kem_client_pub = buf;
+ buf = NULL;
+ out:
+ sshbuf_free(buf);
+ return r;
+}
+
+int
+kex_c25519_enc(struct kex *kex, const u_char *pkblob,
+ size_t pklen, struct sshbuf **server_blobp, struct sshbuf **shared_secretp)
+{
+ struct sshbuf *server_blob = NULL;
+ struct sshbuf *buf = NULL;
+ u_char *server_pub;
+ u_char server_key[CURVE25519_SIZE];
+ int r;
+
+ *server_blobp = NULL;
+ *shared_secretp = NULL;
+
+ if (pklen != CURVE25519_SIZE) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
+#ifdef DEBUG_KEXECDH
+ dump_digest("client public key 25519:", pkblob, 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, pkblob, 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 u_char *pkblob,
+ size_t pklen, struct sshbuf **shared_secretp)
+{
+ struct sshbuf *buf = NULL;
+ int r;
+
+ *shared_secretp = NULL;
+
+ if (pklen != CURVE25519_SIZE) {
+ r = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ }
+#ifdef DEBUG_KEXECDH
+ dump_digest("server public key c25519:", pkblob, 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, pkblob,
+ 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;
+}