- (djm) [kexc25519.c kexc25519c.c kexc25519s.c] Import missed files from

   KEX/curve25519 change

4 files changed, 380 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index e7b773de8..1d3e74671 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -24,6 +24,8 @@
      [roaming_common.c]
      fix a couple of function definitions foo() -> foo(void)
      (-Wold-style-definition)
+ - (djm) [kexc25519.c kexc25519c.c kexc25519s.c] Import missed files from
+   KEX/curve25519 change
 
 20131103
  - (dtucker) [openbsd-compat/bsd-misc.c] Include time.h for nanosleep.
diff --git a/kexc25519.c b/kexc25519.c
new file mode 100644
index 000000000..348a7d50d
--- /dev/null
+++ b/kexc25519.c
@@ -0,0 +1,127 @@
+/* $OpenBSD: kexc25519.c,v 1.2 2013/11/02 22:02:14 markus Exp $ */
+/*
+ * Copyright (c) 2001, 2013 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 <signal.h>
+#include <string.h>
+
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+
+#include "buffer.h"
+#include "ssh2.h"
+#include "key.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.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);
+}
+
+BIGNUM *
+kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
+    const u_char pub[CURVE25519_SIZE])
+{
+        u_char shared_key[CURVE25519_SIZE];
+        BIGNUM *shared_secret;
+
+        crypto_scalarmult_curve25519(shared_key, key, pub);
+#ifdef DEBUG_KEXECDH
+        dump_digest("shared secret", shared_key, CURVE25519_SIZE);
+#endif
+        if ((shared_secret = BN_new()) == NULL)
+                fatal("%s: BN_new failed", __func__);
+        if (BN_bin2bn(shared_key, sizeof(shared_key), shared_secret) == NULL)
+                fatal("%s: BN_bin2bn failed", __func__);
+        memset(shared_key, 0, CURVE25519_SIZE); /* XXX explicit_bzero() */
+        return (shared_secret);
+}
+
+void
+kex_c25519_hash(
+    const EVP_MD *evp_md,
+    char *client_version_string,
+    char *server_version_string,
+    char *ckexinit, int ckexinitlen,
+    char *skexinit, int skexinitlen,
+    u_char *serverhostkeyblob, int sbloblen,
+    const u_char client_dh_pub[CURVE25519_SIZE],
+    const u_char server_dh_pub[CURVE25519_SIZE],
+    const BIGNUM *shared_secret,
+    u_char **hash, u_int *hashlen)
+{
+        Buffer b;
+        EVP_MD_CTX md;
+        static u_char digest[EVP_MAX_MD_SIZE];
+
+        buffer_init(&b);
+        buffer_put_cstring(&b, client_version_string);
+        buffer_put_cstring(&b, server_version_string);
+
+        /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
+        buffer_put_int(&b, ckexinitlen+1);
+        buffer_put_char(&b, SSH2_MSG_KEXINIT);
+        buffer_append(&b, ckexinit, ckexinitlen);
+        buffer_put_int(&b, skexinitlen+1);
+        buffer_put_char(&b, SSH2_MSG_KEXINIT);
+        buffer_append(&b, skexinit, skexinitlen);
+
+        buffer_put_string(&b, serverhostkeyblob, sbloblen);
+        buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE);
+        buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE);
+        buffer_put_bignum2(&b, shared_secret);
+
+#ifdef DEBUG_KEX
+        buffer_dump(&b);
+#endif
+        EVP_DigestInit(&md, evp_md);
+        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
+        EVP_DigestFinal(&md, digest, NULL);
+
+        buffer_free(&b);
+
+#ifdef DEBUG_KEX
+        dump_digest("hash", digest, EVP_MD_size(evp_md));
+#endif
+        *hash = digest;
+        *hashlen = EVP_MD_size(evp_md);
+}
diff --git a/kexc25519c.c b/kexc25519c.c
new file mode 100644
index 000000000..f741566cc
--- /dev/null
+++ b/kexc25519c.c
@@ -0,0 +1,128 @@
+/* $OpenBSD: kexc25519c.c,v 1.2 2013/11/02 22:02:14 markus Exp $ */
+/*
+ * Copyright (c) 2001 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 "xmalloc.h"
+#include "buffer.h"
+#include "key.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "ssh2.h"
+
+void
+kexc25519_client(Kex *kex)
+{
+        BIGNUM *shared_secret;
+        Key *server_host_key;
+        u_char client_key[CURVE25519_SIZE];
+        u_char client_pubkey[CURVE25519_SIZE];
+        u_char *server_pubkey = NULL;
+        u_char *server_host_key_blob = NULL, *signature = NULL;
+        u_char *hash;
+        u_int slen, sbloblen, hashlen;
+
+        kexc25519_keygen(client_key, client_pubkey);
+
+        packet_start(SSH2_MSG_KEX_ECDH_INIT);
+        packet_put_string(client_pubkey, sizeof(client_pubkey));
+        packet_send();
+        debug("sending SSH2_MSG_KEX_ECDH_INIT");
+
+#ifdef DEBUG_KEXECDH
+        dump_digest("client private key:", client_key, sizeof(client_key));
+#endif
+
+        debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
+        packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
+
+        /* hostkey */
+        server_host_key_blob = packet_get_string(&sbloblen);
+        server_host_key = key_from_blob(server_host_key_blob, sbloblen);
+        if (server_host_key == NULL)
+                fatal("cannot decode server_host_key_blob");
+        if (server_host_key->type != kex->hostkey_type)
+                fatal("type mismatch for decoded server_host_key_blob");
+        if (kex->verify_host_key == NULL)
+                fatal("cannot verify server_host_key");
+        if (kex->verify_host_key(server_host_key) == -1)
+                fatal("server_host_key verification failed");
+
+        /* Q_S, server public key */
+        server_pubkey = packet_get_string(&slen);
+        if (slen != CURVE25519_SIZE)
+                fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
+
+#ifdef DEBUG_KEXECDH
+        dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
+#endif
+
+        /* signed H */
+        signature = packet_get_string(&slen);
+        packet_check_eom();
+
+        shared_secret = kexc25519_shared_key(client_key, server_pubkey);
+
+        /* calc and verify H */
+        kex_c25519_hash(
+            kex->evp_md,
+            kex->client_version_string,
+            kex->server_version_string,
+            buffer_ptr(&kex->my), buffer_len(&kex->my),
+            buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+            server_host_key_blob, sbloblen,
+            client_pubkey,
+            server_pubkey,
+            shared_secret,
+            &hash, &hashlen
+        );
+        free(server_host_key_blob);
+        free(server_pubkey);
+        if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
+                fatal("key_verify failed for server_host_key");
+        key_free(server_host_key);
+        free(signature);
+
+        /* save session id */
+        if (kex->session_id == NULL) {
+                kex->session_id_len = hashlen;
+                kex->session_id = xmalloc(kex->session_id_len);
+                memcpy(kex->session_id, hash, kex->session_id_len);
+        }
+
+        kex_derive_keys(kex, hash, hashlen, shared_secret);
+        BN_clear_free(shared_secret);
+        kex_finish(kex);
+}
diff --git a/kexc25519s.c b/kexc25519s.c
new file mode 100644
index 000000000..784841b82
--- /dev/null
+++ b/kexc25519s.c
@@ -0,0 +1,123 @@
+/* $OpenBSD: kexc25519s.c,v 1.2 2013/11/02 22:02:14 markus Exp $ */
+/*
+ * Copyright (c) 2001 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2010 Damien Miller.  All rights reserved.
+ * Copyright (c) 2013 Aris Adamantiadis.  All rights reserved.
+ *
+ * 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 <string.h>
+#include <signal.h>
+
+#include "xmalloc.h"
+#include "buffer.h"
+#include "key.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "ssh2.h"
+
+void
+kexc25519_server(Kex *kex)
+{
+        BIGNUM *shared_secret;
+        Key *server_host_private, *server_host_public;
+        u_char *server_host_key_blob = NULL, *signature = NULL;
+        u_char server_key[CURVE25519_SIZE];
+        u_char *client_pubkey = NULL;
+        u_char server_pubkey[CURVE25519_SIZE];
+        u_char *hash;
+        u_int slen, sbloblen, hashlen;
+
+        /* generate private key */
+        kexc25519_keygen(server_key, server_pubkey);
+#ifdef DEBUG_KEXECDH
+        dump_digest("server private key:", server_key, sizeof(server_key));
+#endif
+
+        if (kex->load_host_public_key == NULL ||
+            kex->load_host_private_key == NULL)
+                fatal("Cannot load hostkey");
+        server_host_public = kex->load_host_public_key(kex->hostkey_type);
+        if (server_host_public == NULL)
+                fatal("Unsupported hostkey type %d", kex->hostkey_type);
+        server_host_private = kex->load_host_private_key(kex->hostkey_type);
+
+        debug("expecting SSH2_MSG_KEX_ECDH_INIT");
+        packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
+        client_pubkey = packet_get_string(&slen);
+        if (slen != CURVE25519_SIZE)
+                fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
+        packet_check_eom();
+
+#ifdef DEBUG_KEXECDH
+        dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
+#endif
+
+        shared_secret = kexc25519_shared_key(server_key, client_pubkey);
+
+        /* calc H */
+        key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
+        kex_c25519_hash(
+            kex->evp_md,
+            kex->client_version_string,
+            kex->server_version_string,
+            buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+            buffer_ptr(&kex->my), buffer_len(&kex->my),
+            server_host_key_blob, sbloblen,
+            client_pubkey,
+            server_pubkey,
+            shared_secret,
+            &hash, &hashlen
+        );
+
+        /* save session id := H */
+        if (kex->session_id == NULL) {
+                kex->session_id_len = hashlen;
+                kex->session_id = xmalloc(kex->session_id_len);
+                memcpy(kex->session_id, hash, kex->session_id_len);
+        }
+
+        /* sign H */
+        kex->sign(server_host_private, server_host_public, &signature, &slen,
+            hash, hashlen);
+
+        /* destroy_sensitive_data(); */
+
+        /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
+        packet_start(SSH2_MSG_KEX_ECDH_REPLY);
+        packet_put_string(server_host_key_blob, sbloblen);
+        packet_put_string(server_pubkey, sizeof(server_pubkey));
+        packet_put_string(signature, slen);
+        packet_send();
+
+        free(signature);
+        free(server_host_key_blob);
+        /* have keys, free server key */
+        free(client_pubkey);
+        kex_derive_keys(kex, hash, hashlen, shared_secret);
+        BN_clear_free(shared_secret);
+        kex_finish(kex);
+}