diff options
| -rw-r--r-- | ChangeLog | 2 | ||||
| -rw-r--r-- | kexc25519.c | 127 | ||||
| -rw-r--r-- | kexc25519c.c | 128 | ||||
| -rw-r--r-- | kexc25519s.c | 123 |
4 files changed, 380 insertions, 0 deletions
@@ -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 00000000..348a7d50 --- /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 00000000..f741566c --- /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 00000000..784841b8 --- /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); +} |