diff options
Diffstat (limited to 'kexdh.c')
| -rw-r--r-- | kexdh.c | 234 |
1 files changed, 4 insertions, 230 deletions
@@ -23,23 +23,16 @@ */ #include "includes.h" -RCSID("$OpenBSD: kexdh.c,v 1.18 2002/03/18 17:50:31 provos Exp $"); +RCSID("$OpenBSD: kexdh.c,v 1.19 2003/02/16 17:09:57 markus Exp $"); -#include <openssl/crypto.h> -#include <openssl/bn.h> +#include <openssl/evp.h> -#include "xmalloc.h" #include "buffer.h" #include "bufaux.h" -#include "key.h" -#include "kex.h" -#include "log.h" -#include "packet.h" -#include "dh.h" #include "ssh2.h" -#include "monitor_wrap.h" +#include "kex.h" -static u_char * +u_char * kex_dh_hash( char *client_version_string, char *server_version_string, @@ -86,222 +79,3 @@ kex_dh_hash( #endif return digest; } - -/* client */ - -static void -kexdh_client(Kex *kex) -{ - BIGNUM *dh_server_pub = NULL, *shared_secret = NULL; - DH *dh; - Key *server_host_key; - u_char *server_host_key_blob = NULL, *signature = NULL; - u_char *kbuf, *hash; - u_int klen, kout, slen, sbloblen; - - /* generate and send 'e', client DH public key */ - dh = dh_new_group1(); - dh_gen_key(dh, kex->we_need * 8); - packet_start(SSH2_MSG_KEXDH_INIT); - packet_put_bignum2(dh->pub_key); - packet_send(); - - debug("sending SSH2_MSG_KEXDH_INIT"); -#ifdef DEBUG_KEXDH - DHparams_print_fp(stderr, dh); - fprintf(stderr, "pub= "); - BN_print_fp(stderr, dh->pub_key); - fprintf(stderr, "\n"); -#endif - - debug("expecting SSH2_MSG_KEXDH_REPLY"); - packet_read_expect(SSH2_MSG_KEXDH_REPLY); - - /* key, cert */ - 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"); - - /* DH paramter f, server public DH key */ - if ((dh_server_pub = BN_new()) == NULL) - fatal("dh_server_pub == NULL"); - packet_get_bignum2(dh_server_pub); - -#ifdef DEBUG_KEXDH - fprintf(stderr, "dh_server_pub= "); - BN_print_fp(stderr, dh_server_pub); - fprintf(stderr, "\n"); - debug("bits %d", BN_num_bits(dh_server_pub)); -#endif - - /* signed H */ - signature = packet_get_string(&slen); - packet_check_eom(); - - if (!dh_pub_is_valid(dh, dh_server_pub)) - packet_disconnect("bad server public DH value"); - - klen = DH_size(dh); - kbuf = xmalloc(klen); - kout = DH_compute_key(kbuf, dh_server_pub, dh); -#ifdef DEBUG_KEXDH - dump_digest("shared secret", kbuf, kout); -#endif - if ((shared_secret = BN_new()) == NULL) - fatal("kexdh_client: BN_new failed"); - BN_bin2bn(kbuf, kout, shared_secret); - memset(kbuf, 0, klen); - xfree(kbuf); - - /* calc and verify H */ - hash = kex_dh_hash( - 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, - dh->pub_key, - dh_server_pub, - shared_secret - ); - xfree(server_host_key_blob); - BN_clear_free(dh_server_pub); - DH_free(dh); - - if (key_verify(server_host_key, signature, slen, hash, 20) != 1) - fatal("key_verify failed for server_host_key"); - key_free(server_host_key); - xfree(signature); - - /* save session id */ - if (kex->session_id == NULL) { - kex->session_id_len = 20; - kex->session_id = xmalloc(kex->session_id_len); - memcpy(kex->session_id, hash, kex->session_id_len); - } - - kex_derive_keys(kex, hash, shared_secret); - BN_clear_free(shared_secret); - kex_finish(kex); -} - -/* server */ - -static void -kexdh_server(Kex *kex) -{ - BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; - DH *dh; - Key *server_host_key; - u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL; - u_int sbloblen, klen, kout; - u_int slen; - - /* generate server DH public key */ - dh = dh_new_group1(); - dh_gen_key(dh, kex->we_need * 8); - - debug("expecting SSH2_MSG_KEXDH_INIT"); - packet_read_expect(SSH2_MSG_KEXDH_INIT); - - if (kex->load_host_key == NULL) - fatal("Cannot load hostkey"); - server_host_key = kex->load_host_key(kex->hostkey_type); - if (server_host_key == NULL) - fatal("Unsupported hostkey type %d", kex->hostkey_type); - - /* key, cert */ - if ((dh_client_pub = BN_new()) == NULL) - fatal("dh_client_pub == NULL"); - packet_get_bignum2(dh_client_pub); - packet_check_eom(); - -#ifdef DEBUG_KEXDH - fprintf(stderr, "dh_client_pub= "); - BN_print_fp(stderr, dh_client_pub); - fprintf(stderr, "\n"); - debug("bits %d", BN_num_bits(dh_client_pub)); -#endif - -#ifdef DEBUG_KEXDH - DHparams_print_fp(stderr, dh); - fprintf(stderr, "pub= "); - BN_print_fp(stderr, dh->pub_key); - fprintf(stderr, "\n"); -#endif - if (!dh_pub_is_valid(dh, dh_client_pub)) - packet_disconnect("bad client public DH value"); - - klen = DH_size(dh); - kbuf = xmalloc(klen); - kout = DH_compute_key(kbuf, dh_client_pub, dh); -#ifdef DEBUG_KEXDH - dump_digest("shared secret", kbuf, kout); -#endif - if ((shared_secret = BN_new()) == NULL) - fatal("kexdh_server: BN_new failed"); - BN_bin2bn(kbuf, kout, shared_secret); - memset(kbuf, 0, klen); - xfree(kbuf); - - key_to_blob(server_host_key, &server_host_key_blob, &sbloblen); - - /* calc H */ - hash = kex_dh_hash( - 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, - dh_client_pub, - dh->pub_key, - shared_secret - ); - BN_clear_free(dh_client_pub); - - /* save session id := H */ - /* XXX hashlen depends on KEX */ - if (kex->session_id == NULL) { - kex->session_id_len = 20; - kex->session_id = xmalloc(kex->session_id_len); - memcpy(kex->session_id, hash, kex->session_id_len); - } - - /* sign H */ - /* XXX hashlen depends on KEX */ - PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, 20)); - - /* destroy_sensitive_data(); */ - - /* send server hostkey, DH pubkey 'f' and singed H */ - packet_start(SSH2_MSG_KEXDH_REPLY); - packet_put_string(server_host_key_blob, sbloblen); - packet_put_bignum2(dh->pub_key); /* f */ - packet_put_string(signature, slen); - packet_send(); - - xfree(signature); - xfree(server_host_key_blob); - /* have keys, free DH */ - DH_free(dh); - - kex_derive_keys(kex, hash, shared_secret); - BN_clear_free(shared_secret); - kex_finish(kex); -} - -void -kexdh(Kex *kex) -{ - if (kex->server) - kexdh_server(kex); - else - kexdh_client(kex); -} |