X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/d8ee838b135272f2f58f749bf32996d6b11a0b96..c4f51837081fc00e2c67c70da918a948590cd392:/kexdh.c diff --git a/kexdh.c b/kexdh.c index 7b6a2204..4bbb7d1d 100644 --- a/kexdh.c +++ b/kexdh.c @@ -23,20 +23,14 @@ */ #include "includes.h" -RCSID("$OpenBSD: kexdh.c,v 1.3 2001/04/04 09:48:34 markus Exp $"); +RCSID("$OpenBSD: kexdh.c,v 1.19 2003/02/16 17:09:57 markus Exp $"); -#include -#include +#include -#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 "kex.h" u_char * kex_dh_hash( @@ -44,19 +38,19 @@ kex_dh_hash( char *server_version_string, char *ckexinit, int ckexinitlen, char *skexinit, int skexinitlen, - char *serverhostkeyblob, int sbloblen, + u_char *serverhostkeyblob, int sbloblen, BIGNUM *client_dh_pub, BIGNUM *server_dh_pub, BIGNUM *shared_secret) { Buffer b; static u_char digest[EVP_MAX_MD_SIZE]; - EVP_MD *evp_md = EVP_sha1(); + const EVP_MD *evp_md = EVP_sha1(); EVP_MD_CTX md; buffer_init(&b); - buffer_put_string(&b, client_version_string, strlen(client_version_string)); - buffer_put_string(&b, server_version_string, strlen(server_version_string)); + 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); @@ -81,224 +75,7 @@ kex_dh_hash( buffer_free(&b); #ifdef DEBUG_KEX - dump_digest("hash", digest, evp_md->md_size); + dump_digest("hash", digest, EVP_MD_size(evp_md)); #endif return digest; } - -/* client */ - -void -kexdh_client(Kex *kex) -{ - BIGNUM *dh_server_pub = NULL, *shared_secret = NULL; - DH *dh; - Key *server_host_key; - char *server_host_key_blob = NULL, *signature = NULL; - u_char *kbuf, *hash; - u_int klen, kout, slen, sbloblen; - int dlen, plen; - - /* 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(&plen, 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 (kex->check_host_key == NULL) - fatal("cannot check server_host_key"); - kex->check_host_key(server_host_key); - - /* DH paramter f, server public DH key */ - dh_server_pub = BN_new(); - if (dh_server_pub == NULL) - fatal("dh_server_pub == NULL"); - packet_get_bignum2(dh_server_pub, &dlen); - -#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_done(); - - 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 - shared_secret = BN_new(); - 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_free(dh_server_pub); - DH_free(dh); - - if (key_verify(server_host_key, (u_char *)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 */ - -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; - int dlen, slen, plen; - - /* 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(&plen, 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 */ - dh_client_pub = BN_new(); - if (dh_client_pub == NULL) - fatal("dh_client_pub == NULL"); - packet_get_bignum2(dh_client_pub, &dlen); - -#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 - shared_secret = BN_new(); - 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), - (char *)server_host_key_blob, sbloblen, - dh_client_pub, - dh->pub_key, - shared_secret - ); - BN_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 */ - 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((char *)server_host_key_blob, sbloblen); - packet_put_bignum2(dh->pub_key); /* f */ - packet_put_string((char *)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); -}