/* * Copyright (C) 2005-2006 Martin Willi * Copyright (C) 2005 Jan Hutter * Hochschule fuer Technik Rapperswil * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. See . * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * * $Id$ */ #include #include "psk_authenticator.h" #include #include /** * Key pad for the AUTH method SHARED_KEY_MESSAGE_INTEGRITY_CODE. */ #define IKEV2_KEY_PAD "Key Pad for IKEv2" #define IKEV2_KEY_PAD_LENGTH 17 typedef struct private_psk_authenticator_t private_psk_authenticator_t; /** * Private data of an psk_authenticator_t object. */ struct private_psk_authenticator_t { /** * Public authenticator_t interface. */ psk_authenticator_t public; /** * Assigned IKE_SA */ ike_sa_t *ike_sa; }; /** * Builds the octets to be signed as described in section 2.15 of RFC 4306 */ chunk_t build_tbs_octets(chunk_t ike_sa_init, chunk_t nonce, identification_t *id, prf_t *prf) { u_int8_t id_header_buf[] = {0x00, 0x00, 0x00, 0x00}; chunk_t id_header = chunk_from_buf(id_header_buf); chunk_t id_with_header, id_prfd, id_encoding; id_header_buf[0] = id->get_type(id); id_encoding = id->get_encoding(id); id_with_header = chunk_cat("cc", id_header, id_encoding); prf->allocate_bytes(prf, id_with_header, &id_prfd); chunk_free(&id_with_header); return chunk_cat("ccm", ike_sa_init, nonce, id_prfd); } /** * Creates the AUTH data using auth method SHARED_KEY_MESSAGE_INTEGRITY_CODE. */ chunk_t build_shared_key_signature(chunk_t ike_sa_init, chunk_t nonce, chunk_t secret, identification_t *id, chunk_t skp, prf_t *prf) { chunk_t key_pad, key, auth_data, octets; prf->set_key(prf, skp); octets = build_tbs_octets(ike_sa_init, nonce, id, prf); /* AUTH = prf(prf(Shared Secret,"Key Pad for IKEv2"), ) */ key_pad.ptr = IKEV2_KEY_PAD; key_pad.len = IKEV2_KEY_PAD_LENGTH; prf->set_key(prf, secret); prf->allocate_bytes(prf, key_pad, &key); prf->set_key(prf, key); prf->allocate_bytes(prf, octets, &auth_data); DBG3(DBG_IKE, "octets = message + nonce + prf(Sk_px, IDx') %B", &octets); DBG3(DBG_IKE, "secret %B", &secret); DBG3(DBG_IKE, "keypad %B", &key_pad); DBG3(DBG_IKE, "prf(secret, keypad) %B", &key); DBG3(DBG_IKE, "AUTH = prf(prf(secret, keypad), octets) %B", &auth_data); chunk_free(&octets); chunk_free(&key); return auth_data; } /** * Implementation of authenticator_t.verify. */ static status_t verify(private_psk_authenticator_t *this, chunk_t ike_sa_init, chunk_t my_nonce, auth_payload_t *auth_payload) { chunk_t auth_data, recv_auth_data; identification_t *my_id, *other_id; shared_key_t *shared_key; enumerator_t *enumerator; bool authenticated = FALSE; int keys_found = 0; my_id = this->ike_sa->get_my_id(this->ike_sa); other_id = this->ike_sa->get_other_id(this->ike_sa); enumerator = charon->credentials->create_shared_enumerator( charon->credentials, SHARED_IKE, my_id, other_id); while (!authenticated && enumerator->enumerate(enumerator, &shared_key, NULL, NULL)) { keys_found++; auth_data = build_shared_key_signature(ike_sa_init, my_nonce, shared_key->get_key(shared_key), other_id, this->ike_sa->get_skp_verify(this->ike_sa), this->ike_sa->get_prf(this->ike_sa)); recv_auth_data = auth_payload->get_data(auth_payload); if (auth_data.len == recv_auth_data.len && memeq(auth_data.ptr, recv_auth_data.ptr, auth_data.len)) { DBG1(DBG_IKE, "authentication of '%D' with %N successful", other_id, auth_method_names, AUTH_PSK); authenticated = TRUE; } chunk_free(&auth_data); } enumerator->destroy(enumerator); if (!authenticated) { if (keys_found == 0) { DBG1(DBG_IKE, "no shared key found for '%D' - '%D'", my_id, other_id); return NOT_FOUND; } DBG1(DBG_IKE, "tried %d shared key%s for '%D' - '%D', but MAC mismatched", keys_found, keys_found == 1 ? "" : "s", my_id, other_id); return FAILED; } return SUCCESS; } /** * Implementation of authenticator_t.build. */ static status_t build(private_psk_authenticator_t *this, chunk_t ike_sa_init, chunk_t other_nonce, auth_payload_t **auth_payload) { shared_key_t *shared_key; chunk_t auth_data; identification_t *my_id, *other_id; my_id = this->ike_sa->get_my_id(this->ike_sa); other_id = this->ike_sa->get_other_id(this->ike_sa); DBG1(DBG_IKE, "authentication of '%D' (myself) with %N", my_id, auth_method_names, AUTH_PSK); shared_key = charon->credentials->get_shared(charon->credentials, SHARED_IKE, my_id, other_id); if (shared_key == NULL) { DBG1(DBG_IKE, "no shared key found for '%D' - '%D'", my_id, other_id); return NOT_FOUND; } auth_data = build_shared_key_signature(ike_sa_init, other_nonce, shared_key->get_key(shared_key), my_id, this->ike_sa->get_skp_build(this->ike_sa), this->ike_sa->get_prf(this->ike_sa)); shared_key->destroy(shared_key); DBG2(DBG_IKE, "successfully created shared key MAC"); *auth_payload = auth_payload_create(); (*auth_payload)->set_auth_method(*auth_payload, AUTH_PSK); (*auth_payload)->set_data(*auth_payload, auth_data); chunk_free(&auth_data); return SUCCESS; } /** * Implementation of authenticator_t.destroy. */ static void destroy(private_psk_authenticator_t *this) { free(this); } /* * Described in header. */ psk_authenticator_t *psk_authenticator_create(ike_sa_t *ike_sa) { private_psk_authenticator_t *this = malloc_thing(private_psk_authenticator_t); /* public functions */ this->public.authenticator_interface.verify = (status_t(*)(authenticator_t*,chunk_t,chunk_t,auth_payload_t*))verify; this->public.authenticator_interface.build = (status_t(*)(authenticator_t*,chunk_t,chunk_t,auth_payload_t**))build; this->public.authenticator_interface.destroy = (void(*)(authenticator_t*))destroy; /* private data */ this->ike_sa = ike_sa; return &this->public; }