src/libcharon/plugins/eap_sim/eap_sim_peer.c - manifest_repos/strongswan - Git at Google

 /*
  * Copyright (C) 2007-2009 Martin Willi
  * HSR 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 <http://www.fsf.org/copyleft/gpl.txt>.
  *
  * 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.
  */

 #include "eap_sim_peer.h"

 #include <daemon.h>

 #include <simaka_message.h>
 #include <simaka_manager.h>

 /* number of tries we do authenticate */
 #define MAX_TRIES 3

 /* number of triplets for one authentication */
 #define TRIPLET_COUNT 3

 /** length of the AT_NONCE_MT nonce value */
 #define NONCE_LEN 16

 typedef struct private_eap_sim_peer_t private_eap_sim_peer_t;

 /**
  * Private data of an eap_sim_peer_t object.
  */
 struct private_eap_sim_peer_t {

 	/**
 	 * Public authenticator_t interface.
 	 */
 	eap_sim_peer_t public;

 	/**
 	 * SIM backend manager
 	 */
 	simaka_manager_t *mgr;

 	/**
 	 * permanent ID of peer
 	 */
 	identification_t *permanent;

 	/**
 	 * Pseudonym identity the peer uses
 	 */
 	identification_t *pseudonym;

 	/**
 	 * Reauthentication identity the peer uses
 	 */
 	identification_t *reauth;

 	/**
 	 * EAP message identifier
 	 */
 	uint8_t identifier;

 	/**
 	 * EAP-SIM crypto helper
 	 */
 	simaka_crypto_t *crypto;

 	/**
 	 * how many times we try to authenticate
 	 */
 	int tries;

 	/**
 	 * version list received from server
 	 */
 	chunk_t version_list;

 	/**
 	 * Nonce value used in AT_NONCE_MT/AT_NONCE_S
 	 */
 	chunk_t nonce;

 	/**
 	 * MSK, used for EAP-SIM based IKEv2 authentication
 	 */
 	chunk_t msk;

 	/**
 	 * Master key, if reauthentication is used
 	 */
 	char mk[HASH_SIZE_SHA1];

 	/**
 	 * Counter value if reauthentication is used
 	 */
 	uint16_t counter;
 };

 /* version of SIM protocol we speak */
 static chunk_t version = chunk_from_chars(0x00,0x01);

 /**
  * Generate a payload from a message, destroy message
  */
 static bool generate_payload(simaka_message_t *message, chunk_t data,
 							 eap_payload_t **out)
 {
 	chunk_t chunk;
 	bool ok;

 	ok = message->generate(message, data, &chunk);
 	if (ok)
 	{
 		*out = eap_payload_create_data_own(chunk);
 	}
 	message->destroy(message);
 	return ok;
 }

 /**
  * Create a SIM_CLIENT_ERROR
  */
 static bool create_client_error(private_eap_sim_peer_t *this,
 								simaka_client_error_t code, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	uint16_t encoded;

 	DBG1(DBG_IKE, "sending client error '%N'", simaka_client_error_names, code);

 	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
 									SIM_CLIENT_ERROR, this->crypto);
 	encoded = htons(code);
 	message->add_attribute(message, AT_CLIENT_ERROR_CODE,
 						   chunk_create((char*)&encoded, sizeof(encoded)));
 	return generate_payload(message, chunk_empty, out);
 }

 /**
  * process an EAP-SIM/Request/Start message
  */
 static status_t process_start(private_eap_sim_peer_t *this,
 							  simaka_message_t *in, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	enumerator_t *enumerator;
 	simaka_attribute_t type;
 	chunk_t data, id = chunk_empty;
 	rng_t *rng;
 	bool supported = FALSE;
 	simaka_attribute_t id_req = 0;

 	/* reset previously uses reauthentication/pseudonym data */
 	this->crypto->clear_keys(this->crypto);
 	DESTROY_IF(this->pseudonym);
 	this->pseudonym = NULL;
 	DESTROY_IF(this->reauth);
 	this->reauth = NULL;

 	enumerator = in->create_attribute_enumerator(in);
 	while (enumerator->enumerate(enumerator, &type, &data))
 	{
 		switch (type)
 		{
 			case AT_VERSION_LIST:
 			{
 				free(this->version_list.ptr);
 				this->version_list = chunk_clone(data);
 				while (data.len >= version.len)
 				{
 					if (memeq(data.ptr, version.ptr, version.len))
 					{
 						supported = TRUE;
 						break;
 					}
 				}
 				break;
 			}
 			case AT_ANY_ID_REQ:
 			case AT_FULLAUTH_ID_REQ:
 			case AT_PERMANENT_ID_REQ:
 				id_req = type;
 				break;
 			default:
 				if (!simaka_attribute_skippable(type))
 				{
 					enumerator->destroy(enumerator);
 					if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 					{
 						return FAILED;
 					}
 					return NEED_MORE;
 				}
 				break;
 		}
 	}
 	enumerator->destroy(enumerator);

 	if (!supported)
 	{
 		DBG1(DBG_IKE, "server does not support EAP-SIM version number 1");
 		if (!create_client_error(this, SIM_UNSUPPORTED_VERSION, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}

 	switch (id_req)
 	{
 		case AT_ANY_ID_REQ:
 			this->reauth = this->mgr->card_get_reauth(this->mgr,
 									this->permanent, this->mk, &this->counter);
 			if (this->reauth)
 			{
 				id = this->reauth->get_encoding(this->reauth);
 				break;
 			}
 			/* FALL */
 		case AT_FULLAUTH_ID_REQ:
 			this->pseudonym = this->mgr->card_get_pseudonym(this->mgr,
 															this->permanent);
 			if (this->pseudonym)
 			{
 				id = this->pseudonym->get_encoding(this->pseudonym);
 				break;
 			}
 			/* FALL */
 		case AT_PERMANENT_ID_REQ:
 			id = this->permanent->get_encoding(this->permanent);
 			break;
 		default:
 			break;
 	}

 	/* generate AT_NONCE_MT value */
 	rng = this->crypto->get_rng(this->crypto);
 	free(this->nonce.ptr);
 	if (!rng->allocate_bytes(rng, NONCE_LEN, &this->nonce))
 	{
 		return FAILED;
 	}

 	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
 									SIM_START, this->crypto);
 	if (!this->reauth)
 	{
 		message->add_attribute(message, AT_SELECTED_VERSION, version);
 		message->add_attribute(message, AT_NONCE_MT, this->nonce);
 	}
 	if (id.len)
 	{
 		message->add_attribute(message, AT_IDENTITY, id);
 	}
 	if (!generate_payload(message, chunk_empty, out))
 	{
 		return FAILED;
 	}
 	return NEED_MORE;
 }

 /**
  * process an EAP-SIM/Request/Challenge message
  */
 static status_t process_challenge(private_eap_sim_peer_t *this,
 								  simaka_message_t *in, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	enumerator_t *enumerator;
 	simaka_attribute_t type;
 	chunk_t data, rands = chunk_empty, kcs, kc, sreses, sres, mk;
 	identification_t *id;

 	if (this->tries-- <= 0)
 	{
 		/* give up without notification. This hack is required as some buggy
 		 * server implementations won't respect our client-error. */
 		return FAILED;
 	}

 	enumerator = in->create_attribute_enumerator(in);
 	while (enumerator->enumerate(enumerator, &type, &data))
 	{
 		switch (type)
 		{
 			case AT_RAND:
 				rands = data;
 				break;
 			default:
 				if (!simaka_attribute_skippable(type))
 				{
 					enumerator->destroy(enumerator);
 					if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 					{
 						return FAILED;
 					}
 					return NEED_MORE;
 				}
 				break;
 		}
 	}
 	enumerator->destroy(enumerator);

 	/* excepting two or three RAND, each 16 bytes. We require two valid
 	 * and different RANDs */
 	if ((rands.len != 2 * SIM_RAND_LEN && rands.len != 3 * SIM_RAND_LEN) ||
 		memeq_const(rands.ptr, rands.ptr + SIM_RAND_LEN, SIM_RAND_LEN))
 	{
 		DBG1(DBG_IKE, "no valid AT_RAND received");
 		if (!create_client_error(this, SIM_INSUFFICIENT_CHALLENGES, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}
 	/* get two or three KCs/SRESes from SIM using RANDs */
 	kcs = kc = chunk_alloca(rands.len / 2);
 	sreses = sres = chunk_alloca(rands.len / 4);
 	while (rands.len >= SIM_RAND_LEN)
 	{
 		if (!this->mgr->card_get_triplet(this->mgr, this->permanent,
 										 rands.ptr, sres.ptr, kc.ptr))
 		{
 			DBG1(DBG_IKE, "unable to get EAP-SIM triplet");
 			if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 			{
 				return FAILED;
 			}
 			return NEED_MORE;
 		}
 		DBG3(DBG_IKE, "got triplet for RAND %b\n  Kc %b\n  SRES %b",
 			 rands.ptr, SIM_RAND_LEN, sres.ptr, SIM_SRES_LEN, kc.ptr, SIM_KC_LEN);
 		kc = chunk_skip(kc, SIM_KC_LEN);
 		sres = chunk_skip(sres, SIM_SRES_LEN);
 		rands = chunk_skip(rands, SIM_RAND_LEN);
 	}

 	id = this->permanent;
 	if (this->pseudonym)
 	{
 		id = this->pseudonym;
 	}
 	data = chunk_cata("cccc", kcs, this->nonce, this->version_list, version);
 	chunk_clear(&this->msk);
 	if (!this->crypto->derive_keys_full(this->crypto, id, data, &mk, &this->msk))
 	{
 		return FAILED;
 	}
 	memcpy(this->mk, mk.ptr, mk.len);
 	chunk_clear(&mk);

 	/* Verify AT_MAC attribute, signature is over "EAP packet | NONCE_MT", and
 	 * parse() again after key derivation, reading encrypted attributes */
 	if (!in->verify(in, this->nonce) || !in->parse(in))
 	{
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}

 	enumerator = in->create_attribute_enumerator(in);
 	while (enumerator->enumerate(enumerator, &type, &data))
 	{
 		switch (type)
 		{
 			case AT_NEXT_REAUTH_ID:
 				this->counter = 0;
 				id = identification_create_from_data(data);
 				this->mgr->card_set_reauth(this->mgr, this->permanent, id,
 										   this->mk, this->counter);
 				id->destroy(id);
 				break;
 			case AT_NEXT_PSEUDONYM:
 				id = identification_create_from_data(data);
 				this->mgr->card_set_pseudonym(this->mgr, this->permanent, id);
 				id->destroy(id);
 				break;
 			default:
 				break;
 		}
 	}
 	enumerator->destroy(enumerator);

 	/* build response with AT_MAC, built over "EAP packet | n*SRES" */
 	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
 									SIM_CHALLENGE, this->crypto);
 	if (!generate_payload(message, sreses, out))
 	{
 		return FAILED;
 	}
 	return NEED_MORE;
 }

 /**
  * Check if a received counter value is acceptable
  */
 static bool counter_too_small(private_eap_sim_peer_t *this, chunk_t chunk)
 {
 	uint16_t counter;

 	memcpy(&counter, chunk.ptr, sizeof(counter));
 	counter = htons(counter);
 	return counter < this->counter;
 }

 /**
  * process an EAP-SIM/Request/Re-Authentication message
  */
 static status_t process_reauthentication(private_eap_sim_peer_t *this,
 									simaka_message_t *in, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	enumerator_t *enumerator;
 	simaka_attribute_t type;
 	chunk_t data, counter = chunk_empty, nonce = chunk_empty, id = chunk_empty;

 	if (!this->reauth)
 	{
 		DBG1(DBG_IKE, "received %N, but not expected",
 			 simaka_subtype_names, SIM_REAUTHENTICATION);
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}

 	if (!this->crypto->derive_keys_reauth(this->crypto,
 									chunk_create(this->mk, HASH_SIZE_SHA1)))
 	{
 		return FAILED;
 	}

 	/* verify MAC and parse again with decryption key */
 	if (!in->verify(in, chunk_empty) || !in->parse(in))
 	{
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}

 	enumerator = in->create_attribute_enumerator(in);
 	while (enumerator->enumerate(enumerator, &type, &data))
 	{
 		switch (type)
 		{
 			case AT_COUNTER:
 				counter = data;
 				break;
 			case AT_NONCE_S:
 				nonce = data;
 				break;
 			case AT_NEXT_REAUTH_ID:
 				id = data;
 				break;
 			default:
 				if (!simaka_attribute_skippable(type))
 				{
 					enumerator->destroy(enumerator);
 					if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 					{
 						return FAILED;
 					}
 					return NEED_MORE;
 				}
 				break;
 		}
 	}
 	enumerator->destroy(enumerator);

 	if (!nonce.len || !counter.len)
 	{
 		DBG1(DBG_IKE, "EAP-SIM/Request/Re-Authentication message incomplete");
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}

 	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
 									SIM_REAUTHENTICATION, this->crypto);
 	if (counter_too_small(this, counter))
 	{
 		DBG1(DBG_IKE, "reauthentication counter too small");
 		message->add_attribute(message, AT_COUNTER_TOO_SMALL, chunk_empty);
 	}
 	else
 	{
 		chunk_clear(&this->msk);
 		if (!this->crypto->derive_keys_reauth_msk(this->crypto,
 						this->reauth, counter, nonce,
 						chunk_create(this->mk, HASH_SIZE_SHA1), &this->msk))
 		{
 			message->destroy(message);
 			return FAILED;
 		}
 		if (id.len)
 		{
 			identification_t *reauth;

 			reauth = identification_create_from_data(data);
 			this->mgr->card_set_reauth(this->mgr, this->permanent, reauth,
 									   this->mk, this->counter);
 			reauth->destroy(reauth);
 		}
 	}
 	message->add_attribute(message, AT_COUNTER, counter);
 	if (!generate_payload(message, nonce, out))
 	{
 		return FAILED;
 	}
 	return NEED_MORE;
 }

 /**
  * process an EAP-SIM/Request/Notification message
  */
 static status_t process_notification(private_eap_sim_peer_t *this,
 									 simaka_message_t *in, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	enumerator_t *enumerator;
 	simaka_attribute_t type;
 	chunk_t data;
 	bool success = TRUE;

 	enumerator = in->create_attribute_enumerator(in);
 	while (enumerator->enumerate(enumerator, &type, &data))
 	{
 		if (type == AT_NOTIFICATION)
 		{
 			uint16_t code;

 			memcpy(&code, data.ptr, sizeof(code));
 			code = ntohs(code);

 			/* test success bit */
 			if (!(data.ptr[0] & 0x80))
 			{
 				DBG1(DBG_IKE, "received EAP-SIM notification error '%N'",
 					 simaka_notification_names, code);
 			}
 			else
 			{
 				DBG1(DBG_IKE, "received EAP-SIM notification '%N'",
 					 simaka_notification_names, code);
 			}
 		}
 		else if (!simaka_attribute_skippable(type))
 		{
 			success = FALSE;
 			break;
 		}
 	}
 	enumerator->destroy(enumerator);

 	if (success)
 	{	/* empty notification reply */
 		message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
 										SIM_NOTIFICATION, this->crypto);
 		if (!generate_payload(message, chunk_empty, out))
 		{
 			return FAILED;
 		}
 	}
 	else
 	{
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 	}
 	return NEED_MORE;
 }

 METHOD(eap_method_t, process, status_t,
 	private_eap_sim_peer_t *this, eap_payload_t *in, eap_payload_t **out)
 {
 	simaka_message_t *message;
 	status_t status;

 	/* store received EAP message identifier */
 	this->identifier = in->get_identifier(in);

 	message = simaka_message_create_from_payload(in->get_data(in), this->crypto);
 	if (!message)
 	{
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}
 	if (!message->parse(message))
 	{
 		message->destroy(message);
 		if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 		{
 			return FAILED;
 		}
 		return NEED_MORE;
 	}
 	switch (message->get_subtype(message))
 	{
 		case SIM_START:
 			status = process_start(this, message, out);
 			break;
 		case SIM_CHALLENGE:
 			status = process_challenge(this, message, out);
 			break;
 		case SIM_REAUTHENTICATION:
 			status = process_reauthentication(this, message, out);
 			break;
 		case SIM_NOTIFICATION:
 			status = process_notification(this, message, out);
 			break;
 		default:
 			DBG1(DBG_IKE, "unable to process EAP-SIM subtype %N",
 				 simaka_subtype_names, message->get_subtype(message));
 			if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
 			{
 				status = FAILED;
 			}
 			else
 			{
 				status = NEED_MORE;
 			}
 			break;
 	}
 	message->destroy(message);
 	return status;
 }

 METHOD(eap_method_t, initiate, status_t,
 	private_eap_sim_peer_t *this, eap_payload_t **out)
 {
 	/* peer never initiates */
 	return FAILED;
 }

 METHOD(eap_method_t, get_type, eap_type_t,
 	private_eap_sim_peer_t *this, uint32_t *vendor)
 {
 	*vendor = 0;
 	return EAP_SIM;
 }

 METHOD(eap_method_t, get_msk, status_t,
 	private_eap_sim_peer_t *this, chunk_t *msk)
 {
 	if (this->msk.ptr)
 	{
 		*msk = this->msk;
 		return SUCCESS;
 	}
 	return FAILED;
 }

 METHOD(eap_method_t, get_identifier, uint8_t,
 	private_eap_sim_peer_t *this)
 {
 	return this->identifier;
 }

 METHOD(eap_method_t, set_identifier, void,
 	private_eap_sim_peer_t *this, uint8_t identifier)
 {
 	this->identifier = identifier;
 }

 METHOD(eap_method_t, is_mutual, bool,
 	private_eap_sim_peer_t *this)
 {
 	return TRUE;
 }

 METHOD(eap_method_t, destroy, void,
 	private_eap_sim_peer_t *this)
 {
 	this->permanent->destroy(this->permanent);
 	DESTROY_IF(this->pseudonym);
 	DESTROY_IF(this->reauth);
 	this->crypto->destroy(this->crypto);
 	free(this->version_list.ptr);
 	free(this->nonce.ptr);
 	free(this->msk.ptr);
 	free(this);
 }

 /*
  * Described in header.
  */
 eap_sim_peer_t *eap_sim_peer_create(identification_t *server,
 									identification_t *peer)
 {
 	private_eap_sim_peer_t *this;

 	INIT(this,
 		.public = {
 			.interface = {
 				.initiate = _initiate,
 				.process = _process,
 				.get_type = _get_type,
 				.is_mutual = _is_mutual,
 				.get_msk = _get_msk,
 				.get_identifier = _get_identifier,
 				.set_identifier = _set_identifier,
 				.destroy = _destroy,
 			},
 		},
 		.crypto = simaka_crypto_create(EAP_SIM),
 		.mgr = lib->get(lib, "sim-manager"),
 	);

 	if (!this->crypto)
 	{
 		free(this);
 		return NULL;
 	}

 	this->permanent = peer->clone(peer);
 	this->tries = MAX_TRIES;

 	return &this->public;
 }
	/*
	* Copyright (C) 2007-2009 Martin Willi
	* HSR 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 <http://www.fsf.org/copyleft/gpl.txt>.
	*
	* 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.
	*/

	#include "eap_sim_peer.h"

	#include <daemon.h>

	#include <simaka_message.h>
	#include <simaka_manager.h>

	/* number of tries we do authenticate */
	#define MAX_TRIES 3

	/* number of triplets for one authentication */
	#define TRIPLET_COUNT 3

	/** length of the AT_NONCE_MT nonce value */
	#define NONCE_LEN 16

	typedef struct private_eap_sim_peer_t private_eap_sim_peer_t;

	/**
	* Private data of an eap_sim_peer_t object.
	*/
	struct private_eap_sim_peer_t {

	/**
	* Public authenticator_t interface.
	*/
	eap_sim_peer_t public;

	/**
	* SIM backend manager
	*/
	simaka_manager_t *mgr;

	/**
	* permanent ID of peer
	*/
	identification_t *permanent;

	/**
	* Pseudonym identity the peer uses
	*/
	identification_t *pseudonym;

	/**
	* Reauthentication identity the peer uses
	*/
	identification_t *reauth;

	/**
	* EAP message identifier
	*/
	uint8_t identifier;

	/**
	* EAP-SIM crypto helper
	*/
	simaka_crypto_t *crypto;

	/**
	* how many times we try to authenticate
	*/
	int tries;

	/**
	* version list received from server
	*/
	chunk_t version_list;

	/**
	* Nonce value used in AT_NONCE_MT/AT_NONCE_S
	*/
	chunk_t nonce;

	/**
	* MSK, used for EAP-SIM based IKEv2 authentication
	*/
	chunk_t msk;

	/**
	* Master key, if reauthentication is used
	*/
	char mk[HASH_SIZE_SHA1];

	/**
	* Counter value if reauthentication is used
	*/
	uint16_t counter;
	};

	/* version of SIM protocol we speak */
	static chunk_t version = chunk_from_chars(0x00,0x01);

	/**
	* Generate a payload from a message, destroy message
	*/
	static bool generate_payload(simaka_message_t *message, chunk_t data,
	eap_payload_t **out)
	{
	chunk_t chunk;
	bool ok;

	ok = message->generate(message, data, &chunk);
	if (ok)
	{
	*out = eap_payload_create_data_own(chunk);
	}
	message->destroy(message);
	return ok;
	}

	/**
	* Create a SIM_CLIENT_ERROR
	*/
	static bool create_client_error(private_eap_sim_peer_t *this,
	simaka_client_error_t code, eap_payload_t **out)
	{
	simaka_message_t *message;
	uint16_t encoded;

	DBG1(DBG_IKE, "sending client error '%N'", simaka_client_error_names, code);

	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
	SIM_CLIENT_ERROR, this->crypto);
	encoded = htons(code);
	message->add_attribute(message, AT_CLIENT_ERROR_CODE,
	chunk_create((char*)&encoded, sizeof(encoded)));
	return generate_payload(message, chunk_empty, out);
	}

	/**
	* process an EAP-SIM/Request/Start message
	*/
	static status_t process_start(private_eap_sim_peer_t *this,
	simaka_message_t in, eap_payload_t *out)
	{
	simaka_message_t *message;
	enumerator_t *enumerator;
	simaka_attribute_t type;
	chunk_t data, id = chunk_empty;
	rng_t *rng;
	bool supported = FALSE;
	simaka_attribute_t id_req = 0;

	/* reset previously uses reauthentication/pseudonym data */
	this->crypto->clear_keys(this->crypto);
	DESTROY_IF(this->pseudonym);
	this->pseudonym = NULL;
	DESTROY_IF(this->reauth);
	this->reauth = NULL;

	enumerator = in->create_attribute_enumerator(in);
	while (enumerator->enumerate(enumerator, &type, &data))
	{
	switch (type)
	{
	case AT_VERSION_LIST:
	{
	free(this->version_list.ptr);
	this->version_list = chunk_clone(data);
	while (data.len >= version.len)
	{
	if (memeq(data.ptr, version.ptr, version.len))
	{
	supported = TRUE;
	break;
	}
	}
	break;
	}
	case AT_ANY_ID_REQ:
	case AT_FULLAUTH_ID_REQ:
	case AT_PERMANENT_ID_REQ:
	id_req = type;
	break;
	default:
	if (!simaka_attribute_skippable(type))
	{
	enumerator->destroy(enumerator);
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	break;
	}
	}
	enumerator->destroy(enumerator);

	if (!supported)
	{
	DBG1(DBG_IKE, "server does not support EAP-SIM version number 1");
	if (!create_client_error(this, SIM_UNSUPPORTED_VERSION, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	switch (id_req)
	{
	case AT_ANY_ID_REQ:
	this->reauth = this->mgr->card_get_reauth(this->mgr,
	this->permanent, this->mk, &this->counter);
	if (this->reauth)
	{
	id = this->reauth->get_encoding(this->reauth);
	break;
	}
	/* FALL */
	case AT_FULLAUTH_ID_REQ:
	this->pseudonym = this->mgr->card_get_pseudonym(this->mgr,
	this->permanent);
	if (this->pseudonym)
	{
	id = this->pseudonym->get_encoding(this->pseudonym);
	break;
	}
	/* FALL */
	case AT_PERMANENT_ID_REQ:
	id = this->permanent->get_encoding(this->permanent);
	break;
	default:
	break;
	}

	/* generate AT_NONCE_MT value */
	rng = this->crypto->get_rng(this->crypto);
	free(this->nonce.ptr);
	if (!rng->allocate_bytes(rng, NONCE_LEN, &this->nonce))
	{
	return FAILED;
	}

	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
	SIM_START, this->crypto);
	if (!this->reauth)
	{
	message->add_attribute(message, AT_SELECTED_VERSION, version);
	message->add_attribute(message, AT_NONCE_MT, this->nonce);
	}
	if (id.len)
	{
	message->add_attribute(message, AT_IDENTITY, id);
	}
	if (!generate_payload(message, chunk_empty, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	/**
	* process an EAP-SIM/Request/Challenge message
	*/
	static status_t process_challenge(private_eap_sim_peer_t *this,
	simaka_message_t in, eap_payload_t *out)
	{
	simaka_message_t *message;
	enumerator_t *enumerator;
	simaka_attribute_t type;
	chunk_t data, rands = chunk_empty, kcs, kc, sreses, sres, mk;
	identification_t *id;

	if (this->tries-- <= 0)
	{
	/* give up without notification. This hack is required as some buggy
	* server implementations won't respect our client-error. */
	return FAILED;
	}

	enumerator = in->create_attribute_enumerator(in);
	while (enumerator->enumerate(enumerator, &type, &data))
	{
	switch (type)
	{
	case AT_RAND:
	rands = data;
	break;
	default:
	if (!simaka_attribute_skippable(type))
	{
	enumerator->destroy(enumerator);
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	break;
	}
	}
	enumerator->destroy(enumerator);

	/* excepting two or three RAND, each 16 bytes. We require two valid
	* and different RANDs */
	if ((rands.len != 2 * SIM_RAND_LEN && rands.len != 3 * SIM_RAND_LEN) \|\|
	memeq_const(rands.ptr, rands.ptr + SIM_RAND_LEN, SIM_RAND_LEN))
	{
	DBG1(DBG_IKE, "no valid AT_RAND received");
	if (!create_client_error(this, SIM_INSUFFICIENT_CHALLENGES, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	/* get two or three KCs/SRESes from SIM using RANDs */
	kcs = kc = chunk_alloca(rands.len / 2);
	sreses = sres = chunk_alloca(rands.len / 4);
	while (rands.len >= SIM_RAND_LEN)
	{
	if (!this->mgr->card_get_triplet(this->mgr, this->permanent,
	rands.ptr, sres.ptr, kc.ptr))
	{
	DBG1(DBG_IKE, "unable to get EAP-SIM triplet");
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	DBG3(DBG_IKE, "got triplet for RAND %b\n Kc %b\n SRES %b",
	rands.ptr, SIM_RAND_LEN, sres.ptr, SIM_SRES_LEN, kc.ptr, SIM_KC_LEN);
	kc = chunk_skip(kc, SIM_KC_LEN);
	sres = chunk_skip(sres, SIM_SRES_LEN);
	rands = chunk_skip(rands, SIM_RAND_LEN);
	}

	id = this->permanent;
	if (this->pseudonym)
	{
	id = this->pseudonym;
	}
	data = chunk_cata("cccc", kcs, this->nonce, this->version_list, version);
	chunk_clear(&this->msk);
	if (!this->crypto->derive_keys_full(this->crypto, id, data, &mk, &this->msk))
	{
	return FAILED;
	}
	memcpy(this->mk, mk.ptr, mk.len);
	chunk_clear(&mk);

	/* Verify AT_MAC attribute, signature is over "EAP packet \| NONCE_MT", and
	* parse() again after key derivation, reading encrypted attributes */
	if (!in->verify(in, this->nonce) \|\| !in->parse(in))
	{
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	enumerator = in->create_attribute_enumerator(in);
	while (enumerator->enumerate(enumerator, &type, &data))
	{
	switch (type)
	{
	case AT_NEXT_REAUTH_ID:
	this->counter = 0;
	id = identification_create_from_data(data);
	this->mgr->card_set_reauth(this->mgr, this->permanent, id,
	this->mk, this->counter);
	id->destroy(id);
	break;
	case AT_NEXT_PSEUDONYM:
	id = identification_create_from_data(data);
	this->mgr->card_set_pseudonym(this->mgr, this->permanent, id);
	id->destroy(id);
	break;
	default:
	break;
	}
	}
	enumerator->destroy(enumerator);

	/* build response with AT_MAC, built over "EAP packet \| nSRES" /
	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
	SIM_CHALLENGE, this->crypto);
	if (!generate_payload(message, sreses, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	/**
	* Check if a received counter value is acceptable
	*/
	static bool counter_too_small(private_eap_sim_peer_t *this, chunk_t chunk)
	{
	uint16_t counter;

	memcpy(&counter, chunk.ptr, sizeof(counter));
	counter = htons(counter);
	return counter < this->counter;
	}

	/**
	* process an EAP-SIM/Request/Re-Authentication message
	*/
	static status_t process_reauthentication(private_eap_sim_peer_t *this,
	simaka_message_t in, eap_payload_t *out)
	{
	simaka_message_t *message;
	enumerator_t *enumerator;
	simaka_attribute_t type;
	chunk_t data, counter = chunk_empty, nonce = chunk_empty, id = chunk_empty;

	if (!this->reauth)
	{
	DBG1(DBG_IKE, "received %N, but not expected",
	simaka_subtype_names, SIM_REAUTHENTICATION);
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	if (!this->crypto->derive_keys_reauth(this->crypto,
	chunk_create(this->mk, HASH_SIZE_SHA1)))
	{
	return FAILED;
	}

	/* verify MAC and parse again with decryption key */
	if (!in->verify(in, chunk_empty) \|\| !in->parse(in))
	{
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	enumerator = in->create_attribute_enumerator(in);
	while (enumerator->enumerate(enumerator, &type, &data))
	{
	switch (type)
	{
	case AT_COUNTER:
	counter = data;
	break;
	case AT_NONCE_S:
	nonce = data;
	break;
	case AT_NEXT_REAUTH_ID:
	id = data;
	break;
	default:
	if (!simaka_attribute_skippable(type))
	{
	enumerator->destroy(enumerator);
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	break;
	}
	}
	enumerator->destroy(enumerator);

	if (!nonce.len \|\| !counter.len)
	{
	DBG1(DBG_IKE, "EAP-SIM/Request/Re-Authentication message incomplete");
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
	SIM_REAUTHENTICATION, this->crypto);
	if (counter_too_small(this, counter))
	{
	DBG1(DBG_IKE, "reauthentication counter too small");
	message->add_attribute(message, AT_COUNTER_TOO_SMALL, chunk_empty);
	}
	else
	{
	chunk_clear(&this->msk);
	if (!this->crypto->derive_keys_reauth_msk(this->crypto,
	this->reauth, counter, nonce,
	chunk_create(this->mk, HASH_SIZE_SHA1), &this->msk))
	{
	message->destroy(message);
	return FAILED;
	}
	if (id.len)
	{
	identification_t *reauth;

	reauth = identification_create_from_data(data);
	this->mgr->card_set_reauth(this->mgr, this->permanent, reauth,
	this->mk, this->counter);
	reauth->destroy(reauth);
	}
	}
	message->add_attribute(message, AT_COUNTER, counter);
	if (!generate_payload(message, nonce, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}

	/**
	* process an EAP-SIM/Request/Notification message
	*/
	static status_t process_notification(private_eap_sim_peer_t *this,
	simaka_message_t in, eap_payload_t *out)
	{
	simaka_message_t *message;
	enumerator_t *enumerator;
	simaka_attribute_t type;
	chunk_t data;
	bool success = TRUE;

	enumerator = in->create_attribute_enumerator(in);
	while (enumerator->enumerate(enumerator, &type, &data))
	{
	if (type == AT_NOTIFICATION)
	{
	uint16_t code;

	memcpy(&code, data.ptr, sizeof(code));
	code = ntohs(code);

	/* test success bit */
	if (!(data.ptr[0] & 0x80))
	{
	DBG1(DBG_IKE, "received EAP-SIM notification error '%N'",
	simaka_notification_names, code);
	}
	else
	{
	DBG1(DBG_IKE, "received EAP-SIM notification '%N'",
	simaka_notification_names, code);
	}
	}
	else if (!simaka_attribute_skippable(type))
	{
	success = FALSE;
	break;
	}
	}
	enumerator->destroy(enumerator);

	if (success)
	{ /* empty notification reply */
	message = simaka_message_create(FALSE, this->identifier, EAP_SIM,
	SIM_NOTIFICATION, this->crypto);
	if (!generate_payload(message, chunk_empty, out))
	{
	return FAILED;
	}
	}
	else
	{
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	}
	return NEED_MORE;
	}

	METHOD(eap_method_t, process, status_t,
	private_eap_sim_peer_t this, eap_payload_t in, eap_payload_t **out)
	{
	simaka_message_t *message;
	status_t status;

	/* store received EAP message identifier */
	this->identifier = in->get_identifier(in);

	message = simaka_message_create_from_payload(in->get_data(in), this->crypto);
	if (!message)
	{
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	if (!message->parse(message))
	{
	message->destroy(message);
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	return FAILED;
	}
	return NEED_MORE;
	}
	switch (message->get_subtype(message))
	{
	case SIM_START:
	status = process_start(this, message, out);
	break;
	case SIM_CHALLENGE:
	status = process_challenge(this, message, out);
	break;
	case SIM_REAUTHENTICATION:
	status = process_reauthentication(this, message, out);
	break;
	case SIM_NOTIFICATION:
	status = process_notification(this, message, out);
	break;
	default:
	DBG1(DBG_IKE, "unable to process EAP-SIM subtype %N",
	simaka_subtype_names, message->get_subtype(message));
	if (!create_client_error(this, SIM_UNABLE_TO_PROCESS, out))
	{
	status = FAILED;
	}
	else
	{
	status = NEED_MORE;
	}
	break;
	}
	message->destroy(message);
	return status;
	}

	METHOD(eap_method_t, initiate, status_t,
	private_eap_sim_peer_t this, eap_payload_t *out)
	{
	/* peer never initiates */
	return FAILED;
	}

	METHOD(eap_method_t, get_type, eap_type_t,
	private_eap_sim_peer_t this, uint32_t vendor)
	{
	*vendor = 0;
	return EAP_SIM;
	}

	METHOD(eap_method_t, get_msk, status_t,
	private_eap_sim_peer_t this, chunk_t msk)
	{
	if (this->msk.ptr)
	{
	*msk = this->msk;
	return SUCCESS;
	}
	return FAILED;
	}

	METHOD(eap_method_t, get_identifier, uint8_t,
	private_eap_sim_peer_t *this)
	{
	return this->identifier;
	}

	METHOD(eap_method_t, set_identifier, void,
	private_eap_sim_peer_t *this, uint8_t identifier)
	{
	this->identifier = identifier;
	}

	METHOD(eap_method_t, is_mutual, bool,
	private_eap_sim_peer_t *this)
	{
	return TRUE;
	}

	METHOD(eap_method_t, destroy, void,
	private_eap_sim_peer_t *this)
	{
	this->permanent->destroy(this->permanent);
	DESTROY_IF(this->pseudonym);
	DESTROY_IF(this->reauth);
	this->crypto->destroy(this->crypto);
	free(this->version_list.ptr);
	free(this->nonce.ptr);
	free(this->msk.ptr);
	free(this);
	}

	/*
	* Described in header.
	*/
	eap_sim_peer_t eap_sim_peer_create(identification_t server,
	identification_t *peer)
	{
	private_eap_sim_peer_t *this;

	INIT(this,
	.public = {
	.interface = {
	.initiate = _initiate,
	.process = _process,
	.get_type = _get_type,
	.is_mutual = _is_mutual,
	.get_msk = _get_msk,
	.get_identifier = _get_identifier,
	.set_identifier = _set_identifier,
	.destroy = _destroy,
	},
	},
	.crypto = simaka_crypto_create(EAP_SIM),
	.mgr = lib->get(lib, "sim-manager"),
	);

	if (!this->crypto)
	{
	free(this);
	return NULL;
	}

	this->permanent = peer->clone(peer);
	this->tries = MAX_TRIES;

	return &this->public;
	}