text: /*
   * EAP peer method: EAP-pwd (RFC 5931)
   * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org>
   *
   * This software may be distributed under the terms of the BSD license.
   * See README for more details.
   */
  
  #include "includes.h"
  
  #include "common.h"
  #include "crypto/sha256.h"
  #include "crypto/ms_funcs.h"
  #include "eap_peer/eap_i.h"
  #include "eap_common/eap_pwd_common.h"
  
  
  struct eap_pwd_data {
  	enum {
  		PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req,
  		SUCCESS_ON_FRAG_COMPLETION, SUCCESS, FAILURE
  	} state;
  	u8 *id_peer;
  	size_t id_peer_len;
  	u8 *id_server;
  	size_t id_server_len;
  	u8 *password;
  	size_t password_len;
  	int password_hash;
  	u16 group_num;
  	EAP_PWD_group *grp;
  
  	struct wpabuf *inbuf;
  	size_t in_frag_pos;
  	struct wpabuf *outbuf;
  	size_t out_frag_pos;
  	size_t mtu;
  
  	BIGNUM *k;
  	BIGNUM *private_value;
  	BIGNUM *server_scalar;
  	BIGNUM *my_scalar;
  	EC_POINT *my_element;
  	EC_POINT *server_element;
  
  	u8 msk[EAP_MSK_LEN];
  	u8 emsk[EAP_EMSK_LEN];
  	u8 session_id[1 + SHA256_MAC_LEN];
  
  	BN_CTX *bnctx;
  };
  
  
  #ifndef CONFIG_NO_STDOUT_DEBUG
  static const char * eap_pwd_state_txt(int state)
  {
  	switch (state) {
          case PWD_ID_Req:
  		return "PWD-ID-Req";
          case PWD_Commit_Req:
  		return "PWD-Commit-Req";
          case PWD_Confirm_Req:
  		return "PWD-Confirm-Req";
  	case SUCCESS_ON_FRAG_COMPLETION:
  		return "SUCCESS_ON_FRAG_COMPLETION";
          case SUCCESS:
  		return "SUCCESS";
          case FAILURE:
  		return "FAILURE";
          default:
  		return "PWD-UNK";
  	}
  }
  #endif  /* CONFIG_NO_STDOUT_DEBUG */
  
  
  static void eap_pwd_state(struct eap_pwd_data *data, int state)
  {
  	wpa_printf(MSG_DEBUG, "EAP-PWD: %s -> %s",
  		   eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
  	data->state = state;
  }
  
  
  static void * eap_pwd_init(struct eap_sm *sm)
  {
  	struct eap_pwd_data *data;
  	const u8 *identity, *password;
  	size_t identity_len, password_len;
  	int fragment_size;
  	int pwhash;
  
  	password = eap_get_config_password2(sm, &password_len, &pwhash);
  	if (password == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: No password configured!");
  		return NULL;
  	}
  
  	identity = eap_get_config_identity(sm, &identity_len);
  	if (identity == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: No identity configured!");
  		return NULL;
  	}
  
  	if ((data = os_zalloc(sizeof(*data))) == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation data fail");
  		return NULL;
  	}
  
  	if ((data->bnctx = BN_CTX_new()) == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
  		os_free(data);
  		return NULL;
  	}
  
  	if ((data->id_peer = os_malloc(identity_len)) == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
  		BN_CTX_free(data->bnctx);
  		os_free(data);
  		return NULL;
  	}
  
  	os_memcpy(data->id_peer, identity, identity_len);
  	data->id_peer_len = identity_len;
  
  	if ((data->password = os_malloc(password_len)) == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation psk fail");
  		BN_CTX_free(data->bnctx);
  		bin_clear_free(data->id_peer, data->id_peer_len);
  		os_free(data);
  		return NULL;
  	}
  	os_memcpy(data->password, password, password_len);
  	data->password_len = password_len;
  	data->password_hash = pwhash;
  
  	data->out_frag_pos = data->in_frag_pos = 0;
  	data->inbuf = data->outbuf = NULL;
  	fragment_size = eap_get_config_fragment_size(sm);
  	if (fragment_size <= 0)
  		data->mtu = 1020; /* default from RFC 5931 */
  	else
  		data->mtu = fragment_size;
  
  	data->state = PWD_ID_Req;
  
  	return data;
  }
  
  
  static void eap_pwd_deinit(struct eap_sm *sm, void *priv)
  {
  	struct eap_pwd_data *data = priv;
  
  	BN_clear_free(data->private_value);
  	BN_clear_free(data->server_scalar);
  	BN_clear_free(data->my_scalar);
  	BN_clear_free(data->k);
  	BN_CTX_free(data->bnctx);
  	EC_POINT_clear_free(data->my_element);
  	EC_POINT_clear_free(data->server_element);
  	bin_clear_free(data->id_peer, data->id_peer_len);
  	bin_clear_free(data->id_server, data->id_server_len);
  	bin_clear_free(data->password, data->password_len);
  	if (data->grp) {
  		EC_GROUP_free(data->grp->group);
  		EC_POINT_clear_free(data->grp->pwe);
  		BN_clear_free(data->grp->order);
  		BN_clear_free(data->grp->prime);
  		os_free(data->grp);
  	}
  	wpabuf_free(data->inbuf);
  	wpabuf_free(data->outbuf);
  	bin_clear_free(data, sizeof(*data));
  }
  
  
  static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	key = os_malloc(EAP_MSK_LEN);
  	if (key == NULL)
  		return NULL;
  
  	os_memcpy(key, data->msk, EAP_MSK_LEN);
  	*len = EAP_MSK_LEN;
  
  	return key;
  }
  
  
  static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *id;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	id = os_malloc(1 + SHA256_MAC_LEN);
  	if (id == NULL)
  		return NULL;
  
  	os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
  	*len = 1 + SHA256_MAC_LEN;
  
  	return id;
  }
  
  
  static void
  eap_pwd_perform_id_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
  			    struct eap_method_ret *ret,
  			    const struct wpabuf *reqData,
  			    const u8 *payload, size_t payload_len)
  {
  	struct eap_pwd_id *id;
  	const u8 *password;
  	size_t password_len;
  	u8 pwhashhash[16];
  	int res;
  
  	if (data->state != PWD_ID_Req) {
  		ret->ignore = TRUE;
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	if (payload_len < sizeof(struct eap_pwd_id)) {
  		ret->ignore = TRUE;
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	id = (struct eap_pwd_id *) payload;
  	data->group_num = be_to_host16(id->group_num);
  	wpa_printf(MSG_DEBUG,
  		   "EAP-PWD: Server EAP-pwd-ID proposal: group=%u random=%u prf=%u prep=%u",
  		   data->group_num, id->random_function, id->prf, id->prep);
  	if ((id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
  	    (id->prf != EAP_PWD_DEFAULT_PRF)) {
  		ret->ignore = TRUE;
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	if (id->prep != EAP_PWD_PREP_NONE &&
  	    id->prep != EAP_PWD_PREP_MS) {
  		wpa_printf(MSG_DEBUG,
  			   "EAP-PWD: Unsupported password pre-processing technique (Prep=%u)",
  			   id->prep);
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	if (id->prep == EAP_PWD_PREP_NONE && data->password_hash) {
  		wpa_printf(MSG_DEBUG,
  			   "EAP-PWD: Unhashed password not available");
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	wpa_printf(MSG_DEBUG, "EAP-PWD (peer): using group %d",
  		   data->group_num);
  
  	data->id_server = os_malloc(payload_len - sizeof(struct eap_pwd_id));
  	if (data->id_server == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  	data->id_server_len = payload_len - sizeof(struct eap_pwd_id);
  	os_memcpy(data->id_server, id->identity, data->id_server_len);
  	wpa_hexdump_ascii(MSG_INFO, "EAP-PWD (peer): server sent id of",
  			  data->id_server, data->id_server_len);
  
  	data->grp = os_zalloc(sizeof(EAP_PWD_group));
  	if (data->grp == NULL) {
  		wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
  			   "group");
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	if (id->prep == EAP_PWD_PREP_MS) {
  		if (data->password_hash) {
  			res = hash_nt_password_hash(data->password, pwhashhash);
  		} else {
  			u8 pwhash[16];
  
  			res = nt_password_hash(data->password,
  					       data->password_len, pwhash);
  			if (res == 0)
  				res = hash_nt_password_hash(pwhash, pwhashhash);
  			os_memset(pwhash, 0, sizeof(pwhash));
  		}
  
  		if (res) {
  			eap_pwd_state(data, FAILURE);
  			return;
  		}
  
  		password = pwhashhash;
  		password_len = sizeof(pwhashhash);
  	} else {
  		password = data->password;
  		password_len = data->password_len;
  	}
  
  	/* compute PWE */
  	res = compute_password_element(data->grp, data->group_num,
  				       password, password_len,
  				       data->id_server, data->id_server_len,
  				       data->id_peer, data->id_peer_len,
  				       id->token);
  	os_memset(pwhashhash, 0, sizeof(pwhashhash));
  	if (res) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute PWE");
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  
  	wpa_printf(MSG_DEBUG, "EAP-PWD (peer): computed %d bit PWE...",
  		   BN_num_bits(data->grp->prime));
  
  	data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
  				    data->id_peer_len);
  	if (data->outbuf == NULL) {
  		eap_pwd_state(data, FAILURE);
  		return;
  	}
  	wpabuf_put_be16(data->outbuf, data->group_num);
  	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
  	wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
  	wpabuf_put_data(data->outbuf, id->token, sizeof(id->token));
  	wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
  	wpabuf_put_data(data->outbuf, data->id_peer, data->id_peer_len);
  
  	eap_pwd_state(data, PWD_Commit_Req);
  }
  
  
  static void
  eap_pwd_perform_commit_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
  				struct eap_method_ret *ret,
  				const struct wpabuf *reqData,
  				const u8 *payload, size_t payload_len)
  {
  	EC_POINT *K = NULL, *point = NULL;
  	BIGNUM *mask = NULL, *x = NULL, *y = NULL, *cofactor = NULL;
  	u16 offset;
  	u8 *ptr, *scalar = NULL, *element = NULL;
  	size_t prime_len, order_len;
  
  	if (data->state != PWD_Commit_Req) {
  		ret->ignore = TRUE;
  		goto fin;
  	}
  
  	prime_len = BN_num_bytes(data->grp->prime);
  	order_len = BN_num_bytes(data->grp->order);
  
  	if (payload_len != 2 * prime_len + order_len) {
  		wpa_printf(MSG_INFO,
  			   "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
  			   (unsigned int) payload_len,
  			   (unsigned int) (2 * prime_len + order_len));
  		goto fin;
  	}
  
  	if (((data->private_value = BN_new()) == NULL) ||
  	    ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
  	    ((cofactor = BN_new()) == NULL) ||
  	    ((data->my_scalar = BN_new()) == NULL) ||
  	    ((mask = BN_new()) == NULL)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): scalar allocation fail");
  		goto fin;
  	}
  
  	if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
  		wpa_printf(MSG_INFO, "EAP-pwd (peer): unable to get cofactor "
  			   "for curve");
  		goto fin;
  	}
  
  	if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
  	    BN_rand_range(mask, data->grp->order) != 1 ||
  	    BN_add(data->my_scalar, data->private_value, mask) != 1 ||
  	    BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
  		   data->bnctx) != 1) {
  		wpa_printf(MSG_INFO,
  			   "EAP-pwd (peer): unable to get randomness");
  		goto fin;
  	}
  
  	if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
  			  data->grp->pwe, mask, data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): element allocation "
  			   "fail");
  		eap_pwd_state(data, FAILURE);
  		goto fin;
  	}
  
  	if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
  	{
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): element inversion fail");
  		goto fin;
  	}
  	BN_clear_free(mask);
  
  	if (((x = BN_new()) == NULL) ||
  	    ((y = BN_new()) == NULL)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): point allocation fail");
  		goto fin;
  	}
  
  	/* process the request */
  	if (((data->server_scalar = BN_new()) == NULL) ||
  	    ((data->k = BN_new()) == NULL) ||
  	    ((K = EC_POINT_new(data->grp->group)) == NULL) ||
  	    ((point = EC_POINT_new(data->grp->group)) == NULL) ||
  	    ((data->server_element = EC_POINT_new(data->grp->group)) == NULL))
  	{
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): peer data allocation "
  			   "fail");
  		goto fin;
  	}
  
  	/* element, x then y, followed by scalar */
  	ptr = (u8 *) payload;
  	BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
  	ptr += BN_num_bytes(data->grp->prime);
  	BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
  	ptr += BN_num_bytes(data->grp->prime);
  	BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->server_scalar);
  	if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
  						 data->server_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): setting peer element "
  			   "fail");
  		goto fin;
  	}
  
  	/* check to ensure server's element is not in a small sub-group */
  	if (BN_cmp(cofactor, BN_value_one())) {
  		if (!EC_POINT_mul(data->grp->group, point, NULL,
  				  data->server_element, cofactor, NULL)) {
  			wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
  				   "server element by order!\n");
  			goto fin;
  		}
  		if (EC_POINT_is_at_infinity(data->grp->group, point)) {
  			wpa_printf(MSG_INFO, "EAP-PWD (peer): server element "
  				   "is at infinity!\n");
  			goto fin;
  		}
  	}
  
  	/* compute the shared key, k */
  	if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
  			   data->server_scalar, data->bnctx)) ||
  	    (!EC_POINT_add(data->grp->group, K, K, data->server_element,
  			   data->bnctx)) ||
  	    (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
  			   data->bnctx))) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): computing shared key "
  			   "fail");
  		goto fin;
  	}
  
  	/* ensure that the shared key isn't in a small sub-group */
  	if (BN_cmp(cofactor, BN_value_one())) {
  		if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
  				  NULL)) {
  			wpa_printf(MSG_INFO, "EAP-PWD (peer): cannot multiply "
  				   "shared key point by order");
  			goto fin;
  		}
  	}
  
  	/*
  	 * This check is strictly speaking just for the case above where
  	 * co-factor > 1 but it was suggested that even though this is probably
  	 * never going to happen it is a simple and safe check "just to be
  	 * sure" so let's be safe.
  	 */
  	if (EC_POINT_is_at_infinity(data->grp->group, K)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): shared key point is at "
  			   "infinity!\n");
  		goto fin;
  	}
  
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
  						 NULL, data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to extract "
  			   "shared secret from point");
  		goto fin;
  	}
  
  	/* now do the response */
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
  						 data->my_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): point assignment fail");
  		goto fin;
  	}
  
  	if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
  	    ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
  	     NULL)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): data allocation fail");
  		goto fin;
  	}
  
  	/*
  	 * bignums occupy as little memory as possible so one that is
  	 * sufficiently smaller than the prime or order might need pre-pending
  	 * with zeros.
  	 */
  	os_memset(scalar, 0, BN_num_bytes(data->grp->order));
  	os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
  	offset = BN_num_bytes(data->grp->order) -
  		BN_num_bytes(data->my_scalar);
  	BN_bn2bin(data->my_scalar, scalar + offset);
  
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
  	BN_bn2bin(x, element + offset);
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
  	BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
  
  	data->outbuf = wpabuf_alloc(BN_num_bytes(data->grp->order) +
  				    2 * BN_num_bytes(data->grp->prime));
  	if (data->outbuf == NULL)
  		goto fin;
  
  	/* we send the element as (x,y) follwed by the scalar */
  	wpabuf_put_data(data->outbuf, element,
  			2 * BN_num_bytes(data->grp->prime));
  	wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
  
  fin:
  	os_free(scalar);
  	os_free(element);
  	BN_clear_free(x);
  	BN_clear_free(y);
  	BN_clear_free(cofactor);
  	EC_POINT_clear_free(K);
  	EC_POINT_clear_free(point);
  	if (data->outbuf == NULL)
  		eap_pwd_state(data, FAILURE);
  	else
  		eap_pwd_state(data, PWD_Confirm_Req);
  }
  
  
  static void
  eap_pwd_perform_confirm_exchange(struct eap_sm *sm, struct eap_pwd_data *data,
  				 struct eap_method_ret *ret,
  				 const struct wpabuf *reqData,
  				 const u8 *payload, size_t payload_len)
  {
  	BIGNUM *x = NULL, *y = NULL;
  	struct crypto_hash *hash;
  	u32 cs;
  	u16 grp;
  	u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
  	int offset;
  
  	if (data->state != PWD_Confirm_Req) {
  		ret->ignore = TRUE;
  		goto fin;
  	}
  
  	if (payload_len != SHA256_MAC_LEN) {
  		wpa_printf(MSG_INFO,
  			   "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
  			   (unsigned int) payload_len, SHA256_MAC_LEN);
  		goto fin;
  	}
  
  	/*
  	 * first build up the ciphersuite which is group | random_function |
  	 *	prf
  	 */
  	grp = htons(data->group_num);
  	ptr = (u8 *) &cs;
  	os_memcpy(ptr, &grp, sizeof(u16));
  	ptr += sizeof(u16);
  	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
  	ptr += sizeof(u8);
  	*ptr = EAP_PWD_DEFAULT_PRF;
  
  	/* each component of the cruft will be at most as big as the prime */
  	if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
  	    ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm allocation "
  			   "fail");
  		goto fin;
  	}
  
  	/*
  	 * server's commit is H(k | server_element | server_scalar |
  	 *			peer_element | peer_scalar | ciphersuite)
  	 */
  	hash = eap_pwd_h_init();
  	if (hash == NULL)
  		goto fin;
  
  	/*
  	 * zero the memory each time because this is mod prime math and some
  	 * value may start with a few zeros and the previous one did not.
  	 */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
  	BN_bn2bin(data->k, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* server element: x, y */
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
  						 data->server_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
  	BN_bn2bin(x, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
  	BN_bn2bin(y, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* server scalar */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->order) -
  		BN_num_bytes(data->server_scalar);
  	BN_bn2bin(data->server_scalar, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
  
  	/* my element: x, y */
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
  						 data->my_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
  	BN_bn2bin(x, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
  	BN_bn2bin(y, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* my scalar */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->order) -
  		BN_num_bytes(data->my_scalar);
  	BN_bn2bin(data->my_scalar, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
  
  	/* the ciphersuite */
  	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
  
  	/* random function fin */
  	eap_pwd_h_final(hash, conf);
  
  	ptr = (u8 *) payload;
  	if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm did not verify");
  		goto fin;
  	}
  
  	wpa_printf(MSG_DEBUG, "EAP-pwd (peer): confirm verified");
  
  	/*
  	 * compute confirm:
  	 *  H(k | peer_element | peer_scalar | server_element | server_scalar |
  	 *    ciphersuite)
  	 */
  	hash = eap_pwd_h_init();
  	if (hash == NULL)
  		goto fin;
  
  	/* k */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
  	BN_bn2bin(data->k, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* my element */
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
  						 data->my_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
  	BN_bn2bin(x, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
  	BN_bn2bin(y, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* my scalar */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->order) -
  		BN_num_bytes(data->my_scalar);
  	BN_bn2bin(data->my_scalar, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
  
  	/* server element: x, y */
  	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
  						 data->server_element, x, y,
  						 data->bnctx)) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): confirm point "
  			   "assignment fail");
  		goto fin;
  	}
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
  	BN_bn2bin(x, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
  	BN_bn2bin(y, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
  
  	/* server scalar */
  	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
  	offset = BN_num_bytes(data->grp->order) -
  		BN_num_bytes(data->server_scalar);
  	BN_bn2bin(data->server_scalar, cruft + offset);
  	eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
  
  	/* the ciphersuite */
  	eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
  
  	/* all done */
  	eap_pwd_h_final(hash, conf);
  
  	if (compute_keys(data->grp, data->bnctx, data->k,
  			 data->my_scalar, data->server_scalar, conf, ptr,
  			 &cs, data->msk, data->emsk, data->session_id) < 0) {
  		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
  			   "EMSK");
  		goto fin;
  	}
  
  	data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
  	if (data->outbuf == NULL)
  		goto fin;
  
  	wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
  
  fin:
  	bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
  	BN_clear_free(x);
  	BN_clear_free(y);
  	if (data->outbuf == NULL) {
  		ret->methodState = METHOD_DONE;
  		ret->decision = DECISION_FAIL;
  		eap_pwd_state(data, FAILURE);
  	} else {
  		eap_pwd_state(data, SUCCESS_ON_FRAG_COMPLETION);
  	}
  }
  
  
  static struct wpabuf *
  eap_pwd_process(struct eap_sm *sm, void *priv, struct eap_method_ret *ret,
  		const struct wpabuf *reqData)
  {
  	struct eap_pwd_data *data = priv;
  	struct wpabuf *resp = NULL;
  	const u8 *pos, *buf;
  	size_t len;
  	u16 tot_len = 0;
  	u8 lm_exch;
  
  	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, reqData, &len);
  	if ((pos == NULL) || (len < 1)) {
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Got a frame but pos is %s and "
  			   "len is %d",
  			   pos == NULL ? "NULL" : "not NULL", (int) len);
  		ret->ignore = TRUE;
  		return NULL;
  	}
  
  	ret->ignore = FALSE;
  	ret->methodState = METHOD_MAY_CONT;
  	ret->decision = DECISION_FAIL;
  	ret->allowNotifications = FALSE;
  
  	lm_exch = *pos;
  	pos++;                  /* skip over the bits and the exch */
  	len--;
  
  	/*
  	 * we're fragmenting so send out the next fragment
  	 */
  	if (data->out_frag_pos) {
  		/*
  		 * this should be an ACK
  		 */
  		if (len)
  			wpa_printf(MSG_INFO, "Bad Response! Fragmenting but "
  				   "not an ACK");
  
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Got an ACK for a fragment");
  		/*
  		 * check if there are going to be more fragments
  		 */
  		len = wpabuf_len(data->outbuf) - data->out_frag_pos;
  		if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
  			len = data->mtu - EAP_PWD_HDR_SIZE;
  			EAP_PWD_SET_MORE_BIT(lm_exch);
  		}
  		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
  				     EAP_PWD_HDR_SIZE + len,
  				     EAP_CODE_RESPONSE, eap_get_id(reqData));
  		if (resp == NULL) {
  			wpa_printf(MSG_INFO, "Unable to allocate memory for "
  				   "next fragment!");
  			return NULL;
  		}
  		wpabuf_put_u8(resp, lm_exch);
  		buf = wpabuf_head_u8(data->outbuf);
  		wpabuf_put_data(resp, buf + data->out_frag_pos, len);
  		data->out_frag_pos += len;
  		/*
  		 * this is the last fragment so get rid of the out buffer
  		 */
  		if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
  			wpabuf_free(data->outbuf);
  			data->outbuf = NULL;
  			data->out_frag_pos = 0;
  		}
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Send %s fragment of %d bytes",
  			   data->out_frag_pos == 0 ? "last" : "next",
  			   (int) len);
  		if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
  			ret->methodState = METHOD_DONE;
  			ret->decision = DECISION_UNCOND_SUCC;
  			eap_pwd_state(data, SUCCESS);
  		}
  		return resp;
  	}
  
  	/*
  	 * see if this is a fragment that needs buffering
  	 *
  	 * if it's the first fragment there'll be a length field
  	 */
  	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
  		if (len < 2) {
  			wpa_printf(MSG_DEBUG,
  				   "EAP-pwd: Frame too short to contain Total-Length field");
  			ret->ignore = TRUE;
  			return NULL;
  		}
  		tot_len = WPA_GET_BE16(pos);
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments whose "
  			   "total length = %d", tot_len);
  		if (tot_len > 15000)
  			return NULL;
  		if (data->inbuf) {
  			wpa_printf(MSG_DEBUG,
  				   "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
  			ret->ignore = TRUE;
  			return NULL;
  		}
  		data->inbuf = wpabuf_alloc(tot_len);
  		if (data->inbuf == NULL) {
  			wpa_printf(MSG_INFO, "Out of memory to buffer "
  				   "fragments!");
  			return NULL;
  		}
  		data->in_frag_pos = 0;
  		pos += sizeof(u16);
  		len -= sizeof(u16);
  	}
  	/*
  	 * buffer and ACK the fragment
  	 */
  	if (EAP_PWD_GET_MORE_BIT(lm_exch) || data->in_frag_pos) {
  		data->in_frag_pos += len;
  		if (data->in_frag_pos > wpabuf_size(data->inbuf)) {
  			wpa_printf(MSG_INFO, "EAP-pwd: Buffer overflow attack "
  				   "detected (%d vs. %d)!",
  				   (int) data->in_frag_pos,
  				   (int) wpabuf_len(data->inbuf));
  			wpabuf_free(data->inbuf);
  			data->inbuf = NULL;
  			data->in_frag_pos = 0;
  			return NULL;
  		}
  		wpabuf_put_data(data->inbuf, pos, len);
  	}
  	if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
  		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
  				     EAP_PWD_HDR_SIZE,
  				     EAP_CODE_RESPONSE, eap_get_id(reqData));
  		if (resp != NULL)
  			wpabuf_put_u8(resp, (EAP_PWD_GET_EXCHANGE(lm_exch)));
  		wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a %d byte fragment",
  			   (int) len);
  		return resp;
  	}
  	/*
  	 * we're buffering and this is the last fragment
  	 */
  	if (data->in_frag_pos) {
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
  			   (int) len);
  		pos = wpabuf_head_u8(data->inbuf);
  		len = data->in_frag_pos;
  	}
  	wpa_printf(MSG_DEBUG, "EAP-pwd: processing frame: exch %d, len %d",
  		   EAP_PWD_GET_EXCHANGE(lm_exch), (int) len);
  
  	switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
  	case EAP_PWD_OPCODE_ID_EXCH:
  		eap_pwd_perform_id_exchange(sm, data, ret, reqData,
  					    pos, len);
  		break;
  	case EAP_PWD_OPCODE_COMMIT_EXCH:
  		eap_pwd_perform_commit_exchange(sm, data, ret, reqData,
  						pos, len);
  		break;
  	case EAP_PWD_OPCODE_CONFIRM_EXCH:
  		eap_pwd_perform_confirm_exchange(sm, data, ret, reqData,
  						 pos, len);
  		break;
  	default:
  		wpa_printf(MSG_INFO, "EAP-pwd: Ignoring message with unknown "
  			   "opcode %d", lm_exch);
  		break;
  	}
  	/*
  	 * if we buffered the just processed input now's the time to free it
  	 */
  	if (data->in_frag_pos) {
  		wpabuf_free(data->inbuf);
  		data->inbuf = NULL;
  		data->in_frag_pos = 0;
  	}
  
  	if (data->outbuf == NULL) {
  		ret->methodState = METHOD_DONE;
  		ret->decision = DECISION_FAIL;
  		return NULL;        /* generic failure */
  	}
  
  	/*
  	 * we have output! Do we need to fragment it?
  	 */
  	lm_exch = EAP_PWD_GET_EXCHANGE(lm_exch);
  	len = wpabuf_len(data->outbuf);
  	if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
  		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, data->mtu,
  				     EAP_CODE_RESPONSE, eap_get_id(reqData));
  		/*
  		 * if so it's the first so include a length field
  		 */
  		EAP_PWD_SET_LENGTH_BIT(lm_exch);
  		EAP_PWD_SET_MORE_BIT(lm_exch);
  		tot_len = len;
  		/*
  		 * keep the packet at the MTU
  		 */
  		len = data->mtu - EAP_PWD_HDR_SIZE - sizeof(u16);
  		wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, total "
  			   "length = %d", tot_len);
  	} else {
  		resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
  				     EAP_PWD_HDR_SIZE + len,
  				     EAP_CODE_RESPONSE, eap_get_id(reqData));
  	}
  	if (resp == NULL)
  		return NULL;
  
  	wpabuf_put_u8(resp, lm_exch);
  	if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
  		wpabuf_put_be16(resp, tot_len);
  		data->out_frag_pos += len;
  	}
  	buf = wpabuf_head_u8(data->outbuf);
  	wpabuf_put_data(resp, buf, len);
  	/*
  	 * if we're not fragmenting then there's no need to carry this around
  	 */
  	if (data->out_frag_pos == 0) {
  		wpabuf_free(data->outbuf);
  		data->outbuf = NULL;
  		data->out_frag_pos = 0;
  		if (data->state == SUCCESS_ON_FRAG_COMPLETION) {
  			ret->methodState = METHOD_DONE;
  			ret->decision = DECISION_UNCOND_SUCC;
  			eap_pwd_state(data, SUCCESS);
  		}
  	}
  
  	return resp;
  }
  
  
  static Boolean eap_pwd_key_available(struct eap_sm *sm, void *priv)
  {
  	struct eap_pwd_data *data = priv;
  	return data->state == SUCCESS;
  }
  
  
  static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
  {
  	struct eap_pwd_data *data = priv;
  	u8 *key;
  
  	if (data->state != SUCCESS)
  		return NULL;
  
  	if ((key = os_malloc(EAP_EMSK_LEN)) == NULL)
  		return NULL;
  
  	os_memcpy(key, data->emsk, EAP_EMSK_LEN);
  	*len = EAP_EMSK_LEN;
  
  	return key;
  }
  
  
  int eap_peer_pwd_register(void)
  {
  	struct eap_method *eap;
  	int ret;
  
  	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
  				    EAP_VENDOR_IETF, EAP_TYPE_PWD, "PWD");
  	if (eap == NULL)
  		return -1;
  
  	eap->init = eap_pwd_init;
  	eap->deinit = eap_pwd_deinit;
  	eap->process = eap_pwd_process;
  	eap->isKeyAvailable = eap_pwd_key_available;
  	eap->getKey = eap_pwd_getkey;
  	eap->getSessionId = eap_pwd_get_session_id;
  	eap->get_emsk = eap_pwd_get_emsk;
  
  	ret = eap_peer_method_register(eap);
  	if (ret)
  		eap_peer_method_free(eap);
  	return ret;
  }
  