示例#1
0
int
compute_keys (pwd_session_t *sess, uint8_t *peer_confirm,
	      uint8_t *msk, uint8_t *emsk)
{
    HMAC_CTX ctx;
    uint8_t mk[SHA256_DIGEST_LENGTH], *cruft;
    uint8_t session_id[SHA256_DIGEST_LENGTH + 1];
    uint8_t msk_emsk[128];		/* 64 each */
    int offset;

    if ((cruft = talloc_array(sess, uint8_t, BN_num_bytes(sess->prime))) == NULL) {
	DEBUG2("pwd: unable to allocate space to compute keys");
	return -1;
    }
    /*
     * first compute the session-id = TypeCode | H(ciphersuite | scal_p |
     *	scal_s)
     */
    session_id[0] = PW_EAP_PWD;
    H_Init(&ctx);
    H_Update(&ctx, (uint8_t *)&sess->ciphersuite, sizeof(sess->ciphersuite));
    offset = BN_num_bytes(sess->order) - BN_num_bytes(sess->peer_scalar);
    memset(cruft, 0, BN_num_bytes(sess->prime));
    BN_bn2bin(sess->peer_scalar, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->order));
    offset = BN_num_bytes(sess->order) - BN_num_bytes(sess->my_scalar);
    memset(cruft, 0, BN_num_bytes(sess->prime));
    BN_bn2bin(sess->my_scalar, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->order));
    H_Final(&ctx, (uint8_t *)&session_id[1]);

    /* then compute MK = H(k | commit-peer | commit-server) */
    H_Init(&ctx);

    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(sess->k);
    BN_bn2bin(sess->k, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    H_Update(&ctx, peer_confirm, SHA256_DIGEST_LENGTH);

    H_Update(&ctx, sess->my_confirm, SHA256_DIGEST_LENGTH);

    H_Final(&ctx, mk);

    /* stretch the mk with the session-id to get MSK | EMSK */
    eap_pwd_kdf(mk, SHA256_DIGEST_LENGTH,
		(const char *)session_id, SHA256_DIGEST_LENGTH+1,
		msk_emsk, 1024);  /* it's bits, ((64 + 64) * 8) */

    memcpy(msk, msk_emsk, 64);
    memcpy(emsk, msk_emsk + 64, 64);

    talloc_free(cruft);
    return 0;
}
示例#2
0
int compute_keys(EAP_PWD_group *grp, BN_CTX *bnctx, BIGNUM *k,
		 BIGNUM *peer_scalar, BIGNUM *server_scalar,
		 u8 *commit_peer, u8 *commit_server,
		 u32 *ciphersuite, u8 *msk, u8 *emsk)
{
	HMAC_CTX ctx;
	u8 mk[SHA256_DIGEST_LENGTH], *cruft;
	u8 session_id[SHA256_DIGEST_LENGTH + 1];
	u8 msk_emsk[EAP_MSK_LEN + EAP_EMSK_LEN];
	int offset;

	if ((cruft = os_malloc(BN_num_bytes(grp->prime))) == NULL)
		return -1;

	/*
	 * first compute the session-id = TypeCode | H(ciphersuite | scal_p |
	 *	scal_s)
	 */
	session_id[0] = EAP_TYPE_PWD;
	H_Init(&ctx);
	H_Update(&ctx, (u8 *)ciphersuite, sizeof(u32));
	offset = BN_num_bytes(grp->order) - BN_num_bytes(peer_scalar);
	os_memset(cruft, 0, BN_num_bytes(grp->prime));
	BN_bn2bin(peer_scalar, cruft + offset);
	H_Update(&ctx, cruft, BN_num_bytes(grp->order));
	offset = BN_num_bytes(grp->order) - BN_num_bytes(server_scalar);
	os_memset(cruft, 0, BN_num_bytes(grp->prime));
	BN_bn2bin(server_scalar, cruft + offset);
	H_Update(&ctx, cruft, BN_num_bytes(grp->order));
	H_Final(&ctx, &session_id[1]);

	/* then compute MK = H(k | commit-peer | commit-server) */
	H_Init(&ctx);
	offset = BN_num_bytes(grp->prime) - BN_num_bytes(k);
	os_memset(cruft, 0, BN_num_bytes(grp->prime));
	BN_bn2bin(k, cruft + offset);
	H_Update(&ctx, cruft, BN_num_bytes(grp->prime));
	H_Update(&ctx, commit_peer, SHA256_DIGEST_LENGTH);
	H_Update(&ctx, commit_server, SHA256_DIGEST_LENGTH);
	H_Final(&ctx, mk);

	/* stretch the mk with the session-id to get MSK | EMSK */
	eap_pwd_kdf(mk, SHA256_DIGEST_LENGTH,
		    session_id, SHA256_DIGEST_LENGTH+1,
		    msk_emsk, (EAP_MSK_LEN + EAP_EMSK_LEN) * 8);

	os_memcpy(msk, msk_emsk, EAP_MSK_LEN);
	os_memcpy(emsk, msk_emsk + EAP_MSK_LEN, EAP_EMSK_LEN);

	os_free(cruft);

	return 1;
}
示例#3
0
int
compute_peer_confirm (pwd_session_t *sess, uint8_t *buf, BN_CTX *bnctx)
{
    BIGNUM *x = NULL, *y = NULL;
    HMAC_CTX ctx;
    uint8_t *cruft = NULL;
    int offset, req = -1;

    /*
     * Each component of the cruft will be at most as big as the prime
     */
    if (((cruft = talloc_zero_array(sess, uint8_t, BN_num_bytes(sess->prime))) == NULL) ||
	((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
	DEBUG2("pwd: unable to allocate space to compute confirm!");
	goto fin;
    }

    /*
     * commit is H(k | server_element | server_scalar | peer_element |
     *	       peer_scalar | ciphersuite)
     */
    H_Init(&ctx);

    /*
     * 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.
     *
     * First is k
     */
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(sess->k);
    BN_bn2bin(sess->k, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    /*
     * then peer element: x, y
     */
    if (!EC_POINT_get_affine_coordinates_GFp(sess->group,
					     sess->peer_element, x, y,
					     bnctx)) {
	DEBUG2("pwd: unable to get coordinates of peer's element");
	goto fin;
    }

    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(x);
    BN_bn2bin(x, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(y);
    BN_bn2bin(y, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    /*
     * and peer scalar
     */
    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->order) - BN_num_bytes(sess->peer_scalar);
    BN_bn2bin(sess->peer_scalar, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->order));

    /*
     * then server element: x, y
     */
    if (!EC_POINT_get_affine_coordinates_GFp(sess->group,
					     sess->my_element, x, y,
					     bnctx)) {
	DEBUG2("pwd: unable to get coordinates of server element");
	goto fin;
    }
    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(x);
    BN_bn2bin(x, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->prime) - BN_num_bytes(y);
    BN_bn2bin(y, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->prime));

    /*
     * and server scalar
     */
    memset(cruft, 0, BN_num_bytes(sess->prime));
    offset = BN_num_bytes(sess->order) - BN_num_bytes(sess->my_scalar);
    BN_bn2bin(sess->my_scalar, cruft + offset);
    H_Update(&ctx, cruft, BN_num_bytes(sess->order));

    /*
     * finally, ciphersuite
     */
    H_Update(&ctx, (uint8_t *)&sess->ciphersuite, sizeof(sess->ciphersuite));

    H_Final(&ctx, buf);

    req = 0;
fin:
    if (cruft != NULL) {
	    talloc_free(cruft);
    }
    BN_free(x);
    BN_free(y);

    return req;
}
示例#4
0
int
compute_password_element (pwd_session_t *sess, uint16_t grp_num,
			  char *password, int password_len,
			  char *id_server, int id_server_len,
			  char *id_peer, int id_peer_len,
			  uint32_t *token)
{
    BIGNUM *x_candidate = NULL, *rnd = NULL, *cofactor = NULL;
    HMAC_CTX ctx;
    uint8_t pwe_digest[SHA256_DIGEST_LENGTH], *prfbuf = NULL, ctr;
    int nid, is_odd, primebitlen, primebytelen, ret = 0;

    switch (grp_num) { /* from IANA registry for IKE D-H groups */
	case 19:
	    nid = NID_X9_62_prime256v1;
	    break;
	case 20:
	    nid = NID_secp384r1;
	    break;
	case 21:
	    nid = NID_secp521r1;
	    break;
	case 25:
	    nid = NID_X9_62_prime192v1;
	    break;
	case 26:
	    nid = NID_secp224r1;
	    break;
	default:
	    DEBUG("unknown group %d", grp_num);
	    goto fail;
    }

    sess->pwe = NULL;
    sess->order = NULL;
    sess->prime = NULL;

    if ((sess->group = EC_GROUP_new_by_curve_name(nid)) == NULL) {
	DEBUG("unable to create EC_GROUP");
	goto fail;
    }

    if (((rnd = BN_new()) == NULL) ||
	((cofactor = BN_new()) == NULL) ||
	((sess->pwe = EC_POINT_new(sess->group)) == NULL) ||
	((sess->order = BN_new()) == NULL) ||
	((sess->prime = BN_new()) == NULL) ||
	((x_candidate = BN_new()) == NULL)) {
	DEBUG("unable to create bignums");
	goto fail;
    }

    if (!EC_GROUP_get_curve_GFp(sess->group, sess->prime, NULL, NULL, NULL))
    {
	DEBUG("unable to get prime for GFp curve");
	goto fail;
    }
    if (!EC_GROUP_get_order(sess->group, sess->order, NULL)) {
	DEBUG("unable to get order for curve");
	goto fail;
    }
    if (!EC_GROUP_get_cofactor(sess->group, cofactor, NULL)) {
	DEBUG("unable to get cofactor for curve");
	goto fail;
    }
    primebitlen = BN_num_bits(sess->prime);
    primebytelen = BN_num_bytes(sess->prime);
    if ((prfbuf = talloc_zero_array(sess, uint8_t, primebytelen)) == NULL) {
	DEBUG("unable to alloc space for prf buffer");
	goto fail;
    }
    ctr = 0;
    while (1) {
	if (ctr > 10) {
	    DEBUG("unable to find random point on curve for group %d, something's fishy", grp_num);
	    goto fail;
	}
	ctr++;

	/*
	 * compute counter-mode password value and stretch to prime
	 *    pwd-seed = H(token | peer-id | server-id | password |
	 *		   counter)
	 */
	H_Init(&ctx);
	H_Update(&ctx, (uint8_t *)token, sizeof(*token));
	H_Update(&ctx, (uint8_t *)id_peer, id_peer_len);
	H_Update(&ctx, (uint8_t *)id_server, id_server_len);
	H_Update(&ctx, (uint8_t *)password, password_len);
	H_Update(&ctx, (uint8_t *)&ctr, sizeof(ctr));
	H_Final(&ctx, pwe_digest);

	BN_bin2bn(pwe_digest, SHA256_DIGEST_LENGTH, rnd);
	eap_pwd_kdf(pwe_digest, SHA256_DIGEST_LENGTH,
		    "EAP-pwd Hunting And Pecking",
		    strlen("EAP-pwd Hunting And Pecking"),
		    prfbuf, primebitlen);

	BN_bin2bn(prfbuf, primebytelen, x_candidate);
	/*
	 * eap_pwd_kdf() returns a string of bits 0..primebitlen but
	 * BN_bin2bn will treat that string of bits as a big endian
	 * number. If the primebitlen is not an even multiple of 8
	 * then excessive bits-- those _after_ primebitlen-- so now
	 * we have to shift right the amount we masked off.
	 */
	if (primebitlen % 8) {
	    BN_rshift(x_candidate, x_candidate, (8 - (primebitlen % 8)));
	}
	if (BN_ucmp(x_candidate, sess->prime) >= 0) {
	    continue;
	}
	/*
	 * need to unambiguously identify the solution, if there is
	 * one...
	 */
	if (BN_is_odd(rnd)) {
	    is_odd = 1;
	} else {
	    is_odd = 0;
	}
	/*
	 * solve the quadratic equation, if it's not solvable then we
	 * don't have a point
	 */
	if (!EC_POINT_set_compressed_coordinates_GFp(sess->group,
						     sess->pwe,
						     x_candidate,
						     is_odd, NULL)) {
	    continue;
	}
	/*
	 * If there's a solution to the equation then the point must be
	 * on the curve so why check again explicitly? OpenSSL code
	 * says this is required by X9.62. We're not X9.62 but it can't
	 * hurt just to be sure.
	 */
	if (!EC_POINT_is_on_curve(sess->group, sess->pwe, NULL)) {
	    DEBUG("EAP-pwd: point is not on curve");
	    continue;
	}

	if (BN_cmp(cofactor, BN_value_one())) {
	    /* make sure the point is not in a small sub-group */
	    if (!EC_POINT_mul(sess->group, sess->pwe, NULL, sess->pwe,
			      cofactor, NULL)) {
		DEBUG("EAP-pwd: cannot multiply generator by order");
		continue;
	    }
	    if (EC_POINT_is_at_infinity(sess->group, sess->pwe)) {
		DEBUG("EAP-pwd: point is at infinity");
		continue;
	    }
	}
	/* if we got here then we have a new generator. */
	break;
    }
    sess->group_num = grp_num;
    if (0) {
fail:				/* DON'T free sess, it's in handler->opaque */
	ret = -1;
    }
    /* cleanliness and order.... */
    BN_free(cofactor);
    BN_free(x_candidate);
    BN_free(rnd);
    talloc_free(prfbuf);

    return ret;
}
示例#5
0
static void
eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
			     const u8 *payload, size_t payload_len)
{
	BIGNUM *x = NULL, *y = NULL;
	HMAC_CTX ctx;
	u32 cs;
	u16 grp;
	u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;

	/* build up the ciphersuite: 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 (peer): allocation fail");
		goto fin;
	}

	/*
	 * commit is H(k | peer_element | peer_scalar | server_element |
	 *	       server_scalar | ciphersuite)
	 */
	H_Init(&ctx);

	/* k */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->k, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* peer element: x, y */
	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
						 data->peer_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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* peer scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->peer_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* server 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* server scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->my_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* ciphersuite */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	H_Update(&ctx, (u8 *)&cs, sizeof(u32));

	/* all done */
	H_Final(&ctx, conf);

	ptr = (u8 *) payload;
	if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) {
		wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
			   "verify");
		goto fin;
	}

	wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
	if (compute_keys(data->grp, data->bnctx, data->k,
			 data->peer_scalar, data->my_scalar, conf,
			 data->my_confirm, &cs, data->msk, data->emsk) < 0)
		eap_pwd_state(data, FAILURE);
	else
		eap_pwd_state(data, SUCCESS);

fin:
	os_free(cruft);
	BN_free(x);
	BN_free(y);
}
示例#6
0
static struct wpabuf *
eap_pwd_build_confirm_req(struct eap_sm *sm, struct eap_pwd_data *data, u8 id)
{
	struct wpabuf *req = NULL;
	BIGNUM *x = NULL, *y = NULL;
	HMAC_CTX ctx;
	u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;
	u16 grp;

	wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");

	/* 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): debug allocation "
			   "fail");
		goto fin;
	}

	/*
	 * commit is H(k | server_element | server_scalar | peer_element |
	 *	       peer_scalar | ciphersuite)
	 */
	H_Init(&ctx);

	/*
	 * 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.
	 *
	 * First is k
	 */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->k, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* server 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* server scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->my_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* peer element: x, y */
	if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
						 data->peer_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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* peer scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->peer_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* ciphersuite */
	grp = htons(data->group_num);
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	ptr = cruft;
	os_memcpy(ptr, &grp, sizeof(u16));
	ptr += sizeof(u16);
	*ptr = EAP_PWD_DEFAULT_RAND_FUNC;
	ptr += sizeof(u8);
	*ptr = EAP_PWD_DEFAULT_PRF;
	ptr += sizeof(u8);
	H_Update(&ctx, cruft, ptr-cruft);

	/* all done with the random function */
	H_Final(&ctx, conf);
	os_memcpy(data->my_confirm, conf, SHA256_DIGEST_LENGTH);

	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
			    sizeof(struct eap_pwd_hdr) + SHA256_DIGEST_LENGTH,
			    EAP_CODE_REQUEST, id);
	if (req == NULL)
		goto fin;

	wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
	wpabuf_put_data(req, conf, SHA256_DIGEST_LENGTH);

fin:
	os_free(cruft);
	BN_free(x);
	BN_free(y);
	if (req == NULL)
		eap_pwd_state(data, FAILURE);

	return req;
}
示例#7
0
static struct wpabuf *
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)
{
	struct wpabuf *resp = NULL;
	BIGNUM *x = NULL, *y = NULL;
	HMAC_CTX ctx;
	u32 cs;
	u16 grp;
	u8 conf[SHA256_DIGEST_LENGTH], *cruft = NULL, *ptr;

	/*
	 * 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): debug allocation "
			   "fail");
		goto fin;
	}

	/*
	 * server's commit is H(k | server_element | server_scalar |
	 *			peer_element | peer_scalar | ciphersuite)
	 */
	H_Init(&ctx);

	/*
	 * 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));
	BN_bn2bin(data->k, cruft);
	H_Update(&ctx, 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* server scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->server_scalar, cruft);
	H_Update(&ctx, 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* my scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->my_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* the ciphersuite */
	H_Update(&ctx, (u8 *) &cs, sizeof(u32));

	/* random function fin */
	H_Final(&ctx, conf);

	ptr = (u8 *) payload;
	if (os_memcmp(conf, ptr, SHA256_DIGEST_LENGTH)) {
		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)
	 */
	H_Init(&ctx);

	/* k */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->k, cruft);
	H_Update(&ctx, 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* my scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->my_scalar, cruft);
	H_Update(&ctx, 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));
	BN_bn2bin(x, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(y, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->prime));

	/* server scalar */
	os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
	BN_bn2bin(data->server_scalar, cruft);
	H_Update(&ctx, cruft, BN_num_bytes(data->grp->order));

	/* the ciphersuite */
	H_Update(&ctx, (u8 *) &cs, sizeof(u32));

	/* all done */
	H_Final(&ctx, conf);

	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
			     sizeof(struct eap_pwd_hdr) + SHA256_DIGEST_LENGTH,
			     EAP_CODE_RESPONSE, eap_get_id(reqData));
	if (resp == NULL)
		goto fin;

	wpabuf_put_u8(resp, EAP_PWD_OPCODE_CONFIRM_EXCH);
	wpabuf_put_data(resp, conf, SHA256_DIGEST_LENGTH);

	if (compute_keys(data->grp, data->bnctx, data->k,
			 data->my_scalar, data->server_scalar, conf, ptr,
			 &cs, data->msk, data->emsk) < 0) {
		wpa_printf(MSG_INFO, "EAP-PWD (peer): unable to compute MSK | "
			   "EMSK");
		goto fin;
	}

fin:
	os_free(cruft);
	BN_free(x);
	BN_free(y);
	ret->methodState = METHOD_DONE;
	if (resp == NULL) {
		ret->decision = DECISION_FAIL;
		eap_pwd_state(data, FAILURE);
	} else {
		ret->decision = DECISION_UNCOND_SUCC;
		eap_pwd_state(data, SUCCESS);
	}

	return resp;
}
示例#8
0
/*
 * compute a "random" secret point on an elliptic curve based
 * on the password and identities.
 */
int compute_password_element(EAP_PWD_group *grp, u16 num,
			     u8 *password, int password_len,
			     u8 *id_server, int id_server_len,
			     u8 *id_peer, int id_peer_len, u8 *token)
{
	BIGNUM *x_candidate = NULL, *rnd = NULL, *cofactor = NULL;
	HMAC_CTX ctx;
	unsigned char pwe_digest[SHA256_DIGEST_LENGTH], *prfbuf = NULL, ctr;
	int nid, is_odd, primebitlen, primebytelen, ret = 0;

	switch (num) { /* from IANA registry for IKE D-H groups */
        case 19:
		nid = NID_X9_62_prime256v1;
		break;
        case 20:
		nid = NID_secp384r1;
		break;
        case 21:
		nid = NID_secp521r1;
		break;
        case 25:
		nid = NID_X9_62_prime192v1;
		break;
        case 26:
		nid = NID_secp224r1;
		break;
        default:
		wpa_printf(MSG_INFO, "EAP-pwd: unsupported group %d", num);
		return -1;
	}

	grp->pwe = NULL;
	grp->order = NULL;
	grp->prime = NULL;

	if ((grp->group = EC_GROUP_new_by_curve_name(nid)) == NULL) {
		wpa_printf(MSG_INFO, "EAP-pwd: unable to create EC_GROUP");
		goto fail;
	}

	if (((rnd = BN_new()) == NULL) ||
	    ((cofactor = BN_new()) == NULL) ||
	    ((grp->pwe = EC_POINT_new(grp->group)) == NULL) ||
	    ((grp->order = BN_new()) == NULL) ||
	    ((grp->prime = BN_new()) == NULL) ||
	    ((x_candidate = BN_new()) == NULL)) {
		wpa_printf(MSG_INFO, "EAP-pwd: unable to create bignums");
		goto fail;
	}

	if (!EC_GROUP_get_curve_GFp(grp->group, grp->prime, NULL, NULL, NULL))
	{
		wpa_printf(MSG_INFO, "EAP-pwd: unable to get prime for GFp "
			   "curve");
		goto fail;
	}
	if (!EC_GROUP_get_order(grp->group, grp->order, NULL)) {
		wpa_printf(MSG_INFO, "EAP-pwd: unable to get order for curve");
		goto fail;
	}
	if (!EC_GROUP_get_cofactor(grp->group, cofactor, NULL)) {
		wpa_printf(MSG_INFO, "EAP-pwd: unable to get cofactor for "
			   "curve");
		goto fail;
	}
	primebitlen = BN_num_bits(grp->prime);
	primebytelen = BN_num_bytes(grp->prime);
	if ((prfbuf = os_malloc(primebytelen)) == NULL) {
		wpa_printf(MSG_INFO, "EAP-pwd: unable to malloc space for prf "
			   "buffer");
		goto fail;
	}
	os_memset(prfbuf, 0, primebytelen);
	ctr = 0;
	while (1) {
		if (ctr > 30) {
			wpa_printf(MSG_INFO, "EAP-pwd: unable to find random "
				   "point on curve for group %d, something's "
				   "fishy", num);
			goto fail;
		}
		ctr++;

		/*
		 * compute counter-mode password value and stretch to prime
		 *    pwd-seed = H(token | peer-id | server-id | password |
		 *		   counter)
		 */
		H_Init(&ctx);
		H_Update(&ctx, token, sizeof(u32));
		H_Update(&ctx, id_peer, id_peer_len);
		H_Update(&ctx, id_server, id_server_len);
		H_Update(&ctx, password, password_len);
		H_Update(&ctx, &ctr, sizeof(ctr));
		H_Final(&ctx, pwe_digest);

		BN_bin2bn(pwe_digest, SHA256_DIGEST_LENGTH, rnd);

		eap_pwd_kdf(pwe_digest, SHA256_DIGEST_LENGTH,
			    (unsigned char *) "EAP-pwd Hunting And Pecking",
			    os_strlen("EAP-pwd Hunting And Pecking"),
			    prfbuf, primebitlen);

		BN_bin2bn(prfbuf, primebytelen, x_candidate);

		/*
		 * eap_pwd_kdf() returns a string of bits 0..primebitlen but
		 * BN_bin2bn will treat that string of bits as a big endian
		 * number. If the primebitlen is not an even multiple of 8
		 * then excessive bits-- those _after_ primebitlen-- so now
		 * we have to shift right the amount we masked off.
		 */
		if (primebitlen % 8)
			BN_rshift(x_candidate, x_candidate,
				  (8 - (primebitlen % 8)));

		if (BN_ucmp(x_candidate, grp->prime) >= 0)
			continue;

		wpa_hexdump(MSG_DEBUG, "EAP-pwd: x_candidate",
			    prfbuf, primebytelen);

		/*
		 * need to unambiguously identify the solution, if there is
		 * one...
		 */
		if (BN_is_odd(rnd))
			is_odd = 1;
		else
			is_odd = 0;

		/*
		 * solve the quadratic equation, if it's not solvable then we
		 * don't have a point
		 */
		if (!EC_POINT_set_compressed_coordinates_GFp(grp->group,
							     grp->pwe,
							     x_candidate,
							     is_odd, NULL))
			continue;
		/*
		 * If there's a solution to the equation then the point must be
		 * on the curve so why check again explicitly? OpenSSL code
		 * says this is required by X9.62. We're not X9.62 but it can't
		 * hurt just to be sure.
		 */
		if (!EC_POINT_is_on_curve(grp->group, grp->pwe, NULL)) {
			wpa_printf(MSG_INFO, "EAP-pwd: point is not on curve");
			continue;
		}

		if (BN_cmp(cofactor, BN_value_one())) {
			/* make sure the point is not in a small sub-group */
			if (!EC_POINT_mul(grp->group, grp->pwe, NULL, grp->pwe,
					  cofactor, NULL)) {
				wpa_printf(MSG_INFO, "EAP-pwd: cannot "
					   "multiply generator by order");
				continue;
			}
			if (EC_POINT_is_at_infinity(grp->group, grp->pwe)) {
				wpa_printf(MSG_INFO, "EAP-pwd: point is at "
					   "infinity");
				continue;
			}
		}
		/* if we got here then we have a new generator. */
		break;
	}
	wpa_printf(MSG_DEBUG, "EAP-pwd: found a PWE in %d tries", ctr);
	grp->group_num = num;
	if (0) {
 fail:
		EC_GROUP_free(grp->group);
		EC_POINT_free(grp->pwe);
		BN_free(grp->order);
		BN_free(grp->prime);
		os_free(grp);
		grp = NULL;
		ret = 1;
	}
	/* cleanliness and order.... */
	BN_free(cofactor);
	BN_free(x_candidate);
	BN_free(rnd);
	os_free(prfbuf);

	return ret;
}