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3 (C) 2013 Christian Grothoff (and other contributing authors)
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22 * @file scalarproduct/gnunet-service-scalarproduct.c
23 * @brief scalarproduct service implementation
24 * @author Christian M. Fuchs
28 #include "gnunet_util_lib.h"
29 #include "gnunet_core_service.h"
30 #include "gnunet_mesh_service.h"
31 #include "gnunet_applications.h"
32 #include "gnunet_protocols.h"
33 #include "gnunet_scalarproduct_service.h"
34 #include "scalarproduct.h"
36 #define LOG(kind,...) GNUNET_log_from (kind, "scalarproduct", __VA_ARGS__)
38 ///////////////////////////////////////////////////////////////////////////////
39 // Service Structure Definitions
40 ///////////////////////////////////////////////////////////////////////////////
43 * state a session can be in
47 CLIENT_REQUEST_RECEIVED,
48 WAITING_FOR_BOBS_CONNECT,
49 CLIENT_RESPONSE_RECEIVED,
50 WAITING_FOR_SERVICE_REQUEST,
51 WAITING_FOR_SERVICE_RESPONSE,
52 SERVICE_REQUEST_RECEIVED,
53 SERVICE_RESPONSE_RECEIVED,
58 * role a peer in a session can assume
67 * A scalarproduct session which tracks:
69 * a request form the client to our final response.
71 * a request from a service to us(service).
76 * the role this peer has
81 * session information is kept in a DLL
83 struct ServiceSession *next;
86 * session information is kept in a DLL
88 struct ServiceSession *prev;
91 * (hopefully) unique transaction ID
93 struct GNUNET_HashCode key;
96 * state of the session
98 enum SessionState state;
101 * Alice or Bob's peerID
103 struct GNUNET_PeerIdentity peer;
106 * the client this request is related to
108 struct GNUNET_SERVER_Client * client;
111 * The message to send
113 struct GNUNET_MessageHeader * msg;
116 * how many elements we were supplied with from the client
118 uint32_t element_count;
121 * how many elements actually are used after applying the mask
123 uint32_t used_element_count;
126 * how many bytes the mask is long.
127 * just for convenience so we don't have to re-re-re calculate it each time
129 uint32_t mask_length;
132 * all the vector elements we received
137 * mask of which elements to check
139 unsigned char * mask;
142 * Public key of the remote service, only used by bob
144 gcry_sexp_t remote_pubkey;
147 * E(ai)(Bob) or ai(Alice) after applying the mask
152 * The computed scalar
157 * My transmit handle for the current message to a alice/bob
159 struct GNUNET_MESH_TransmitHandle * service_transmit_handle;
162 * My transmit handle for the current message to the client
164 struct GNUNET_SERVER_TransmitHandle * client_transmit_handle;
167 * tunnel-handle associated with our mesh handle
169 struct GNUNET_MESH_Tunnel * tunnel;
171 GNUNET_SCHEDULER_TaskIdentifier client_notification_task;
173 GNUNET_SCHEDULER_TaskIdentifier service_request_task;
176 ///////////////////////////////////////////////////////////////////////////////
178 ///////////////////////////////////////////////////////////////////////////////
182 * Handle to the core service (NULL until we've connected to it).
184 static struct GNUNET_MESH_Handle *my_mesh;
187 * The identity of this host.
189 static struct GNUNET_PeerIdentity me;
192 * Service's own public key represented as string
194 static unsigned char * my_pubkey_external;
197 * Service's own public key represented as string
199 static uint32_t my_pubkey_external_length = 0;
204 static gcry_mpi_t my_n;
207 * Service's own n^2 (kept for performance)
209 static gcry_mpi_t my_nsquare;
212 * Service's own public exponent
214 static gcry_mpi_t my_g;
217 * Service's own private multiplier
219 static gcry_mpi_t my_mu;
222 * Service's own private exponent
224 static gcry_mpi_t my_lambda;
227 * Service's offset for values that could possibly be negative but are plaintext for encryption.
229 static gcry_mpi_t my_offset;
232 * Head of our double linked list for client-requests sent to us.
233 * for all of these elements we calculate a scalar product with a remote peer
234 * split between service->service and client->service for simplicity
236 static struct ServiceSession * from_client_head;
238 * Tail of our double linked list for client-requests sent to us.
239 * for all of these elements we calculate a scalar product with a remote peer
240 * split between service->service and client->service for simplicity
242 static struct ServiceSession * from_client_tail;
245 * Head of our double linked list for service-requests sent to us.
246 * for all of these elements we help the requesting service in calculating a scalar product
247 * split between service->service and client->service for simplicity
249 static struct ServiceSession * from_service_head;
252 * Tail of our double linked list for service-requests sent to us.
253 * for all of these elements we help the requesting service in calculating a scalar product
254 * split between service->service and client->service for simplicity
256 static struct ServiceSession * from_service_tail;
259 * Certain events (callbacks for server & mesh operations) must not be queued after shutdown.
261 static int do_shutdown;
263 ///////////////////////////////////////////////////////////////////////////////
265 ///////////////////////////////////////////////////////////////////////////////
269 * Generates an Paillier private/public keyset and extracts the values using libgrcypt only
274 gcry_sexp_t gen_params;
276 gcry_sexp_t tmp_sexp;
285 // we can still use the RSA keygen for generating p,q,n, but using e is pointless.
286 GNUNET_assert (0 == gcry_sexp_build (&gen_params, &erroff,
287 "(genkey(rsa(nbits %d)(rsa-use-e 3:257)))",
290 GNUNET_assert (0 == gcry_pk_genkey (&key, gen_params));
291 gcry_sexp_release (gen_params);
293 // get n and d of our publickey as MPI
294 tmp_sexp = gcry_sexp_find_token (key, "n", 0);
295 GNUNET_assert (tmp_sexp);
296 my_n = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
297 gcry_sexp_release (tmp_sexp);
298 tmp_sexp = gcry_sexp_find_token (key, "p", 0);
299 GNUNET_assert (tmp_sexp);
300 p = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
301 gcry_sexp_release (tmp_sexp);
302 tmp_sexp = gcry_sexp_find_token (key, "q", 0);
303 GNUNET_assert (tmp_sexp);
304 q = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
305 gcry_sexp_release (key);
307 tmp1 = gcry_mpi_new (0);
308 tmp2 = gcry_mpi_new (0);
309 gcd = gcry_mpi_new (0);
310 my_g = gcry_mpi_new (0);
311 my_mu = gcry_mpi_new (0);
312 my_nsquare = gcry_mpi_new (0);
313 my_lambda = gcry_mpi_new (0);
316 // lambda = \frac{(p-1)*(q-1)}{gcd(p-1,q-1)}
317 gcry_mpi_sub_ui (tmp1, p, 1);
318 gcry_mpi_sub_ui (tmp2, q, 1);
319 gcry_mpi_gcd (gcd, tmp1, tmp2);
320 gcry_mpi_set (my_lambda, tmp1);
321 gcry_mpi_mul (my_lambda, my_lambda, tmp2);
322 gcry_mpi_div (my_lambda, NULL, my_lambda, gcd, 0);
325 gcry_mpi_mul (my_nsquare, my_n, my_n);
331 gcry_mpi_randomize (my_g, KEYBITS * 2, GCRY_WEAK_RANDOM);
332 // g must be smaller than n^2
333 if (0 >= gcry_mpi_cmp (my_g, my_nsquare))
336 // g must have gcd == 1 with n^2
337 gcry_mpi_gcd (gcd, my_g, my_nsquare);
339 while (gcry_mpi_cmp_ui (gcd, 1));
341 // is this a valid g?
342 // if so, gcd(((g^lambda mod n^2)-1 )/n, n) = 1
343 gcry_mpi_powm (tmp1, my_g, my_lambda, my_nsquare);
344 gcry_mpi_sub_ui (tmp1, tmp1, 1);
345 gcry_mpi_div (tmp1, NULL, tmp1, my_n, 0);
346 gcry_mpi_gcd (gcd, tmp1, my_n);
348 while (gcry_mpi_cmp_ui (gcd, 1));
350 // calculate our mu based on g and n.
351 // mu = (((g^lambda mod n^2)-1 )/n)^-1 mod n
352 gcry_mpi_invm (my_mu, tmp1, my_n);
354 GNUNET_assert (0 == gcry_sexp_build (&key, &erroff,
355 "(public-key (paillier (n %M)(g %M)))",
358 // get the length of this sexpression
359 my_pubkey_external_length = gcry_sexp_sprint (key,
364 GNUNET_assert (my_pubkey_external_length > 0);
365 my_pubkey_external = GNUNET_malloc (my_pubkey_external_length);
367 // convert the sexpression to canonical format
368 gcry_sexp_sprint (key,
371 my_pubkey_external_length);
373 gcry_sexp_release (key);
375 // offset has to be sufficiently small to allow computation of:
376 // m1+m2 mod n == (S + a) + (S + b) mod n,
377 // if we have more complex operations, this factor needs to be lowered
378 my_offset = gcry_mpi_new (KEYBITS / 3);
379 gcry_mpi_set_bit (my_offset, KEYBITS / 3);
381 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _ ("Generated key set with key length %d bits.\n"), KEYBITS);
386 * If target != size, move target bytes to the
387 * end of the size-sized buffer and zero out the
388 * first target-size bytes.
390 * @param buf original buffer
391 * @param size number of bytes in the buffer
392 * @param target target size of the buffer
395 adjust (unsigned char *buf, size_t size, size_t target)
399 memmove (&buf[target - size], buf, size);
400 memset (buf, 0, target - size);
406 * encrypts an element using the paillier crypto system
408 * @param c ciphertext (output)
410 * @param g the public base
411 * @param n the module from which which r is chosen (Z*_n)
412 * @param n_square the module for encryption, for performance reasons.
415 encrypt_element (gcry_mpi_t c, gcry_mpi_t m, gcry_mpi_t g, gcry_mpi_t n, gcry_mpi_t n_square)
419 GNUNET_assert (tmp = gcry_mpi_new (0));
421 while (0 >= gcry_mpi_cmp_ui (tmp, 1))
423 gcry_mpi_randomize (tmp, KEYBITS / 3, GCRY_WEAK_RANDOM);
424 // r must be 1 < r < n
427 gcry_mpi_powm (c, g, m, n_square);
428 gcry_mpi_powm (tmp, tmp, n, n_square);
429 gcry_mpi_mulm (c, tmp, c, n_square);
431 gcry_mpi_release (tmp);
436 * decrypts an element using the paillier crypto system
438 * @param m plaintext (output)
439 * @param c the ciphertext
440 * @param mu the modifier to correct encryption
441 * @param lambda the private exponent
442 * @param n the outer module for decryption
443 * @param n_square the inner module for decryption
446 decrypt_element (gcry_mpi_t m, gcry_mpi_t c, gcry_mpi_t mu, gcry_mpi_t lambda, gcry_mpi_t n, gcry_mpi_t n_square)
448 gcry_mpi_powm (m, c, lambda, n_square);
449 gcry_mpi_sub_ui (m, m, 1);
450 gcry_mpi_div (m, NULL, m, n, 0);
451 gcry_mpi_mulm (m, m, mu, n);
456 * computes the square sum over a vector of a given length.
458 * @param vector the vector to encrypt
459 * @param length the length of the vector
460 * @return an MPI value containing the calculated sum, never NULL
463 compute_square_sum (gcry_mpi_t * vector, uint32_t length)
469 GNUNET_assert (sum = gcry_mpi_new (0));
470 GNUNET_assert (elem = gcry_mpi_new (0));
472 // calculare E(sum (ai ^ 2), publickey)
473 for (i = 0; i < length; i++)
475 gcry_mpi_mul (elem, vector[i], vector[i]);
476 gcry_mpi_add (sum, sum, elem);
478 gcry_mpi_release (elem);
485 * Primitive callback for copying over a message, as they
486 * usually are too complex to be handled in the callback itself.
487 * clears a session-callback, if a session was handed over and the transmit handle was stored
489 * @param cls the message object
490 * @param size the size of the buffer we got
491 * @param buf the buffer to copy the message to
492 * @return 0 if we couldn't copy, else the size copied over
495 do_send_message (void *cls, size_t size, void *buf)
497 struct ServiceSession * session = cls;
502 if (ntohs (session->msg->size) == size)
504 memcpy (buf, session->msg, size);
508 switch (ntohs (session->msg->type))
510 case GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT:
511 session->state = FINALIZED;
512 session->client_transmit_handle = NULL;
515 session->service_transmit_handle = NULL;
518 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
519 "Sent a message of type %hu.\n",
520 ntohs (session->msg->type));
521 GNUNET_free (session->msg);
529 * initializes a new vector with fresh MPI values (=0) of a given length
531 * @param length of the vector to create
532 * @return the initialized vector, never NULL
535 initialize_mpi_vector (uint32_t length)
538 gcry_mpi_t * output = GNUNET_malloc (sizeof (gcry_mpi_t) * length);
540 for (i = 0; i < length; i++)
541 GNUNET_assert (NULL != (output[i] = gcry_mpi_new (0)));
547 * permutes an MPI vector according to the given permutation vector
549 * @param vector the vector to permuted
550 * @param perm the permutation to use
551 * @param length the length of the vectors
552 * @return the permuted vector (same as input), never NULL
555 permute_vector (gcry_mpi_t * vector,
559 gcry_mpi_t tmp[length];
562 GNUNET_assert (length > 0);
565 memcpy (tmp, vector, length * sizeof (gcry_mpi_t));
567 // permute vector according to given
568 for (i = 0; i < length; i++)
569 vector[i] = tmp[perm[i]];
576 * Populate a vector with random integer values and convert them to
578 * @param length the length of the vector we must generate
579 * @return an array of MPI values with random values
582 generate_random_vector (uint32_t length)
584 gcry_mpi_t * random_vector;
588 random_vector = initialize_mpi_vector (length);
589 for (i = 0; i < length; i++)
591 value = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
593 // long to gcry_mpi_t
595 gcry_mpi_sub_ui (random_vector[i],
599 random_vector[i] = gcry_mpi_set_ui (random_vector[i], value);
602 return random_vector;
607 * Finds a not terminated client/service session in the
608 * given DLL based on session key, element count and state.
610 * @param tail - the tail of the DLL
611 * @param my - the session to compare it to
612 * @return a pointer to a matching session,
615 static struct ServiceSession *
616 find_matching_session (struct ServiceSession * tail,
617 const struct GNUNET_HashCode * key,
618 uint32_t element_count,
619 enum SessionState * state,
620 const struct GNUNET_PeerIdentity * peerid)
622 struct ServiceSession * curr;
624 for (curr = tail; NULL != curr; curr = curr->prev)
626 // if the key matches, and the element_count is same
627 if ((!memcmp (&curr->key, key, sizeof (struct GNUNET_HashCode)))
628 && (curr->element_count == element_count))
630 // if incoming state is NULL OR is same as state of the queued request
631 if ((NULL == state) || (curr->state == *state))
633 // if peerid is NULL OR same as the peer Id in the queued request
635 || (!memcmp (&curr->peer, peerid, sizeof (struct GNUNET_PeerIdentity))))
636 // matches and is not an already terminated session
647 free_session (struct ServiceSession * session)
653 for (i = 0; i < session->used_element_count; i++)
654 gcry_mpi_release (session->a[i]);
656 GNUNET_free (session->a);
658 if (session->product)
659 gcry_mpi_release (session->product);
661 if (session->remote_pubkey)
662 gcry_sexp_release (session->remote_pubkey);
664 GNUNET_free_non_null (session->vector);
665 GNUNET_free (session);
667 ///////////////////////////////////////////////////////////////////////////////
668 // Event and Message Handlers
669 ///////////////////////////////////////////////////////////////////////////////
673 * A client disconnected.
675 * Remove the associated session(s), release datastructures
676 * and cancel pending outgoing transmissions to the client.
677 * if the session has not yet completed, we also cancel Alice's request to Bob.
679 * @param cls closure, NULL
680 * @param client identification of the client
683 handle_client_disconnect (void *cls,
684 struct GNUNET_SERVER_Client *client)
686 struct ServiceSession *session;
690 session = GNUNET_SERVER_client_get_user_context (client, struct ServiceSession);
693 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
694 _ ("Client (%p) disconnected from us.\n"), client);
695 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
697 if (!(session->role == BOB && session->state == FINALIZED))
699 //we MUST terminate any client message underway
700 if (session->service_transmit_handle && session->tunnel)
701 GNUNET_MESH_notify_transmit_ready_cancel (session->service_transmit_handle);
702 if (session->tunnel && session->state == WAITING_FOR_SERVICE_RESPONSE)
703 GNUNET_MESH_tunnel_destroy (session->tunnel);
705 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
707 GNUNET_SCHEDULER_cancel (session->client_notification_task);
708 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
710 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
712 GNUNET_SCHEDULER_cancel (session->service_request_task);
713 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
715 if (NULL != session->client_transmit_handle)
717 GNUNET_SERVER_notify_transmit_ready_cancel (session->client_transmit_handle);
718 session->client_transmit_handle = NULL;
720 free_session (session);
725 * Notify the client that the session has succeeded or failed completely.
726 * This message gets sent to
727 * * alice's client if bob disconnected or to
728 * * bob's client if the operation completed or alice disconnected
730 * @param client_session the associated client session
731 * @return GNUNET_NO, if we could not notify the client
732 * GNUNET_YES if we notified it.
735 prepare_client_end_notification (void * cls,
736 const struct GNUNET_SCHEDULER_TaskContext * tc)
738 struct ServiceSession * session = cls;
739 struct GNUNET_SCALARPRODUCT_client_response * msg;
741 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
743 msg = GNUNET_new (struct GNUNET_SCALARPRODUCT_client_response);
744 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
745 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
746 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
747 msg->header.size = htons (sizeof (struct GNUNET_SCALARPRODUCT_client_response));
748 // signal error if not signalized, positive result-range field but zero length.
749 msg->product_length = htonl (0);
750 msg->range = (session->state == FINALIZED) ? 0 : -1;
752 session->msg = &msg->header;
754 //transmit this message to our client
755 session->client_transmit_handle =
756 GNUNET_SERVER_notify_transmit_ready (session->client,
757 sizeof (struct GNUNET_SCALARPRODUCT_client_response),
758 GNUNET_TIME_UNIT_FOREVER_REL,
762 // if we could not even queue our request, something is wrong
763 if (NULL == session->client_transmit_handle)
765 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not send message to client (%p)!\n"), session->client);
766 // usually gets freed by do_send_message
771 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Sending session-end notification to client (%p) for session %s\n"), &session->client, GNUNET_h2s (&session->key));
778 * generates the response message to be sent to alice after computing
779 * the values (1), (2), S and S'
780 * (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
781 * (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
782 * S: $S := E_A(sum (r_i + b_i)^2)$
783 * S': $S' := E_A(sum r_i^2)$
785 * @param r (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
786 * @param r_prime (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
787 * @param s S: $S := E_A(sum (r_i + b_i)^2)$
788 * @param s_prime S': $S' := E_A(sum r_i^2)$
789 * @param request the associated requesting session with alice
790 * @param response the associated responder session with bob's client
791 * @return GNUNET_SYSERR if the function was called with NULL parameters or if there was an error
792 * GNUNET_NO if we could not send our message
793 * GNUNET_OK if the operation succeeded
796 prepare_service_response (gcry_mpi_t * r,
797 gcry_mpi_t * r_prime,
800 struct ServiceSession * request,
801 struct ServiceSession * response)
803 struct GNUNET_SCALARPRODUCT_service_response * msg;
804 uint32_t msg_length = 0;
805 unsigned char * current = NULL;
806 unsigned char * element_exported = NULL;
807 size_t element_length = 0;
810 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
811 + 2 * request->used_element_count * PAILLIER_ELEMENT_LENGTH // kp, kq
812 + 2 * PAILLIER_ELEMENT_LENGTH; // s, stick
814 msg = GNUNET_malloc (msg_length);
816 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE);
817 msg->header.size = htons (msg_length);
818 msg->element_count = htonl (request->element_count);
819 msg->used_element_count = htonl (request->used_element_count);
820 memcpy (&msg->key, &request->key, sizeof (struct GNUNET_HashCode));
821 current = (unsigned char *) &msg[1];
823 // 4 times the same logics with slight variations.
824 // doesn't really justify having 2 functions for that
825 // so i put it into blocks to enhance readability
828 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
829 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
830 element_exported, PAILLIER_ELEMENT_LENGTH,
833 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
834 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
835 GNUNET_free (element_exported);
836 current += PAILLIER_ELEMENT_LENGTH;
841 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
842 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
843 element_exported, PAILLIER_ELEMENT_LENGTH,
846 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
847 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
848 GNUNET_free (element_exported);
849 current += PAILLIER_ELEMENT_LENGTH;
853 for (i = 0; i < request->used_element_count; i++)
855 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
856 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
857 element_exported, PAILLIER_ELEMENT_LENGTH,
860 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
861 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
862 GNUNET_free (element_exported);
863 current += PAILLIER_ELEMENT_LENGTH;
868 for (i = 0; i < request->used_element_count; i++)
870 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
871 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
872 element_exported, PAILLIER_ELEMENT_LENGTH,
875 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
876 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
877 GNUNET_free (element_exported);
878 current += PAILLIER_ELEMENT_LENGTH;
881 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= msg_length)
883 request->msg = (struct GNUNET_MessageHeader *) msg;
884 request->service_transmit_handle =
885 GNUNET_MESH_notify_transmit_ready (request->tunnel,
887 GNUNET_TIME_UNIT_FOREVER_REL,
891 request->state = FINALIZED;
894 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!)\n"));
896 //disconnect our client
897 if (NULL == request->service_transmit_handle)
899 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Could not send service-response message via mesh!)\n"));
901 response->client_notification_task =
902 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
913 * (1)[]: $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
914 * (2)[]: $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
915 * S: $S := E_A(\sum (r_i + b_i)^2)$
916 * S': $S' := E_A(\sum r_i^2)$
918 * @param request the requesting session + bob's requesting peer
919 * @param response the responding session + bob's client handle
920 * @return GNUNET_SYSERR if the computation failed
921 * GNUNET_OK if everything went well.
924 compute_service_response (struct ServiceSession * request,
925 struct ServiceSession * response)
929 int ret = GNUNET_SYSERR;
933 gcry_mpi_t * rand = NULL;
934 gcry_mpi_t * r = NULL;
935 gcry_mpi_t * r_prime = NULL;
938 gcry_mpi_t * a_pi_prime;
940 gcry_mpi_t * rand_pi;
941 gcry_mpi_t * rand_pi_prime;
943 gcry_mpi_t s_prime = NULL;
944 gcry_mpi_t remote_n = NULL;
945 gcry_mpi_t remote_nsquare;
946 gcry_mpi_t remote_g = NULL;
950 count = request->used_element_count;
952 b = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
953 a_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
954 b_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
955 a_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
956 rand_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
957 rand_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
959 // convert responder session to from long to mpi
960 for (i = 0, j = 0; i < response->element_count && j < count; i++)
962 if (request->mask[i / 8] & (1 << (i % 8)))
964 value = response->vector[i] >= 0 ? response->vector[i] : -response->vector[i];
965 // long to gcry_mpi_t
966 if (0 > response->vector[i])
968 b[j] = gcry_mpi_new (0);
969 gcry_mpi_sub_ui (b[j], b[j], value);
973 b[j] = gcry_mpi_set_ui (NULL, value);
978 GNUNET_free (response->vector);
979 response->vector = NULL;
981 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "n", 0);
985 gcry_sexp_release (request->remote_pubkey);
986 request->remote_pubkey = NULL;
989 remote_n = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
993 gcry_sexp_release (tmp_exp);
996 remote_nsquare = gcry_mpi_new (KEYBITS + 1);
997 gcry_mpi_mul (remote_nsquare, remote_n, remote_n);
998 gcry_sexp_release (tmp_exp);
999 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "g", 0);
1000 gcry_sexp_release (request->remote_pubkey);
1001 request->remote_pubkey = NULL;
1004 GNUNET_break_op (0);
1005 gcry_mpi_release (remote_n);
1008 remote_g = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
1012 gcry_mpi_release (remote_n);
1013 gcry_sexp_release (tmp_exp);
1016 gcry_sexp_release (tmp_exp);
1018 // generate r, p and q
1019 rand = generate_random_vector (count);
1020 p = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1021 q = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1022 //initialize the result vectors
1023 r = initialize_mpi_vector (count);
1024 r_prime = initialize_mpi_vector (count);
1026 // copy the REFERNCES of a, b and r into aq and bq. we will not change
1027 // those values, thus we can work with the references
1028 memcpy (a_pi, request->a, sizeof (gcry_mpi_t) * count);
1029 memcpy (a_pi_prime, request->a, sizeof (gcry_mpi_t) * count);
1030 memcpy (b_pi, b, sizeof (gcry_mpi_t) * count);
1031 memcpy (rand_pi, rand, sizeof (gcry_mpi_t) * count);
1032 memcpy (rand_pi_prime, rand, sizeof (gcry_mpi_t) * count);
1034 // generate p and q permutations for a, b and r
1035 GNUNET_assert (permute_vector (a_pi, p, count));
1036 GNUNET_assert (permute_vector (b_pi, p, count));
1037 GNUNET_assert (permute_vector (rand_pi, p, count));
1038 GNUNET_assert (permute_vector (a_pi_prime, q, count));
1039 GNUNET_assert (permute_vector (rand_pi_prime, q, count));
1041 // encrypt the element
1042 // for the sake of readability I decided to have dedicated permutation
1043 // vectors, which get rid of all the lookups in p/q.
1044 // however, ap/aq are not absolutely necessary but are just abstraction
1045 // Calculate Kp = E(S + a_pi) (+) E(S - r_pi - b_pi)
1046 for (i = 0; i < count; i++)
1048 // E(S - r_pi - b_pi)
1049 gcry_mpi_sub (r[i], my_offset, rand_pi[i]);
1050 gcry_mpi_sub (r[i], r[i], b_pi[i]);
1051 encrypt_element (r[i], r[i], remote_g, remote_n, remote_nsquare);
1053 // E(S - r_pi - b_pi) * E(S + a_pi) == E(2*S + a - r - b)
1054 gcry_mpi_mulm (r[i], r[i], a_pi[i], remote_nsquare);
1058 GNUNET_free (rand_pi);
1060 // Calculate Kq = E(S + a_qi) (+) E(S - r_qi)
1061 for (i = 0; i < count; i++)
1064 gcry_mpi_sub (r_prime[i], my_offset, rand_pi_prime[i]);
1065 encrypt_element (r_prime[i], r_prime[i], remote_g, remote_n, remote_nsquare);
1067 // E(S - r_qi) * E(S + a_qi) == E(2*S + a_qi - r_qi)
1068 gcry_mpi_mulm (r_prime[i], r_prime[i], a_pi_prime[i], remote_nsquare);
1070 GNUNET_free (a_pi_prime);
1071 GNUNET_free (rand_pi_prime);
1073 // Calculate S' = E(SUM( r_i^2 ))
1074 s_prime = compute_square_sum (rand, count);
1075 encrypt_element (s_prime, s_prime, remote_g, remote_n, remote_nsquare);
1077 // Calculate S = E(SUM( (r_i + b_i)^2 ))
1078 for (i = 0; i < count; i++)
1080 gcry_mpi_add (rand[i], rand[i], b[i]);
1082 s = compute_square_sum (rand, count);
1083 encrypt_element (s, s, remote_g, remote_n, remote_nsquare);
1084 gcry_mpi_release (remote_n);
1085 gcry_mpi_release (remote_g);
1086 gcry_mpi_release (remote_nsquare);
1088 // release r and tmp
1089 for (i = 0; i < count; i++)
1090 // rp, rq, aq, ap, bp, bq are released along with a, r, b respectively, (a and b are handled at except:)
1091 gcry_mpi_release (rand[i]);
1093 // copy the Kp[], Kq[], S and Stick into a new message
1094 if (GNUNET_YES != prepare_service_response (r, r_prime, s, s_prime, request, response))
1095 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Failed to communicate with `%s', scalar product calculation aborted.\n"),
1096 GNUNET_i2s (&request->peer));
1100 for (i = 0; i < count; i++)
1102 gcry_mpi_release (r_prime[i]);
1103 gcry_mpi_release (r[i]);
1106 gcry_mpi_release (s);
1107 gcry_mpi_release (s_prime);
1110 for (i = 0; i < count; i++)
1112 gcry_mpi_release (b[i]);
1113 gcry_mpi_release (request->a[i]);
1117 GNUNET_free (request->a);
1125 * Executed by Alice, fills in a service-request message and sends it to the given peer
1127 * @param session the session associated with this request, then also holds the CORE-handle
1128 * @return #GNUNET_SYSERR if we could not send the message
1129 * #GNUNET_NO if the message was too large
1130 * #GNUNET_OK if we sent it
1133 prepare_service_request (void *cls,
1134 const struct GNUNET_SCHEDULER_TaskContext *tc)
1136 struct ServiceSession * session = cls;
1137 unsigned char * current;
1138 struct GNUNET_SCALARPRODUCT_service_request * msg;
1141 uint32_t msg_length;
1142 size_t element_length = 0; // initialized by gcry_mpi_print, but the compiler doesn't know that
1146 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
1148 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _ ("Successfully created new tunnel to peer (%s)!\n"), GNUNET_i2s (&session->peer));
1150 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1151 +session->used_element_count * PAILLIER_ELEMENT_LENGTH
1152 + session->mask_length
1153 + my_pubkey_external_length;
1155 if (GNUNET_SERVER_MAX_MESSAGE_SIZE < sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1156 +session->used_element_count * PAILLIER_ELEMENT_LENGTH
1157 + session->mask_length
1158 + my_pubkey_external_length)
1160 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1161 session->client_notification_task =
1162 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1167 msg = GNUNET_malloc (msg_length);
1168 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB);
1169 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1170 msg->mask_length = htonl (session->mask_length);
1171 msg->pk_length = htonl (my_pubkey_external_length);
1172 msg->used_element_count = htonl (session->used_element_count);
1173 msg->element_count = htonl (session->element_count);
1174 msg->header.size = htons (msg_length);
1176 // fill in the payload
1177 current = (unsigned char *) &msg[1];
1178 // copy over the mask
1179 memcpy (current, session->mask, session->mask_length);
1180 // copy over our public key
1181 current += session->mask_length;
1182 memcpy (current, my_pubkey_external, my_pubkey_external_length);
1183 current += my_pubkey_external_length;
1185 // now copy over the element vector
1186 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * session->used_element_count);
1187 a = gcry_mpi_new (KEYBITS * 2);
1188 // encrypt our vector and generate string representations
1189 for (i = 0, j = 0; i < session->element_count; i++)
1191 // if this is a used element...
1192 if (session->mask[i / 8] & 1 << (i % 8))
1194 unsigned char * element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
1195 value = session->vector[i] >= 0 ? session->vector[i] : -session->vector[i];
1197 a = gcry_mpi_set_ui (a, 0);
1198 // long to gcry_mpi_t
1199 if (session->vector[i] < 0)
1200 gcry_mpi_sub_ui (a, a, value);
1202 gcry_mpi_add_ui (a, a, value);
1204 session->a[j++] = gcry_mpi_set (NULL, a);
1205 gcry_mpi_add (a, a, my_offset);
1206 encrypt_element (a, a, my_g, my_n, my_nsquare);
1208 // get representation as string
1209 // we always supply some value, so gcry_mpi_print fails only if it can't reserve memory
1210 GNUNET_assert (!gcry_mpi_print (GCRYMPI_FMT_USG,
1211 element_exported, PAILLIER_ELEMENT_LENGTH,
1215 // move buffer content to the end of the buffer so it can easily be read by libgcrypt. also this now has fixed size
1216 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
1218 // copy over to the message
1219 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
1220 current += PAILLIER_ELEMENT_LENGTH;
1223 gcry_mpi_release (a);
1225 session->msg = (struct GNUNET_MessageHeader *) msg;
1226 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Transmitting service request.\n"));
1228 //transmit via mesh messaging
1229 session->service_transmit_handle = GNUNET_MESH_notify_transmit_ready (session->tunnel, GNUNET_YES,
1230 GNUNET_TIME_UNIT_FOREVER_REL,
1234 if (!session->service_transmit_handle)
1236 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Could not send mutlicast message to tunnel!\n"));
1238 session->msg = NULL;
1239 session->client_notification_task =
1240 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1244 session->state = WAITING_FOR_SERVICE_RESPONSE;
1249 * Handler for a client request message.
1250 * Can either be type A or B
1251 * A: request-initiation to compute a scalar product with a peer
1252 * B: response role, keep the values + session and wait for a matching session or process a waiting request
1254 * @param cls closure
1255 * @param client identification of the client
1256 * @param message the actual message
1259 handle_client_request (void *cls,
1260 struct GNUNET_SERVER_Client *client,
1261 const struct GNUNET_MessageHeader *message)
1263 const struct GNUNET_SCALARPRODUCT_client_request * msg = (const struct GNUNET_SCALARPRODUCT_client_request *) message;
1264 struct ServiceSession * session;
1265 uint32_t element_count;
1266 uint32_t mask_length;
1271 // only one concurrent session per client connection allowed, simplifies logics a lot...
1272 session = GNUNET_SERVER_client_get_user_context (client, struct ServiceSession);
1273 if ((NULL != session) && (session->state != FINALIZED))
1275 GNUNET_SERVER_receive_done (client, GNUNET_OK);
1278 else if (NULL != session)
1280 // old session is already completed, clean it up
1281 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
1282 free_session (session);
1285 //we need at least a peer and one message id to compare
1286 if (sizeof (struct GNUNET_SCALARPRODUCT_client_request) > ntohs (msg->header.size))
1288 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1289 _ ("Too short message received from client!\n"));
1290 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1294 msg_type = ntohs (msg->header.type);
1295 element_count = ntohl (msg->element_count);
1296 mask_length = ntohl (msg->mask_length);
1298 //sanity check: is the message as long as the message_count fields suggests?
1299 if ((ntohs (msg->header.size) != (sizeof (struct GNUNET_SCALARPRODUCT_client_request) +element_count * sizeof (int32_t) + mask_length))
1300 || (0 == element_count))
1302 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1303 _ ("Invalid message received from client, session information incorrect!\n"));
1304 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1308 // do we have a duplicate session here already?
1309 if (NULL != find_matching_session (from_client_tail,
1314 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1315 _ ("Duplicate session information received, cannot create new session with key `%s'\n"),
1316 GNUNET_h2s (&msg->key));
1317 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1321 session = GNUNET_new (struct ServiceSession);
1322 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
1323 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1324 session->client = client;
1325 session->element_count = element_count;
1326 session->mask_length = mask_length;
1327 // get our transaction key
1328 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1329 //allocate memory for vector and encrypted vector
1330 session->vector = GNUNET_malloc (sizeof (int32_t) * element_count);
1331 vector = (int32_t *) & msg[1];
1333 if (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE == msg_type)
1335 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1336 _ ("Got client-request-session with key %s, preparing tunnel to remote service.\n"),
1337 GNUNET_h2s (&session->key));
1339 session->role = ALICE;
1341 session->mask = GNUNET_malloc (mask_length);
1342 memcpy (session->mask, &vector[element_count], mask_length);
1344 // copy over the elements
1345 session->used_element_count = 0;
1346 for (i = 0; i < element_count; i++)
1348 session->vector[i] = ntohl (vector[i]);
1349 if (session->vector[i] == 0)
1350 session->mask[i / 8] &= ~(1 << (i % 8));
1351 if (session->mask[i / 8] & (1 << (i % 8)))
1352 session->used_element_count++;
1355 if (0 == session->used_element_count)
1357 GNUNET_break_op (0);
1358 GNUNET_free (session->vector);
1359 GNUNET_free (session);
1360 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1363 //session with ourself makes no sense!
1364 if (!memcmp (&msg->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1367 GNUNET_free (session->vector);
1368 GNUNET_free (session);
1369 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1373 memcpy (&session->peer, &msg->peer, sizeof (struct GNUNET_PeerIdentity));
1374 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1375 _ ("Creating new tunnel to for session with key %s.\n"),
1376 GNUNET_h2s (&session->key));
1377 session->tunnel = GNUNET_MESH_tunnel_create (my_mesh, session,
1379 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
1382 //prepare_service_request, tunnel_peer_disconnect_handler,
1383 if (!session->tunnel)
1386 GNUNET_free (session->vector);
1387 GNUNET_free (session);
1388 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1391 GNUNET_SERVER_client_set_user_context (client, session);
1392 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1394 session->state = CLIENT_REQUEST_RECEIVED;
1395 session->service_request_task =
1396 GNUNET_SCHEDULER_add_now (&prepare_service_request,
1402 struct ServiceSession * requesting_session;
1403 enum SessionState needed_state = SERVICE_REQUEST_RECEIVED;
1405 session->role = BOB;
1406 session->mask = NULL;
1407 // copy over the elements
1408 session->used_element_count = element_count;
1409 for (i = 0; i < element_count; i++)
1410 session->vector[i] = ntohl (vector[i]);
1411 session->state = CLIENT_RESPONSE_RECEIVED;
1413 GNUNET_SERVER_client_set_user_context (client, session);
1414 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1416 //check if service queue contains a matching request
1417 requesting_session = find_matching_session (from_service_tail,
1419 session->element_count,
1420 &needed_state, NULL);
1421 if (NULL != requesting_session)
1423 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got client-responder-session with key %s and a matching service-request-session set, processing.\n"), GNUNET_h2s (&session->key));
1424 if (GNUNET_OK != compute_service_response (requesting_session, session))
1425 session->client_notification_task =
1426 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1432 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got client-responder-session with key %s but NO matching service-request-session set, queuing element for later use.\n"), GNUNET_h2s (&session->key));
1433 // no matching session exists yet, store the response
1434 // for later processing by handle_service_request()
1437 GNUNET_SERVER_receive_done (client, GNUNET_YES);
1442 * Function called for inbound tunnels.
1444 * @param cls closure
1445 * @param tunnel new handle to the tunnel
1446 * @param initiator peer that started the tunnel
1447 * @param atsi performance information for the tunnel
1448 * @return initial tunnel context for the tunnel
1449 * (can be NULL -- that's not an error)
1452 tunnel_incoming_handler (void *cls,
1453 struct GNUNET_MESH_Tunnel *tunnel,
1454 const struct GNUNET_PeerIdentity *initiator,
1457 struct ServiceSession * c = GNUNET_new (struct ServiceSession);
1459 c->peer = *initiator;
1462 c->state = WAITING_FOR_SERVICE_REQUEST;
1468 * Function called whenever a tunnel is destroyed. Should clean up
1469 * any associated state.
1471 * It must NOT call GNUNET_MESH_tunnel_destroy on the tunnel.
1473 * @param cls closure (set from GNUNET_MESH_connect)
1474 * @param tunnel connection to the other end (henceforth invalid)
1475 * @param tunnel_ctx place where local state associated
1476 * with the tunnel is stored
1479 tunnel_destruction_handler (void *cls,
1480 const struct GNUNET_MESH_Tunnel *tunnel,
1483 struct ServiceSession * session = tunnel_ctx;
1484 struct ServiceSession * client_session;
1485 struct ServiceSession * curr;
1487 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1488 _ ("Peer disconnected, terminating session %s with peer (%s)\n"),
1489 GNUNET_h2s (&session->key),
1490 GNUNET_i2s (&session->peer));
1491 if (ALICE == session->role)
1493 // as we have only one peer connected in each session, just remove the session
1495 if ((SERVICE_RESPONSE_RECEIVED > session->state) && (!do_shutdown))
1497 session->tunnel = NULL;
1498 // if this happened before we received the answer, we must terminate the session
1499 session->client_notification_task =
1500 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1505 { //(BOB == session->role) service session
1506 // remove the session, unless it has already been dequeued, but somehow still active
1507 // this could bug without the IF in case the queue is empty and the service session was the only one know to the service
1508 // scenario: disconnect before alice can send her message to bob.
1509 for (curr = from_service_head; NULL != curr; curr = curr->next)
1510 if (curr == session)
1512 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, curr);
1515 // there is a client waiting for this service session, terminate it, too!
1516 // i assume the tupel of key and element count is unique. if it was not the rest of the code would not work either.
1517 client_session = find_matching_session (from_client_tail,
1519 session->element_count,
1521 free_session (session);
1523 // the client has to check if it was waiting for a result
1524 // or if it was a responder, no point in adding more statefulness
1525 if (client_session && (!do_shutdown))
1527 client_session->state = FINALIZED;
1528 client_session->client_notification_task =
1529 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1537 * Compute our scalar product, done by Alice
1539 * @param session - the session associated with this computation
1540 * @param kp - (1) from the protocol definition:
1541 * $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
1542 * @param kq - (2) from the protocol definition:
1543 * $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
1544 * @param s - S from the protocol definition:
1545 * $S := E_A(\sum (r_i + b_i)^2)$
1546 * @param stick - S' from the protocol definition:
1547 * $S' := E_A(\sum r_i^2)$
1548 * @return product as MPI, never NULL
1551 compute_scalar_product (struct ServiceSession * session,
1552 gcry_mpi_t * r, gcry_mpi_t * r_prime, gcry_mpi_t s, gcry_mpi_t s_prime)
1563 count = session->used_element_count;
1564 tmp = gcry_mpi_new (KEYBITS);
1565 // due to the introduced static offset S, we now also have to remove this
1566 // from the E(a_pi)(+)E(-b_pi-r_pi) and E(a_qi)(+)E(-r_qi) twice each,
1567 // the result is E((S + a_pi) + (S -b_pi-r_pi)) and E(S + a_qi + S - r_qi)
1568 for (i = 0; i < count; i++)
1570 decrypt_element (r[i], r[i], my_mu, my_lambda, my_n, my_nsquare);
1571 gcry_mpi_sub (r[i], r[i], my_offset);
1572 gcry_mpi_sub (r[i], r[i], my_offset);
1573 decrypt_element (r_prime[i], r_prime[i], my_mu, my_lambda, my_n, my_nsquare);
1574 gcry_mpi_sub (r_prime[i], r_prime[i], my_offset);
1575 gcry_mpi_sub (r_prime[i], r_prime[i], my_offset);
1578 // calculate t = sum(ai)
1579 t = compute_square_sum (session->a, count);
1582 u = gcry_mpi_new (0);
1583 tmp = compute_square_sum (r, count);
1584 gcry_mpi_sub (u, u, tmp);
1585 gcry_mpi_release (tmp);
1588 utick = gcry_mpi_new (0);
1589 tmp = compute_square_sum (r_prime, count);
1590 gcry_mpi_sub (utick, utick, tmp);
1592 GNUNET_assert (p = gcry_mpi_new (0));
1593 GNUNET_assert (ptick = gcry_mpi_new (0));
1596 decrypt_element (s, s, my_mu, my_lambda, my_n, my_nsquare);
1597 decrypt_element (s_prime, s_prime, my_mu, my_lambda, my_n, my_nsquare);
1600 gcry_mpi_add (p, s, t);
1601 gcry_mpi_add (p, p, u);
1604 gcry_mpi_add (ptick, s_prime, t);
1605 gcry_mpi_add (ptick, ptick, utick);
1607 gcry_mpi_release (t);
1608 gcry_mpi_release (u);
1609 gcry_mpi_release (utick);
1612 gcry_mpi_sub (p, p, ptick);
1613 gcry_mpi_release (ptick);
1614 tmp = gcry_mpi_set_ui (tmp, 2);
1615 gcry_mpi_div (p, NULL, p, tmp, 0);
1617 gcry_mpi_release (tmp);
1618 for (i = 0; i < count; i++)
1619 gcry_mpi_release (session->a[i]);
1620 GNUNET_free (session->a);
1628 * prepare the response we will send to alice or bobs' clients.
1629 * in Bobs case the product will be NULL.
1631 * @param session the session associated with our client.
1634 prepare_client_response (void *cls,
1635 const struct GNUNET_SCHEDULER_TaskContext *tc)
1637 struct ServiceSession * session = cls;
1638 struct GNUNET_SCALARPRODUCT_client_response * msg;
1639 unsigned char * product_exported = NULL;
1640 size_t product_length = 0;
1641 uint32_t msg_length = 0;
1646 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1648 if (session->product)
1650 gcry_mpi_t value = gcry_mpi_new (0);
1652 sign = gcry_mpi_cmp_ui (session->product, 0);
1653 // libgcrypt can not handle a print of a negative number
1654 // if (a->sign) return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */
1657 gcry_mpi_sub (value, value, session->product);
1662 gcry_mpi_add (value, value, session->product);
1667 gcry_mpi_release (session->product);
1668 session->product = NULL;
1670 // get representation as string
1672 && (0 != (rc = gcry_mpi_aprint (GCRYMPI_FMT_STD,
1677 LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
1679 range = -1; // signal error with product-length = 0 and range = -1
1681 gcry_mpi_release (value);
1684 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_client_response) +product_length;
1685 msg = GNUNET_malloc (msg_length);
1686 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1687 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
1688 if (product_exported != NULL)
1690 memcpy (&msg[1], product_exported, product_length);
1691 GNUNET_free (product_exported);
1693 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
1694 msg->header.size = htons (msg_length);
1696 msg->product_length = htonl (product_length);
1698 session->msg = (struct GNUNET_MessageHeader *) msg;
1699 //transmit this message to our client
1700 session->client_transmit_handle =
1701 GNUNET_SERVER_notify_transmit_ready (session->client,
1703 GNUNET_TIME_UNIT_FOREVER_REL,
1706 if (NULL == session->client_transmit_handle)
1708 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1709 _ ("Could not send message to client (%p)!\n"),
1711 session->client = NULL;
1712 // callback was not called!
1714 session->msg = NULL;
1717 // gracefully sent message, just terminate session structure
1718 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1719 _ ("Sent result to client (%p), this session (%s) has ended!\n"),
1721 GNUNET_h2s (&session->key));
1726 * Handle a request from another service to calculate a scalarproduct with us.
1728 * @param cls closure (set from #GNUNET_MESH_connect)
1729 * @param tunnel connection to the other end
1730 * @param tunnel_ctx place to store local state associated with the tunnel
1731 * @param sender who sent the message
1732 * @param message the actual message
1733 * @param atsi performance data for the connection
1734 * @return #GNUNET_OK to keep the connection open,
1735 * #GNUNET_SYSERR to close it (signal serious error)
1738 handle_service_request (void *cls,
1739 struct GNUNET_MESH_Tunnel * tunnel,
1741 const struct GNUNET_MessageHeader * message)
1743 struct ServiceSession * session;
1744 const struct GNUNET_SCALARPRODUCT_service_request * msg = (const struct GNUNET_SCALARPRODUCT_service_request *) message;
1745 uint32_t mask_length;
1747 uint32_t used_elements;
1748 uint32_t element_count;
1749 uint32_t msg_length;
1750 unsigned char * current;
1751 struct ServiceSession * responder_session;
1753 enum SessionState needed_state;
1755 session = (struct ServiceSession *) * tunnel_ctx;
1756 if (BOB != session->role)
1758 GNUNET_break_op (0);
1759 return GNUNET_SYSERR;
1761 // is this tunnel already in use?
1762 if ((session->next) || (from_service_head == session))
1764 GNUNET_break_op (0);
1765 return GNUNET_SYSERR;
1767 // Check if message was sent by me, which would be bad!
1768 if (!memcmp (&session->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1770 GNUNET_free (session);
1772 return GNUNET_SYSERR;
1775 //we need at least a peer and one message id to compare
1776 if (ntohs (msg->header.size) < sizeof (struct GNUNET_SCALARPRODUCT_service_request))
1778 GNUNET_free (session);
1779 GNUNET_break_op (0);
1780 return GNUNET_SYSERR;
1782 mask_length = ntohl (msg->mask_length);
1783 pk_length = ntohl (msg->pk_length);
1784 used_elements = ntohl (msg->used_element_count);
1785 element_count = ntohl (msg->element_count);
1786 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1787 +mask_length + pk_length + used_elements * PAILLIER_ELEMENT_LENGTH;
1789 //sanity check: is the message as long as the message_count fields suggests?
1790 if ((ntohs (msg->header.size) != msg_length) || (element_count < used_elements)
1791 || (used_elements == 0) || (mask_length != (element_count / 8 + (element_count % 8 ? 1 : 0)))
1794 GNUNET_free (session);
1795 GNUNET_break_op (0);
1796 return GNUNET_SYSERR;
1798 if (find_matching_session (from_service_tail,
1804 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Got message with duplicate session key (`%s'), ignoring service request.\n"), (const char *) &(msg->key));
1805 GNUNET_free (session);
1806 return GNUNET_SYSERR;
1809 memcpy (&session->peer, &session->peer, sizeof (struct GNUNET_PeerIdentity));
1810 session->state = SERVICE_REQUEST_RECEIVED;
1811 session->element_count = ntohl (msg->element_count);
1812 session->used_element_count = used_elements;
1813 session->tunnel = tunnel;
1816 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1817 current = (unsigned char *) &msg[1];
1818 //preserve the mask, we will need that later on
1819 session->mask = GNUNET_malloc (mask_length);
1820 memcpy (session->mask, current, mask_length);
1822 current += mask_length;
1824 //convert the publickey to sexp
1825 if (gcry_sexp_new (&session->remote_pubkey, current, pk_length, 1))
1827 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate remote public key to sexpression!\n"));
1828 GNUNET_free (session->mask);
1829 GNUNET_free (session);
1830 return GNUNET_SYSERR;
1833 current += pk_length;
1835 //check if service queue contains a matching request
1836 needed_state = CLIENT_RESPONSE_RECEIVED;
1837 responder_session = find_matching_session (from_client_tail,
1839 session->element_count,
1840 &needed_state, NULL);
1842 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1844 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1847 + used_elements * PAILLIER_ELEMENT_LENGTH)
1849 gcry_error_t ret = 0;
1850 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1851 // Convert each vector element to MPI_value
1852 for (i = 0; i < used_elements; i++)
1856 ret = gcry_mpi_scan (&session->a[i],
1858 ¤t[i * PAILLIER_ELEMENT_LENGTH],
1859 PAILLIER_ELEMENT_LENGTH,
1863 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate E[a%d] to MPI!\n%s/%s\n"),
1864 i, gcry_strsource (ret), gcry_strerror (ret));
1868 GNUNET_CONTAINER_DLL_insert (from_service_head, from_service_tail, session);
1869 if (responder_session)
1871 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s and a matching element set, processing.\n"), GNUNET_h2s (&session->key));
1872 if (GNUNET_OK != compute_service_response (session, responder_session))
1874 //something went wrong, remove it again...
1875 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, session);
1880 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s without a matching element set, queueing.\n"), GNUNET_h2s (&session->key));
1886 // TODO FEATURE: fallback to fragmentation, in case the message is too long
1887 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1891 for (i = 0; i < used_elements; i++)
1893 gcry_mpi_release (session->a[i]);
1894 gcry_sexp_release (session->remote_pubkey);
1895 session->remote_pubkey = NULL;
1896 GNUNET_free_non_null (session->a);
1898 free_session (session);
1899 // and notify our client-session that we could not complete the session
1900 if (responder_session)
1901 // we just found the responder session in this queue
1902 responder_session->client_notification_task =
1903 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1905 return GNUNET_SYSERR;
1910 * Handle a response we got from another service we wanted to calculate a scalarproduct with.
1912 * @param cls closure (set from #GNUNET_MESH_connect)
1913 * @param tunnel connection to the other end
1914 * @param tunnel_ctx place to store local state associated with the tunnel
1915 * @param sender who sent the message
1916 * @param message the actual message
1917 * @param atsi performance data for the connection
1918 * @return #GNUNET_OK to keep the connection open,
1919 * #GNUNET_SYSERR to close it (we are done)
1922 handle_service_response (void *cls,
1923 struct GNUNET_MESH_Tunnel * tunnel,
1925 const struct GNUNET_MessageHeader * message)
1927 struct ServiceSession * session;
1928 const struct GNUNET_SCALARPRODUCT_service_response * msg = (const struct GNUNET_SCALARPRODUCT_service_response *) message;
1929 unsigned char * current;
1931 gcry_mpi_t s = NULL;
1932 gcry_mpi_t s_prime = NULL;
1935 uint32_t used_element_count;
1937 gcry_mpi_t * r = NULL;
1938 gcry_mpi_t * r_prime = NULL;
1941 GNUNET_assert (NULL != message);
1942 session = (struct ServiceSession *) * tunnel_ctx;
1943 if (ALICE != session->role)
1945 GNUNET_break_op (0);
1946 return GNUNET_SYSERR;
1949 count = session->used_element_count;
1950 session->product = NULL;
1951 session->state = SERVICE_RESPONSE_RECEIVED;
1953 //we need at least a peer and one message id to compare
1954 if (sizeof (struct GNUNET_SCALARPRODUCT_service_response) > ntohs (msg->header.size))
1956 GNUNET_break_op (0);
1959 used_element_count = ntohl (msg->used_element_count);
1960 msg_size = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
1961 + 2 * used_element_count * PAILLIER_ELEMENT_LENGTH
1962 + 2 * PAILLIER_ELEMENT_LENGTH;
1963 //sanity check: is the message as long as the message_count fields suggests?
1964 if ((ntohs (msg->header.size) != msg_size) || (count != used_element_count))
1966 GNUNET_break_op (0);
1971 current = (unsigned char *) &msg[1];
1972 if (0 != (rc = gcry_mpi_scan (&s, GCRYMPI_FMT_USG, current,
1973 PAILLIER_ELEMENT_LENGTH, &read)))
1975 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1976 GNUNET_break_op (0);
1979 current += PAILLIER_ELEMENT_LENGTH;
1981 if (0 != (rc = gcry_mpi_scan (&s_prime, GCRYMPI_FMT_USG, current,
1982 PAILLIER_ELEMENT_LENGTH, &read)))
1984 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1985 GNUNET_break_op (0);
1988 current += PAILLIER_ELEMENT_LENGTH;
1990 r = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
1991 // Convert each kp[] to its MPI_value
1992 for (i = 0; i < count; i++)
1994 if (0 != (rc = gcry_mpi_scan (&r[i], GCRYMPI_FMT_USG, current,
1995 PAILLIER_ELEMENT_LENGTH, &read)))
1997 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1998 GNUNET_break_op (0);
2001 current += PAILLIER_ELEMENT_LENGTH;
2005 r_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
2006 // Convert each kq[] to its MPI_value
2007 for (i = 0; i < count; i++)
2009 if (0 != (rc = gcry_mpi_scan (&r_prime[i], GCRYMPI_FMT_USG, current,
2010 PAILLIER_ELEMENT_LENGTH, &read)))
2012 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
2013 GNUNET_break_op (0);
2016 current += PAILLIER_ELEMENT_LENGTH;
2018 session->product = compute_scalar_product (session, r, r_prime, s, s_prime);
2022 gcry_mpi_release (s);
2024 gcry_mpi_release (s_prime);
2025 for (i = 0; r && i < count; i++)
2026 if (r[i]) gcry_mpi_release (r[i]);
2027 for (i = 0; r_prime && i < count; i++)
2028 if (r_prime[i]) gcry_mpi_release (r_prime[i]);
2029 GNUNET_free_non_null (r);
2030 GNUNET_free_non_null (r_prime);
2032 session->tunnel = NULL;
2033 // send message with product to client
2034 session->client_notification_task =
2035 GNUNET_SCHEDULER_add_now (&prepare_client_response,
2037 // the tunnel has done its job, terminate our connection and the tunnel
2038 // the peer will be notified that the tunnel was destroyed via tunnel_destruction_handler
2039 // just close the connection, as recommended by Christian
2040 return GNUNET_SYSERR;
2045 * Task run during shutdown.
2051 shutdown_task (void *cls,
2052 const struct GNUNET_SCHEDULER_TaskContext *tc)
2054 struct ServiceSession * session;
2055 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Shutting down, initiating cleanup.\n"));
2057 do_shutdown = GNUNET_YES;
2059 // terminate all owned open tunnels.
2060 for (session = from_client_head; NULL != session; session = session->next)
2062 if ((FINALIZED != session->state) && (NULL != session->tunnel)){
2063 GNUNET_MESH_tunnel_destroy (session->tunnel);
2064 session->tunnel = NULL;
2066 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
2068 GNUNET_SCHEDULER_cancel (session->client_notification_task);
2069 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
2071 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
2073 GNUNET_SCHEDULER_cancel (session->service_request_task);
2074 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
2076 if (NULL != session->client)
2078 GNUNET_SERVER_client_disconnect (session->client);
2079 session->client = NULL;
2082 for (session = from_service_head; NULL != session; session = session->next)
2083 if (NULL != session->tunnel){
2084 GNUNET_MESH_tunnel_destroy (session->tunnel);
2085 session->tunnel = NULL;
2090 GNUNET_MESH_disconnect (my_mesh);
2097 * Initialization of the program and message handlers
2099 * @param cls closure
2100 * @param server the initialized server
2101 * @param c configuration to use
2105 struct GNUNET_SERVER_Handle *server,
2106 const struct GNUNET_CONFIGURATION_Handle *c)
2108 static const struct GNUNET_SERVER_MessageHandler server_handlers[] = {
2109 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE, 0},
2110 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_BOB, 0},
2113 static const struct GNUNET_MESH_MessageHandler mesh_handlers[] = {
2114 { &handle_service_request, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB, 0},
2115 { &handle_service_response, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE, 0},
2118 static const uint32_t ports[] = {
2119 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
2122 //generate private/public key set
2123 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Generating Paillier-Keyset.\n"));
2125 // register server callbacks and disconnect handler
2126 GNUNET_SERVER_add_handlers (server, server_handlers);
2127 GNUNET_SERVER_disconnect_notify (server,
2128 &handle_client_disconnect,
2130 GNUNET_break (GNUNET_OK ==
2131 GNUNET_CRYPTO_get_host_identity (c,
2133 my_mesh = GNUNET_MESH_connect (c, NULL,
2134 &tunnel_incoming_handler,
2135 &tunnel_destruction_handler,
2136 mesh_handlers, ports);
2139 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Connect to MESH failed\n"));
2140 GNUNET_SCHEDULER_shutdown ();
2143 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Mesh initialized\n"));
2144 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
2151 * The main function for the scalarproduct service.
2153 * @param argc number of arguments from the command line
2154 * @param argv command line arguments
2155 * @return 0 ok, 1 on error
2158 main (int argc, char *const *argv)
2160 return (GNUNET_OK ==
2161 GNUNET_SERVICE_run (argc, argv,
2163 GNUNET_SERVICE_OPTION_NONE,
2164 &run, NULL)) ? 0 : 1;
2167 /* end of gnunet-service-ext.c */