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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 WAITING_FOR_BOBS_CONNECT,
48 MESSAGE_FROM_RESPONDING_CLIENT_RECEIVED,
49 WAITING_FOR_RESPONSE_FROM_SERVICE,
50 REQUEST_FROM_SERVICE_RECEIVED,
55 * role a peer in a session can assume
65 * A scalarproduct session which tracks:
67 * a request form the client to our final response.
69 * a request from a service to us(service).
74 * the role this peer has
79 * session information is kept in a DLL
81 struct ServiceSession *next;
84 * session information is kept in a DLL
86 struct ServiceSession *prev;
89 * (hopefully) unique transaction ID
91 struct GNUNET_HashCode key;
94 * state of the session
96 enum SessionState state;
99 * Alice or Bob's peerID
101 struct GNUNET_PeerIdentity peer;
104 * the client this request is related to
106 struct GNUNET_SERVER_Client * client;
109 * The message to send
111 struct GNUNET_MessageHeader * msg;
114 * how many elements we were supplied with from the client
116 uint16_t element_count;
119 * how many elements actually are used after applying the mask
121 uint16_t used_element_count;
124 * how many bytes the mask is long.
125 * just for convenience so we don't have to re-re-re calculate it each time
127 uint16_t mask_length;
130 * all the vector elements we received
135 * mask of which elements to check
137 unsigned char * mask;
140 * Public key of the remote service, only used by bob
142 gcry_sexp_t remote_pubkey;
145 * E(ai)(Bob) or ai(Alice) after applying the mask
150 * The computed scalar
155 * My transmit handle for the current message to a alice/bob
157 struct GNUNET_MESH_TransmitHandle * service_transmit_handle;
160 * My transmit handle for the current message to the client
162 struct GNUNET_SERVER_TransmitHandle * client_transmit_handle;
165 * tunnel-handle associated with our mesh handle
167 struct GNUNET_MESH_Tunnel * tunnel;
169 GNUNET_SCHEDULER_TaskIdentifier client_notification_task;
171 GNUNET_SCHEDULER_TaskIdentifier service_request_task;
174 ///////////////////////////////////////////////////////////////////////////////
176 ///////////////////////////////////////////////////////////////////////////////
180 * Handle to the core service (NULL until we've connected to it).
182 static struct GNUNET_MESH_Handle *my_mesh;
185 * The identity of this host.
187 static struct GNUNET_PeerIdentity me;
190 * Service's own public key represented as string
192 static unsigned char * my_pubkey_external;
195 * Service's own public key represented as string
197 static uint16_t my_pubkey_external_length = 0;
202 static gcry_mpi_t my_n;
205 * Service's own n^2 (kept for performance)
207 static gcry_mpi_t my_nsquare;
210 * Service's own public exponent
212 static gcry_mpi_t my_g;
215 * Service's own private multiplier
217 static gcry_mpi_t my_mu;
220 * Service's own private exponent
222 static gcry_mpi_t my_lambda;
225 * Service's offset for values that could possibly be negative but are plaintext for encryption.
227 static gcry_mpi_t my_offset;
230 * Head of our double linked list for client-requests sent to us.
231 * for all of these elements we calculate a scalar product with a remote peer
232 * split between service->service and client->service for simplicity
234 static struct ServiceSession * from_client_head;
236 * Tail of our double linked list for client-requests sent to us.
237 * for all of these elements we calculate a scalar product with a remote peer
238 * split between service->service and client->service for simplicity
240 static struct ServiceSession * from_client_tail;
243 * Head of our double linked list for service-requests sent to us.
244 * for all of these elements we help the requesting service in calculating a scalar product
245 * split between service->service and client->service for simplicity
247 static struct ServiceSession * from_service_head;
250 * Tail of our double linked list for service-requests sent to us.
251 * for all of these elements we help the requesting service in calculating a scalar product
252 * split between service->service and client->service for simplicity
254 static struct ServiceSession * from_service_tail;
257 * Certain events (callbacks for server & mesh operations) must not be queued after shutdown.
259 static int do_shutdown;
261 ///////////////////////////////////////////////////////////////////////////////
263 ///////////////////////////////////////////////////////////////////////////////
266 * Generates an Paillier private/public keyset and extracts the values using libgrcypt only
271 gcry_sexp_t gen_parms;
273 gcry_sexp_t tmp_sexp;
282 // we can still use the RSA keygen for generating p,q,n, but using e is pointless.
283 GNUNET_assert (0 == gcry_sexp_build (&gen_parms, &erroff,
284 "(genkey(rsa(nbits %d)(rsa-use-e 3:257)))",
287 GNUNET_assert (0 == gcry_pk_genkey (&key, gen_parms));
288 gcry_sexp_release (gen_parms);
290 // get n and d of our publickey as MPI
291 tmp_sexp = gcry_sexp_find_token (key, "n", 0);
292 GNUNET_assert (tmp_sexp);
293 my_n = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
294 gcry_sexp_release (tmp_sexp);
295 tmp_sexp = gcry_sexp_find_token (key, "p", 0);
296 GNUNET_assert (tmp_sexp);
297 p = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
298 gcry_sexp_release (tmp_sexp);
299 tmp_sexp = gcry_sexp_find_token (key, "q", 0);
300 GNUNET_assert (tmp_sexp);
301 q = gcry_sexp_nth_mpi (tmp_sexp, 1, GCRYMPI_FMT_USG);
302 gcry_sexp_release (key);
304 tmp1 = gcry_mpi_new (0);
305 tmp2 = gcry_mpi_new (0);
306 gcd = gcry_mpi_new (0);
307 my_g = gcry_mpi_new (0);
308 my_mu = gcry_mpi_new (0);
309 my_nsquare = gcry_mpi_new (0);
310 my_lambda = gcry_mpi_new (0);
313 // lambda = \frac{(p-1)*(q-1)}{gcd(p-1,q-1)}
314 gcry_mpi_sub_ui (tmp1, p, 1);
315 gcry_mpi_sub_ui (tmp2, q, 1);
316 gcry_mpi_gcd (gcd, tmp1, tmp2);
317 gcry_mpi_set (my_lambda, tmp1);
318 gcry_mpi_mul (my_lambda, my_lambda, tmp2);
319 gcry_mpi_div (my_lambda, NULL, my_lambda, gcd, 0);
322 gcry_mpi_mul (my_nsquare, my_n, my_n);
328 gcry_mpi_randomize (my_g, KEYBITS * 2, GCRY_WEAK_RANDOM);
329 // g must be smaller than n^2
330 if (0 >= gcry_mpi_cmp (my_g, my_nsquare))
333 // g must have gcd == 1 with n^2
334 gcry_mpi_gcd (gcd, my_g, my_nsquare);
336 while (gcry_mpi_cmp_ui (gcd, 1));
338 // is this a valid g?
339 // if so, gcd(((g^lambda mod n^2)-1 )/n, n) = 1
340 gcry_mpi_powm (tmp1, my_g, my_lambda, my_nsquare);
341 gcry_mpi_sub_ui (tmp1, tmp1, 1);
342 gcry_mpi_div (tmp1, NULL, tmp1, my_n, 0);
343 gcry_mpi_gcd (gcd, tmp1, my_n);
345 while (gcry_mpi_cmp_ui (gcd, 1));
347 // calculate our mu based on g and n.
348 // mu = (((g^lambda mod n^2)-1 )/n)^-1 mod n
349 gcry_mpi_invm (my_mu, tmp1, my_n);
351 GNUNET_assert (0 == gcry_sexp_build (&key, &erroff,
352 "(public-key (paillier (n %M)(g %M)))",
355 // get the length of this sexpression
356 my_pubkey_external_length = gcry_sexp_sprint (key,
361 GNUNET_assert (my_pubkey_external_length > 0);
362 my_pubkey_external = GNUNET_malloc (my_pubkey_external_length);
364 // convert the sexpression to canonical format
365 gcry_sexp_sprint (key,
368 my_pubkey_external_length);
370 gcry_sexp_release (key);
372 // offset has to be sufficiently small to allow computation of:
373 // m1+m2 mod n == (S + a) + (S + b) mod n,
374 // if we have more complex operations, this factor needs to be lowered
375 my_offset = gcry_mpi_new(KEYBITS/3);
376 gcry_mpi_set_bit(my_offset, KEYBITS/3);
378 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _ ("Generated key set with key length %d bits.\n"), KEYBITS);
383 * If target != size, move target bytes to the
384 * end of the size-sized buffer and zero out the
385 * first target-size bytes.
387 * @param buf original buffer
388 * @param size number of bytes in the buffer
389 * @param target target size of the buffer
392 adjust (unsigned char *buf, size_t size, size_t target)
396 memmove (&buf[target - size], buf, size);
397 memset (buf, 0, target - size);
403 * encrypts an element using the paillier crypto system
405 * @param c ciphertext (output)
407 * @param g the public base
408 * @param n the module from which which r is chosen (Z*_n)
409 * @param n_square the module for encryption, for performance reasons.
412 encrypt_element (gcry_mpi_t c, gcry_mpi_t m, gcry_mpi_t g, gcry_mpi_t n, gcry_mpi_t n_square)
416 GNUNET_assert (tmp = gcry_mpi_new (0));
418 while (0 >= gcry_mpi_cmp_ui (tmp, 1))
420 gcry_mpi_randomize (tmp, KEYBITS / 3, GCRY_WEAK_RANDOM);
421 // r must be 1 < r < n
424 gcry_mpi_powm (c, g, m, n_square);
425 gcry_mpi_powm (tmp, tmp, n, n_square);
426 gcry_mpi_mulm (c, tmp, c, n_square);
428 gcry_mpi_release (tmp);
432 * decrypts an element using the paillier crypto system
434 * @param m plaintext (output)
435 * @param c the ciphertext
436 * @param mu the modifier to correct encryption
437 * @param lambda the private exponent
438 * @param n the outer module for decryption
439 * @param n_square the inner module for decryption
442 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)
444 gcry_mpi_powm (m, c, lambda, n_square);
445 gcry_mpi_sub_ui (m, m, 1);
446 gcry_mpi_div (m, NULL, m, n, 0);
447 gcry_mpi_mulm (m, m, mu, n);
452 * computes the square sum over a vector of a given length.
454 * @param vector the vector to encrypt
455 * @param length the length of the vector
456 * @return an MPI value containing the calculated sum, never NULL
459 compute_square_sum (gcry_mpi_t * vector, uint16_t length)
465 GNUNET_assert (sum = gcry_mpi_new (0));
466 GNUNET_assert (elem = gcry_mpi_new (0));
468 // calculare E(sum (ai ^ 2), publickey)
469 for (i = 0; i < length; i++)
471 gcry_mpi_mul (elem, vector[i], vector[i]);
472 gcry_mpi_add (sum, sum, elem);
474 gcry_mpi_release (elem);
481 * Primitive callback for copying over a message, as they
482 * usually are too complex to be handled in the callback itself.
483 * clears a session-callback, if a session was handed over and the transmit handle was stored
485 * @param cls the message object
486 * @param size the size of the buffer we got
487 * @param buf the buffer to copy the message to
488 * @return 0 if we couldn't copy, else the size copied over
491 do_send_message (void *cls, size_t size, void *buf)
493 struct ServiceSession * session = cls;
498 if (ntohs (session->msg->size) == size)
500 memcpy (buf, session->msg, size);
504 if (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT == ntohs(session->msg->type)){
505 session->state = FINALIZED;
506 session->client_transmit_handle = NULL;
509 session->service_transmit_handle = NULL;
511 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
512 "Sent a message of type %hu.\n",
513 ntohs (session->msg->type));
514 GNUNET_free(session->msg);
522 * initializes a new vector with fresh MPI values (=0) of a given length
524 * @param length of the vector to create
525 * @return the initialized vector, never NULL
528 initialize_mpi_vector (uint16_t length)
531 gcry_mpi_t * output = GNUNET_malloc (sizeof (gcry_mpi_t) * length);
533 for (i = 0; i < length; i++)
534 GNUNET_assert (NULL != (output[i] = gcry_mpi_new (0)));
540 * permutes an MPI vector according to the given permutation vector
542 * @param vector the vector to permuted
543 * @param perm the permutation to use
544 * @param length the length of the vectors
545 * @return the permuted vector (same as input), never NULL
548 permute_vector (gcry_mpi_t * vector,
552 gcry_mpi_t tmp[length];
555 GNUNET_assert (length > 0);
558 memcpy (tmp, vector, length * sizeof (gcry_mpi_t));
560 // permute vector according to given
561 for (i = 0; i < length; i++)
562 vector[i] = tmp[perm[i]];
569 * Populate a vector with random integer values and convert them to
571 * @param length the length of the vector we must generate
572 * @return an array of MPI values with random values
575 generate_random_vector (uint16_t length)
577 gcry_mpi_t * random_vector;
581 random_vector = initialize_mpi_vector (length);
582 for (i = 0; i < length; i++)
584 value = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
586 // long to gcry_mpi_t
588 gcry_mpi_sub_ui (random_vector[i],
592 random_vector[i] = gcry_mpi_set_ui (random_vector[i], value);
595 return random_vector;
600 * Finds a not terminated client/service session in the
601 * given DLL based on session key, element count and state.
603 * @param tail - the tail of the DLL
604 * @param my - the session to compare it to
605 * @return a pointer to a matching session,
608 static struct ServiceSession *
609 find_matching_session (struct ServiceSession * tail,
610 const struct GNUNET_HashCode * key,
611 uint16_t element_count,
612 enum SessionState * state,
613 const struct GNUNET_PeerIdentity * peerid)
615 struct ServiceSession * curr;
617 for (curr = tail; NULL != curr; curr = curr->prev)
619 // if the key matches, and the element_count is same
620 if ((!memcmp (&curr->key, key, sizeof (struct GNUNET_HashCode)))
621 && (curr->element_count == element_count))
623 // if incoming state is NULL OR is same as state of the queued request
624 if ((NULL == state) || (curr->state == *state))
626 // if peerid is NULL OR same as the peer Id in the queued request
628 || (!memcmp (&curr->peer, peerid, sizeof (struct GNUNET_PeerIdentity))))
629 // matches and is not an already terminated session
640 free_session (struct ServiceSession * session)
646 for (i = 0; i < session->used_element_count; i++)
647 gcry_mpi_release (session->a[i]);
649 GNUNET_free (session->a);
651 if (session->product)
652 gcry_mpi_release (session->product);
654 if (session->remote_pubkey)
655 gcry_sexp_release (session->remote_pubkey);
657 GNUNET_free_non_null (session->vector);
658 GNUNET_free (session);
660 ///////////////////////////////////////////////////////////////////////////////
661 // Event and Message Handlers
662 ///////////////////////////////////////////////////////////////////////////////
665 * A client disconnected.
667 * Remove the associated session(s), release datastructures
668 * and cancel pending outgoing transmissions to the client.
669 * if the session has not yet completed, we also cancel Alice's request to Bob.
671 * @param cls closure, NULL
672 * @param client identification of the client
675 handle_client_disconnect (void *cls,
676 struct GNUNET_SERVER_Client *client)
678 struct ServiceSession *session;
680 session = GNUNET_SERVER_client_get_user_context (client, struct ServiceSession);
683 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
684 _ ("Client (%p) disconnected from us.\n"), client);
685 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
687 if (!(session->role == BOB && session->state == FINALIZED))
689 //we MUST terminate any client message underway
690 if (session->service_transmit_handle && session->tunnel)
691 GNUNET_MESH_notify_transmit_ready_cancel (session->service_transmit_handle);
692 if (session->tunnel && session->state == WAITING_FOR_RESPONSE_FROM_SERVICE)
693 GNUNET_MESH_tunnel_destroy (session->tunnel);
695 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
697 GNUNET_SCHEDULER_cancel (session->client_notification_task);
698 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
700 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
702 GNUNET_SCHEDULER_cancel (session->service_request_task);
703 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
705 if (NULL != session->client_transmit_handle)
707 GNUNET_SERVER_notify_transmit_ready_cancel (session->client_transmit_handle);
708 session->client_transmit_handle = NULL;
710 free_session (session);
715 * Notify the client that the session has succeeded or failed completely.
716 * This message gets sent to
717 * * alice's client if bob disconnected or to
718 * * bob's client if the operation completed or alice disconnected
720 * @param client_session the associated client session
721 * @return GNUNET_NO, if we could not notify the client
722 * GNUNET_YES if we notified it.
725 prepare_client_end_notification (void * cls,
726 const struct GNUNET_SCHEDULER_TaskContext * tc)
728 struct ServiceSession * session = cls;
729 struct GNUNET_SCALARPRODUCT_client_response * msg;
731 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
733 msg = GNUNET_new (struct GNUNET_SCALARPRODUCT_client_response);
734 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
735 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
736 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
737 msg->header.size = htons (sizeof (struct GNUNET_SCALARPRODUCT_client_response));
738 // 0 size and the first char in the product is 0, which should never be zero if encoding is used.
739 msg->product_length = htonl (0);
742 session->msg = &msg->header;
744 //transmit this message to our client
745 session->client_transmit_handle =
746 GNUNET_SERVER_notify_transmit_ready (session->client,
747 sizeof (struct GNUNET_SCALARPRODUCT_client_response),
748 GNUNET_TIME_UNIT_FOREVER_REL,
752 // if we could not even queue our request, something is wrong
753 if ( ! session->client_transmit_handle)
755 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not send message to client (%p)! This is OK if it was disconnected beforehand already.\n"), session->client);
756 // usually gets freed by do_send_message
757 GNUNET_free (msg_obj);
761 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Sending session-end notification to client (%p) for session %s\n"), &session->client, GNUNET_h2s (&session->key));
768 * generates the response message to be sent to alice after computing
769 * the values (1), (2), S and S'
770 * (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
771 * (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
772 * S: $S := E_A(sum (r_i + b_i)^2)$
773 * S': $S' := E_A(sum r_i^2)$
775 * @param r (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
776 * @param r_prime (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
777 * @param s S: $S := E_A(sum (r_i + b_i)^2)$
778 * @param s_prime S': $S' := E_A(sum r_i^2)$
779 * @param request the associated requesting session with alice
780 * @param response the associated responder session with bob's client
781 * @return GNUNET_SYSERR if the function was called with NULL parameters or if there was an error
782 * GNUNET_NO if we could not send our message
783 * GNUNET_OK if the operation succeeded
786 prepare_service_response (gcry_mpi_t * r,
787 gcry_mpi_t * r_prime,
790 struct ServiceSession * request,
791 struct ServiceSession * response)
793 struct GNUNET_SCALARPRODUCT_service_response * msg;
794 uint16_t msg_length = 0;
795 unsigned char * current = NULL;
796 unsigned char * element_exported = NULL;
797 size_t element_length = 0;
800 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
801 + 2 * request->used_element_count * PAILLIER_ELEMENT_LENGTH // kp, kq
802 + 2 * PAILLIER_ELEMENT_LENGTH; // s, stick
804 msg = GNUNET_malloc (msg_length);
806 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE);
807 msg->header.size = htons (msg_length);
808 msg->element_count = htons (request->element_count);
809 msg->used_element_count = htons (request->used_element_count);
810 memcpy (&msg->key, &request->key, sizeof (struct GNUNET_HashCode));
811 current = (unsigned char *) &msg[1];
813 // 4 times the same logics with slight variations.
814 // doesn't really justify having 2 functions for that
815 // so i put it into blocks to enhance readability
818 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
819 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
820 element_exported, PAILLIER_ELEMENT_LENGTH,
823 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
824 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
825 GNUNET_free (element_exported);
826 current += PAILLIER_ELEMENT_LENGTH;
831 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
832 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
833 element_exported, PAILLIER_ELEMENT_LENGTH,
836 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
837 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
838 GNUNET_free (element_exported);
839 current += PAILLIER_ELEMENT_LENGTH;
843 for (i = 0; i < request->used_element_count; i++)
845 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
846 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
847 element_exported, PAILLIER_ELEMENT_LENGTH,
850 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
851 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
852 GNUNET_free (element_exported);
853 current += PAILLIER_ELEMENT_LENGTH;
858 for (i = 0; i < request->used_element_count; i++)
860 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
861 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
862 element_exported, PAILLIER_ELEMENT_LENGTH,
865 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
866 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
867 GNUNET_free (element_exported);
868 current += PAILLIER_ELEMENT_LENGTH;
871 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= msg_length)
873 struct MessageObject * msg_obj;
875 msg_obj = GNUNET_new (struct MessageObject);
876 msg_obj->msg = (struct GNUNET_MessageHeader *) msg;
877 msg_obj->transmit_handle = (void *) &request->service_transmit_handle; //and reset the transmit handle
878 request->service_transmit_handle =
879 GNUNET_MESH_notify_transmit_ready (request->tunnel,
881 GNUNET_TIME_UNIT_FOREVER_REL,
885 // we don't care if it could be send or not. either way, the session is over for us.
886 request->state = FINALIZED;
887 response->state = FINALIZED;
891 // TODO FEATURE: fallback to fragmentation, in case the message is too long
892 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!)\n"));
895 //disconnect our client
896 if ( ! request->service_transmit_handle)
898 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Could not send service-response message via mesh!)\n"));
900 response->client_notification_task =
901 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
912 * (1)[]: $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
913 * (2)[]: $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
914 * S: $S := E_A(\sum (r_i + b_i)^2)$
915 * S': $S' := E_A(\sum r_i^2)$
917 * @param request the requesting session + bob's requesting peer
918 * @param response the responding session + bob's client handle
919 * @return GNUNET_SYSERR if the computation failed
920 * GNUNET_OK if everything went well.
923 compute_service_response (struct ServiceSession * request,
924 struct ServiceSession * response)
928 int ret = GNUNET_SYSERR;
932 gcry_mpi_t * rand = NULL;
933 gcry_mpi_t * r = NULL;
934 gcry_mpi_t * r_prime = NULL;
937 gcry_mpi_t * a_pi_prime;
939 gcry_mpi_t * rand_pi;
940 gcry_mpi_t * rand_pi_prime;
942 gcry_mpi_t s_prime = NULL;
943 gcry_mpi_t remote_n = NULL;
944 gcry_mpi_t remote_nsquare;
945 gcry_mpi_t remote_g = NULL;
949 count = request->used_element_count;
951 b = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
952 a_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
953 b_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
954 a_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
955 rand_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
956 rand_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
958 // convert responder session to from long to mpi
959 for (i = 0, j = 0; i < response->element_count && j < count; i++)
961 if (request->mask[i / 8] & (1 << (i % 8)))
963 value = response->vector[i] >= 0 ? response->vector[i] : -response->vector[i];
964 // long to gcry_mpi_t
965 if (0 > response->vector[i])
967 b[j] = gcry_mpi_new (0);
968 gcry_mpi_sub_ui (b[j], b[j], value);
972 b[j] = gcry_mpi_set_ui (NULL, value);
977 GNUNET_free (response->vector);
978 response->vector = NULL;
980 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "n", 0);
984 gcry_sexp_release (request->remote_pubkey);
985 request->remote_pubkey = NULL;
988 remote_n = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
992 gcry_sexp_release (tmp_exp);
995 remote_nsquare = gcry_mpi_new (KEYBITS + 1);
996 gcry_mpi_mul (remote_nsquare, remote_n, remote_n);
997 gcry_sexp_release (tmp_exp);
998 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "g", 0);
999 gcry_sexp_release (request->remote_pubkey);
1000 request->remote_pubkey = NULL;
1003 GNUNET_break_op (0);
1004 gcry_mpi_release (remote_n);
1007 remote_g = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
1011 gcry_mpi_release (remote_n);
1012 gcry_sexp_release (tmp_exp);
1015 gcry_sexp_release (tmp_exp);
1017 // generate r, p and q
1018 rand = generate_random_vector (count);
1019 p = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1020 q = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1021 //initialize the result vectors
1022 r = initialize_mpi_vector (count);
1023 r_prime = initialize_mpi_vector (count);
1025 // copy the REFERNCES of a, b and r into aq and bq. we will not change
1026 // those values, thus we can work with the references
1027 memcpy (a_pi, request->a, sizeof (gcry_mpi_t) * count);
1028 memcpy (a_pi_prime, request->a, sizeof (gcry_mpi_t) * count);
1029 memcpy (b_pi, b, sizeof (gcry_mpi_t) * count);
1030 memcpy (rand_pi, rand, sizeof (gcry_mpi_t) * count);
1031 memcpy (rand_pi_prime, rand, sizeof (gcry_mpi_t) * count);
1033 // generate p and q permutations for a, b and r
1034 GNUNET_assert (permute_vector (a_pi, p, count));
1035 GNUNET_assert (permute_vector (b_pi, p, count));
1036 GNUNET_assert (permute_vector (rand_pi, p, count));
1037 GNUNET_assert (permute_vector (a_pi_prime, q, count));
1038 GNUNET_assert (permute_vector (rand_pi_prime, q, count));
1040 // encrypt the element
1041 // for the sake of readability I decided to have dedicated permutation
1042 // vectors, which get rid of all the lookups in p/q.
1043 // however, ap/aq are not absolutely necessary but are just abstraction
1044 // Calculate Kp = E(S + a_pi) (+) E(S - r_pi - b_pi)
1045 for (i = 0; i < count; i++)
1047 // E(S - r_pi - b_pi)
1048 gcry_mpi_sub (r[i], my_offset, rand_pi[i]);
1049 gcry_mpi_sub (r[i], r[i], b_pi[i]);
1050 encrypt_element (r[i], r[i], remote_g, remote_n, remote_nsquare);
1052 // E(S - r_pi - b_pi) * E(S + a_pi) == E(2*S + a - r - b)
1053 gcry_mpi_mulm (r[i], r[i], a_pi[i], remote_nsquare);
1057 GNUNET_free (rand_pi);
1059 // Calculate Kq = E(S + a_qi) (+) E(S - r_qi)
1060 for (i = 0; i < count; i++)
1063 gcry_mpi_sub (r_prime[i], my_offset, rand_pi_prime[i]);
1064 encrypt_element (r_prime[i], r_prime[i], remote_g, remote_n, remote_nsquare);
1066 // E(S - r_qi) * E(S + a_qi) == E(2*S + a_qi - r_qi)
1067 gcry_mpi_mulm (r_prime[i], r_prime[i], a_pi_prime[i], remote_nsquare);
1069 GNUNET_free (a_pi_prime);
1070 GNUNET_free (rand_pi_prime);
1072 // Calculate S' = E(SUM( r_i^2 ))
1073 s_prime = compute_square_sum (rand, count);
1074 encrypt_element (s_prime, s_prime, remote_g, remote_n, remote_nsquare);
1076 // Calculate S = E(SUM( (r_i + b_i)^2 ))
1077 for (i = 0; i < count; i++)
1079 gcry_mpi_add (rand[i], rand[i], b[i]);
1081 s = compute_square_sum (rand, count);
1082 encrypt_element (s, s, remote_g, remote_n, remote_nsquare);
1083 gcry_mpi_release (remote_n);
1084 gcry_mpi_release (remote_g);
1085 gcry_mpi_release (remote_nsquare);
1087 // release r and tmp
1088 for (i = 0; i < count; i++)
1089 // rp, rq, aq, ap, bp, bq are released along with a, r, b respectively, (a and b are handled at except:)
1090 gcry_mpi_release (rand[i]);
1092 // copy the Kp[], Kq[], S and Stick into a new message
1093 if (GNUNET_YES != prepare_service_response (r, r_prime, s, s_prime, request, response))
1094 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Failed to communicate with `%s', scalar product calculation aborted.\n"),
1095 GNUNET_i2s (&request->peer));
1099 for (i = 0; i < count; i++)
1101 gcry_mpi_release (r_prime[i]);
1102 gcry_mpi_release (r[i]);
1105 gcry_mpi_release (s);
1106 gcry_mpi_release (s_prime);
1109 for (i = 0; i < count; i++)
1111 gcry_mpi_release (b[i]);
1112 gcry_mpi_release (request->a[i]);
1116 GNUNET_free (request->a);
1124 * Executed by Alice, fills in a service-request message and sends it to the given peer
1126 * @param session the session associated with this request, then also holds the CORE-handle
1127 * @return #GNUNET_SYSERR if we could not send the message
1128 * #GNUNET_NO if the message was too large
1129 * #GNUNET_OK if we sent it
1132 prepare_service_request (void *cls,
1133 const struct GNUNET_SCHEDULER_TaskContext *tc)
1135 struct ServiceSession * session = cls;
1136 unsigned char * current;
1137 struct GNUNET_SCALARPRODUCT_service_request * msg;
1138 struct MessageObject * msg_obj;
1141 uint16_t msg_length;
1142 size_t element_length = 0; //gets 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 // TODO FEATURE: fallback to fragmentation, in case the message is too long
1161 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1162 session->client_notification_task =
1163 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1167 msg = GNUNET_malloc (msg_length);
1169 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB);
1170 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1171 msg->mask_length = htons (session->mask_length);
1172 msg->pk_length = htons (my_pubkey_external_length);
1173 msg->used_element_count = htons (session->used_element_count);
1174 msg->element_count = htons (session->element_count);
1175 msg->header.size = htons (msg_length);
1177 // fill in the payload
1178 current = (unsigned char *) &msg[1];
1179 // copy over the mask
1180 memcpy (current, session->mask, session->mask_length);
1181 // copy over our public key
1182 current += session->mask_length;
1183 memcpy (current, my_pubkey_external, my_pubkey_external_length);
1184 current += my_pubkey_external_length;
1186 // now copy over the element vector
1187 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * session->used_element_count);
1188 a = gcry_mpi_new (KEYBITS * 2);
1189 // encrypt our vector and generate string representations
1190 for (i = 0, j = 0; i < session->element_count; i++)
1192 // if this is a used element...
1193 if (session->mask[i / 8] & 1 << (i % 8))
1195 unsigned char * element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
1196 value = session->vector[i] >= 0 ? session->vector[i] : -session->vector[i];
1198 a = gcry_mpi_set_ui (a, 0);
1199 // long to gcry_mpi_t
1200 if (session->vector[i] < 0)
1201 gcry_mpi_sub_ui (a, a, value);
1203 gcry_mpi_add_ui (a, a, value);
1205 session->a[j++] = gcry_mpi_set (NULL, a);
1206 gcry_mpi_add (a, a, my_offset);
1207 encrypt_element (a, a, my_g, my_n, my_nsquare);
1209 // get representation as string
1210 // we always supply some value, so gcry_mpi_print fails only if it can't reserve memory
1211 GNUNET_assert ( ! gcry_mpi_print (GCRYMPI_FMT_USG,
1212 element_exported, PAILLIER_ELEMENT_LENGTH,
1216 // move buffer content to the end of the buffer so it can easily be read by libgcrypt. also this now has fixed size
1217 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
1219 // copy over to the message
1220 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
1221 current += PAILLIER_ELEMENT_LENGTH;
1224 gcry_mpi_release (a);
1226 msg_obj = GNUNET_new (struct MessageObject);
1227 msg_obj->msg = (struct GNUNET_MessageHeader *) msg;
1228 msg_obj->transmit_handle = (void *) &session->service_transmit_handle; //and reset the transmit handle
1229 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Transmitting service request.\n"));
1231 //transmit via mesh messaging
1232 session->state = WAITING_FOR_RESPONSE_FROM_SERVICE;
1233 session->service_transmit_handle = GNUNET_MESH_notify_transmit_ready (session->tunnel, GNUNET_YES,
1234 GNUNET_TIME_UNIT_FOREVER_REL,
1238 if ( ! session->service_transmit_handle)
1240 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _("Could not send mutlicast message to tunnel!\n"));
1241 GNUNET_free (msg_obj);
1243 session->client_notification_task =
1244 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1250 * Handler for a client request message.
1251 * Can either be type A or B
1252 * A: request-initiation to compute a scalar product with a peer
1253 * B: response role, keep the values + session and wait for a matching session or process a waiting request
1255 * @param cls closure
1256 * @param client identification of the client
1257 * @param message the actual message
1260 handle_client_request (void *cls,
1261 struct GNUNET_SERVER_Client *client,
1262 const struct GNUNET_MessageHeader *message)
1264 const struct GNUNET_SCALARPRODUCT_client_request * msg = (const struct GNUNET_SCALARPRODUCT_client_request *) message;
1265 struct ServiceSession * session;
1266 uint16_t element_count;
1267 uint16_t mask_length;
1272 GNUNET_SERVER_client_get_user_context (client, session);
1273 if ((NULL != session) && (session->state != FINALIZED)){
1274 // only one concurrent session per client connection allowed
1275 GNUNET_SERVER_receive_done (client, GNUNET_OK);
1278 else if(NULL != session){
1279 // old session is already completed, clean it up
1280 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
1281 free_session(session);
1284 //we need at least a peer and one message id to compare
1285 if (sizeof (struct GNUNET_SCALARPRODUCT_client_request) > ntohs (msg->header.size))
1287 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1288 _ ("Too short message received from client!\n"));
1289 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1293 msg_type = ntohs (msg->header.type);
1294 element_count = ntohs (msg->element_count);
1295 mask_length = ntohs (msg->mask_length);
1297 //sanity check: is the message as long as the message_count fields suggests?
1298 if (( ntohs (msg->header.size) != (sizeof (struct GNUNET_SCALARPRODUCT_client_request) + element_count * sizeof (int32_t) + mask_length))
1299 || (0 == element_count))
1301 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1302 _ ("Invalid message received from client, session information incorrect!\n"));
1303 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1307 // do we have a duplicate session here already?
1308 if (NULL != find_matching_session (from_client_tail,
1313 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1314 _ ("Duplicate session information received, cannot create new session with key `%s'\n"),
1315 GNUNET_h2s (&msg->key));
1316 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1320 session = GNUNET_new (struct ServiceSession);
1321 //FIXME: this actually should not happen here!
1322 GNUNET_SERVER_client_set_user_context (client, session);
1323 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
1324 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1325 session->client = client;
1326 session->element_count = element_count;
1327 session->mask_length = mask_length;
1328 // get our transaction key
1329 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1330 //allocate memory for vector and encrypted vector
1331 session->vector = GNUNET_malloc (sizeof (int32_t) * element_count);
1332 vector = (int32_t *) & msg[1];
1334 if (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE == msg_type)
1336 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1337 _ ("Got client-request-session with key %s, preparing tunnel to remote service.\n"),
1338 GNUNET_h2s (&session->key));
1340 session->role = ALICE;
1342 session->mask = GNUNET_malloc (mask_length);
1343 memcpy (session->mask, &vector[element_count], mask_length);
1345 // copy over the elements
1346 session->used_element_count = 0;
1347 for (i = 0; i < element_count; i++)
1349 session->vector[i] = ntohl (vector[i]);
1350 if (session->vector[i] == 0)
1351 session->mask[i / 8] &= ~(1 << (i % 8));
1352 if (session->mask[i / 8] & (1 << (i % 8)))
1353 session->used_element_count++;
1356 if ( ! session->used_element_count)
1358 GNUNET_break_op (0);
1359 GNUNET_free (session->vector);
1360 GNUNET_free (session->a);
1361 GNUNET_free (session);
1362 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1365 //session with ourself makes no sense!
1366 if ( ! memcmp (&msg->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1369 GNUNET_free (session->vector);
1370 GNUNET_free (session->a);
1371 GNUNET_free (session);
1372 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1376 memcpy (&session->peer, &msg->peer, sizeof (struct GNUNET_PeerIdentity));
1377 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1378 _ ("Creating new tunnel to for session with key %s.\n"),
1379 GNUNET_h2s (&session->key));
1380 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1381 session->tunnel = GNUNET_MESH_tunnel_create (my_mesh, session,
1383 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
1386 //prepare_service_request, tunnel_peer_disconnect_handler,
1387 if ( ! session->tunnel)
1390 GNUNET_free (session->vector);
1391 GNUNET_free (session->a);
1392 GNUNET_free (session);
1393 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1396 session->state = WAITING_FOR_BOBS_CONNECT;
1398 session->service_request_task =
1399 GNUNET_SCHEDULER_add_now (&prepare_service_request,
1405 struct ServiceSession * requesting_session;
1406 enum SessionState needed_state = REQUEST_FROM_SERVICE_RECEIVED;
1408 session->role = BOB;
1409 session->mask = NULL;
1410 // copy over the elements
1411 session->used_element_count = element_count;
1412 for (i = 0; i < element_count; i++)
1413 session->vector[i] = ntohl (vector[i]);
1414 session->state = MESSAGE_FROM_RESPONDING_CLIENT_RECEIVED;
1416 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1417 //check if service queue contains a matching request
1418 requesting_session = find_matching_session (from_service_tail,
1420 session->element_count,
1421 &needed_state, NULL);
1422 if (NULL != requesting_session)
1424 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));
1425 if (GNUNET_OK != compute_service_response (requesting_session, session))
1426 session->client_notification_task =
1427 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;
1467 * Function called whenever a tunnel is destroyed. Should clean up
1468 * any associated state.
1470 * It must NOT call GNUNET_MESH_tunnel_destroy on the tunnel.
1472 * @param cls closure (set from GNUNET_MESH_connect)
1473 * @param tunnel connection to the other end (henceforth invalid)
1474 * @param tunnel_ctx place where local state associated
1475 * with the tunnel is stored
1478 tunnel_destruction_handler (void *cls,
1479 const struct GNUNET_MESH_Tunnel *tunnel,
1482 struct ServiceSession * session = tunnel_ctx;
1483 struct ServiceSession * client_session;
1484 struct ServiceSession * curr;
1486 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1487 _("Peer disconnected, terminating session %s with peer (%s)\n"),
1488 GNUNET_h2s (&session->key),
1489 GNUNET_i2s (&session->peer));
1490 if (ALICE == session->role) {
1491 // as we have only one peer connected in each session, just remove the session
1493 if ((FINALIZED != session->state) && (!do_shutdown))
1495 session->tunnel = NULL;
1496 // if this happened before we received the answer, we must terminate the session
1497 session->client_notification_task =
1498 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1502 else { //(BOB == session->role) service session
1504 // remove the session, unless it has already been dequeued, but somehow still active
1505 // this could bug without the IF in case the queue is empty and the service session was the only one know to the service
1506 // scenario: disconnect before alice can send her message to bob.
1507 for (curr = from_service_head; NULL != curr; curr = curr->next)
1508 if (curr == session)
1510 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, curr);
1513 // there is a client waiting for this service session, terminate it, too!
1514 // i assume the tupel of key and element count is unique. if it was not the rest of the code would not work either.
1515 client_session = find_matching_session (from_client_tail,
1517 session->element_count,
1519 free_session (session);
1521 // the client has to check if it was waiting for a result
1522 // or if it was a responder, no point in adding more statefulness
1523 if (client_session && (!do_shutdown))
1525 client_session->client_notification_task =
1526 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1534 * Compute our scalar product, done by Alice
1536 * @param session - the session associated with this computation
1537 * @param kp - (1) from the protocol definition:
1538 * $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
1539 * @param kq - (2) from the protocol definition:
1540 * $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
1541 * @param s - S from the protocol definition:
1542 * $S := E_A(\sum (r_i + b_i)^2)$
1543 * @param stick - S' from the protocol definition:
1544 * $S' := E_A(\sum r_i^2)$
1545 * @return product as MPI, never NULL
1548 compute_scalar_product (struct ServiceSession * session,
1549 gcry_mpi_t * r, gcry_mpi_t * r_prime, gcry_mpi_t s, gcry_mpi_t s_prime)
1560 count = session->used_element_count;
1561 tmp = gcry_mpi_new (KEYBITS);
1562 // due to the introduced static offset S, we now also have to remove this
1563 // from the E(a_pi)(+)E(-b_pi-r_pi) and E(a_qi)(+)E(-r_qi) twice each,
1564 // the result is E((S + a_pi) + (S -b_pi-r_pi)) and E(S + a_qi + S - r_qi)
1565 for (i = 0; i < count; i++)
1567 decrypt_element (r[i], r[i], my_mu, my_lambda, my_n, my_nsquare);
1568 gcry_mpi_sub(r[i],r[i],my_offset);
1569 gcry_mpi_sub(r[i],r[i],my_offset);
1570 decrypt_element (r_prime[i], r_prime[i], my_mu, my_lambda, my_n, my_nsquare);
1571 gcry_mpi_sub(r_prime[i],r_prime[i],my_offset);
1572 gcry_mpi_sub(r_prime[i],r_prime[i],my_offset);
1575 // calculate t = sum(ai)
1576 t = compute_square_sum (session->a, count);
1579 u = gcry_mpi_new (0);
1580 tmp = compute_square_sum (r, count);
1581 gcry_mpi_sub (u, u, tmp);
1582 gcry_mpi_release (tmp);
1585 utick = gcry_mpi_new (0);
1586 tmp = compute_square_sum (r_prime, count);
1587 gcry_mpi_sub (utick, utick, tmp);
1589 GNUNET_assert (p = gcry_mpi_new (0));
1590 GNUNET_assert (ptick = gcry_mpi_new (0));
1593 decrypt_element (s, s, my_mu, my_lambda, my_n, my_nsquare);
1594 decrypt_element (s_prime, s_prime, my_mu, my_lambda, my_n, my_nsquare);
1597 gcry_mpi_add (p, s, t);
1598 gcry_mpi_add (p, p, u);
1601 gcry_mpi_add (ptick, s_prime, t);
1602 gcry_mpi_add (ptick, ptick, utick);
1604 gcry_mpi_release (t);
1605 gcry_mpi_release (u);
1606 gcry_mpi_release (utick);
1609 gcry_mpi_sub (p, p, ptick);
1610 gcry_mpi_release (ptick);
1611 tmp = gcry_mpi_set_ui (tmp, 2);
1612 gcry_mpi_div (p, NULL, p, tmp, 0);
1614 gcry_mpi_release (tmp);
1615 for (i = 0; i < count; i++)
1616 gcry_mpi_release (session->a[i]);
1617 GNUNET_free (session->a);
1625 * prepare the response we will send to alice or bobs' clients.
1626 * in Bobs case the product will be NULL.
1628 * @param session the session associated with our client.
1631 prepare_client_response (void *cls,
1632 const struct GNUNET_SCHEDULER_TaskContext *tc)
1634 struct ServiceSession * session = cls;
1635 struct GNUNET_SCALARPRODUCT_client_response * msg;
1636 unsigned char * product_exported = NULL;
1637 size_t product_length = 0;
1638 uint16_t msg_length = 0;
1639 struct MessageObject * msg_obj;
1644 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1646 if (session->product)
1648 gcry_mpi_t value = gcry_mpi_new(0);
1650 sign = gcry_mpi_cmp_ui(session->product, 0);
1651 // libgcrypt can not handle a print of a negative number
1653 gcry_mpi_sub(value, value, session->product);
1657 gcry_mpi_add(value, value, session->product);
1662 // get representation as string
1663 // unfortunately libgcrypt is too stupid to implement print-support in
1664 // signed GCRYMPI_FMT_STD format, and simply asserts in that case.
1665 // here is the associated sourcecode:
1666 // if (a->sign) return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */
1668 && (0 != (rc = gcry_mpi_aprint (GCRYMPI_FMT_USG,
1671 session->product)))){
1672 LOG_GCRY(GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
1674 range = -1; // signal error with product-length = 0 and range = -1
1677 gcry_mpi_release (session->product);
1678 session->product = NULL;
1681 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_client_response) + product_length;
1682 msg = GNUNET_malloc (msg_length);
1683 memcpy (&msg[1], product_exported, product_length);
1684 GNUNET_free_non_null (product_exported);
1685 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
1686 msg->header.size = htons (msg_length);
1688 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1689 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
1690 msg->product_length = htonl (product_length);
1692 msg_obj = GNUNET_new (struct MessageObject);
1693 msg_obj->msg = (struct GNUNET_MessageHeader *) msg;
1694 msg_obj->transmit_handle = NULL; // don't reset the transmit handle
1696 //transmit this message to our client
1697 session->client_transmit_handle =
1698 GNUNET_SERVER_notify_transmit_ready (session->client,
1700 GNUNET_TIME_UNIT_FOREVER_REL,
1703 if ( ! session->client_transmit_handle)
1705 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1706 _ ("Could not send message to client (%p)! This probably is OK if the client disconnected before us.\n"),
1708 session->client = NULL;
1709 // callback was not called!
1710 GNUNET_free (msg_obj);
1714 // gracefully sent message, just terminate session structure
1715 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1716 _ ("Sent result to client (%p), this session (%s) has ended!\n"),
1718 GNUNET_h2s (&session->key));
1723 * Handle a request from another service to calculate a scalarproduct with us.
1725 * @param cls closure (set from #GNUNET_MESH_connect)
1726 * @param tunnel connection to the other end
1727 * @param tunnel_ctx place to store local state associated with the tunnel
1728 * @param sender who sent the message
1729 * @param message the actual message
1730 * @param atsi performance data for the connection
1731 * @return #GNUNET_OK to keep the connection open,
1732 * #GNUNET_SYSERR to close it (signal serious error)
1735 handle_service_request (void *cls,
1736 struct GNUNET_MESH_Tunnel * tunnel,
1738 const struct GNUNET_MessageHeader * message)
1740 struct ServiceSession * session;
1741 const struct GNUNET_SCALARPRODUCT_service_request * msg = (const struct GNUNET_SCALARPRODUCT_service_request *) message;
1742 uint16_t mask_length;
1744 uint16_t used_elements;
1745 uint16_t element_count;
1746 uint16_t msg_length;
1747 unsigned char * current;
1748 struct ServiceSession * responder_session;
1750 enum SessionState needed_state;
1752 session = (struct ServiceSession *) * tunnel_ctx;
1753 if (BOB != session->role){
1755 return GNUNET_SYSERR;
1757 // is this tunnel already in use?
1758 if ( (session->next) || (from_service_head == session))
1761 return GNUNET_SYSERR;
1763 // Check if message was sent by me, which would be bad!
1764 if ( ! memcmp (&session->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1767 GNUNET_free (session);
1768 return GNUNET_SYSERR;
1771 //we need at least a peer and one message id to compare
1772 if (ntohs (msg->header.size) < sizeof (struct GNUNET_SCALARPRODUCT_service_request))
1774 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Too short message received from peer!\n"));
1775 GNUNET_free (session);
1776 return GNUNET_SYSERR;
1778 mask_length = ntohs (msg->mask_length);
1779 pk_length = ntohs (msg->pk_length);
1780 used_elements = ntohs (msg->used_element_count);
1781 element_count = ntohs (msg->element_count);
1782 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1783 + mask_length + pk_length + used_elements * PAILLIER_ELEMENT_LENGTH;
1785 //sanity check: is the message as long as the message_count fields suggests?
1786 if ((ntohs (msg->header.size) != msg_length) || (element_count < used_elements)
1787 || (used_elements == 0) || (mask_length != (element_count / 8 + (element_count % 8 ? 1 : 0)))
1790 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Invalid message received from peer, message count does not match message length!\n"));
1791 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Used elements: %hu\nElement Count: %hu\nExpected Mask Length: %hu\nCalculated Masklength: %d\n"), used_elements, element_count, mask_length, (element_count / 8 + (element_count % 8 ? 1 : 0)));
1792 GNUNET_free (session);
1793 return GNUNET_SYSERR;
1795 if (find_matching_session (from_service_tail,
1801 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Got message with duplicate session key (`%s'), ignoring service request.\n"), (const char *) &(msg->key));
1802 GNUNET_free (session);
1803 return GNUNET_SYSERR;
1806 memcpy (&session->peer, &session->peer, sizeof (struct GNUNET_PeerIdentity));
1807 session->state = REQUEST_FROM_SERVICE_RECEIVED;
1808 session->element_count = ntohs (msg->element_count);
1809 session->used_element_count = used_elements;
1810 session->tunnel = tunnel;
1813 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1814 current = (unsigned char *) &msg[1];
1815 //preserve the mask, we will need that later on
1816 session->mask = GNUNET_malloc (mask_length);
1817 memcpy (session->mask, current, mask_length);
1819 current += mask_length;
1821 //convert the publickey to sexp
1822 if (gcry_sexp_new (&session->remote_pubkey, current, pk_length, 1))
1824 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate remote public key to sexpression!\n"));
1825 GNUNET_free (session->mask);
1826 GNUNET_free (session);
1827 return GNUNET_SYSERR;
1830 current += pk_length;
1832 //check if service queue contains a matching request
1833 needed_state = MESSAGE_FROM_RESPONDING_CLIENT_RECEIVED;
1834 responder_session = find_matching_session (from_client_tail,
1836 session->element_count,
1837 &needed_state, NULL);
1839 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1841 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1844 + used_elements * PAILLIER_ELEMENT_LENGTH)
1846 gcry_error_t ret = 0;
1847 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1848 // Convert each vector element to MPI_value
1849 for (i = 0; i < used_elements; i++)
1853 ret = gcry_mpi_scan (&session->a[i],
1855 ¤t[i * PAILLIER_ELEMENT_LENGTH],
1856 PAILLIER_ELEMENT_LENGTH,
1860 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate E[a%d] to MPI!\n%s/%s\n"),
1861 i, gcry_strsource (ret), gcry_strerror (ret));
1865 GNUNET_CONTAINER_DLL_insert (from_service_head, from_service_tail, session);
1866 if (responder_session)
1868 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s and a matching element set, processing.\n"), GNUNET_h2s (&session->key));
1869 if (GNUNET_OK != compute_service_response (session, responder_session))
1871 //something went wrong, remove it again...
1872 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, session);
1877 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s without a matching element set, queueing.\n"), GNUNET_h2s (&session->key));
1882 // TODO FEATURE: fallback to fragmentation, in case the message is too long
1883 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1887 for (i = 0; i < used_elements; i++)
1889 gcry_mpi_release (session->a[i]);
1890 gcry_sexp_release (session->remote_pubkey);
1891 session->remote_pubkey = NULL;
1892 GNUNET_free_non_null (session->a);
1894 free_session (session);
1895 // and notify our client-session that we could not complete the session
1896 if (responder_session)
1898 // we just found the responder session in this queue
1899 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, responder_session);
1900 responder_session->client_notification_task =
1901 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1904 return GNUNET_SYSERR;
1909 * Handle a response we got from another service we wanted to calculate a scalarproduct with.
1911 * @param cls closure (set from #GNUNET_MESH_connect)
1912 * @param tunnel connection to the other end
1913 * @param tunnel_ctx place to store local state associated with the tunnel
1914 * @param sender who sent the message
1915 * @param message the actual message
1916 * @param atsi performance data for the connection
1917 * @return #GNUNET_OK to keep the connection open,
1918 * #GNUNET_SYSERR to close it (we are done)
1921 handle_service_response (void *cls,
1922 struct GNUNET_MESH_Tunnel * tunnel,
1924 const struct GNUNET_MessageHeader * message)
1926 struct ServiceSession * session;
1927 const struct GNUNET_SCALARPRODUCT_service_response * msg = (const struct GNUNET_SCALARPRODUCT_service_response *) message;
1928 unsigned char * current;
1930 gcry_mpi_t s = NULL;
1931 gcry_mpi_t s_prime = NULL;
1934 uint16_t used_element_count;
1936 gcry_mpi_t * r = NULL;
1937 gcry_mpi_t * r_prime = NULL;
1940 GNUNET_assert (NULL != message);
1941 session = (struct ServiceSession *) * tunnel_ctx;
1942 if (ALICE != session->role){
1944 return GNUNET_SYSERR;
1947 count = session->used_element_count;
1948 session->product = NULL;
1950 //we need at least a peer and one message id to compare
1951 if (sizeof (struct GNUNET_SCALARPRODUCT_service_response) > ntohs (msg->header.size))
1953 GNUNET_break_op (0);
1956 used_element_count = ntohs (msg->used_element_count);
1957 msg_size = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
1958 + 2 * used_element_count * PAILLIER_ELEMENT_LENGTH
1959 + 2 * PAILLIER_ELEMENT_LENGTH;
1960 //sanity check: is the message as long as the message_count fields suggests?
1961 if ((ntohs (msg->header.size) != msg_size) || (count != used_element_count))
1963 GNUNET_break_op (0);
1968 current = (unsigned char *) &msg[1];
1969 if (0 != (rc = gcry_mpi_scan (&s, GCRYMPI_FMT_USG, current,
1970 PAILLIER_ELEMENT_LENGTH, &read)))
1972 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1973 GNUNET_break_op (0);
1976 current += PAILLIER_ELEMENT_LENGTH;
1978 if (0 != (rc = gcry_mpi_scan (&s_prime, GCRYMPI_FMT_USG, current,
1979 PAILLIER_ELEMENT_LENGTH, &read)))
1981 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1982 GNUNET_break_op (0);
1985 current += PAILLIER_ELEMENT_LENGTH;
1987 r = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
1988 // Convert each kp[] to its MPI_value
1989 for (i = 0; i < count; i++)
1991 if (0 != (rc = gcry_mpi_scan (&r[i], GCRYMPI_FMT_USG, current,
1992 PAILLIER_ELEMENT_LENGTH, &read)))
1994 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1995 GNUNET_break_op (0);
1998 current += PAILLIER_ELEMENT_LENGTH;
2002 r_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
2003 // Convert each kq[] to its MPI_value
2004 for (i = 0; i < count; i++)
2006 if (0 != (rc = gcry_mpi_scan (&r_prime[i], GCRYMPI_FMT_USG, current,
2007 PAILLIER_ELEMENT_LENGTH, &read)))
2009 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
2010 GNUNET_break_op (0);
2013 current += PAILLIER_ELEMENT_LENGTH;
2016 session->product = compute_scalar_product (session, r, r_prime, s, s_prime);
2020 gcry_mpi_release (s);
2022 gcry_mpi_release (s_prime);
2023 for (i = 0; r && i < count; i++)
2024 if (r[i]) gcry_mpi_release (r[i]);
2025 for (i = 0; r_prime && i < count; i++)
2026 if (r_prime[i]) gcry_mpi_release (r_prime[i]);
2027 GNUNET_free_non_null (r);
2028 GNUNET_free_non_null (r_prime);
2030 session->state = FINALIZED;
2031 // the tunnel has done its job, terminate our connection and the tunnel
2032 // the peer will be notified that the tunnel was destroyed via tunnel_destruction_handler
2033 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
2034 // send message with product to client
2036 session->client_notification_task =
2037 GNUNET_SCHEDULER_add_now (&prepare_client_response,
2039 // just close the connection.
2040 return GNUNET_SYSERR;
2044 * Task run during shutdown.
2050 shutdown_task (void *cls,
2051 const struct GNUNET_SCHEDULER_TaskContext *tc)
2053 struct ServiceSession * session;
2054 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Shutting down, initiating cleanup.\n"));
2056 do_shutdown = GNUNET_YES;
2058 // terminate all owned open tunnels.
2059 for (session = from_client_head; NULL != session; session = session->next)
2061 if (FINALIZED != session->state)
2062 GNUNET_MESH_tunnel_destroy (session->tunnel);
2063 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
2065 GNUNET_SCHEDULER_cancel (session->client_notification_task);
2066 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
2068 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
2070 GNUNET_SCHEDULER_cancel (session->service_request_task);
2071 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
2074 for (session = from_service_head; NULL != session; session = session->next)
2078 GNUNET_MESH_disconnect (my_mesh);
2085 * Initialization of the program and message handlers
2087 * @param cls closure
2088 * @param server the initialized server
2089 * @param c configuration to use
2093 struct GNUNET_SERVER_Handle *server,
2094 const struct GNUNET_CONFIGURATION_Handle *c)
2096 static const struct GNUNET_SERVER_MessageHandler server_handlers[] = {
2097 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE, 0},
2098 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_BOB, 0},
2101 static const struct GNUNET_MESH_MessageHandler mesh_handlers[] = {
2102 { &handle_service_request, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB, 0},
2103 { &handle_service_response, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE, 0},
2106 static const uint32_t ports[] = {
2107 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
2110 //generate private/public key set
2111 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Generating Paillier-Keyset.\n"));
2113 // register server callbacks and disconnect handler
2114 GNUNET_SERVER_add_handlers (server, server_handlers);
2115 GNUNET_SERVER_disconnect_notify (server,
2116 &handle_client_disconnect,
2118 GNUNET_break (GNUNET_OK ==
2119 GNUNET_CRYPTO_get_host_identity (c,
2121 my_mesh = GNUNET_MESH_connect (c, NULL,
2122 &tunnel_incoming_handler,
2123 &tunnel_destruction_handler,
2124 mesh_handlers, ports);
2127 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Connect to MESH failed\n"));
2128 GNUNET_SCHEDULER_shutdown ();
2131 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Mesh initialized\n"));
2132 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
2139 * The main function for the scalarproduct service.
2141 * @param argc number of arguments from the command line
2142 * @param argv command line arguments
2143 * @return 0 ok, 1 on error
2146 main (int argc, char *const *argv)
2148 return (GNUNET_OK ==
2149 GNUNET_SERVICE_run (argc, argv,
2151 GNUNET_SERVICE_OPTION_NONE,
2152 &run, NULL)) ? 0 : 1;
2155 /* end of gnunet-service-ext.c */