2 This file is part of GNUnet.
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
68 * A scalarproduct session which tracks:
70 * a request form the client to our final response.
72 * a request from a service to us(service).
77 * the role this peer has
82 * session information is kept in a DLL
84 struct ServiceSession *next;
87 * session information is kept in a DLL
89 struct ServiceSession *prev;
92 * (hopefully) unique transaction ID
94 struct GNUNET_HashCode key;
97 * state of the session
99 enum SessionState state;
102 * Alice or Bob's peerID
104 struct GNUNET_PeerIdentity peer;
107 * the client this request is related to
109 struct GNUNET_SERVER_Client * client;
112 * The message to send
114 struct GNUNET_MessageHeader * msg;
117 * how many elements we were supplied with from the client
119 uint16_t element_count;
122 * how many elements actually are used after applying the mask
124 uint16_t used_element_count;
127 * how many bytes the mask is long.
128 * just for convenience so we don't have to re-re-re calculate it each time
130 uint16_t mask_length;
133 * all the vector elements we received
138 * mask of which elements to check
140 unsigned char * mask;
143 * Public key of the remote service, only used by bob
145 gcry_sexp_t remote_pubkey;
148 * E(ai)(Bob) or ai(Alice) after applying the mask
153 * The computed scalar
158 * My transmit handle for the current message to a alice/bob
160 struct GNUNET_MESH_TransmitHandle * service_transmit_handle;
163 * My transmit handle for the current message to the client
165 struct GNUNET_SERVER_TransmitHandle * client_transmit_handle;
168 * tunnel-handle associated with our mesh handle
170 struct GNUNET_MESH_Tunnel * tunnel;
172 GNUNET_SCHEDULER_TaskIdentifier client_notification_task;
174 GNUNET_SCHEDULER_TaskIdentifier service_request_task;
177 ///////////////////////////////////////////////////////////////////////////////
179 ///////////////////////////////////////////////////////////////////////////////
183 * Handle to the core service (NULL until we've connected to it).
185 static struct GNUNET_MESH_Handle *my_mesh;
188 * The identity of this host.
190 static struct GNUNET_PeerIdentity me;
193 * Service's own public key represented as string
195 static unsigned char * my_pubkey_external;
198 * Service's own public key represented as string
200 static uint16_t my_pubkey_external_length = 0;
205 static gcry_mpi_t my_n;
208 * Service's own n^2 (kept for performance)
210 static gcry_mpi_t my_nsquare;
213 * Service's own public exponent
215 static gcry_mpi_t my_g;
218 * Service's own private multiplier
220 static gcry_mpi_t my_mu;
223 * Service's own private exponent
225 static gcry_mpi_t my_lambda;
228 * Service's offset for values that could possibly be negative but are plaintext for encryption.
230 static gcry_mpi_t my_offset;
233 * Head of our double linked list for client-requests sent to us.
234 * for all of these elements we calculate a scalar product with a remote peer
235 * split between service->service and client->service for simplicity
237 static struct ServiceSession * from_client_head;
239 * Tail of our double linked list for client-requests sent to us.
240 * for all of these elements we calculate a scalar product with a remote peer
241 * split between service->service and client->service for simplicity
243 static struct ServiceSession * from_client_tail;
246 * Head of our double linked list for service-requests sent to us.
247 * for all of these elements we help the requesting service in calculating a scalar product
248 * split between service->service and client->service for simplicity
250 static struct ServiceSession * from_service_head;
253 * Tail of our double linked list for service-requests sent to us.
254 * for all of these elements we help the requesting service in calculating a scalar product
255 * split between service->service and client->service for simplicity
257 static struct ServiceSession * from_service_tail;
260 * Certain events (callbacks for server & mesh operations) must not be queued after shutdown.
262 static int do_shutdown;
264 ///////////////////////////////////////////////////////////////////////////////
266 ///////////////////////////////////////////////////////////////////////////////
269 * Generates an Paillier private/public keyset and extracts the values using libgrcypt only
274 gcry_sexp_t gen_parms;
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_parms, &erroff,
287 "(genkey(rsa(nbits %d)(rsa-use-e 3:257)))",
290 GNUNET_assert (0 == gcry_pk_genkey (&key, gen_parms));
291 gcry_sexp_release (gen_parms);
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);
435 * decrypts an element using the paillier crypto system
437 * @param m plaintext (output)
438 * @param c the ciphertext
439 * @param mu the modifier to correct encryption
440 * @param lambda the private exponent
441 * @param n the outer module for decryption
442 * @param n_square the inner module for decryption
445 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)
447 gcry_mpi_powm (m, c, lambda, n_square);
448 gcry_mpi_sub_ui (m, m, 1);
449 gcry_mpi_div (m, NULL, m, n, 0);
450 gcry_mpi_mulm (m, m, mu, n);
455 * computes the square sum over a vector of a given length.
457 * @param vector the vector to encrypt
458 * @param length the length of the vector
459 * @return an MPI value containing the calculated sum, never NULL
462 compute_square_sum (gcry_mpi_t * vector, uint16_t length)
468 GNUNET_assert (sum = gcry_mpi_new (0));
469 GNUNET_assert (elem = gcry_mpi_new (0));
471 // calculare E(sum (ai ^ 2), publickey)
472 for (i = 0; i < length; i++)
474 gcry_mpi_mul (elem, vector[i], vector[i]);
475 gcry_mpi_add (sum, sum, elem);
477 gcry_mpi_release (elem);
484 * Primitive callback for copying over a message, as they
485 * usually are too complex to be handled in the callback itself.
486 * clears a session-callback, if a session was handed over and the transmit handle was stored
488 * @param cls the message object
489 * @param size the size of the buffer we got
490 * @param buf the buffer to copy the message to
491 * @return 0 if we couldn't copy, else the size copied over
494 do_send_message (void *cls, size_t size, void *buf)
496 struct ServiceSession * session = cls;
501 if (ntohs (session->msg->size) == size)
503 memcpy (buf, session->msg, size);
507 if (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT == ntohs(session->msg->type)){
508 session->state = FINALIZED;
509 session->client_transmit_handle = NULL;
512 session->service_transmit_handle = NULL;
514 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
515 "Sent a message of type %hu.\n",
516 ntohs (session->msg->type));
517 GNUNET_free(session->msg);
525 * initializes a new vector with fresh MPI values (=0) of a given length
527 * @param length of the vector to create
528 * @return the initialized vector, never NULL
531 initialize_mpi_vector (uint16_t length)
534 gcry_mpi_t * output = GNUNET_malloc (sizeof (gcry_mpi_t) * length);
536 for (i = 0; i < length; i++)
537 GNUNET_assert (NULL != (output[i] = gcry_mpi_new (0)));
543 * permutes an MPI vector according to the given permutation vector
545 * @param vector the vector to permuted
546 * @param perm the permutation to use
547 * @param length the length of the vectors
548 * @return the permuted vector (same as input), never NULL
551 permute_vector (gcry_mpi_t * vector,
555 gcry_mpi_t tmp[length];
558 GNUNET_assert (length > 0);
561 memcpy (tmp, vector, length * sizeof (gcry_mpi_t));
563 // permute vector according to given
564 for (i = 0; i < length; i++)
565 vector[i] = tmp[perm[i]];
572 * Populate a vector with random integer values and convert them to
574 * @param length the length of the vector we must generate
575 * @return an array of MPI values with random values
578 generate_random_vector (uint16_t length)
580 gcry_mpi_t * random_vector;
584 random_vector = initialize_mpi_vector (length);
585 for (i = 0; i < length; i++)
587 value = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
589 // long to gcry_mpi_t
591 gcry_mpi_sub_ui (random_vector[i],
595 random_vector[i] = gcry_mpi_set_ui (random_vector[i], value);
598 return random_vector;
603 * Finds a not terminated client/service session in the
604 * given DLL based on session key, element count and state.
606 * @param tail - the tail of the DLL
607 * @param my - the session to compare it to
608 * @return a pointer to a matching session,
611 static struct ServiceSession *
612 find_matching_session (struct ServiceSession * tail,
613 const struct GNUNET_HashCode * key,
614 uint16_t element_count,
615 enum SessionState * state,
616 const struct GNUNET_PeerIdentity * peerid)
618 struct ServiceSession * curr;
620 for (curr = tail; NULL != curr; curr = curr->prev)
622 // if the key matches, and the element_count is same
623 if ((!memcmp (&curr->key, key, sizeof (struct GNUNET_HashCode)))
624 && (curr->element_count == element_count))
626 // if incoming state is NULL OR is same as state of the queued request
627 if ((NULL == state) || (curr->state == *state))
629 // if peerid is NULL OR same as the peer Id in the queued request
631 || (!memcmp (&curr->peer, peerid, sizeof (struct GNUNET_PeerIdentity))))
632 // matches and is not an already terminated session
643 free_session (struct ServiceSession * session)
649 for (i = 0; i < session->used_element_count; i++)
650 gcry_mpi_release (session->a[i]);
652 GNUNET_free (session->a);
654 if (session->product)
655 gcry_mpi_release (session->product);
657 if (session->remote_pubkey)
658 gcry_sexp_release (session->remote_pubkey);
660 GNUNET_free_non_null (session->vector);
661 GNUNET_free (session);
663 ///////////////////////////////////////////////////////////////////////////////
664 // Event and Message Handlers
665 ///////////////////////////////////////////////////////////////////////////////
668 * A client disconnected.
670 * Remove the associated session(s), release datastructures
671 * and cancel pending outgoing transmissions to the client.
672 * if the session has not yet completed, we also cancel Alice's request to Bob.
674 * @param cls closure, NULL
675 * @param client identification of the client
678 handle_client_disconnect (void *cls,
679 struct GNUNET_SERVER_Client *client)
681 struct ServiceSession *session;
683 session = GNUNET_SERVER_client_get_user_context (client, struct ServiceSession);
686 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
687 _ ("Client (%p) disconnected from us.\n"), client);
688 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
690 if (!(session->role == BOB && session->state == FINALIZED))
692 //we MUST terminate any client message underway
693 if (session->service_transmit_handle && session->tunnel)
694 GNUNET_MESH_notify_transmit_ready_cancel (session->service_transmit_handle);
695 if (session->tunnel && session->state == WAITING_FOR_SERVICE_RESPONSE)
696 GNUNET_MESH_tunnel_destroy (session->tunnel);
698 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
700 GNUNET_SCHEDULER_cancel (session->client_notification_task);
701 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
703 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
705 GNUNET_SCHEDULER_cancel (session->service_request_task);
706 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
708 if (NULL != session->client_transmit_handle)
710 GNUNET_SERVER_notify_transmit_ready_cancel (session->client_transmit_handle);
711 session->client_transmit_handle = NULL;
713 free_session (session);
718 * Notify the client that the session has succeeded or failed completely.
719 * This message gets sent to
720 * * alice's client if bob disconnected or to
721 * * bob's client if the operation completed or alice disconnected
723 * @param client_session the associated client session
724 * @return GNUNET_NO, if we could not notify the client
725 * GNUNET_YES if we notified it.
728 prepare_client_end_notification (void * cls,
729 const struct GNUNET_SCHEDULER_TaskContext * tc)
731 struct ServiceSession * session = cls;
732 struct GNUNET_SCALARPRODUCT_client_response * msg;
734 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
736 msg = GNUNET_new (struct GNUNET_SCALARPRODUCT_client_response);
737 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
738 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
739 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
740 msg->header.size = htons (sizeof (struct GNUNET_SCALARPRODUCT_client_response));
741 // 0 size and the first char in the product is 0, which should never be zero if encoding is used.
742 msg->product_length = htonl (0);
745 session->msg = &msg->header;
747 //transmit this message to our client
748 session->client_transmit_handle =
749 GNUNET_SERVER_notify_transmit_ready (session->client,
750 sizeof (struct GNUNET_SCALARPRODUCT_client_response),
751 GNUNET_TIME_UNIT_FOREVER_REL,
755 // if we could not even queue our request, something is wrong
756 if ( NULL == session->client_transmit_handle)
758 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not send message to client (%p)!\n"), session->client);
759 // usually gets freed by do_send_message
764 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Sending session-end notification to client (%p) for session %s\n"), &session->client, GNUNET_h2s (&session->key));
771 * generates the response message to be sent to alice after computing
772 * the values (1), (2), S and S'
773 * (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
774 * (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
775 * S: $S := E_A(sum (r_i + b_i)^2)$
776 * S': $S' := E_A(sum r_i^2)$
778 * @param r (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
779 * @param r_prime (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
780 * @param s S: $S := E_A(sum (r_i + b_i)^2)$
781 * @param s_prime S': $S' := E_A(sum r_i^2)$
782 * @param request the associated requesting session with alice
783 * @param response the associated responder session with bob's client
784 * @return GNUNET_SYSERR if the function was called with NULL parameters or if there was an error
785 * GNUNET_NO if we could not send our message
786 * GNUNET_OK if the operation succeeded
789 prepare_service_response (gcry_mpi_t * r,
790 gcry_mpi_t * r_prime,
793 struct ServiceSession * request,
794 struct ServiceSession * response)
796 struct GNUNET_SCALARPRODUCT_service_response * msg;
797 uint16_t msg_length = 0;
798 unsigned char * current = NULL;
799 unsigned char * element_exported = NULL;
800 size_t element_length = 0;
803 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
804 + 2 * request->used_element_count * PAILLIER_ELEMENT_LENGTH // kp, kq
805 + 2 * PAILLIER_ELEMENT_LENGTH; // s, stick
807 msg = GNUNET_malloc (msg_length);
809 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE);
810 msg->header.size = htons (msg_length);
811 msg->element_count = htons (request->element_count);
812 msg->used_element_count = htons (request->used_element_count);
813 memcpy (&msg->key, &request->key, sizeof (struct GNUNET_HashCode));
814 current = (unsigned char *) &msg[1];
816 // 4 times the same logics with slight variations.
817 // doesn't really justify having 2 functions for that
818 // so i put it into blocks to enhance readability
821 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
822 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
823 element_exported, PAILLIER_ELEMENT_LENGTH,
826 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
827 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
828 GNUNET_free (element_exported);
829 current += PAILLIER_ELEMENT_LENGTH;
834 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
835 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
836 element_exported, PAILLIER_ELEMENT_LENGTH,
839 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
840 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
841 GNUNET_free (element_exported);
842 current += PAILLIER_ELEMENT_LENGTH;
846 for (i = 0; i < request->used_element_count; i++)
848 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
849 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
850 element_exported, PAILLIER_ELEMENT_LENGTH,
853 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
854 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
855 GNUNET_free (element_exported);
856 current += PAILLIER_ELEMENT_LENGTH;
861 for (i = 0; i < request->used_element_count; i++)
863 element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
864 GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG,
865 element_exported, PAILLIER_ELEMENT_LENGTH,
868 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
869 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
870 GNUNET_free (element_exported);
871 current += PAILLIER_ELEMENT_LENGTH;
874 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= msg_length)
876 request->msg = (struct GNUNET_MessageHeader *) msg;
877 request->service_transmit_handle =
878 GNUNET_MESH_notify_transmit_ready (request->tunnel,
880 GNUNET_TIME_UNIT_FOREVER_REL,
884 // we don't care if it could be send or not. either way, the session is over for us.
885 request->state = FINALIZED;
888 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!)\n"));
890 //disconnect our client
891 if ( NULL == request->service_transmit_handle)
893 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Could not send service-response message via mesh!)\n"));
895 response->client_notification_task =
896 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
907 * (1)[]: $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
908 * (2)[]: $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
909 * S: $S := E_A(\sum (r_i + b_i)^2)$
910 * S': $S' := E_A(\sum r_i^2)$
912 * @param request the requesting session + bob's requesting peer
913 * @param response the responding session + bob's client handle
914 * @return GNUNET_SYSERR if the computation failed
915 * GNUNET_OK if everything went well.
918 compute_service_response (struct ServiceSession * request,
919 struct ServiceSession * response)
923 int ret = GNUNET_SYSERR;
927 gcry_mpi_t * rand = NULL;
928 gcry_mpi_t * r = NULL;
929 gcry_mpi_t * r_prime = NULL;
932 gcry_mpi_t * a_pi_prime;
934 gcry_mpi_t * rand_pi;
935 gcry_mpi_t * rand_pi_prime;
937 gcry_mpi_t s_prime = NULL;
938 gcry_mpi_t remote_n = NULL;
939 gcry_mpi_t remote_nsquare;
940 gcry_mpi_t remote_g = NULL;
944 count = request->used_element_count;
946 b = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
947 a_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
948 b_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
949 a_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
950 rand_pi = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
951 rand_pi_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
953 // convert responder session to from long to mpi
954 for (i = 0, j = 0; i < response->element_count && j < count; i++)
956 if (request->mask[i / 8] & (1 << (i % 8)))
958 value = response->vector[i] >= 0 ? response->vector[i] : -response->vector[i];
959 // long to gcry_mpi_t
960 if (0 > response->vector[i])
962 b[j] = gcry_mpi_new (0);
963 gcry_mpi_sub_ui (b[j], b[j], value);
967 b[j] = gcry_mpi_set_ui (NULL, value);
972 GNUNET_free (response->vector);
973 response->vector = NULL;
975 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "n", 0);
979 gcry_sexp_release (request->remote_pubkey);
980 request->remote_pubkey = NULL;
983 remote_n = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
987 gcry_sexp_release (tmp_exp);
990 remote_nsquare = gcry_mpi_new (KEYBITS + 1);
991 gcry_mpi_mul (remote_nsquare, remote_n, remote_n);
992 gcry_sexp_release (tmp_exp);
993 tmp_exp = gcry_sexp_find_token (request->remote_pubkey, "g", 0);
994 gcry_sexp_release (request->remote_pubkey);
995 request->remote_pubkey = NULL;
999 gcry_mpi_release (remote_n);
1002 remote_g = gcry_sexp_nth_mpi (tmp_exp, 1, GCRYMPI_FMT_USG);
1006 gcry_mpi_release (remote_n);
1007 gcry_sexp_release (tmp_exp);
1010 gcry_sexp_release (tmp_exp);
1012 // generate r, p and q
1013 rand = generate_random_vector (count);
1014 p = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1015 q = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK, count);
1016 //initialize the result vectors
1017 r = initialize_mpi_vector (count);
1018 r_prime = initialize_mpi_vector (count);
1020 // copy the REFERNCES of a, b and r into aq and bq. we will not change
1021 // those values, thus we can work with the references
1022 memcpy (a_pi, request->a, sizeof (gcry_mpi_t) * count);
1023 memcpy (a_pi_prime, request->a, sizeof (gcry_mpi_t) * count);
1024 memcpy (b_pi, b, sizeof (gcry_mpi_t) * count);
1025 memcpy (rand_pi, rand, sizeof (gcry_mpi_t) * count);
1026 memcpy (rand_pi_prime, rand, sizeof (gcry_mpi_t) * count);
1028 // generate p and q permutations for a, b and r
1029 GNUNET_assert (permute_vector (a_pi, p, count));
1030 GNUNET_assert (permute_vector (b_pi, p, count));
1031 GNUNET_assert (permute_vector (rand_pi, p, count));
1032 GNUNET_assert (permute_vector (a_pi_prime, q, count));
1033 GNUNET_assert (permute_vector (rand_pi_prime, q, count));
1035 // encrypt the element
1036 // for the sake of readability I decided to have dedicated permutation
1037 // vectors, which get rid of all the lookups in p/q.
1038 // however, ap/aq are not absolutely necessary but are just abstraction
1039 // Calculate Kp = E(S + a_pi) (+) E(S - r_pi - b_pi)
1040 for (i = 0; i < count; i++)
1042 // E(S - r_pi - b_pi)
1043 gcry_mpi_sub (r[i], my_offset, rand_pi[i]);
1044 gcry_mpi_sub (r[i], r[i], b_pi[i]);
1045 encrypt_element (r[i], r[i], remote_g, remote_n, remote_nsquare);
1047 // E(S - r_pi - b_pi) * E(S + a_pi) == E(2*S + a - r - b)
1048 gcry_mpi_mulm (r[i], r[i], a_pi[i], remote_nsquare);
1052 GNUNET_free (rand_pi);
1054 // Calculate Kq = E(S + a_qi) (+) E(S - r_qi)
1055 for (i = 0; i < count; i++)
1058 gcry_mpi_sub (r_prime[i], my_offset, rand_pi_prime[i]);
1059 encrypt_element (r_prime[i], r_prime[i], remote_g, remote_n, remote_nsquare);
1061 // E(S - r_qi) * E(S + a_qi) == E(2*S + a_qi - r_qi)
1062 gcry_mpi_mulm (r_prime[i], r_prime[i], a_pi_prime[i], remote_nsquare);
1064 GNUNET_free (a_pi_prime);
1065 GNUNET_free (rand_pi_prime);
1067 // Calculate S' = E(SUM( r_i^2 ))
1068 s_prime = compute_square_sum (rand, count);
1069 encrypt_element (s_prime, s_prime, remote_g, remote_n, remote_nsquare);
1071 // Calculate S = E(SUM( (r_i + b_i)^2 ))
1072 for (i = 0; i < count; i++)
1074 gcry_mpi_add (rand[i], rand[i], b[i]);
1076 s = compute_square_sum (rand, count);
1077 encrypt_element (s, s, remote_g, remote_n, remote_nsquare);
1078 gcry_mpi_release (remote_n);
1079 gcry_mpi_release (remote_g);
1080 gcry_mpi_release (remote_nsquare);
1082 // release r and tmp
1083 for (i = 0; i < count; i++)
1084 // rp, rq, aq, ap, bp, bq are released along with a, r, b respectively, (a and b are handled at except:)
1085 gcry_mpi_release (rand[i]);
1087 // copy the Kp[], Kq[], S and Stick into a new message
1088 if (GNUNET_YES != prepare_service_response (r, r_prime, s, s_prime, request, response))
1089 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Failed to communicate with `%s', scalar product calculation aborted.\n"),
1090 GNUNET_i2s (&request->peer));
1094 for (i = 0; i < count; i++)
1096 gcry_mpi_release (r_prime[i]);
1097 gcry_mpi_release (r[i]);
1100 gcry_mpi_release (s);
1101 gcry_mpi_release (s_prime);
1104 for (i = 0; i < count; i++)
1106 gcry_mpi_release (b[i]);
1107 gcry_mpi_release (request->a[i]);
1111 GNUNET_free (request->a);
1119 * Executed by Alice, fills in a service-request message and sends it to the given peer
1121 * @param session the session associated with this request, then also holds the CORE-handle
1122 * @return #GNUNET_SYSERR if we could not send the message
1123 * #GNUNET_NO if the message was too large
1124 * #GNUNET_OK if we sent it
1127 prepare_service_request (void *cls,
1128 const struct GNUNET_SCHEDULER_TaskContext *tc)
1130 struct ServiceSession * session = cls;
1131 unsigned char * current;
1132 struct GNUNET_SCALARPRODUCT_service_request * msg;
1135 uint16_t msg_length;
1136 size_t element_length = 0; // initialized by gcry_mpi_print, but the compiler doesn't know that
1140 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
1142 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _ ("Successfully created new tunnel to peer (%s)!\n"), GNUNET_i2s (&session->peer));
1144 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1145 + session->used_element_count * PAILLIER_ELEMENT_LENGTH
1146 + session->mask_length
1147 + my_pubkey_external_length;
1149 if (GNUNET_SERVER_MAX_MESSAGE_SIZE < sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1150 + session->used_element_count * PAILLIER_ELEMENT_LENGTH
1151 + session->mask_length
1152 + my_pubkey_external_length)
1154 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1155 session->client_notification_task =
1156 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1161 msg = GNUNET_malloc (msg_length);
1162 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB);
1163 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1164 msg->mask_length = htons (session->mask_length);
1165 msg->pk_length = htons (my_pubkey_external_length);
1166 msg->used_element_count = htons (session->used_element_count);
1167 msg->element_count = htons (session->element_count);
1168 msg->header.size = htons (msg_length);
1170 // fill in the payload
1171 current = (unsigned char *) &msg[1];
1172 // copy over the mask
1173 memcpy (current, session->mask, session->mask_length);
1174 // copy over our public key
1175 current += session->mask_length;
1176 memcpy (current, my_pubkey_external, my_pubkey_external_length);
1177 current += my_pubkey_external_length;
1179 // now copy over the element vector
1180 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * session->used_element_count);
1181 a = gcry_mpi_new (KEYBITS * 2);
1182 // encrypt our vector and generate string representations
1183 for (i = 0, j = 0; i < session->element_count; i++)
1185 // if this is a used element...
1186 if (session->mask[i / 8] & 1 << (i % 8))
1188 unsigned char * element_exported = GNUNET_malloc (PAILLIER_ELEMENT_LENGTH);
1189 value = session->vector[i] >= 0 ? session->vector[i] : -session->vector[i];
1191 a = gcry_mpi_set_ui (a, 0);
1192 // long to gcry_mpi_t
1193 if (session->vector[i] < 0)
1194 gcry_mpi_sub_ui (a, a, value);
1196 gcry_mpi_add_ui (a, a, value);
1198 session->a[j++] = gcry_mpi_set (NULL, a);
1199 gcry_mpi_add (a, a, my_offset);
1200 encrypt_element (a, a, my_g, my_n, my_nsquare);
1202 // get representation as string
1203 // we always supply some value, so gcry_mpi_print fails only if it can't reserve memory
1204 GNUNET_assert ( ! gcry_mpi_print (GCRYMPI_FMT_USG,
1205 element_exported, PAILLIER_ELEMENT_LENGTH,
1209 // move buffer content to the end of the buffer so it can easily be read by libgcrypt. also this now has fixed size
1210 adjust (element_exported, element_length, PAILLIER_ELEMENT_LENGTH);
1212 // copy over to the message
1213 memcpy (current, element_exported, PAILLIER_ELEMENT_LENGTH);
1214 current += PAILLIER_ELEMENT_LENGTH;
1217 gcry_mpi_release (a);
1219 session->msg = (struct GNUNET_MessageHeader *) msg;
1220 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("Transmitting service request.\n"));
1222 //transmit via mesh messaging
1223 session->service_transmit_handle = GNUNET_MESH_notify_transmit_ready (session->tunnel, GNUNET_YES,
1224 GNUNET_TIME_UNIT_FOREVER_REL,
1228 if ( ! session->service_transmit_handle)
1230 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _("Could not send mutlicast message to tunnel!\n"));
1232 session->msg = NULL;
1233 session->client_notification_task =
1234 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1238 session->state = WAITING_FOR_SERVICE_RESPONSE;
1242 * Handler for a client request message.
1243 * Can either be type A or B
1244 * A: request-initiation to compute a scalar product with a peer
1245 * B: response role, keep the values + session and wait for a matching session or process a waiting request
1247 * @param cls closure
1248 * @param client identification of the client
1249 * @param message the actual message
1252 handle_client_request (void *cls,
1253 struct GNUNET_SERVER_Client *client,
1254 const struct GNUNET_MessageHeader *message)
1256 const struct GNUNET_SCALARPRODUCT_client_request * msg = (const struct GNUNET_SCALARPRODUCT_client_request *) message;
1257 struct ServiceSession * session;
1258 uint16_t element_count;
1259 uint16_t mask_length;
1264 // only one concurrent session per client connection allowed, simplifies logics a lot...
1265 session = GNUNET_SERVER_client_get_user_context (client, struct ServiceSession);
1266 if ((NULL != session) && (session->state != FINALIZED)){
1267 GNUNET_SERVER_receive_done (client, GNUNET_OK);
1270 else if(NULL != session){
1271 // old session is already completed, clean it up
1272 GNUNET_CONTAINER_DLL_remove (from_client_head, from_client_tail, session);
1273 free_session(session);
1276 //we need at least a peer and one message id to compare
1277 if (sizeof (struct GNUNET_SCALARPRODUCT_client_request) > ntohs (msg->header.size))
1279 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1280 _ ("Too short message received from client!\n"));
1281 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1285 msg_type = ntohs (msg->header.type);
1286 element_count = ntohs (msg->element_count);
1287 mask_length = ntohs (msg->mask_length);
1289 //sanity check: is the message as long as the message_count fields suggests?
1290 if (( ntohs (msg->header.size) != (sizeof (struct GNUNET_SCALARPRODUCT_client_request) + element_count * sizeof (int32_t) + mask_length))
1291 || (0 == element_count))
1293 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1294 _ ("Invalid message received from client, session information incorrect!\n"));
1295 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1299 // do we have a duplicate session here already?
1300 if (NULL != find_matching_session (from_client_tail,
1305 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1306 _ ("Duplicate session information received, cannot create new session with key `%s'\n"),
1307 GNUNET_h2s (&msg->key));
1308 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1312 session = GNUNET_new (struct ServiceSession);
1313 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
1314 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1315 session->client = client;
1316 session->element_count = element_count;
1317 session->mask_length = mask_length;
1318 // get our transaction key
1319 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1320 //allocate memory for vector and encrypted vector
1321 session->vector = GNUNET_malloc (sizeof (int32_t) * element_count);
1322 vector = (int32_t *) & msg[1];
1324 if (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE == msg_type)
1326 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1327 _ ("Got client-request-session with key %s, preparing tunnel to remote service.\n"),
1328 GNUNET_h2s (&session->key));
1330 session->role = ALICE;
1332 session->mask = GNUNET_malloc (mask_length);
1333 memcpy (session->mask, &vector[element_count], mask_length);
1335 // copy over the elements
1336 session->used_element_count = 0;
1337 for (i = 0; i < element_count; i++)
1339 session->vector[i] = ntohl (vector[i]);
1340 if (session->vector[i] == 0)
1341 session->mask[i / 8] &= ~(1 << (i % 8));
1342 if (session->mask[i / 8] & (1 << (i % 8)))
1343 session->used_element_count++;
1346 if ( ! session->used_element_count)
1348 GNUNET_break_op (0);
1349 GNUNET_free (session->vector);
1350 GNUNET_free (session->a);
1351 GNUNET_free (session);
1352 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1355 //session with ourself makes no sense!
1356 if ( ! memcmp (&msg->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1359 GNUNET_free (session->vector);
1360 GNUNET_free (session->a);
1361 GNUNET_free (session);
1362 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1366 memcpy (&session->peer, &msg->peer, sizeof (struct GNUNET_PeerIdentity));
1367 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1368 _ ("Creating new tunnel to for session with key %s.\n"),
1369 GNUNET_h2s (&session->key));
1370 session->tunnel = GNUNET_MESH_tunnel_create (my_mesh, session,
1372 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
1375 //prepare_service_request, tunnel_peer_disconnect_handler,
1376 if ( ! session->tunnel)
1379 GNUNET_free (session->vector);
1380 GNUNET_free (session->a);
1381 GNUNET_free (session);
1382 GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
1385 GNUNET_SERVER_client_set_user_context (client, session);
1386 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1388 session->state = CLIENT_REQUEST_RECEIVED;
1389 session->service_request_task =
1390 GNUNET_SCHEDULER_add_now (&prepare_service_request,
1396 struct ServiceSession * requesting_session;
1397 enum SessionState needed_state = SERVICE_REQUEST_RECEIVED;
1399 session->role = BOB;
1400 session->mask = NULL;
1401 // copy over the elements
1402 session->used_element_count = element_count;
1403 for (i = 0; i < element_count; i++)
1404 session->vector[i] = ntohl (vector[i]);
1405 session->state = CLIENT_RESPONSE_RECEIVED;
1407 GNUNET_SERVER_client_set_user_context (client, session);
1408 GNUNET_CONTAINER_DLL_insert (from_client_head, from_client_tail, session);
1410 //check if service queue contains a matching request
1411 requesting_session = find_matching_session (from_service_tail,
1413 session->element_count,
1414 &needed_state, NULL);
1415 if (NULL != requesting_session)
1417 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));
1418 if (GNUNET_OK != compute_service_response (requesting_session, session))
1419 session->client_notification_task =
1420 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1425 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));
1426 // no matching session exists yet, store the response
1427 // for later processing by handle_service_request()
1430 GNUNET_SERVER_receive_done (client, GNUNET_YES);
1435 * Function called for inbound tunnels.
1437 * @param cls closure
1438 * @param tunnel new handle to the tunnel
1439 * @param initiator peer that started the tunnel
1440 * @param atsi performance information for the tunnel
1441 * @return initial tunnel context for the tunnel
1442 * (can be NULL -- that's not an error)
1445 tunnel_incoming_handler (void *cls,
1446 struct GNUNET_MESH_Tunnel *tunnel,
1447 const struct GNUNET_PeerIdentity *initiator,
1450 struct ServiceSession * c = GNUNET_new (struct ServiceSession);
1452 c->peer = *initiator;
1455 c->state = WAITING_FOR_SERVICE_REQUEST;
1461 * Function called whenever a tunnel is destroyed. Should clean up
1462 * any associated state.
1464 * It must NOT call GNUNET_MESH_tunnel_destroy on the tunnel.
1466 * @param cls closure (set from GNUNET_MESH_connect)
1467 * @param tunnel connection to the other end (henceforth invalid)
1468 * @param tunnel_ctx place where local state associated
1469 * with the tunnel is stored
1472 tunnel_destruction_handler (void *cls,
1473 const struct GNUNET_MESH_Tunnel *tunnel,
1476 struct ServiceSession * session = tunnel_ctx;
1477 struct ServiceSession * client_session;
1478 struct ServiceSession * curr;
1480 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1481 _("Peer disconnected, terminating session %s with peer (%s)\n"),
1482 GNUNET_h2s (&session->key),
1483 GNUNET_i2s (&session->peer));
1484 if (ALICE == session->role) {
1485 // as we have only one peer connected in each session, just remove the session
1487 if ((FINALIZED != session->state) && (!do_shutdown))
1489 session->tunnel = NULL;
1490 // if this happened before we received the answer, we must terminate the session
1491 session->client_notification_task =
1492 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1496 else { //(BOB == session->role) service session
1498 // remove the session, unless it has already been dequeued, but somehow still active
1499 // this could bug without the IF in case the queue is empty and the service session was the only one know to the service
1500 // scenario: disconnect before alice can send her message to bob.
1501 for (curr = from_service_head; NULL != curr; curr = curr->next)
1502 if (curr == session)
1504 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, curr);
1507 // there is a client waiting for this service session, terminate it, too!
1508 // i assume the tupel of key and element count is unique. if it was not the rest of the code would not work either.
1509 client_session = find_matching_session (from_client_tail,
1511 session->element_count,
1513 free_session (session);
1515 // the client has to check if it was waiting for a result
1516 // or if it was a responder, no point in adding more statefulness
1517 if (client_session && (!do_shutdown))
1519 client_session->client_notification_task =
1520 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1528 * Compute our scalar product, done by Alice
1530 * @param session - the session associated with this computation
1531 * @param kp - (1) from the protocol definition:
1532 * $E_A(a_{\pi(i)}) \otimes E_A(- r_{\pi(i)} - b_{\pi(i)}) &= E_A(a_{\pi(i)} - r_{\pi(i)} - b_{\pi(i)})$
1533 * @param kq - (2) from the protocol definition:
1534 * $E_A(a_{\pi'(i)}) \otimes E_A(- r_{\pi'(i)}) &= E_A(a_{\pi'(i)} - r_{\pi'(i)})$
1535 * @param s - S from the protocol definition:
1536 * $S := E_A(\sum (r_i + b_i)^2)$
1537 * @param stick - S' from the protocol definition:
1538 * $S' := E_A(\sum r_i^2)$
1539 * @return product as MPI, never NULL
1542 compute_scalar_product (struct ServiceSession * session,
1543 gcry_mpi_t * r, gcry_mpi_t * r_prime, gcry_mpi_t s, gcry_mpi_t s_prime)
1554 count = session->used_element_count;
1555 tmp = gcry_mpi_new (KEYBITS);
1556 // due to the introduced static offset S, we now also have to remove this
1557 // from the E(a_pi)(+)E(-b_pi-r_pi) and E(a_qi)(+)E(-r_qi) twice each,
1558 // the result is E((S + a_pi) + (S -b_pi-r_pi)) and E(S + a_qi + S - r_qi)
1559 for (i = 0; i < count; i++)
1561 decrypt_element (r[i], r[i], my_mu, my_lambda, my_n, my_nsquare);
1562 gcry_mpi_sub(r[i],r[i],my_offset);
1563 gcry_mpi_sub(r[i],r[i],my_offset);
1564 decrypt_element (r_prime[i], r_prime[i], my_mu, my_lambda, my_n, my_nsquare);
1565 gcry_mpi_sub(r_prime[i],r_prime[i],my_offset);
1566 gcry_mpi_sub(r_prime[i],r_prime[i],my_offset);
1569 // calculate t = sum(ai)
1570 t = compute_square_sum (session->a, count);
1573 u = gcry_mpi_new (0);
1574 tmp = compute_square_sum (r, count);
1575 gcry_mpi_sub (u, u, tmp);
1576 gcry_mpi_release (tmp);
1579 utick = gcry_mpi_new (0);
1580 tmp = compute_square_sum (r_prime, count);
1581 gcry_mpi_sub (utick, utick, tmp);
1583 GNUNET_assert (p = gcry_mpi_new (0));
1584 GNUNET_assert (ptick = gcry_mpi_new (0));
1587 decrypt_element (s, s, my_mu, my_lambda, my_n, my_nsquare);
1588 decrypt_element (s_prime, s_prime, my_mu, my_lambda, my_n, my_nsquare);
1591 gcry_mpi_add (p, s, t);
1592 gcry_mpi_add (p, p, u);
1595 gcry_mpi_add (ptick, s_prime, t);
1596 gcry_mpi_add (ptick, ptick, utick);
1598 gcry_mpi_release (t);
1599 gcry_mpi_release (u);
1600 gcry_mpi_release (utick);
1603 gcry_mpi_sub (p, p, ptick);
1604 gcry_mpi_release (ptick);
1605 tmp = gcry_mpi_set_ui (tmp, 2);
1606 gcry_mpi_div (p, NULL, p, tmp, 0);
1608 gcry_mpi_release (tmp);
1609 for (i = 0; i < count; i++)
1610 gcry_mpi_release (session->a[i]);
1611 GNUNET_free (session->a);
1619 * prepare the response we will send to alice or bobs' clients.
1620 * in Bobs case the product will be NULL.
1622 * @param session the session associated with our client.
1625 prepare_client_response (void *cls,
1626 const struct GNUNET_SCHEDULER_TaskContext *tc)
1628 struct ServiceSession * session = cls;
1629 struct GNUNET_SCALARPRODUCT_client_response * msg;
1630 unsigned char * product_exported = NULL;
1631 size_t product_length = 0;
1632 uint16_t msg_length = 0;
1637 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
1639 if (session->product)
1641 gcry_mpi_t value = gcry_mpi_new(0);
1643 sign = gcry_mpi_cmp_ui(session->product, 0);
1644 // libgcrypt can not handle a print of a negative number
1646 gcry_mpi_sub(value, value, session->product);
1650 gcry_mpi_add(value, value, session->product);
1655 // get representation as string
1656 // unfortunately libgcrypt is too stupid to implement print-support in
1657 // signed GCRYMPI_FMT_STD format, and simply asserts in that case.
1658 // here is the associated sourcecode:
1659 // if (a->sign) return gcry_error (GPG_ERR_INTERNAL); /* Can't handle it yet. */
1661 && (0 != (rc = gcry_mpi_aprint (GCRYMPI_FMT_USG,
1664 session->product)))){
1665 LOG_GCRY(GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
1667 range = -1; // signal error with product-length = 0 and range = -1
1670 gcry_mpi_release (session->product);
1671 session->product = NULL;
1674 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_client_response) + product_length;
1675 msg = GNUNET_malloc (msg_length);
1676 memcpy (&msg[1], product_exported, product_length);
1677 GNUNET_free_non_null (product_exported);
1678 msg->header.type = htons (GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SERVICE_TO_CLIENT);
1679 msg->header.size = htons (msg_length);
1681 memcpy (&msg->key, &session->key, sizeof (struct GNUNET_HashCode));
1682 memcpy (&msg->peer, &session->peer, sizeof ( struct GNUNET_PeerIdentity));
1683 msg->product_length = htonl (product_length);
1685 session->msg = (struct GNUNET_MessageHeader *) msg;
1686 //transmit this message to our client
1687 session->client_transmit_handle =
1688 GNUNET_SERVER_notify_transmit_ready (session->client,
1690 GNUNET_TIME_UNIT_FOREVER_REL,
1693 if ( NULL == session->client_transmit_handle)
1695 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
1696 _ ("Could not send message to client (%p)!\n"),
1698 session->client = NULL;
1699 // callback was not called!
1701 session->msg = NULL;
1704 // gracefully sent message, just terminate session structure
1705 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1706 _ ("Sent result to client (%p), this session (%s) has ended!\n"),
1708 GNUNET_h2s (&session->key));
1713 * Handle a request from another service to calculate a scalarproduct with us.
1715 * @param cls closure (set from #GNUNET_MESH_connect)
1716 * @param tunnel connection to the other end
1717 * @param tunnel_ctx place to store local state associated with the tunnel
1718 * @param sender who sent the message
1719 * @param message the actual message
1720 * @param atsi performance data for the connection
1721 * @return #GNUNET_OK to keep the connection open,
1722 * #GNUNET_SYSERR to close it (signal serious error)
1725 handle_service_request (void *cls,
1726 struct GNUNET_MESH_Tunnel * tunnel,
1728 const struct GNUNET_MessageHeader * message)
1730 struct ServiceSession * session;
1731 const struct GNUNET_SCALARPRODUCT_service_request * msg = (const struct GNUNET_SCALARPRODUCT_service_request *) message;
1732 uint16_t mask_length;
1734 uint16_t used_elements;
1735 uint16_t element_count;
1736 uint16_t msg_length;
1737 unsigned char * current;
1738 struct ServiceSession * responder_session;
1740 enum SessionState needed_state;
1742 session = (struct ServiceSession *) * tunnel_ctx;
1743 if (BOB != session->role){
1745 return GNUNET_SYSERR;
1747 // is this tunnel already in use?
1748 if ( (session->next) || (from_service_head == session))
1751 return GNUNET_SYSERR;
1753 // Check if message was sent by me, which would be bad!
1754 if ( ! memcmp (&session->peer, &me, sizeof (struct GNUNET_PeerIdentity)))
1756 GNUNET_free (session);
1758 return GNUNET_SYSERR;
1761 //we need at least a peer and one message id to compare
1762 if (ntohs (msg->header.size) < sizeof (struct GNUNET_SCALARPRODUCT_service_request))
1764 GNUNET_free (session);
1766 return GNUNET_SYSERR;
1768 mask_length = ntohs (msg->mask_length);
1769 pk_length = ntohs (msg->pk_length);
1770 used_elements = ntohs (msg->used_element_count);
1771 element_count = ntohs (msg->element_count);
1772 msg_length = sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1773 + mask_length + pk_length + used_elements * PAILLIER_ELEMENT_LENGTH;
1775 //sanity check: is the message as long as the message_count fields suggests?
1776 if ((ntohs (msg->header.size) != msg_length) || (element_count < used_elements)
1777 || (used_elements == 0) || (mask_length != (element_count / 8 + (element_count % 8 ? 1 : 0)))
1780 GNUNET_free (session);
1782 return GNUNET_SYSERR;
1784 if (find_matching_session (from_service_tail,
1790 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Got message with duplicate session key (`%s'), ignoring service request.\n"), (const char *) &(msg->key));
1791 GNUNET_free (session);
1792 return GNUNET_SYSERR;
1795 memcpy (&session->peer, &session->peer, sizeof (struct GNUNET_PeerIdentity));
1796 session->state = SERVICE_REQUEST_RECEIVED;
1797 session->element_count = ntohs (msg->element_count);
1798 session->used_element_count = used_elements;
1799 session->tunnel = tunnel;
1802 memcpy (&session->key, &msg->key, sizeof (struct GNUNET_HashCode));
1803 current = (unsigned char *) &msg[1];
1804 //preserve the mask, we will need that later on
1805 session->mask = GNUNET_malloc (mask_length);
1806 memcpy (session->mask, current, mask_length);
1808 current += mask_length;
1810 //convert the publickey to sexp
1811 if (gcry_sexp_new (&session->remote_pubkey, current, pk_length, 1))
1813 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate remote public key to sexpression!\n"));
1814 GNUNET_free (session->mask);
1815 GNUNET_free (session);
1816 return GNUNET_SYSERR;
1819 current += pk_length;
1821 //check if service queue contains a matching request
1822 needed_state = CLIENT_RESPONSE_RECEIVED;
1823 responder_session = find_matching_session (from_client_tail,
1825 session->element_count,
1826 &needed_state, NULL);
1828 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1830 if (GNUNET_SERVER_MAX_MESSAGE_SIZE >= sizeof (struct GNUNET_SCALARPRODUCT_service_request)
1833 + used_elements * PAILLIER_ELEMENT_LENGTH)
1835 gcry_error_t ret = 0;
1836 session->a = GNUNET_malloc (sizeof (gcry_mpi_t) * used_elements);
1837 // Convert each vector element to MPI_value
1838 for (i = 0; i < used_elements; i++)
1842 ret = gcry_mpi_scan (&session->a[i],
1844 ¤t[i * PAILLIER_ELEMENT_LENGTH],
1845 PAILLIER_ELEMENT_LENGTH,
1849 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Could not translate E[a%d] to MPI!\n%s/%s\n"),
1850 i, gcry_strsource (ret), gcry_strerror (ret));
1854 GNUNET_CONTAINER_DLL_insert (from_service_head, from_service_tail, session);
1855 if (responder_session)
1857 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s and a matching element set, processing.\n"), GNUNET_h2s (&session->key));
1858 if (GNUNET_OK != compute_service_response (session, responder_session))
1860 //something went wrong, remove it again...
1861 GNUNET_CONTAINER_DLL_remove (from_service_head, from_service_tail, session);
1866 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Got session with key %s without a matching element set, queueing.\n"), GNUNET_h2s (&session->key));
1872 // TODO FEATURE: fallback to fragmentation, in case the message is too long
1873 GNUNET_log (GNUNET_ERROR_TYPE_WARNING, _ ("Message too large, fragmentation is currently not supported!\n"));
1877 for (i = 0; i < used_elements; i++)
1879 gcry_mpi_release (session->a[i]);
1880 gcry_sexp_release (session->remote_pubkey);
1881 session->remote_pubkey = NULL;
1882 GNUNET_free_non_null (session->a);
1884 free_session (session);
1885 // and notify our client-session that we could not complete the session
1886 if (responder_session)
1887 // we just found the responder session in this queue
1888 responder_session->client_notification_task =
1889 GNUNET_SCHEDULER_add_now (&prepare_client_end_notification,
1891 return GNUNET_SYSERR;
1896 * Handle a response we got from another service we wanted to calculate a scalarproduct with.
1898 * @param cls closure (set from #GNUNET_MESH_connect)
1899 * @param tunnel connection to the other end
1900 * @param tunnel_ctx place to store local state associated with the tunnel
1901 * @param sender who sent the message
1902 * @param message the actual message
1903 * @param atsi performance data for the connection
1904 * @return #GNUNET_OK to keep the connection open,
1905 * #GNUNET_SYSERR to close it (we are done)
1908 handle_service_response (void *cls,
1909 struct GNUNET_MESH_Tunnel * tunnel,
1911 const struct GNUNET_MessageHeader * message)
1913 struct ServiceSession * session;
1914 const struct GNUNET_SCALARPRODUCT_service_response * msg = (const struct GNUNET_SCALARPRODUCT_service_response *) message;
1915 unsigned char * current;
1917 gcry_mpi_t s = NULL;
1918 gcry_mpi_t s_prime = NULL;
1921 uint16_t used_element_count;
1923 gcry_mpi_t * r = NULL;
1924 gcry_mpi_t * r_prime = NULL;
1927 GNUNET_assert (NULL != message);
1928 session = (struct ServiceSession *) * tunnel_ctx;
1929 if (ALICE != session->role){
1931 return GNUNET_SYSERR;
1934 count = session->used_element_count;
1935 session->product = NULL;
1936 session->state = SERVICE_RESPONSE_RECEIVED;
1938 //we need at least a peer and one message id to compare
1939 if (sizeof (struct GNUNET_SCALARPRODUCT_service_response) > ntohs (msg->header.size))
1941 GNUNET_break_op (0);
1944 used_element_count = ntohs (msg->used_element_count);
1945 msg_size = sizeof (struct GNUNET_SCALARPRODUCT_service_response)
1946 + 2 * used_element_count * PAILLIER_ELEMENT_LENGTH
1947 + 2 * PAILLIER_ELEMENT_LENGTH;
1948 //sanity check: is the message as long as the message_count fields suggests?
1949 if ((ntohs (msg->header.size) != msg_size) || (count != used_element_count))
1951 GNUNET_break_op (0);
1956 current = (unsigned char *) &msg[1];
1957 if (0 != (rc = gcry_mpi_scan (&s, GCRYMPI_FMT_USG, current,
1958 PAILLIER_ELEMENT_LENGTH, &read)))
1960 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1961 GNUNET_break_op (0);
1964 current += PAILLIER_ELEMENT_LENGTH;
1966 if (0 != (rc = gcry_mpi_scan (&s_prime, GCRYMPI_FMT_USG, current,
1967 PAILLIER_ELEMENT_LENGTH, &read)))
1969 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1970 GNUNET_break_op (0);
1973 current += PAILLIER_ELEMENT_LENGTH;
1975 r = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
1976 // Convert each kp[] to its MPI_value
1977 for (i = 0; i < count; i++)
1979 if (0 != (rc = gcry_mpi_scan (&r[i], GCRYMPI_FMT_USG, current,
1980 PAILLIER_ELEMENT_LENGTH, &read)))
1982 LOG_GCRY (GNUNET_ERROR_TYPE_DEBUG, "gcry_mpi_scan", rc);
1983 GNUNET_break_op (0);
1986 current += PAILLIER_ELEMENT_LENGTH;
1990 r_prime = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
1991 // Convert each kq[] to its MPI_value
1992 for (i = 0; i < count; i++)
1994 if (0 != (rc = gcry_mpi_scan (&r_prime[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;
2003 session->product = compute_scalar_product (session, r, r_prime, s, s_prime);
2007 gcry_mpi_release (s);
2009 gcry_mpi_release (s_prime);
2010 for (i = 0; r && i < count; i++)
2011 if (r[i]) gcry_mpi_release (r[i]);
2012 for (i = 0; r_prime && i < count; i++)
2013 if (r_prime[i]) gcry_mpi_release (r_prime[i]);
2014 GNUNET_free_non_null (r);
2015 GNUNET_free_non_null (r_prime);
2017 session->tunnel = NULL;
2018 // send message with product to client
2019 session->client_notification_task =
2020 GNUNET_SCHEDULER_add_now (&prepare_client_response,
2022 // the tunnel has done its job, terminate our connection and the tunnel
2023 // the peer will be notified that the tunnel was destroyed via tunnel_destruction_handler
2024 // just close the connection, as recommended by Christian
2025 return GNUNET_SYSERR;
2029 * Task run during shutdown.
2035 shutdown_task (void *cls,
2036 const struct GNUNET_SCHEDULER_TaskContext *tc)
2038 struct ServiceSession * session;
2039 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Shutting down, initiating cleanup.\n"));
2041 do_shutdown = GNUNET_YES;
2043 // terminate all owned open tunnels.
2044 for (session = from_client_head; NULL != session; session = session->next)
2046 if (FINALIZED != session->state)
2047 GNUNET_MESH_tunnel_destroy (session->tunnel);
2048 if (GNUNET_SCHEDULER_NO_TASK != session->client_notification_task)
2050 GNUNET_SCHEDULER_cancel (session->client_notification_task);
2051 session->client_notification_task = GNUNET_SCHEDULER_NO_TASK;
2053 if (GNUNET_SCHEDULER_NO_TASK != session->service_request_task)
2055 GNUNET_SCHEDULER_cancel (session->service_request_task);
2056 session->service_request_task = GNUNET_SCHEDULER_NO_TASK;
2059 for (session = from_service_head; NULL != session; session = session->next)
2063 GNUNET_MESH_disconnect (my_mesh);
2070 * Initialization of the program and message handlers
2072 * @param cls closure
2073 * @param server the initialized server
2074 * @param c configuration to use
2078 struct GNUNET_SERVER_Handle *server,
2079 const struct GNUNET_CONFIGURATION_Handle *c)
2081 static const struct GNUNET_SERVER_MessageHandler server_handlers[] = {
2082 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_ALICE, 0},
2083 {&handle_client_request, NULL, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_BOB, 0},
2086 static const struct GNUNET_MESH_MessageHandler mesh_handlers[] = {
2087 { &handle_service_request, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_TO_BOB, 0},
2088 { &handle_service_response, GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_TO_ALICE, 0},
2091 static const uint32_t ports[] = {
2092 GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
2095 //generate private/public key set
2096 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Generating Paillier-Keyset.\n"));
2098 // register server callbacks and disconnect handler
2099 GNUNET_SERVER_add_handlers (server, server_handlers);
2100 GNUNET_SERVER_disconnect_notify (server,
2101 &handle_client_disconnect,
2103 GNUNET_break (GNUNET_OK ==
2104 GNUNET_CRYPTO_get_host_identity (c,
2106 my_mesh = GNUNET_MESH_connect (c, NULL,
2107 &tunnel_incoming_handler,
2108 &tunnel_destruction_handler,
2109 mesh_handlers, ports);
2112 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, _ ("Connect to MESH failed\n"));
2113 GNUNET_SCHEDULER_shutdown ();
2116 GNUNET_log (GNUNET_ERROR_TYPE_INFO, _ ("Mesh initialized\n"));
2117 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
2124 * The main function for the scalarproduct service.
2126 * @param argc number of arguments from the command line
2127 * @param argv command line arguments
2128 * @return 0 ok, 1 on error
2131 main (int argc, char *const *argv)
2133 return (GNUNET_OK ==
2134 GNUNET_SERVICE_run (argc, argv,
2136 GNUNET_SERVICE_OPTION_NONE,
2137 &run, NULL)) ? 0 : 1;
2140 /* end of gnunet-service-ext.c */