X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Fscalarproduct%2Fgnunet-service-scalarproduct-ecc_bob.c;h=0b0333332a34b56e908fea8714c52671d28f35fb;hb=04a46ba5acf180be6f3a7d85cd6f6ce0ff13b1ba;hp=d08f5b8584b4f63506a60c614676443254f96e80;hpb=110973ebdd4f267cbaca4f793dae6c2ff325eeb9;p=oweals%2Fgnunet.git

diff --git a/src/scalarproduct/gnunet-service-scalarproduct-ecc_bob.c b/src/scalarproduct/gnunet-service-scalarproduct-ecc_bob.c
index d08f5b858..0b0333332 100644
--- a/src/scalarproduct/gnunet-service-scalarproduct-ecc_bob.c
+++ b/src/scalarproduct/gnunet-service-scalarproduct-ecc_bob.c
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     Copyright (C) 2013, 2014 Christian Grothoff (and other contributing authors)
+     Copyright (C) 2013-2017 GNUnet e.V.
 
      GNUnet is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
@@ -18,7 +18,7 @@
      Boston, MA 02110-1301, USA.
  */
 /**
- * @file scalarproduct/gnunet-service-scalarproduct_bob.c
+ * @file scalarproduct/gnunet-service-scalarproduct-ecc_bob.c
  * @brief scalarproduct service implementation
  * @author Christian M. Fuchs
  * @author Christian Grothoff
@@ -34,7 +34,7 @@
 #include "gnunet_scalarproduct_service.h"
 #include "gnunet_set_service.h"
 #include "scalarproduct.h"
-#include "gnunet-service-scalarproduct.h"
+#include "gnunet-service-scalarproduct-ecc.h"
 
 #define LOG(kind,...) GNUNET_log_from (kind, "scalarproduct-bob", __VA_ARGS__)
 
@@ -58,12 +58,6 @@ struct MpiElement
 };
 
 
-/**
- * An incoming session from CADET.
- */
-struct CadetIncomingSession;
-
-
 /**
  * A scalarproduct session which tracks an offer for a
  * multiplication service by a local client.
@@ -71,15 +65,10 @@ struct CadetIncomingSession;
 struct BobServiceSession
 {
 
-  /**
-   * (hopefully) unique transaction ID
-   */
-  struct GNUNET_HashCode session_id;
-
   /**
    * The client this request is related to.
    */
-  struct GNUNET_SERVER_Client *client;
+  struct GNUNET_SERVICE_Client *client;
 
   /**
    * Client message queue.
@@ -104,45 +93,24 @@ struct BobServiceSession
   struct GNUNET_SET_OperationHandle *intersection_op;
 
   /**
-   * a(Alice)
-   */
-  struct MpiElement *sorted_elements;
-
-  /**
-   * E(ai)(Bob) after applying the mask
+   * Our open port.
    */
-  struct GNUNET_CRYPTO_PaillierCiphertext *e_a;
+  struct GNUNET_CADET_Port *port;
 
   /**
-   * Bob's permutation p of R
+   * b(Bob)
    */
-  struct GNUNET_CRYPTO_PaillierCiphertext *r;
-
-  /**
-   * Bob's permutation q of R
-   */
-  struct GNUNET_CRYPTO_PaillierCiphertext *r_prime;
-
-  /**
-   * Bob's "s"
-   */
-  struct GNUNET_CRYPTO_PaillierCiphertext s;
-
-  /**
-   * Bob's "s'"
-   */
-  struct GNUNET_CRYPTO_PaillierCiphertext s_prime;
+  struct MpiElement *sorted_elements;
 
   /**
-   * Handle for our associated incoming CADET session, or NULL
-   * if we have not gotten one yet.
+   * Product of the g_i^{b_i}
    */
-  struct CadetIncomingSession *cadet;
+  gcry_mpi_point_t prod_g_i_b_i;
 
   /**
-   * The computed scalar
+   * Product of the h_i^{b_i}
    */
-  gcry_mpi_t product;
+  gcry_mpi_point_t prod_h_i_b_i;
 
   /**
    * How many elements will be supplied in total from the client.
@@ -168,12 +136,6 @@ struct BobServiceSession
    */
   uint32_t cadet_received_element_count;
 
-  /**
-   * Counts the number of values transmitted from us to Alice.
-   * Always less than @e used_element_count.
-   */
-  uint32_t cadet_transmitted_element_count;
-
   /**
    * State of this session.   In
    * #GNUNET_SCALARPRODUCT_STATUS_ACTIVE while operation is
@@ -187,20 +149,6 @@ struct BobServiceSession
    */
   int in_destroy;
 
-};
-
-
-/**
- * An incoming session from CADET.
- */
-struct CadetIncomingSession
-{
-
-  /**
-   * Associated client session, or NULL.
-   */
-  struct BobServiceSession *s;
-
   /**
    * The CADET channel.
    */
@@ -216,28 +164,11 @@ struct CadetIncomingSession
    */
   struct GNUNET_HashCode session_id;
 
-  /**
-   * Public key of the remote service.
-   */
-  struct GNUNET_CRYPTO_PaillierPublicKey remote_pubkey;
-
   /**
    * The message queue for this channel.
    */
   struct GNUNET_MQ_Handle *cadet_mq;
 
-  /**
-   * Has this CADET session been added to the map yet?
-   * #GNUNET_YES if so, in which case @e session_id is
-   * the key.
-   */
-  int in_map;
-
-  /**
-   * Are we already in #destroy_cadet_session()?
-   */
-  int in_destroy;
-
 };
 
 
@@ -246,65 +177,15 @@ struct CadetIncomingSession
  */
 static const struct GNUNET_CONFIGURATION_Handle *cfg;
 
-/**
- * Service's own public key
- */
-static struct GNUNET_CRYPTO_PaillierPublicKey my_pubkey;
-
-/**
- * Service's own private key
- */
-static struct GNUNET_CRYPTO_PaillierPrivateKey my_privkey;
-
-/**
- * Service's offset for values that could possibly be negative but are plaintext for encryption.
- */
-static gcry_mpi_t my_offset;
-
-/**
- * Map of `struct BobServiceSession`, by session keys.
- */
-static struct GNUNET_CONTAINER_MultiHashMap *client_sessions;
-
-/**
- * Map of `struct CadetIncomingSession`, by session keys.
- */
-static struct GNUNET_CONTAINER_MultiHashMap *cadet_sessions;
-
 /**
  * Handle to the CADET service.
  */
 static struct GNUNET_CADET_Handle *my_cadet;
 
-
-
-/**
- * Finds a not terminated client session in the respective map based on
- * session key.
- *
- * @param key the session key we want to search for
- * @return the matching session, or NULL for none
- */
-static struct BobServiceSession *
-find_matching_client_session (const struct GNUNET_HashCode *key)
-{
-  return GNUNET_CONTAINER_multihashmap_get (client_sessions,
-                                            key);
-}
-
-
 /**
- * Finds a CADET session in the respective map based on session key.
- *
- * @param key the session key we want to search for
- * @return the matching session, or NULL for none
+ * Context for DLOG operations on a curve.
  */
-static struct CadetIncomingSession *
-find_matching_cadet_session (const struct GNUNET_HashCode *key)
-{
-  return GNUNET_CONTAINER_multihashmap_get (cadet_sessions,
-                                            key);
-}
+static struct GNUNET_CRYPTO_EccDlogContext *edc;
 
 
 /**
@@ -326,15 +207,6 @@ free_element_cb (void *cls,
 }
 
 
-/**
- * Destroy session state, we are done with it.
- *
- * @param session the session to free elements from
- */
-static void
-destroy_cadet_session (struct CadetIncomingSession *s);
-
-
 /**
  * Destroy session state, we are done with it.
  *
@@ -343,31 +215,18 @@ destroy_cadet_session (struct CadetIncomingSession *s);
 static void
 destroy_service_session (struct BobServiceSession *s)
 {
-  struct CadetIncomingSession *in;
   unsigned int i;
 
   if (GNUNET_YES == s->in_destroy)
     return;
   s->in_destroy = GNUNET_YES;
-  if (NULL != (in = s->cadet))
-  {
-    s->cadet = NULL;
-    destroy_cadet_session (in);
-  }
-  if (NULL != s->client_mq)
-  {
-    GNUNET_MQ_destroy (s->client_mq);
-    s->client_mq = NULL;
-  }
   if (NULL != s->client)
   {
-    GNUNET_SERVER_client_disconnect (s->client);
+    struct GNUNET_SERVICE_Client *c = s->client;
+
     s->client = NULL;
+    GNUNET_SERVICE_client_drop (c);
   }
-  GNUNET_assert (GNUNET_YES ==
-                 GNUNET_CONTAINER_multihashmap_remove (client_sessions,
-                                                       &s->session_id,
-                                                       s));
   if (NULL != s->intersected_elements)
   {
     GNUNET_CONTAINER_multihashmap_iterate (s->intersected_elements,
@@ -386,11 +245,6 @@ destroy_service_session (struct BobServiceSession *s)
     GNUNET_SET_destroy (s->intersection_set);
     s->intersection_set = NULL;
   }
-  if (NULL != s->e_a)
-  {
-    GNUNET_free (s->e_a);
-    s->e_a = NULL;
-  }
   if (NULL != s->sorted_elements)
   {
     for (i=0;i<s->used_element_count;i++)
@@ -398,62 +252,27 @@ destroy_service_session (struct BobServiceSession *s)
     GNUNET_free (s->sorted_elements);
     s->sorted_elements = NULL;
   }
-  if (NULL != s->r)
+  if (NULL != s->prod_g_i_b_i)
   {
-    GNUNET_free (s->r);
-    s->r = NULL;
+    gcry_mpi_point_release (s->prod_g_i_b_i);
+    s->prod_g_i_b_i = NULL;
   }
-  if (NULL != s->r_prime)
+  if (NULL != s->prod_h_i_b_i)
   {
-    GNUNET_free (s->r_prime);
-    s->r_prime = NULL;
+    gcry_mpi_point_release (s->prod_h_i_b_i);
+    s->prod_h_i_b_i = NULL;
   }
-  if (NULL != s->product)
+  if (NULL != s->port)
   {
-    gcry_mpi_release (s->product);
-    s->product = NULL;
+    GNUNET_CADET_close_port (s->port);
+    s->port = NULL;
   }
-  GNUNET_free (s);
-}
-
-
-/**
- * Destroy incoming CADET session state, we are done with it.
- *
- * @param in the session to free elements from
- */
-static void
-destroy_cadet_session (struct CadetIncomingSession *in)
-{
-  struct BobServiceSession *s;
-
-  if (GNUNET_YES == in->in_destroy)
-    return;
-  in->in_destroy = GNUNET_YES;
-  if (NULL != (s = in->s))
-  {
-    in->s = NULL;
-    destroy_service_session (s);
-  }
-  if (GNUNET_YES == in->in_map)
-  {
-    GNUNET_assert (GNUNET_YES ==
-                   GNUNET_CONTAINER_multihashmap_remove (cadet_sessions,
-                                                         &in->session_id,
-                                                         in));
-    in->in_map = GNUNET_NO;
-  }
-  if (NULL != in->cadet_mq)
+  if (NULL != s->channel)
   {
-    GNUNET_MQ_destroy (in->cadet_mq);
-    in->cadet_mq = NULL;
+    GNUNET_CADET_channel_destroy (s->channel);
+    s->channel = NULL;
   }
-  if (NULL != in->channel)
-  {
-    GNUNET_CADET_channel_destroy (in->channel);
-    in->channel = NULL;
-  }
-  GNUNET_free (in);
+  GNUNET_free (s);
 }
 
 
@@ -470,6 +289,8 @@ prepare_client_end_notification (struct BobServiceSession *session)
   struct ClientResponseMessage *msg;
   struct GNUNET_MQ_Envelope *e;
 
+  if (NULL == session->client_mq)
+    return; /* no client left to be notified */
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Sending session-end notification with status %d to client for session %s\n",
               session->status,
@@ -490,38 +311,28 @@ prepare_client_end_notification (struct BobServiceSession *session)
  *
  * It must NOT call #GNUNET_CADET_channel_destroy() on the channel.
  *
- * @param cls closure (set from #GNUNET_CADET_connect())
+ * @param cls the `struct BobServiceSession`
  * @param channel connection to the other end (henceforth invalid)
  * @param channel_ctx place where local state associated
  *                   with the channel is stored
  */
 static void
 cb_channel_destruction (void *cls,
-                        const struct GNUNET_CADET_Channel *channel,
-                        void *channel_ctx)
+                        const struct GNUNET_CADET_Channel *channel)
 {
-  struct CadetIncomingSession *in = channel_ctx;
-  struct BobServiceSession *s;
+  struct BobServiceSession *s = cls;
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Peer disconnected, terminating session %s with peer %s\n",
-              GNUNET_h2s (&in->session_id),
-              GNUNET_i2s (&in->peer));
-  if (NULL != in->cadet_mq)
-  {
-    GNUNET_MQ_destroy (in->cadet_mq);
-    in->cadet_mq = NULL;
-  }
-  in->channel = NULL;
-  if (NULL != (s = in->s))
+              GNUNET_h2s (&s->session_id),
+              GNUNET_i2s (&s->peer));
+  s->channel = NULL;
+  if (GNUNET_SCALARPRODUCT_STATUS_ACTIVE == s->status)
   {
-    if (GNUNET_SCALARPRODUCT_STATUS_ACTIVE == s->status)
-    {
-      s->status = GNUNET_SCALARPRODUCT_STATUS_FAILURE;
-      prepare_client_end_notification (s);
-    }
+    s->status = GNUNET_SCALARPRODUCT_STATUS_FAILURE;
+    prepare_client_end_notification (s);
   }
-  destroy_cadet_session (in);
+  destroy_service_session (s);
 }
 
 
@@ -540,306 +351,34 @@ bob_cadet_done_cb (void *cls)
 
 
 /**
- * Maximum count of elements we can put into a multipart message
- */
-#define ELEMENT_CAPACITY ((GNUNET_CONSTANTS_MAX_CADET_MESSAGE_SIZE - 1 - sizeof (struct BobCryptodataMultipartMessage)) / sizeof (struct GNUNET_CRYPTO_PaillierCiphertext))
-
-
-/**
- * Send a multipart chunk of a service response from Bob to Alice.
- * This element only contains the two permutations of R, R'.
- *
- * @param s the associated service session
- */
-static void
-transmit_bobs_cryptodata_message_multipart (struct BobServiceSession *s)
-{
-  struct GNUNET_CRYPTO_PaillierCiphertext *payload;
-  struct BobCryptodataMultipartMessage *msg;
-  struct GNUNET_MQ_Envelope *e;
-  unsigned int i;
-  unsigned int j;
-  uint32_t todo_count;
-
-  while (s->cadet_transmitted_element_count != s->used_element_count)
-  {
-    todo_count = s->used_element_count - s->cadet_transmitted_element_count;
-    if (todo_count > ELEMENT_CAPACITY / 2)
-      todo_count = ELEMENT_CAPACITY / 2;
-
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                "Sending %u additional crypto values to Alice\n",
-                (unsigned int) todo_count);
-    e = GNUNET_MQ_msg_extra (msg,
-                             todo_count * sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) * 2,
-                             GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_CRYPTODATA_MULTIPART);
-    msg->contained_element_count = htonl (todo_count);
-    payload = (struct GNUNET_CRYPTO_PaillierCiphertext *) &msg[1];
-    for (i = s->cadet_transmitted_element_count, j = 0; i < s->cadet_transmitted_element_count + todo_count; i++)
-    {
-      //r[i][p] and r[i][q]
-      memcpy (&payload[j++],
-              &s->r[i],
-              sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-      memcpy (&payload[j++],
-              &s->r_prime[i],
-              sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-    }
-    s->cadet_transmitted_element_count += todo_count;
-    if (s->cadet_transmitted_element_count == s->used_element_count)
-      GNUNET_MQ_notify_sent (e,
-                             &bob_cadet_done_cb,
-                             s);
-    GNUNET_MQ_send (s->cadet->cadet_mq,
-                    e);
-  }
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "All values queued for Alice, Bob is done\n");
-}
-
-
-/**
- * Bob generates the response message to be sent to Alice after
- * computing the values (1), (2), S and S'.
- *
- *  (1)[]: $E_A(a_{pi(i)}) times E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
- *  (2)[]: $E_A(a_{pi'(i)}) times E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
- *      S: $S := E_A(sum (r_i + b_i)^2)$
- *     S': $S' := E_A(sum r_i^2)$
+ * Bob generates the response message to be sent to Alice.
  *
  * @param s the associated requesting session with Alice
  */
 static void
 transmit_bobs_cryptodata_message (struct BobServiceSession *s)
 {
-  struct BobCryptodataMessage *msg;
+  struct EccBobCryptodataMessage *msg;
   struct GNUNET_MQ_Envelope *e;
-  struct GNUNET_CRYPTO_PaillierCiphertext *payload;
-  unsigned int i;
-
-  s->cadet_transmitted_element_count
-    = ((GNUNET_CONSTANTS_MAX_CADET_MESSAGE_SIZE - 1 - sizeof (struct BobCryptodataMessage))
-       / sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) / 2) - 1;
-  if (s->cadet_transmitted_element_count > s->used_element_count)
-    s->cadet_transmitted_element_count = s->used_element_count;
-
-  e = GNUNET_MQ_msg_extra (msg,
-                           (2 + s->cadet_transmitted_element_count * 2)
-                           * sizeof (struct GNUNET_CRYPTO_PaillierCiphertext),
-                           GNUNET_MESSAGE_TYPE_SCALARPRODUCT_BOB_CRYPTODATA);
-  msg->contained_element_count = htonl (s->cadet_transmitted_element_count);
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Sending %u/%u crypto values to Alice\n",
-              (unsigned int) s->cadet_transmitted_element_count,
-              (unsigned int) s->used_element_count);
-
-  payload = (struct GNUNET_CRYPTO_PaillierCiphertext *) &msg[1];
-  memcpy (&payload[0],
-          &s->s,
-          sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-  memcpy (&payload[1],
-          &s->s_prime,
-          sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-
-  payload = &payload[2];
-  // convert k[][]
-  for (i = 0; i < s->cadet_transmitted_element_count; i++)
-  {
-    //k[i][p] and k[i][q]
-    memcpy (&payload[i * 2],
-            &s->r[i],
-            sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-    memcpy (&payload[i * 2 + 1],
-            &s->r_prime[i],
-            sizeof (struct GNUNET_CRYPTO_PaillierCiphertext));
-  }
-  if (s->cadet_transmitted_element_count == s->used_element_count)
-    GNUNET_MQ_notify_sent (e,
-                           &bob_cadet_done_cb,
-                           s);
-  GNUNET_MQ_send (s->cadet->cadet_mq,
+              "Sending response to Alice\n");
+  e = GNUNET_MQ_msg (msg,
+                     GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ECC_BOB_CRYPTODATA);
+  msg->contained_element_count = htonl (2);
+  if (NULL != s->prod_g_i_b_i)
+    GNUNET_CRYPTO_ecc_point_to_bin (edc,
+                                    s->prod_g_i_b_i,
+                                    &msg->prod_g_i_b_i);
+  if (NULL != s->prod_h_i_b_i)
+    GNUNET_CRYPTO_ecc_point_to_bin (edc,
+                                    s->prod_h_i_b_i,
+                                    &msg->prod_h_i_b_i);
+  GNUNET_MQ_notify_sent (e,
+                         &bob_cadet_done_cb,
+                         s);
+  GNUNET_MQ_send (s->cadet_mq,
                   e);
-  transmit_bobs_cryptodata_message_multipart (s);
-}
-#undef ELEMENT_CAPACITY
-
-
-/**
- * Computes the square sum over a vector of a given length.
- *
- * @param vector the vector to compute over
- * @param length the length of the vector
- * @return an MPI value containing the calculated sum, never NULL
- * TODO: code duplication with Alice!
- */
-static gcry_mpi_t
-compute_square_sum (const gcry_mpi_t *vector,
-                    uint32_t length)
-{
-  gcry_mpi_t elem;
-  gcry_mpi_t sum;
-  uint32_t i;
-
-  GNUNET_assert (NULL != (sum = gcry_mpi_new (0)));
-  GNUNET_assert (NULL != (elem = gcry_mpi_new (0)));
-  for (i = 0; i < length; i++)
-  {
-    gcry_mpi_mul (elem, vector[i], vector[i]);
-    gcry_mpi_add (sum, sum, elem);
-  }
-  gcry_mpi_release (elem);
-  return sum;
-}
-
-
-/**
- * Compute the values
- *  (1)[]: $E_A(a_{pi(i)}) otimes E_A(- r_{pi(i)} - b_{pi(i)}) &= E_A(a_{pi(i)} - r_{pi(i)} - b_{pi(i)})$
- *  (2)[]: $E_A(a_{pi'(i)}) otimes E_A(- r_{pi'(i)}) &= E_A(a_{pi'(i)} - r_{pi'(i)})$
- *      S: $S := E_A(sum (r_i + b_i)^2)$
- *     S': $S' := E_A(sum r_i^2)$
- *
- * @param request the requesting session + bob's requesting peer
- * @return #GNUNET_OK on success
- */
-static int
-compute_service_response (struct BobServiceSession *session)
-{
-  uint32_t i;
-  unsigned int *p;
-  unsigned int *q;
-  uint32_t count;
-  gcry_mpi_t *rand;
-  gcry_mpi_t tmp;
-  const struct MpiElement *b;
-  struct GNUNET_CRYPTO_PaillierCiphertext *a;
-  struct GNUNET_CRYPTO_PaillierCiphertext *r;
-  struct GNUNET_CRYPTO_PaillierCiphertext *r_prime;
-
-  count = session->used_element_count;
-  a = session->e_a;
-  b = session->sorted_elements;
-  q = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK,
-                                    count);
-  p = GNUNET_CRYPTO_random_permute (GNUNET_CRYPTO_QUALITY_WEAK,
-                                    count);
-  rand = GNUNET_malloc (sizeof (gcry_mpi_t) * count);
-  for (i = 0; i < count; i++)
-    GNUNET_assert (NULL != (rand[i] = gcry_mpi_new (0)));
-  r = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) * count);
-  r_prime = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) * count);
-
-  for (i = 0; i < count; i++)
-  {
-    int32_t svalue;
-
-    svalue = (int32_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
-                                                 UINT32_MAX);
-    // long to gcry_mpi_t
-    if (svalue < 0)
-      gcry_mpi_sub_ui (rand[i],
-                       rand[i],
-                       - svalue);
-    else
-      rand[i] = gcry_mpi_set_ui (rand[i], svalue);
-  }
-
-  tmp = gcry_mpi_new (0);
-  // encrypt the element
-  // for the sake of readability I decided to have dedicated permutation
-  // vectors, which get rid of all the lookups in p/q.
-  // however, ap/aq are not absolutely necessary but are just abstraction
-  // Calculate Kp = E(S + a_pi) (+) E(S - r_pi - b_pi)
-  for (i = 0; i < count; i++)
-  {
-    // E(S - r_pi - b_pi)
-    gcry_mpi_sub (tmp, my_offset, rand[p[i]]);
-    gcry_mpi_sub (tmp, tmp, b[p[i]].value);
-    GNUNET_assert (2 ==
-                   GNUNET_CRYPTO_paillier_encrypt (&session->cadet->remote_pubkey,
-                                                   tmp,
-                                                   2,
-                                                   &r[i]));
-
-    // E(S - r_pi - b_pi) * E(S + a_pi) ==  E(2*S + a - r - b)
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_paillier_hom_add (&session->cadet->remote_pubkey,
-                                        &r[i],
-                                        &a[p[i]],
-                                        &r[i]))
-    {
-      GNUNET_break_op (0);
-      goto error_cleanup;
-    }
-  }
-
-  // Calculate Kq = E(S + a_qi) (+) E(S - r_qi)
-  for (i = 0; i < count; i++)
-  {
-    // E(S - r_qi)
-    gcry_mpi_sub (tmp, my_offset, rand[q[i]]);
-    GNUNET_assert (2 ==
-                   GNUNET_CRYPTO_paillier_encrypt (&session->cadet->remote_pubkey,
-                                                   tmp,
-                                                   2,
-                                                   &r_prime[i]));
-
-    // E(S - r_qi) * E(S + a_qi) == E(2*S + a_qi - r_qi)
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_paillier_hom_add (&session->cadet->remote_pubkey,
-                                        &r_prime[i],
-                                        &a[q[i]],
-                                        &r_prime[i]))
-    {
-      GNUNET_break_op (0);
-      goto error_cleanup;
-    }
-  }
-  gcry_mpi_release (tmp);
-
-  // Calculate S' =  E(SUM( r_i^2 ))
-  tmp = compute_square_sum (rand, count);
-  GNUNET_assert (1 ==
-                 GNUNET_CRYPTO_paillier_encrypt (&session->cadet->remote_pubkey,
-                                                 tmp,
-                                                 1,
-                                                 &session->s_prime));
-  gcry_mpi_release (tmp);
-
-  // Calculate S = E(SUM( (r_i + b_i)^2 ))
-  for (i = 0; i < count; i++)
-    gcry_mpi_add (rand[i], rand[i], b[i].value);
-  tmp = compute_square_sum (rand, count);
-  GNUNET_assert (1 ==
-                 GNUNET_CRYPTO_paillier_encrypt (&session->cadet->remote_pubkey,
-                                                 tmp,
-                                                 1,
-                                                 &session->s));
-  gcry_mpi_release (tmp);
-
-  session->r = r;
-  session->r_prime = r_prime;
-
-  for (i = 0; i < count; i++)
-    gcry_mpi_release (rand[i]);
-  GNUNET_free (session->e_a);
-  session->e_a = NULL;
-  GNUNET_free (p);
-  GNUNET_free (q);
-  GNUNET_free (rand);
-  return GNUNET_OK;
-
- error_cleanup:
-  GNUNET_free (r);
-  GNUNET_free (r_prime);
-  gcry_mpi_release (tmp);
-  GNUNET_free (p);
-  GNUNET_free (q);
-  for (i = 0; i < count; i++)
-    gcry_mpi_release (rand[i]);
-  GNUNET_free (rand);
-  return GNUNET_SYSERR;
 }
 
 
@@ -896,93 +435,36 @@ element_cmp (const void *a,
 
 
 /**
- * Intersection operation and receiving data via CADET from
- * Alice are both done, compute and transmit our reply via
- * CADET.
- *
- * @param s session to transmit reply for.
- */
-static void
-transmit_cryptographic_reply (struct BobServiceSession *s)
-{
-  struct GNUNET_CADET_Channel *channel;
-
-  /* TODO: code duplication with Alice! */
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Received everything, building reply for Alice\n");
-  s->sorted_elements
-    = GNUNET_malloc (GNUNET_CONTAINER_multihashmap_size (s->intersected_elements) *
-                     sizeof (struct MpiElement));
-  s->used_element_count = 0;
-  GNUNET_CONTAINER_multihashmap_iterate (s->intersected_elements,
-                                         &copy_element_cb,
-                                         s);
-  qsort (s->sorted_elements,
-         s->used_element_count,
-         sizeof (struct MpiElement),
-         &element_cmp);
-  if (GNUNET_OK !=
-      compute_service_response (s))
-  {
-    channel = s->cadet->channel;
-    s->cadet->channel = NULL;
-    GNUNET_CADET_channel_destroy (channel);
-    return;
-  }
-  transmit_bobs_cryptodata_message (s);
-}
-
-
-/**
- * Handle a multipart-chunk of a request from another service to
+ * Check a multipart-chunk of a request from another service to
  * calculate a scalarproduct with us.
  *
  * @param cls closure (set from #GNUNET_CADET_connect)
- * @param channel connection to the other end
- * @param channel_ctx place to store local state associated with the @a channel
- * @param message the actual message
+ * @param msg the actual message
  * @return #GNUNET_OK to keep the connection open,
  *         #GNUNET_SYSERR to close it (signal serious error)
  */
 static int
-handle_alices_cryptodata_message (void *cls,
-                                  struct GNUNET_CADET_Channel *channel,
-                                  void **channel_ctx,
-                                  const struct GNUNET_MessageHeader *message)
+check_alices_cryptodata_message (void *cls,
+                                 const struct EccAliceCryptodataMessage *msg)
 {
-  struct CadetIncomingSession *in = *channel_ctx;
-  struct BobServiceSession *s;
-  const struct AliceCryptodataMessage *msg;
-  const struct GNUNET_CRYPTO_PaillierCiphertext *payload;
+  struct BobServiceSession *s = cls;
   uint32_t contained_elements;
   size_t msg_length;
   uint16_t msize;
   unsigned int max;
 
-  if (NULL == in)
+  msize = ntohs (msg->header.size);
+  if (msize <= sizeof (struct EccAliceCryptodataMessage))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
   }
-  s = in->s;
-  if (NULL == s)
-  {
-    GNUNET_break_op (0);
-    return GNUNET_SYSERR;
-  }
-  msize = ntohs (message->size);
-  if (msize <= sizeof (struct AliceCryptodataMessage))
-  {
-    GNUNET_break_op (0);
-    return GNUNET_SYSERR;
-  }
-  msg = (const struct AliceCryptodataMessage *) message;
   contained_elements = ntohl (msg->contained_element_count);
   /* Our intersection may still be ongoing, but this is nevertheless
      an upper bound on the required array size */
   max = GNUNET_CONTAINER_multihashmap_size (s->intersected_elements);
-  msg_length = sizeof (struct AliceCryptodataMessage)
-    + contained_elements * sizeof (struct GNUNET_CRYPTO_PaillierCiphertext);
+  msg_length = sizeof (struct EccAliceCryptodataMessage)
+    + contained_elements * sizeof (struct GNUNET_CRYPTO_EccPoint) * 2;
   if ( (msize != msg_length) ||
        (0 == contained_elements) ||
        (contained_elements > UINT16_MAX) ||
@@ -991,29 +473,104 @@ handle_alices_cryptodata_message (void *cls,
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
   }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle a multipart-chunk of a request from another service to
+ * calculate a scalarproduct with us.
+ *
+ * @param cls closure (set from #GNUNET_CADET_connect)
+ * @param msg the actual message
+ */
+static void
+handle_alices_cryptodata_message (void *cls,
+                                  const struct EccAliceCryptodataMessage *msg)
+{
+  struct BobServiceSession *s = cls;
+  const struct GNUNET_CRYPTO_EccPoint *payload;
+  uint32_t contained_elements;
+  unsigned int max;
+  unsigned int i;
+  const struct MpiElement *b_i;
+  gcry_mpi_point_t tmp;
+  gcry_mpi_point_t g_i;
+  gcry_mpi_point_t h_i;
+  gcry_mpi_point_t g_i_b_i;
+  gcry_mpi_point_t h_i_b_i;
+
+  contained_elements = ntohl (msg->contained_element_count);
+  max = GNUNET_CONTAINER_multihashmap_size (s->intersected_elements);
+  /* sort our vector for the computation */
+  if (NULL == s->sorted_elements)
+  {
+    s->sorted_elements
+      = GNUNET_new_array (GNUNET_CONTAINER_multihashmap_size (s->intersected_elements),
+                          struct MpiElement);
+    s->used_element_count = 0;
+    GNUNET_CONTAINER_multihashmap_iterate (s->intersected_elements,
+                                           &copy_element_cb,
+                                           s);
+    qsort (s->sorted_elements,
+           s->used_element_count,
+           sizeof (struct MpiElement),
+           &element_cmp);
+  }
+
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Received %u crypto values from Alice\n",
               (unsigned int) contained_elements);
+  payload = (const struct GNUNET_CRYPTO_EccPoint *) &msg[1];
 
-  payload = (const struct GNUNET_CRYPTO_PaillierCiphertext *) &msg[1];
-  if (NULL == s->e_a)
-    s->e_a = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) *
-                            max);
-  memcpy (&s->e_a[s->cadet_received_element_count],
-          payload,
-          sizeof (struct GNUNET_CRYPTO_PaillierCiphertext) * contained_elements);
+  for (i=0;i<contained_elements;i++)
+  {
+    b_i = &s->sorted_elements[i + s->cadet_received_element_count];
+    g_i = GNUNET_CRYPTO_ecc_bin_to_point (edc,
+                                          &payload[i * 2]);
+    g_i_b_i = GNUNET_CRYPTO_ecc_pmul_mpi (edc,
+                                          g_i,
+                                          b_i->value);
+    gcry_mpi_point_release (g_i);
+    h_i = GNUNET_CRYPTO_ecc_bin_to_point (edc,
+                                          &payload[i * 2 + 1]);
+    h_i_b_i = GNUNET_CRYPTO_ecc_pmul_mpi (edc,
+                                          h_i,
+                                          b_i->value);
+    gcry_mpi_point_release (h_i);
+    if (0 == i + s->cadet_received_element_count)
+    {
+      /* first iteration, nothing to add */
+      s->prod_g_i_b_i = g_i_b_i;
+      s->prod_h_i_b_i = h_i_b_i;
+    }
+    else
+    {
+      /* further iterations, cummulate resulting value */
+      tmp = GNUNET_CRYPTO_ecc_add (edc,
+                                   s->prod_g_i_b_i,
+                                   g_i_b_i);
+      gcry_mpi_point_release (s->prod_g_i_b_i);
+      gcry_mpi_point_release (g_i_b_i);
+      s->prod_g_i_b_i = tmp;
+      tmp = GNUNET_CRYPTO_ecc_add (edc,
+                                   s->prod_h_i_b_i,
+                                   h_i_b_i);
+      gcry_mpi_point_release (s->prod_h_i_b_i);
+      gcry_mpi_point_release (h_i_b_i);
+      s->prod_h_i_b_i = tmp;
+    }
+  }
   s->cadet_received_element_count += contained_elements;
-
   if ( (s->cadet_received_element_count == max) &&
        (NULL == s->intersection_op) )
   {
     /* intersection has finished also on our side, and
        we got the full set, so we can proceed with the
        CADET response(s) */
-    transmit_cryptographic_reply (s);
+    transmit_bobs_cryptodata_message (s);
   }
-  GNUNET_CADET_receive_done (s->cadet->channel);
-  return GNUNET_OK;
+  GNUNET_CADET_receive_done (s->channel);
 }
 
 
@@ -1023,11 +580,13 @@ handle_alices_cryptodata_message (void *cls,
  *
  * @param cls closure with the `struct BobServiceSession`
  * @param element a result element, only valid if status is #GNUNET_SET_STATUS_OK
+ * @param current_size current set size
  * @param status what has happened with the set intersection?
  */
 static void
 cb_intersection_element_removed (void *cls,
                                  const struct GNUNET_SET_Element *element,
+                                 uint64_t current_size,
                                  enum GNUNET_SET_Status status)
 {
   struct BobServiceSession *s = cls;
@@ -1053,7 +612,7 @@ cb_intersection_element_removed (void *cls,
   case GNUNET_SET_STATUS_DONE:
     s->intersection_op = NULL;
     GNUNET_break (NULL == s->intersection_set);
-    GNUNET_CADET_receive_done (s->cadet->channel);
+    GNUNET_CADET_receive_done (s->channel);
     LOG (GNUNET_ERROR_TYPE_DEBUG,
          "Finished intersection, %d items remain\n",
          GNUNET_CONTAINER_multihashmap_size (s->intersected_elements));
@@ -1062,7 +621,7 @@ cb_intersection_element_removed (void *cls,
     {
       /* CADET transmission from Alice is also already done,
          start with our own reply */
-      transmit_cryptographic_reply (s);
+      transmit_bobs_cryptodata_message (s);
     }
     return;
   case GNUNET_SET_STATUS_HALF_DONE:
@@ -1098,16 +657,22 @@ cb_intersection_element_removed (void *cls,
 static void
 start_intersection (struct BobServiceSession *s)
 {
+  struct GNUNET_HashCode set_sid;
+
+  GNUNET_CRYPTO_hash (&s->session_id,
+                      sizeof (struct GNUNET_HashCode),
+                      &set_sid);
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Got session with key %s and %u elements, starting intersection.\n",
               GNUNET_h2s (&s->session_id),
               (unsigned int) s->total);
 
   s->intersection_op
-    = GNUNET_SET_prepare (&s->cadet->peer,
-                          &s->session_id,
+    = GNUNET_SET_prepare (&s->peer,
+                          &set_sid,
                           NULL,
                           GNUNET_SET_RESULT_REMOVED,
+                          (struct GNUNET_SET_Option[]) {{ 0 }},
                           &cb_intersection_element_removed,
                           s);
   if (GNUNET_OK !=
@@ -1128,59 +693,24 @@ start_intersection (struct BobServiceSession *s)
  * Handle a request from Alice to calculate a scalarproduct with us (Bob).
  *
  * @param cls closure (set from #GNUNET_CADET_connect)
- * @param channel connection to the other end
- * @param channel_ctx place to store the `struct CadetIncomingSession *`
- * @param message the actual message
- * @return #GNUNET_OK to keep the connection open,
- *         #GNUNET_SYSERR to close it (signal serious error)
+ * @param msg the actual message
  */
-static int
+static void
 handle_alices_computation_request (void *cls,
-                                   struct GNUNET_CADET_Channel *channel,
-                                   void **channel_ctx,
-                                   const struct GNUNET_MessageHeader *message)
+                                   const struct EccServiceRequestMessage *msg)
 {
-  struct CadetIncomingSession *in = *channel_ctx;
-  struct BobServiceSession *s;
-  const struct ServiceRequestMessage *msg;
+  struct BobServiceSession *s = cls;
 
-  if (ntohs (message->size) != sizeof (struct ServiceRequestMessage))
+  s->session_id = msg->session_id; // ??
+  if (s->client_received_element_count < s->total)
   {
-    GNUNET_break_op (0);
-    return GNUNET_SYSERR;
-  }
-  msg = (const struct ServiceRequestMessage *) message;
-  if (GNUNET_YES == in->in_map)
-  {
-    GNUNET_break_op (0);
-    return GNUNET_SYSERR;
-  }
-  if (NULL != find_matching_cadet_session (&msg->session_id))
-  {
-    /* not unique, got one like this already */
-    GNUNET_break_op (0);
-    return GNUNET_SYSERR;
-  }
-  in->session_id = msg->session_id;
-  in->remote_pubkey = msg->public_key;
-  GNUNET_assert (GNUNET_YES ==
-                 GNUNET_CONTAINER_multihashmap_put (cadet_sessions,
-                                                    &in->session_id,
-                                                    in,
-                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
-  s = find_matching_client_session (&in->session_id);
-  if (NULL == s)
-  {
-    /* no client waiting for this request, wait for client */
-    return GNUNET_OK;
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Alice ready, still waiting for Bob client data!\n");
+    return;
   }
-  GNUNET_assert (NULL == s->cadet);
-  /* pair them up */
-  in->s = s;
-  s->cadet = in;
-  if (s->client_received_element_count == s->total)
-    start_intersection (s);
-  return GNUNET_OK;
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Both ready, launching intersection!\n");
+  start_intersection (s);
 }
 
 
@@ -1189,76 +719,47 @@ handle_alices_computation_request (void *cls,
  * preliminary initialization, more happens after we get Alice's first
  * message.
  *
- * @param cls closure
+ * @param cls our `struct BobServiceSession`
  * @param channel new handle to the channel
  * @param initiator peer that started the channel
- * @param port unused
- * @param options unused
  * @return session associated with the channel
  */
 static void *
 cb_channel_incoming (void *cls,
                      struct GNUNET_CADET_Channel *channel,
-                     const struct GNUNET_PeerIdentity *initiator,
-                     uint32_t port,
-                     enum GNUNET_CADET_ChannelOption options)
+                     const struct GNUNET_PeerIdentity *initiator)
 {
-  struct CadetIncomingSession *in;
+  struct BobServiceSession *s = cls;
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "New incoming channel from peer %s.\n",
               GNUNET_i2s (initiator));
-  in = GNUNET_new (struct CadetIncomingSession);
-  in->peer = *initiator;
-  in->channel = channel;
-  in->cadet_mq = GNUNET_CADET_mq_create (in->channel);
-  return in;
+  GNUNET_CADET_close_port (s->port);
+  s->port = NULL;
+  s->peer = *initiator;
+  s->channel = channel;
+  s->cadet_mq = GNUNET_CADET_get_mq (s->channel);
+  return s;
 }
 
 
 /**
- * We're receiving additional set data. Add it to our
- * set and if we are done, initiate the transaction.
+ * We're receiving additional set data. Check it is well-formed.
  *
- * @param cls closure
- * @param client identification of the client
- * @param message the actual message
+ * @param cls identification of the client
+ * @param msg the actual message
+ * @return #GNUNET_OK if @a msg is well-formed
  */
-static void
-GSS_handle_bob_client_message_multipart (void *cls,
-                                         struct GNUNET_SERVER_Client *client,
-                                         const struct GNUNET_MessageHeader *message)
+static int
+check_bob_client_message_multipart (void *cls,
+				    const struct ComputationBobCryptodataMultipartMessage *msg)
 {
-  const struct ComputationBobCryptodataMultipartMessage * msg;
-  struct BobServiceSession *s;
+  struct BobServiceSession *s = cls;
   uint32_t contained_count;
-  const struct GNUNET_SCALARPRODUCT_Element *elements;
-  uint32_t i;
   uint16_t msize;
-  struct GNUNET_SET_Element set_elem;
-  struct GNUNET_SCALARPRODUCT_Element *elem;
 
-  s = GNUNET_SERVER_client_get_user_context (client,
-                                             struct BobServiceSession);
-  if (NULL == s)
-  {
-    /* session needs to already exist */
-    GNUNET_break (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
-  }
-  msize = ntohs (message->size);
-  if (msize < sizeof (struct ComputationBobCryptodataMultipartMessage))
-  {
-    GNUNET_break (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
-  }
-  msg = (const struct ComputationBobCryptodataMultipartMessage *) message;
+  msize = ntohs (msg->header.size);
   contained_count = ntohl (msg->element_count_contained);
-
   if ( (msize != (sizeof (struct ComputationBobCryptodataMultipartMessage) +
                   contained_count * sizeof (struct GNUNET_SCALARPRODUCT_Element))) ||
        (0 == contained_count) ||
@@ -1266,18 +767,38 @@ GSS_handle_bob_client_message_multipart (void *cls,
        (s->total == s->client_received_element_count) ||
        (s->total < s->client_received_element_count + contained_count) )
   {
-    GNUNET_break_op (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
   }
+  return GNUNET_OK;
+}
+
+
+/**
+ * We're receiving additional set data. Add it to our
+ * set and if we are done, initiate the transaction.
+ *
+ * @param cls identification of the client
+ * @param msg the actual message
+ */
+static void
+handle_bob_client_message_multipart (void *cls,
+				     const struct ComputationBobCryptodataMultipartMessage *msg)
+{
+  struct BobServiceSession *s = cls;
+  uint32_t contained_count;
+  const struct GNUNET_SCALARPRODUCT_Element *elements;
+  struct GNUNET_SET_Element set_elem;
+  struct GNUNET_SCALARPRODUCT_Element *elem;
+
+  contained_count = ntohl (msg->element_count_contained);
   elements = (const struct GNUNET_SCALARPRODUCT_Element *) &msg[1];
-  for (i = 0; i < contained_count; i++)
+  for (uint32_t i = 0; i < contained_count; i++)
   {
     elem = GNUNET_new (struct GNUNET_SCALARPRODUCT_Element);
-    memcpy (elem,
-            &elements[i],
-            sizeof (struct GNUNET_SCALARPRODUCT_Element));
+    GNUNET_memcpy (elem,
+		   &elements[i],
+		   sizeof (struct GNUNET_SCALARPRODUCT_Element));
     if (GNUNET_SYSERR ==
         GNUNET_CONTAINER_multihashmap_put (s->intersected_elements,
                                            &elem->key,
@@ -1296,67 +817,50 @@ GSS_handle_bob_client_message_multipart (void *cls,
                             NULL, NULL);
   }
   s->client_received_element_count += contained_count;
-  GNUNET_SERVER_receive_done (client,
-                              GNUNET_OK);
+  GNUNET_SERVICE_client_continue (s->client);
   if (s->total != s->client_received_element_count)
   {
     /* more to come */
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Request still partial, waiting for more client data!\n");
     return;
   }
-  if (NULL == s->cadet)
+  if (NULL == s->channel)
   {
     /* no Alice waiting for this request, wait for Alice */
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Client ready, still waiting for Alice!\n");
     return;
   }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Both ready, launching intersection!\n");
   start_intersection (s);
 }
 
 
 /**
- * Handler for Bob's a client request message.  Bob is in the response
- * role, keep the values + session and waiting for a matching session
- * or process a waiting request from Alice.
+ * Handler for Bob's a client request message.  Check @a msg is
+ * well-formed.
  *
- * @param cls closure
- * @param client identification of the client
- * @param message the actual message
+ * @param cls identification of the client
+ * @param msg the actual message
+ * @return #GNUNET_OK if @a msg is well-formed
  */
-static void
-GSS_handle_bob_client_message (void *cls,
-                               struct GNUNET_SERVER_Client *client,
-                               const struct GNUNET_MessageHeader *message)
+static int
+check_bob_client_message (void *cls,
+			  const struct BobComputationMessage *msg)
 {
-  const struct BobComputationMessage *msg;
-  struct BobServiceSession *s;
-  struct CadetIncomingSession *in;
+  struct BobServiceSession *s = cls;
   uint32_t contained_count;
   uint32_t total_count;
-  const struct GNUNET_SCALARPRODUCT_Element *elements;
-  uint32_t i;
-  struct GNUNET_SET_Element set_elem;
-  struct GNUNET_SCALARPRODUCT_Element *elem;
   uint16_t msize;
 
-  s = GNUNET_SERVER_client_get_user_context (client,
-                                             struct BobServiceSession);
-  if (NULL != s)
-  {
-    /* only one concurrent session per client connection allowed,
-       simplifies logic a lot... */
-    GNUNET_break (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
-  }
-  msize = ntohs (message->size);
-  if (msize < sizeof (struct BobComputationMessage))
+  if (GNUNET_SCALARPRODUCT_STATUS_INIT != s->status)
   {
     GNUNET_break (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
+    return GNUNET_SYSERR;
   }
-  msg = (const struct BobComputationMessage *) message;
+  msize = ntohs (msg->header.size);
   total_count = ntohl (msg->element_count_total);
   contained_count = ntohl (msg->element_count_contained);
   if ( (0 == total_count) ||
@@ -1366,41 +870,62 @@ GSS_handle_bob_client_message (void *cls,
                   contained_count * sizeof (struct GNUNET_SCALARPRODUCT_Element))) )
   {
     GNUNET_break_op (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
-  }
-  if (NULL != find_matching_client_session (&msg->session_key))
-  {
-    GNUNET_break (0);
-    GNUNET_SERVER_receive_done (client,
-                                GNUNET_SYSERR);
-    return;
+    return GNUNET_SYSERR;
   }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handler for Bob's a client request message.  Bob is in the response
+ * role, keep the values + session and waiting for a matching session
+ * or process a waiting request from Alice.
+ *
+ * @param cls identification of the client
+ * @param msg the actual message
+ */
+static void
+handle_bob_client_message (void *cls,
+			   const struct BobComputationMessage *msg)
+{
+  struct BobServiceSession *s = cls;
+  struct GNUNET_MQ_MessageHandler cadet_handlers[] = {
+    GNUNET_MQ_hd_fixed_size (alices_computation_request,
+                             GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ECC_SESSION_INITIALIZATION,
+                             struct EccServiceRequestMessage,
+                             s),
+    GNUNET_MQ_hd_var_size (alices_cryptodata_message,
+                           GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ECC_ALICE_CRYPTODATA,
+                           struct EccAliceCryptodataMessage,
+                           s),
+    GNUNET_MQ_handler_end ()
+  };
+  uint32_t contained_count;
+  uint32_t total_count;
+  const struct GNUNET_SCALARPRODUCT_Element *elements;
+  struct GNUNET_SET_Element set_elem;
+  struct GNUNET_SCALARPRODUCT_Element *elem;
+
+  total_count = ntohl (msg->element_count_total);
+  contained_count = ntohl (msg->element_count_contained);
 
-  s = GNUNET_new (struct BobServiceSession);
   s->status = GNUNET_SCALARPRODUCT_STATUS_ACTIVE;
-  s->client = client;
-  s->client_mq = GNUNET_MQ_queue_for_server_client (client);
   s->total = total_count;
   s->client_received_element_count = contained_count;
   s->session_id = msg->session_key;
-  GNUNET_break (GNUNET_YES ==
-                GNUNET_CONTAINER_multihashmap_put (client_sessions,
-                                                   &s->session_id,
-                                                   s,
-                                                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
   elements = (const struct GNUNET_SCALARPRODUCT_Element *) &msg[1];
-  s->intersected_elements = GNUNET_CONTAINER_multihashmap_create (s->total,
-                                                                  GNUNET_YES);
-  s->intersection_set = GNUNET_SET_create (cfg,
-                                           GNUNET_SET_OPERATION_INTERSECTION);
-  for (i = 0; i < contained_count; i++)
+  s->intersected_elements
+    = GNUNET_CONTAINER_multihashmap_create (s->total,
+					    GNUNET_YES);
+  s->intersection_set
+    = GNUNET_SET_create (cfg,
+			 GNUNET_SET_OPERATION_INTERSECTION);
+  for (uint32_t i = 0; i < contained_count; i++)
   {
     if (0 == GNUNET_ntohll (elements[i].value))
       continue;
     elem = GNUNET_new (struct GNUNET_SCALARPRODUCT_Element);
-    memcpy (elem,
+    GNUNET_memcpy (elem,
             &elements[i],
             sizeof (struct GNUNET_SCALARPRODUCT_Element));
     if (GNUNET_SYSERR ==
@@ -1421,26 +946,23 @@ GSS_handle_bob_client_message (void *cls,
                             NULL, NULL);
     s->used_element_count++;
   }
-  GNUNET_SERVER_client_set_user_context (client,
-                                         s);
-  GNUNET_SERVER_receive_done (client,
-                              GNUNET_YES);
-  if (s->total != s->client_received_element_count)
-  {
-    /* multipart msg */
-    return;
-  }
-  in = find_matching_cadet_session (&s->session_id);
-  if (NULL == in)
+  GNUNET_SERVICE_client_continue (s->client);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Received client request, opening port %s!\n",
+              GNUNET_h2s (&msg->session_key));
+  s->port = GNUNET_CADET_open_port (my_cadet,
+                                    &msg->session_key,
+                                    &cb_channel_incoming,
+                                    s,
+                                    NULL,
+                                    &cb_channel_destruction,
+                                    cadet_handlers);
+  if (NULL == s->port)
   {
-    /* nothing yet, wait for Alice */
+    GNUNET_break (0);
+    GNUNET_SERVICE_client_drop (s->client);
     return;
   }
-  GNUNET_assert (NULL == in->s);
-  /* pair them up */
-  in->s = s;
-  s->cadet = in;
-  start_intersection (s);
 }
 
 
@@ -1448,11 +970,9 @@ GSS_handle_bob_client_message (void *cls,
  * Task run during shutdown.
  *
  * @param cls unused
- * @param tc unused
  */
 static void
-shutdown_task (void *cls,
-               const struct GNUNET_SCHEDULER_TaskContext *tc)
+shutdown_task (void *cls)
 {
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Shutting down, initiating cleanup.\n");
@@ -1462,10 +982,35 @@ shutdown_task (void *cls,
     GNUNET_CADET_disconnect (my_cadet);
     my_cadet = NULL;
   }
-  GNUNET_CONTAINER_multihashmap_destroy (client_sessions);
-  client_sessions = NULL;
-  GNUNET_CONTAINER_multihashmap_destroy (cadet_sessions);
-  cadet_sessions = NULL;
+  if (NULL != edc)
+  {
+    GNUNET_CRYPTO_ecc_dlog_release (edc);
+    edc = NULL;
+  }
+}
+
+
+/**
+ * A client connected.
+ *
+ * Setup the associated data structure.
+ *
+ * @param cls closure, NULL
+ * @param client identification of the client
+ * @param mq message queue to communicate with @a client
+ * @return our `struct BobServiceSession`
+ */
+static void *
+client_connect_cb (void *cls,
+		   struct GNUNET_SERVICE_Client *client,
+		   struct GNUNET_MQ_Handle *mq)
+{
+  struct BobServiceSession *s;
+
+  s = GNUNET_new (struct BobServiceSession);
+  s->client = client;
+  s->client_mq = mq;
+  return s;
 }
 
 
@@ -1477,22 +1022,17 @@ shutdown_task (void *cls,
  *
  * @param cls closure, NULL
  * @param client identification of the client
+ * @param app_cls our `struct BobServiceSession`
  */
 static void
-handle_client_disconnect (void *cls,
-                          struct GNUNET_SERVER_Client *client)
+client_disconnect_cb (void *cls,
+		      struct GNUNET_SERVICE_Client *client,
+		      void *app_cls)
 {
-  struct BobServiceSession *s;
+  struct BobServiceSession *s = app_cls;
 
-  if (NULL == client)
-    return;
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Client disconnected from us.\n",
-              client);
-  s = GNUNET_SERVER_client_get_user_context (client,
-                                             struct BobServiceSession);
-  if (NULL == s)
-    return;
+              "Client disconnected from us.\n");
   s->client = NULL;
   destroy_service_session (s);
 }
@@ -1502,62 +1042,21 @@ handle_client_disconnect (void *cls,
  * Initialization of the program and message handlers
  *
  * @param cls closure
- * @param server the initialized server
  * @param c configuration to use
+ * @param service the initialized service
  */
 static void
 run (void *cls,
-     struct GNUNET_SERVER_Handle *server,
-     const struct GNUNET_CONFIGURATION_Handle *c)
+     const struct GNUNET_CONFIGURATION_Handle *c,
+     struct GNUNET_SERVICE_Handle *service)
 {
-  static const struct GNUNET_SERVER_MessageHandler server_handlers[] = {
-    { &GSS_handle_bob_client_message, NULL,
-      GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_BOB,
-      0},
-    { &GSS_handle_bob_client_message_multipart, NULL,
-      GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_MUTLIPART_BOB,
-      0},
-    { NULL, NULL, 0, 0}
-  };
-  static const struct GNUNET_CADET_MessageHandler cadet_handlers[] = {
-    { &handle_alices_computation_request,
-      GNUNET_MESSAGE_TYPE_SCALARPRODUCT_SESSION_INITIALIZATION,
-      sizeof (struct ServiceRequestMessage) },
-    { &handle_alices_cryptodata_message,
-      GNUNET_MESSAGE_TYPE_SCALARPRODUCT_ALICE_CRYPTODATA,
-      0},
-    { NULL, 0, 0}
-  };
-  static const uint32_t ports[] = {
-    GNUNET_APPLICATION_TYPE_SCALARPRODUCT,
-    0
-  };
-
   cfg = c;
-  /*
-    offset has to be sufficiently small to allow computation of:
-    m1+m2 mod n == (S + a) + (S + b) mod n,
-    if we have more complex operations, this factor needs to be lowered */
-  my_offset = gcry_mpi_new (GNUNET_CRYPTO_PAILLIER_BITS / 3);
-  gcry_mpi_set_bit (my_offset,
-                    GNUNET_CRYPTO_PAILLIER_BITS / 3);
-
-  GNUNET_CRYPTO_paillier_create (&my_pubkey,
-                                 &my_privkey);
-  GNUNET_SERVER_add_handlers (server,
-                              server_handlers);
-  GNUNET_SERVER_disconnect_notify (server,
-                                   &handle_client_disconnect,
-                                   NULL);
-  client_sessions = GNUNET_CONTAINER_multihashmap_create (128,
-                                                          GNUNET_YES);
-  cadet_sessions = GNUNET_CONTAINER_multihashmap_create (128,
-                                                         GNUNET_YES);
-  my_cadet = GNUNET_CADET_connect (cfg, NULL,
-                                   &cb_channel_incoming,
-                                   &cb_channel_destruction,
-                                   cadet_handlers,
-                                   ports);
+  /* We don't really do DLOG, so we can setup with very minimal resources */
+  edc = GNUNET_CRYPTO_ecc_dlog_prepare (4 /* max value */,
+                                        2 /* RAM */);
+  my_cadet = GNUNET_CADET_connect (cfg);
+  GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
+				 NULL);
   if (NULL == my_cadet)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
@@ -1565,28 +1064,28 @@ run (void *cls,
     GNUNET_SCHEDULER_shutdown ();
     return;
   }
-  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
-                                &shutdown_task,
-                                NULL);
 }
 
 
 /**
- * The main function for the scalarproduct service.
- *
- * @param argc number of arguments from the command line
- * @param argv command line arguments
- * @return 0 ok, 1 on error
+ * Define "main" method using service macro.
  */
-int
-main (int argc,
-      char *const *argv)
-{
-  return (GNUNET_OK ==
-          GNUNET_SERVICE_run (argc, argv,
-                              "scalarproduct-bob",
-                              GNUNET_SERVICE_OPTION_NONE,
-                              &run, NULL)) ? 0 : 1;
-}
-
-/* end of gnunet-service-scalarproduct_bob.c */
+GNUNET_SERVICE_MAIN
+("scalarproduct-bob",
+ GNUNET_SERVICE_OPTION_NONE,
+ &run,
+ &client_connect_cb,
+ &client_disconnect_cb,
+ NULL,
+ GNUNET_MQ_hd_var_size (bob_client_message,
+			GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_TO_BOB,
+			struct BobComputationMessage,
+			NULL),
+ GNUNET_MQ_hd_var_size (bob_client_message_multipart,
+                        GNUNET_MESSAGE_TYPE_SCALARPRODUCT_CLIENT_MULTIPART_BOB,
+                        struct ComputationBobCryptodataMultipartMessage,
+                        NULL),
+ GNUNET_MQ_handler_end ());
+
+
+/* end of gnunet-service-scalarproduct-ecc_bob.c */