make kappa global fixed constant, not something to be negotiated, KISS

6 files changed, 58 insertions, 79 deletions

diff --git a/src/mint/plugin_mintdb_postgres.c b/src/mint/plugin_mintdb_postgres.c
index 1c6851d86..5a1ff8c0c 100644
--- a/src/mint/plugin_mintdb_postgres.c
+++ b/src/mint/plugin_mintdb_postgres.c
@@ -247,7 +247,7 @@ postgres_create_tables (void *cls,
           // index of the old coin in the customer's request
           ",oldcoin_index INT2 NOT NULL"
           // index for cut and choose,
-          // ranges from 0 to kappa-1
+          // ranges from 0 to #KAPPA-1
           ",cnc_index INT2 NOT NULL"
           ")");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_commit_coin"
@@ -1486,7 +1486,6 @@ postgres_get_refresh_session (void *cls,
   struct TALER_DB_ResultSpec rs[] = {
     TALER_DB_RESULT_SPEC("num_oldcoins", &refresh_session->num_oldcoins),
     TALER_DB_RESULT_SPEC("num_newcoins", &refresh_session->num_newcoins),
-    TALER_DB_RESULT_SPEC("kappa", &refresh_session->kappa),
     TALER_DB_RESULT_SPEC("noreveal_index", &refresh_session->noreveal_index),
     TALER_DB_RESULT_SPEC_END
   };
@@ -1502,7 +1501,6 @@ postgres_get_refresh_session (void *cls,
 
   refresh_session->num_oldcoins = ntohs (refresh_session->num_oldcoins);
   refresh_session->num_newcoins = ntohs (refresh_session->num_newcoins);
-  refresh_session->kappa = ntohs (refresh_session->kappa);
   refresh_session->noreveal_index = ntohs (refresh_session->noreveal_index);
 
   PQclear (result);
diff --git a/src/mint/taler-mint-httpd.h b/src/mint/taler-mint-httpd.h
index 36d150bbc..50b745703 100644
--- a/src/mint/taler-mint-httpd.h
+++ b/src/mint/taler-mint-httpd.h
@@ -26,12 +26,6 @@
 #include <microhttpd.h>
 
 /**
- * Cut-and-choose size for refreshing.
- * FIXME: maybe make it a config option?
- */
-#define KAPPA 3
-
-/**
  * For now, we just do EUR.  Should become configurable
  * in the future!
  */
diff --git a/src/mint/taler-mint-httpd_db.c b/src/mint/taler-mint-httpd_db.c
index c18936e1f..17f44c9c9 100644
--- a/src/mint/taler-mint-httpd_db.c
+++ b/src/mint/taler-mint-httpd_db.c
@@ -591,12 +591,13 @@ refresh_accept_melts (struct MHD_Connection *connection,
  * @param coin_count number of entries in @a coin_public_infos and @a coin_melt_details, size of y-dimension of @commit_link array
  * @param coin_public_infos information about the coins to melt
  * @param coin_melt_details signatures and (residual) value of the respective coin should be melted
- * @param kappa size of x-dimension of @commit_coin and @commit_link arrays
  * @param commit_coin 2d array of coin commitments (what the mint is to sign
- *                    once the "/refres/reveal" of cut and choose is done)
+ *                    once the "/refres/reveal" of cut and choose is done),
+ *                    x-dimension must be #KAPPA
  * @param commit_link 2d array of coin link commitments (what the mint is
  *                    to return via "/refresh/link" to enable linkage in the
  *                    future)
+ *                    x-dimension must be #KAPPA
  * @return MHD result code
  */
 int
@@ -607,7 +608,6 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
                                     unsigned int coin_count,
                                     const struct TALER_CoinPublicInfo *coin_public_infos,
                                     const struct MeltDetails *coin_melt_details,
-                                    unsigned int kappa,
                                     struct RefreshCommitCoin *const* commit_coin,
                                     struct RefreshCommitLink *const* commit_link)
 {
@@ -684,7 +684,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
     return TALER_MINT_reply_internal_db_error (connection);
   }
 
-  for (i = 0; i < kappa; i++)
+  for (i = 0; i < KAPPA; i++)
   {
     if (GNUNET_OK !=
         plugin->insert_refresh_commit_coins (plugin->cls,
@@ -699,7 +699,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
       return TALER_MINT_reply_internal_db_error (connection);
     }
   }
-  for (i = 0; i < kappa; i++)
+  for (i = 0; i < KAPPA; i++)
   {
     if (GNUNET_OK !=
         plugin->insert_refresh_commit_links (plugin->cls,
@@ -719,10 +719,9 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
   /* store 'global' session data */
   refresh_session.num_oldcoins = coin_count;
   refresh_session.num_newcoins = num_new_denoms;
-  refresh_session.kappa = KAPPA; // FIXME... (#3711)
   refresh_session.noreveal_index
     = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_STRONG,
-                                refresh_session.kappa);
+                                KAPPA);
   if (GNUNET_OK !=
       (res = plugin->create_refresh_session (plugin->cls,
                                              session,
@@ -753,7 +752,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
  * Check if the given @a transfer_privs correspond to an honest
  * commitment for the given session.
  * Checks that the transfer private keys match their commitments.
- * Then derives the shared secret for each kappa, and check that they match.
+ * Then derives the shared secret for each #KAPPA, and check that they match.
  *
  * @param connection the MHD connection to handle
  * @param session database connection to use
@@ -946,7 +945,7 @@ check_commitment (struct MHD_Connection *connection,
                        buf_len)) )
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                  "blind envelope does not match for kappa=%u, old=%d\n",
+                  "blind envelope does not match for k=%u, old=%d\n",
                   off,
                   (int) j);
       /* FIXME: return more specific error with original signature (#3712) */
@@ -1025,22 +1024,21 @@ refresh_mint_coin (struct MHD_Connection *connection,
 
 /**
  * Execute a "/refresh/reveal".  The client is revealing to us the
- * transfer keys for @a kappa-1 sets of coins.  Verify that the
+ * transfer keys for @a #KAPPA-1 sets of coins.  Verify that the
  * revealed transfer keys would allow linkage to the blinded coins,
  * and if so, return the signed coins for corresponding to the set of
  * coins that was not chosen.
  *
  * @param connection the MHD connection to handle
  * @param session_hash hash identifying the refresh session
- * @param kappa size of x-dimension of @transfer_privs array plus one (!)
  * @param num_oldcoins size of y-dimension of @transfer_privs array
- * @param transfer_pubs array with the revealed transfer keys
+ * @param transfer_pubs array with the revealed transfer keys,
+ *                      x-dimension must be #KAPPA - 1
  * @return MHD result code
  */
 int
 TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
                                       const struct GNUNET_HashCode *session_hash,
-                                      unsigned int kappa,
                                       unsigned int num_oldcoins,
                                       struct TALER_TransferPrivateKey **transfer_privs)
 {
@@ -1112,7 +1110,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
 
 
   off = 0;
-  for (i=0;i<refresh_session.kappa - 1;i++)
+  for (i=0;i<KAPPA - 1;i++)
   {
     if (i == refresh_session.noreveal_index)
       off = 1;
diff --git a/src/mint/taler-mint-httpd_db.h b/src/mint/taler-mint-httpd_db.h
index ed96bbd4b..b2061850c 100644
--- a/src/mint/taler-mint-httpd_db.h
+++ b/src/mint/taler-mint-httpd_db.h
@@ -113,7 +113,6 @@ struct MeltDetails
  * @param coin_count number of entries in @a coin_public_infos and @ a coin_melt_details, size of y-dimension of @commit_link array
  * @param coin_public_infos information about the coins to melt
  * @param coin_melt_details signatures and (residual) value of the respective coin should be melted
- * @param kappa size of x-dimension of @commit_coin and @commit_link arrays
  * @param commit_coin 2d array of coin commitments (what the mint is to sign
  *                    once the "/refres/reveal" of cut and choose is done)
  * @param commit_link 2d array of coin link commitments (what the mint is
@@ -129,29 +128,26 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
                                     unsigned int coin_count,
                                     const struct TALER_CoinPublicInfo *coin_public_infos,
                                     const struct MeltDetails *coin_melt_details,
-                                    unsigned int kappa,
                                     struct RefreshCommitCoin *const* commit_coin,
                                     struct RefreshCommitLink *const* commit_link);
 
 
 /**
  * Execute a "/refresh/reveal".  The client is revealing to us the
- * transfer keys for @a kappa-1 sets of coins.  Verify that the
+ * transfer keys for #KAPPA-1 sets of coins.  Verify that the
  * revealed transfer keys would allow linkage to the blinded coins,
  * and if so, return the signed coins for corresponding to the set of
  * coins that was not chosen.
  *
  * @param connection the MHD connection to handle
  * @param session_hash hash over the refresh session
- * @param kappa size of x-dimension of @transfer_privs array plus one (!)
  * @param num_oldcoins size of y-dimension of @transfer_privs array
- * @param transfer_pubs array with the revealed transfer keys
+ * @param transfer_pubs array with the revealed transfer keys, #KAPPA is 1st-dimension
  * @return MHD result code
  */
 int
 TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
                                       const struct GNUNET_HashCode *session_hash,
-                                      unsigned int kappa,
                                       unsigned int num_oldcoins,
                                       struct TALER_TransferPrivateKey **transfer_privs);
 
diff --git a/src/mint/taler-mint-httpd_refresh.c b/src/mint/taler-mint-httpd_refresh.c
index 6575f02c9..5fc8fd5b0 100644
--- a/src/mint/taler-mint-httpd_refresh.c
+++ b/src/mint/taler-mint-httpd_refresh.c
@@ -47,7 +47,6 @@
  * @param coin_melt_details array with @a coin_count entries with melting details
  * @param session_hash hash over the data that the client commits to
  * @param commit_client_sig signature of the client over this commitment
- * @param kappa size of x-dimension of @commit_coin and @commit_link arrays
  * @param commit_coin 2d array of coin commitments (what the mint is to sign
  *                    once the "/refres/reveal" of cut and choose is done)
  * @param commit_link 2d array of coin link commitments (what the mint is
@@ -63,7 +62,6 @@ handle_refresh_melt_binary (struct MHD_Connection *connection,
                             struct TALER_CoinPublicInfo *coin_public_infos,
                             const struct MeltDetails *coin_melt_details,
                             const struct GNUNET_HashCode *session_hash,
-                            unsigned int kappa,
                             struct RefreshCommitCoin *const* commit_coin,
                             struct RefreshCommitLink *const* commit_link)
 
@@ -155,7 +153,6 @@ handle_refresh_melt_binary (struct MHD_Connection *connection,
                                              coin_count,
                                              coin_public_infos,
                                              coin_melt_details,
-                                             kappa,
                                              commit_coin,
                                              commit_link);
 }
@@ -359,13 +356,12 @@ free_commit_links (struct RefreshCommitLink **commit_link,
  * @param melt_coins array of coins to melt
  * @param melt_sig_json signature affirming the melt operation
  * @param commit_signature signature over the commit
- * @param kappa security parameter for cut and choose
  * @param num_oldcoins number of coins that are being melted
- * @param transfer_pubs @a kappa-dimensional array of @a num_oldcoins transfer keys
- * @param secret_encs @a kappa-dimensional array of @a num_oldcoins secrets
+ * @param transfer_pubs #KAPPA-dimensional array of @a num_oldcoins transfer keys
+ * @param secret_encs #KAPPA-dimensional array of @a num_oldcoins secrets
  * @param num_newcoins number of coins that the refresh will generate
- * @param coin_envs @a kappa-dimensional array of @a num_newcoins envelopes to sign
- * @param link_encs @a kappa-dimensional array of @a num_newcoins encrypted links
+ * @param coin_envs #KAPPA-dimensional array of @a num_newcoins envelopes to sign
+ * @param link_encs #KAPPA-dimensional array of @a num_newcoins encrypted links
  * @return MHD result code
  */
 static int
@@ -374,7 +370,6 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
                           const json_t *melt_coins,
                           const json_t *melt_sig_json,
                           const json_t *commit_signature,
-                          unsigned int kappa,
                           unsigned int num_oldcoins,
                           const json_t *transfer_pubs,
                           const json_t *secret_encs,
@@ -393,8 +388,8 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
   unsigned int coin_count;
   struct GNUNET_HashCode session_hash;
   struct GNUNET_HashContext *hash_context;
-  struct RefreshCommitCoin *commit_coin[kappa];
-  struct RefreshCommitLink *commit_link[kappa];
+  struct RefreshCommitCoin *commit_coin[KAPPA];
+  struct RefreshCommitLink *commit_link[KAPPA];
 
   /* For the signature check, we hash most of the inputs together
      (except for the signatures on the coins). */
@@ -494,7 +489,7 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
      together for the signature check */
   memset (commit_coin, 0, sizeof (commit_coin));
   memset (commit_link, 0, sizeof (commit_link));
-  for (i = 0; i < kappa; i++)
+  for (i = 0; i < KAPPA; i++)
   {
     commit_coin[i] = GNUNET_malloc (num_newcoins *
                                     sizeof (struct RefreshCommitCoin));
@@ -515,7 +510,9 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       if (GNUNET_OK != res)
       {
         GNUNET_CRYPTO_hash_context_abort (hash_context);
-        free_commit_coins (commit_coin, kappa, num_newcoins);
+        free_commit_coins (commit_coin,
+                           KAPPA,
+                           num_newcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
       GNUNET_CRYPTO_hash_context_read (hash_context,
@@ -531,7 +528,9 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       if (GNUNET_OK != res)
       {
         GNUNET_CRYPTO_hash_context_abort (hash_context);
-        free_commit_coins (commit_coin, kappa, num_newcoins);
+        free_commit_coins (commit_coin,
+                           KAPPA,
+                           num_newcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
       rcc->refresh_link
@@ -543,7 +542,7 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
     }
   }
 
-  for (i = 0; i < kappa; i++)
+  for (i = 0; i < KAPPA; i++)
   {
     commit_link[i] = GNUNET_malloc (num_oldcoins *
                                     sizeof (struct RefreshCommitLink));
@@ -563,8 +562,12 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       {
         GNUNET_break (GNUNET_SYSERR != res);
         GNUNET_CRYPTO_hash_context_abort (hash_context);
-        free_commit_coins (commit_coin, kappa, num_newcoins);
-        free_commit_links (commit_link, kappa, num_oldcoins);
+        free_commit_coins (commit_coin,
+                           KAPPA,
+                           num_newcoins);
+        free_commit_links (commit_link,
+                           KAPPA,
+                           num_oldcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
       res = GNUNET_MINT_parse_navigate_json (connection,
@@ -579,8 +582,12 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       {
         GNUNET_break (GNUNET_SYSERR != res);
         GNUNET_CRYPTO_hash_context_abort (hash_context);
-        free_commit_coins (commit_coin, kappa, num_newcoins);
-        free_commit_links (commit_link, kappa, num_oldcoins);
+        free_commit_coins (commit_coin,
+                           KAPPA,
+                           num_newcoins);
+        free_commit_links (commit_link,
+                           KAPPA,
+                           num_oldcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
 
@@ -615,12 +622,15 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
                                     coin_public_infos,
                                     coin_melt_details,
                                     &session_hash,
-                                    kappa,
                                     commit_coin,
                                     commit_link);
  cleanup:
-  free_commit_coins (commit_coin, kappa, num_newcoins);
-  free_commit_links (commit_link, kappa, num_oldcoins);
+  free_commit_coins (commit_coin,
+                     KAPPA,
+                     num_newcoins);
+  free_commit_links (commit_link,
+                     KAPPA,
+                     num_oldcoins);
   for (j=0;j<coin_count;j++)
   {
     GNUNET_CRYPTO_rsa_public_key_free (coin_public_infos[j].denom_pub.rsa_public_key);
@@ -664,7 +674,6 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
   json_t *transfer_pubs;
   json_t *secret_encs;
   json_t *commit_sig_json;
-  unsigned int kappa;
   unsigned int num_oldcoins;
   unsigned int num_newcoins;
   json_t *coin_detail;
@@ -699,15 +708,14 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
     return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
 
   /* Determine dimensionality of the request (kappa, #old and #new coins) */
-  kappa = json_array_size (coin_evs);
-  if ( (3 > kappa) || (kappa > 32) )
+  if (KAPPA != json_array_size (coin_evs))
   {
     GNUNET_break_op (0);
     TALER_MINT_release_parsed_data (spec);
     return TALER_MINT_reply_arg_invalid (connection,
                                          "coin_evs");
   }
-  if (json_array_size (transfer_pubs) != kappa)
+  if (KAPPA != json_array_size (transfer_pubs))
   {
     GNUNET_break_op (0);
     TALER_MINT_release_parsed_data (spec);
@@ -741,7 +749,6 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
                                   melt_coins,
                                   melt_sig_json,
                                   commit_sig_json,
-                                  kappa,
                                   num_oldcoins,
                                   transfer_pubs,
                                   secret_encs,
@@ -763,7 +770,6 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
  *
  * @param connection the MHD connection to handle
  * @param session_hash hash identifying the melting session
- * @param kappa length of the 1st dimension of @a transfer_privs array PLUS ONE
  * @param num_oldcoins length of the 2nd dimension of @a transfer_privs array
  * @param tp_json private transfer keys in JSON format
  * @return MHD result code
@@ -771,20 +777,19 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
 static int
 handle_refresh_reveal_json (struct MHD_Connection *connection,
                             const struct GNUNET_HashCode *session_hash,
-                            unsigned int kappa,
                             unsigned int num_oldcoins,
                             const json_t *tp_json)
 {
-  struct TALER_TransferPrivateKey *transfer_privs[kappa - 1];
+  struct TALER_TransferPrivateKey *transfer_privs[KAPPA - 1];
   unsigned int i;
   unsigned int j;
   int res;
 
-  for (i = 0; i < kappa - 1; i++)
+  for (i = 0; i < KAPPA - 1; i++)
     transfer_privs[i] = GNUNET_malloc (num_oldcoins *
                                        sizeof (struct TALER_TransferPrivateKey));
   res = GNUNET_OK;
-  for (i = 0; i < kappa - 1; i++)
+  for (i = 0; i < KAPPA - 1; i++)
   {
     if (GNUNET_OK != res)
       break;
@@ -806,10 +811,9 @@ handle_refresh_reveal_json (struct MHD_Connection *connection,
   else
     res = TALER_MINT_db_execute_refresh_reveal (connection,
                                                 session_hash,
-                                                kappa,
                                                 num_oldcoins,
                                                 transfer_privs);
-  for (i = 0; i < kappa - 1; i++)
+  for (i = 0; i < KAPPA - 1; i++)
     GNUNET_free (transfer_privs[i]);
   return res;
 }
@@ -840,7 +844,6 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
 {
   struct GNUNET_HashCode session_hash;
   int res;
-  unsigned int kappa;
   unsigned int num_oldcoins;
   json_t *reveal_detail;
   json_t *root;
@@ -869,15 +872,13 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
     return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
 
   /* Determine dimensionality of the request (kappa and #old coins) */
-  kappa = json_array_size (transfer_privs) + 1;
-  if ( (2 > kappa) || (kappa > 31) )
+  if (KAPPA != json_array_size (transfer_privs) + 1)
   {
     TALER_MINT_release_parsed_data (spec);
     return TALER_MINT_reply_arg_invalid (connection,
                                          "transfer_privs");
   }
   /* Note we do +1 as 1 row (cut-and-choose!) is missing! */
-  kappa++;
   res = GNUNET_MINT_parse_navigate_json (connection,
                                          transfer_privs,
                                          JNAV_INDEX, 0,
@@ -892,7 +893,6 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
   num_oldcoins = json_array_size (reveal_detail);
   res = handle_refresh_reveal_json (connection,
                                     &session_hash,
-                                    kappa,
                                     num_oldcoins,
                                     transfer_privs);
   TALER_MINT_release_parsed_data (spec);
diff --git a/src/mint/taler_mintdb_plugin.h b/src/mint/taler_mintdb_plugin.h
index d461413f1..08a73479d 100644
--- a/src/mint/taler_mintdb_plugin.h
+++ b/src/mint/taler_mintdb_plugin.h
@@ -247,14 +247,7 @@ struct RefreshSession
   uint16_t num_newcoins;
 
   /**
-   * Number of parallel operations we perform for the cut and choose.
-   * (must be greater or equal to three for security).  0 if not yet
-   * known.
-   */
-  uint16_t kappa;
-
-  /**
-   * Index (smaller @e kappa) which the mint has chosen to not
+   * Index (smaller #KAPPA) which the mint has chosen to not
    * have revealed during cut and choose.
    */
   uint16_t noreveal_index;
@@ -297,7 +290,7 @@ struct RefreshMelt
 
 /**
  * We have as many `struct RefreshCommitCoin` as there are new
- * coins being created by the refresh (for each of the kappa
+ * coins being created by the refresh (for each of the #KAPPA
  * sets).  These are the coins we ask the mint to sign if the
  * respective set is selected.
  */
@@ -816,7 +809,7 @@ struct TALER_MINTDB_Plugin
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
    * @param session_hash hash to identify refresh session
-   * @param i set index (1st dimension), relating to kappa
+   * @param i set index (1st dimension), relating to #KAPPA
    * @param num_newcoins coin index size of the @a commit_coins array
    * @param commit_coin array of coin commitments to store
    * @return #GNUNET_OK on success
@@ -861,7 +854,7 @@ struct TALER_MINTDB_Plugin
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
    * @param session_hash hash to identify refresh session
-   * @param i set index (1st dimension), relating to kappa
+   * @param i set index (1st dimension), relating to #KAPPA
    * @param num_links size of the @a commit_link array
    * @param commit_links array of link information to store
    * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success