address #3708: melt_hash => session_hash, use session_hash for DB access, not session_pub

9 files changed, 231 insertions, 225 deletions

diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 0c0ad8865..a7e902777 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -27,6 +27,8 @@
 
 /* ****************** Coin crypto primitives ************* */
 
+GNUNET_NETWORK_STRUCT_BEGIN
+
 /**
  * Type of public keys for Taler reserves.
  */
@@ -269,6 +271,10 @@ struct TALER_CoinSpendSignature
 };
 
 
+GNUNET_NETWORK_STRUCT_END
+
+
+
 /**
  * Type of blinding keys for Taler.
  */
@@ -358,6 +364,9 @@ TALER_test_coin_valid (const struct TALER_CoinPublicInfo *coin_public_info);
 
 /* ****************** Refresh crypto primitives ************* */
 
+
+GNUNET_NETWORK_STRUCT_BEGIN
+
 /**
  * Secret used to decrypt the key to decrypt link secrets.
  */
@@ -397,45 +406,48 @@ struct TALER_EncryptedLinkSecret
 
 
 /**
- * Representation of an encrypted refresh link.
+ * Representation of an refresh link in cleartext.
  */
-struct TALER_RefreshLinkEncrypted
+struct TALER_RefreshLinkDecrypted
 {
 
   /**
-   * Encrypted blinding key with @e blinding_key_enc_size bytes,
-   * must be allocated at the end of this struct.
-   */
-  const char *blinding_key_enc;
-
-  /**
-   * Number of bytes in @e blinding_key_enc.
+   * Private key of the coin.
    */
-  size_t blinding_key_enc_size;
+  struct TALER_CoinSpendPrivateKey coin_priv;
 
   /**
-   * Encrypted private key of the coin.
+   * Blinding key.
    */
-  char coin_priv_enc[sizeof (struct TALER_CoinSpendPrivateKey)];
+  struct TALER_DenominationBlindingKey blinding_key;
 
 };
 
 
+GNUNET_NETWORK_STRUCT_END
+
+
 /**
- * Representation of an refresh link in cleartext.
+ * Representation of an encrypted refresh link.
  */
-struct TALER_RefreshLinkDecrypted
+struct TALER_RefreshLinkEncrypted
 {
 
   /**
-   * Private key of the coin.
+   * Encrypted blinding key with @e blinding_key_enc_size bytes,
+   * must be allocated at the end of this struct.
    */
-  struct TALER_CoinSpendPrivateKey coin_priv;
+  const char *blinding_key_enc;
 
   /**
-   * Blinding key.
+   * Number of bytes in @e blinding_key_enc.
    */
-  struct TALER_DenominationBlindingKey blinding_key;
+  size_t blinding_key_enc_size;
+
+  /**
+   * Encrypted private key of the coin.
+   */
+  char coin_priv_enc[sizeof (struct TALER_CoinSpendPrivateKey)];
 
 };
 
diff --git a/src/include/taler_signatures.h b/src/include/taler_signatures.h
index 51134bf26..fa713dc42 100644
--- a/src/include/taler_signatures.h
+++ b/src/include/taler_signatures.h
@@ -253,9 +253,9 @@ struct RefreshMeltCoinSignature
   struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
 
   /**
-   * Which melting operation should the coin become a part of.
+   * Which melting session should the coin become a part of.
    */
-  struct GNUNET_HashCode melt_hash;
+  struct GNUNET_HashCode session_hash;
 
   /**
    * How much of the value of the coin should be melted?  This amount
diff --git a/src/mint/plugin_mintdb_postgres.c b/src/mint/plugin_mintdb_postgres.c
index 1c0388427..1c6851d86 100644
--- a/src/mint/plugin_mintdb_postgres.c
+++ b/src/mint/plugin_mintdb_postgres.c
@@ -220,11 +220,11 @@ postgres_create_tables (void *cls,
           ",expended_value INT4 NOT NULL"
           ",expended_fraction INT4 NOT NULL"
           ",expended_currency VARCHAR(4) NOT NULL"
-          ",refresh_session_pub BYTEA"
+          ",refresh_session_hash BYTEA"
           ")");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_sessions "
           "("
-          " session_pub BYTEA PRIMARY KEY CHECK (length(session_pub) = 32)"
+          " session_hash BYTEA PRIMARY KEY CHECK (length(session_hash) = 32)"
           ",session_melt_sig BYTEA"
           ",session_commit_sig BYTEA"
           ",noreveal_index INT2 NOT NULL"
@@ -234,14 +234,14 @@ postgres_create_tables (void *cls,
           ") ");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_order "
           "( "
-          " session_pub BYTEA NOT NULL REFERENCES refresh_sessions (session_pub)"
+          " session_hash BYTEA NOT NULL REFERENCES refresh_sessions (session_hash)"
           ",newcoin_index INT2 NOT NULL "
           ",denom_pub BYTEA NOT NULL "
-          ",PRIMARY KEY (session_pub, newcoin_index)"
+          ",PRIMARY KEY (session_hash, newcoin_index)"
           ") ");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_commit_link"
           "("
-          " session_pub BYTEA NOT NULL REFERENCES refresh_sessions (session_pub)"
+          " session_hash BYTEA NOT NULL REFERENCES refresh_sessions (session_hash)"
           ",transfer_pub BYTEA NOT NULL"
           ",link_secret_enc BYTEA NOT NULL"
           // index of the old coin in the customer's request
@@ -252,7 +252,7 @@ postgres_create_tables (void *cls,
           ")");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_commit_coin"
           "("
-          " session_pub BYTEA NOT NULL REFERENCES refresh_sessions (session_pub) "
+          " session_hash BYTEA NOT NULL REFERENCES refresh_sessions (session_hash) "
           ",link_vector_enc BYTEA NOT NULL"
           // index of the new coin in the customer's request
           ",newcoin_index INT2 NOT NULL"
@@ -262,14 +262,14 @@ postgres_create_tables (void *cls,
           ")");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_melt"
           "("
-          " session_pub BYTEA NOT NULL REFERENCES refresh_sessions (session_pub) "
+          " session_hash BYTEA NOT NULL REFERENCES refresh_sessions (session_hash) "
           ",coin_pub BYTEA NOT NULL REFERENCES known_coins (coin_pub) "
           ",denom_pub BYTEA NOT NULL "
           ",oldcoin_index INT2 NOT NULL"
           ")");
   SQLEXEC("CREATE TABLE IF NOT EXISTS refresh_collectable"
           "("
-          " session_pub BYTEA NOT NULL REFERENCES refresh_sessions (session_pub) "
+          " session_hash BYTEA NOT NULL REFERENCES refresh_sessions (session_hash) "
           ",ev_sig BYTEA NOT NULL"
           ",newcoin_index INT2 NOT NULL"
           ")");
@@ -393,16 +393,16 @@ postgres_prepare (PGconn *db_conn)
 #if 0
   PREPARE ("get_refresh_session",
            "SELECT "
-           " (SELECT count(*) FROM refresh_melt WHERE session_pub = $1)::INT2 as num_oldcoins "
+           " (SELECT count(*) FROM refresh_melt WHERE session_hash = $1)::INT2 as num_oldcoins "
            ",(SELECT count(*) FROM refresh_blind_session_keys "
-           "  WHERE session_pub = $1 and cnc_index = 0)::INT2 as num_newcoins "
+           "  WHERE session_hash = $1 and cnc_index = 0)::INT2 as num_newcoins "
            ",(SELECT count(*) FROM refresh_blind_session_keys "
-           "  WHERE session_pub = $1 and newcoin_index = 0)::INT2 as kappa "
+           "  WHERE session_hash = $1 and newcoin_index = 0)::INT2 as kappa "
            ",noreveal_index"
            ",session_commit_sig "
            ",reveal_ok "
            "FROM refresh_sessions "
-           "WHERE session_pub = $1",
+           "WHERE session_hash = $1",
            1, NULL);
 #endif
 
@@ -410,7 +410,7 @@ postgres_prepare (PGconn *db_conn)
            "SELECT "
            " coin_pub, denom_pub, denom_sig "
            ",expended_value, expended_fraction, expended_currency "
-           ",refresh_session_pub "
+           ",refresh_session_hash "
            "FROM known_coins "
            "WHERE coin_pub = $1",
            1, NULL);
@@ -422,7 +422,7 @@ postgres_prepare (PGconn *db_conn)
            ",expended_value = $4 "
            ",expended_fraction = $5 "
            ",expended_currency = $6 "
-           ",refresh_session_pub = $7 "
+           ",refresh_session_hash = $7 "
            "WHERE "
            " coin_pub = $1 ",
            7, NULL);
@@ -434,7 +434,7 @@ postgres_prepare (PGconn *db_conn)
            ",expended_value"
            ",expended_fraction"
            ",expended_currency"
-           ",refresh_session_pub"
+           ",refresh_session_hash"
            ")"
            "VALUES ($1,$2,$3,$4,$5,$6,$7)",
            7, NULL);
@@ -443,26 +443,26 @@ postgres_prepare (PGconn *db_conn)
            " transfer_pub "
            ",link_secret_enc "
            "FROM refresh_commit_link "
-           "WHERE session_pub = $1 AND cnc_index = $2 AND oldcoin_index = $3",
+           "WHERE session_hash = $1 AND cnc_index = $2 AND oldcoin_index = $3",
            3, NULL);
   PREPARE ("get_refresh_commit_coin",
            "SELECT "
            " link_vector_enc "
            ",coin_ev "
            "FROM refresh_commit_coin "
-           "WHERE session_pub = $1 AND cnc_index = $2 AND newcoin_index = $3",
+           "WHERE session_hash = $1 AND cnc_index = $2 AND newcoin_index = $3",
            3, NULL);
   PREPARE ("insert_refresh_order",
            "INSERT INTO refresh_order ( "
            " newcoin_index "
-           ",session_pub "
+           ",session_hash "
            ",denom_pub "
            ") "
            "VALUES ($1, $2, $3) ",
            3, NULL);
   PREPARE ("insert_refresh_melt",
            "INSERT INTO refresh_melt ( "
-           " session_pub "
+           " session_hash "
            ",oldcoin_index "
            ",coin_pub "
            ",denom_pub "
@@ -472,28 +472,28 @@ postgres_prepare (PGconn *db_conn)
   PREPARE ("get_refresh_order",
            "SELECT denom_pub "
            "FROM refresh_order "
-           "WHERE session_pub = $1 AND newcoin_index = $2",
+           "WHERE session_hash = $1 AND newcoin_index = $2",
            2, NULL);
   PREPARE ("get_refresh_collectable",
            "SELECT ev_sig "
            "FROM refresh_collectable "
-           "WHERE session_pub = $1 AND newcoin_index = $2",
+           "WHERE session_hash = $1 AND newcoin_index = $2",
            2, NULL);
   PREPARE ("get_refresh_melt",
            "SELECT coin_pub "
            "FROM refresh_melt "
-           "WHERE session_pub = $1 AND oldcoin_index = $2",
+           "WHERE session_hash = $1 AND oldcoin_index = $2",
            2, NULL);
   PREPARE ("insert_refresh_session",
            "INSERT INTO refresh_sessions ( "
-           " session_pub "
+           " session_hash "
            ",noreveal_index "
            ") "
            "VALUES ($1, $2) ",
            2, NULL);
   PREPARE ("insert_refresh_commit_link",
            "INSERT INTO refresh_commit_link ( "
-           " session_pub "
+           " session_hash "
            ",transfer_pub "
            ",cnc_index "
            ",oldcoin_index "
@@ -503,7 +503,7 @@ postgres_prepare (PGconn *db_conn)
            5, NULL);
   PREPARE ("insert_refresh_commit_coin",
            "INSERT INTO refresh_commit_coin ( "
-           " session_pub "
+           " session_hash "
            ",coin_ev "
            ",cnc_index "
            ",newcoin_index "
@@ -513,7 +513,7 @@ postgres_prepare (PGconn *db_conn)
            5, NULL);
   PREPARE ("insert_refresh_collectable",
            "INSERT INTO refresh_collectable ( "
-           " session_pub "
+           " session_hash "
            ",newcoin_index "
            ",ev_sig "
            ") "
@@ -522,33 +522,33 @@ postgres_prepare (PGconn *db_conn)
   PREPARE ("set_reveal_ok",
            "UPDATE refresh_sessions "
            "SET reveal_ok = TRUE "
-           "WHERE session_pub = $1 ",
+           "WHERE session_hash = $1 ",
            1, NULL);
   PREPARE ("get_link",
            "SELECT link_vector_enc, ro.denom_pub, ev_sig "
            "FROM refresh_melt rm "
-           "     JOIN refresh_order ro USING (session_pub) "
-           "     JOIN refresh_commit_coin rcc USING (session_pub) "
-           "     JOIN refresh_sessions rs USING (session_pub) "
-           "     JOIN refresh_collectable rc USING (session_pub) "
+           "     JOIN refresh_order ro USING (session_hash) "
+           "     JOIN refresh_commit_coin rcc USING (session_hash) "
+           "     JOIN refresh_sessions rs USING (session_hash) "
+           "     JOIN refresh_collectable rc USING (session_hash) "
            "WHERE rm.coin_pub = $1 "
            "AND ro.newcoin_index = rcc.newcoin_index "
            "AND ro.newcoin_index = rc.newcoin_index "
            "AND  rcc.cnc_index = rs.noreveal_index % ( "
            "         SELECT count(*) FROM refresh_commit_coin rcc2 "
-           "         WHERE rcc2.newcoin_index = 0 AND rcc2.session_pub = rs.session_pub "
+           "         WHERE rcc2.newcoin_index = 0 AND rcc2.session_hash = rs.session_hash "
            "     ) ",
            1, NULL);
   PREPARE ("get_transfer",
            "SELECT transfer_pub, link_secret_enc "
            "FROM refresh_melt rm "
-           "     JOIN refresh_commit_link rcl USING (session_pub) "
-           "     JOIN refresh_sessions rs USING (session_pub) "
+           "     JOIN refresh_commit_link rcl USING (session_hash) "
+           "     JOIN refresh_sessions rs USING (session_hash) "
            "WHERE rm.coin_pub = $1 "
            "AND  rm.oldcoin_index = rcl.oldcoin_index "
            "AND  rcl.cnc_index = rs.noreveal_index % ( "
            "         SELECT count(*) FROM refresh_commit_coin rcc2 "
-           "         WHERE newcoin_index = 0 AND rcc2.session_pub = rm.session_pub "
+           "         WHERE newcoin_index = 0 AND rcc2.session_hash = rm.session_hash "
            "     ) ",
            1, NULL);
   PREPARE ("insert_deposit",
@@ -1434,11 +1434,11 @@ postgres_insert_deposit (void *cls,
 
 
 /**
- * Lookup refresh session data under the given public key.
+ * Lookup refresh session data under the given @a session_hash.
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database handle to use
- * @param refresh_session_pub public key to use for the lookup
+ * @param session_hash hash over the melt to use to locate the session
  * @param refresh_session[OUT] where to store the result
  * @return #GNUNET_YES on success,
  *         #GNUNET_NO if not found,
@@ -1447,13 +1447,13 @@ postgres_insert_deposit (void *cls,
 static int
 postgres_get_refresh_session (void *cls,
                               struct TALER_MINTDB_Session *session,
-                              const struct TALER_SessionPublicKey *refresh_session_pub,
+                              const struct GNUNET_HashCode *session_hash,
                               struct RefreshSession *refresh_session)
 {
   // FIXME: check logic!
   int res;
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_END
   };
 
@@ -1511,11 +1511,11 @@ postgres_get_refresh_session (void *cls,
 
 
 /**
- * Store new refresh session data under the given public key.
+ * Store new refresh session data under the given @a session_hash.
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database handle to use
- * @param refresh_session_pub public key to use to locate the session
+ * @param session_hash hash over the melt to use to locate the session
  * @param refresh_session session data to store
  * @return #GNUNET_YES on success,
  *         #GNUNET_SYSERR on DB failure
@@ -1523,13 +1523,13 @@ postgres_get_refresh_session (void *cls,
 static int
 postgres_create_refresh_session (void *cls,
                                  struct TALER_MINTDB_Session *session,
-                                 const struct TALER_SessionPublicKey *session_pub,
+                                 const struct GNUNET_HashCode *session_hash,
                                  const struct RefreshSession *refresh_session)
 {
   // FIXME: actually store session data!
   uint16_t noreveal_index;
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR(&noreveal_index),
     TALER_DB_QUERY_PARAM_END
   };
@@ -1558,16 +1558,15 @@ postgres_create_refresh_session (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection
- * @param refresh_session session key of the melt operation
  * @param oldcoin_index index of the coin to store
- * @param melt melt operation
+ * @param melt melt operation details to store; includes
+   *             the session hash of the melt
  * @return #GNUNET_OK on success
  *         #GNUNET_SYSERR on internal error
  */
 static int
 postgres_insert_refresh_melt (void *cls,
                               struct TALER_MINTDB_Session *session,
-                              const struct TALER_SessionPublicKey *refresh_session,
                               uint16_t oldcoin_index,
                               const struct RefreshMelt *melt)
 {
@@ -1581,7 +1580,7 @@ postgres_insert_refresh_melt (void *cls,
                                                   &buf);
   {
     struct TALER_DB_QueryParam params[] = {
-      TALER_DB_QUERY_PARAM_PTR(refresh_session),
+      TALER_DB_QUERY_PARAM_PTR(&melt->session_hash),
       TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
       TALER_DB_QUERY_PARAM_PTR(&melt->coin.coin_pub),
       TALER_DB_QUERY_PARAM_PTR_SIZED(buf, buf_size),
@@ -1617,7 +1616,7 @@ postgres_insert_refresh_melt (void *cls,
 static int
 postgres_get_refresh_melt (void *cls,
                            struct TALER_MINTDB_Session *session,
-                           const struct TALER_SessionPublicKey *refresh_session,
+                           const struct GNUNET_HashCode *session_hash,
                            uint16_t oldcoin_index,
                            struct RefreshMelt *melt)
 {
@@ -1633,7 +1632,7 @@ postgres_get_refresh_melt (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection
- * @param session_pub refresh session key
+ * @param session_hash hash to identify refresh session
  * @param num_newcoins number of coins to generate, size of the @a denom_pubs array
  * @param denom_pubs array denominations of the coins to create
  * @return #GNUNET_OK on success
@@ -1642,7 +1641,7 @@ postgres_get_refresh_melt (void *cls,
 static int
 postgres_insert_refresh_order (void *cls,
                                struct TALER_MINTDB_Session *session,
-                               const struct TALER_SessionPublicKey *session_pub,
+                               const struct GNUNET_HashCode *session_hash,
                                uint16_t num_newcoins,
                                const struct TALER_DenominationPublicKey *denom_pubs)
 {
@@ -1658,7 +1657,7 @@ postgres_insert_refresh_order (void *cls,
   {
     struct TALER_DB_QueryParam params[] = {
       TALER_DB_QUERY_PARAM_PTR (&newcoin_index_nbo),
-      TALER_DB_QUERY_PARAM_PTR (session_pub),
+      TALER_DB_QUERY_PARAM_PTR (session_hash),
       TALER_DB_QUERY_PARAM_PTR_SIZED (buf, buf_size),
       TALER_DB_QUERY_PARAM_END
     };
@@ -1689,7 +1688,7 @@ postgres_insert_refresh_order (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection
- * @param session_pub refresh session key
+ * @param session_hash hash to identify refresh session
  * @param newcoin_index array of the @a denom_pubs array
  * @param denom_pubs where to store the deomination keys
  * @return #GNUNET_OK on success
@@ -1698,7 +1697,7 @@ postgres_insert_refresh_order (void *cls,
 static int
 postgres_get_refresh_order (void *cls,
                             struct TALER_MINTDB_Session *session,
-                            const struct TALER_SessionPublicKey *session_pub,
+                            const struct GNUNET_HashCode *session_hash,
                             uint16_t num_newcoins,
                             struct TALER_DenominationPublicKey *denom_pubs)
 {
@@ -1708,7 +1707,7 @@ postgres_get_refresh_order (void *cls,
   uint16_t newcoin_index_nbo = htons (num_newcoins);
 
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
     TALER_DB_QUERY_PARAM_END
   };
@@ -1756,7 +1755,7 @@ postgres_get_refresh_order (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection to use
- * @param refresh_session_pub refresh session this commitment belongs to
+ * @param session_hash hash to identify refresh session
  * @param i set index (1st dimension)
  * @param num_newcoins coin index size of the @a commit_coins array
  * @param commit_coins array of coin commitments to store
@@ -1766,7 +1765,7 @@ postgres_get_refresh_order (void *cls,
 static int
 postgres_insert_refresh_commit_coins (void *cls,
                                       struct TALER_MINTDB_Session *session,
-                                      const struct TALER_SessionPublicKey *refresh_session_pub,
+                                      const struct GNUNET_HashCode *session_hash,
                                       unsigned int i,
                                       unsigned int num_newcoins,
                                       const struct RefreshCommitCoin *commit_coins)
@@ -1775,7 +1774,7 @@ postgres_insert_refresh_commit_coins (void *cls,
   uint16_t cnc_index_nbo = htons (i);
   uint16_t newcoin_index_nbo = htons (num_newcoins);
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR_SIZED(commit_coins->coin_ev, commit_coins->coin_ev_size),
     TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
     TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
@@ -1813,7 +1812,7 @@ postgres_insert_refresh_commit_coins (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection to use
- * @param refresh_session_pub refresh session the commitment belongs to
+ * @param session_hash hash to identify refresh session
  * @param i set index (1st dimension)
  * @param j coin index (2nd dimension), corresponds to refreshed (new) coins
  * @param commit_coin[OUT] coin commitment to return
@@ -1824,7 +1823,7 @@ postgres_insert_refresh_commit_coins (void *cls,
 static int
 postgres_get_refresh_commit_coins (void *cls,
                                    struct TALER_MINTDB_Session *session,
-                                   const struct TALER_SessionPublicKey *refresh_session_pub,
+                                   const struct GNUNET_HashCode *session_hash,
                                    unsigned int cnc_index,
                                    unsigned int newcoin_index,
                                    struct RefreshCommitCoin *cc)
@@ -1833,7 +1832,7 @@ postgres_get_refresh_commit_coins (void *cls,
   uint16_t cnc_index_nbo = htons (cnc_index);
   uint16_t newcoin_index_nbo = htons (newcoin_index);
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
     TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
     TALER_DB_QUERY_PARAM_END
@@ -1894,8 +1893,7 @@ postgres_get_refresh_commit_coins (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection to use
- * @param refresh_session_pub public key of the refresh session this
- *        commitment belongs with  -- FIXME: should not be needed!
+ * @param session_hash hash to identify refresh session
  * @param i set index (1st dimension)
  * @param j coin index (2nd dimension), corresponds to melted (old) coins
  * @param commit_link link information to store
@@ -1904,7 +1902,7 @@ postgres_get_refresh_commit_coins (void *cls,
 static int
 postgres_insert_refresh_commit_links (void *cls,
                                       struct TALER_MINTDB_Session *session,
-                                      const struct TALER_SessionPublicKey *refresh_session_pub,
+                                      const struct GNUNET_HashCode *session_hash,
                                       unsigned int i,
                                       unsigned int j,
                                       const struct RefreshCommitLink *commit_link)
@@ -1913,7 +1911,7 @@ postgres_insert_refresh_commit_links (void *cls,
   uint16_t cnc_index_nbo = htons (i);
   uint16_t oldcoin_index_nbo = htons (j);
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR(&commit_link->transfer_pub),
     TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
     TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
@@ -1948,8 +1946,7 @@ postgres_insert_refresh_commit_links (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection to use
- * @param refresh_session_pub public key of the refresh session this
- *        commitment belongs with -- FIXME: should not be needed!
+ * @param session_hash hash to identify refresh session
  * @param i set index (1st dimension)
  * @param num_links size of the @a commit_link array
  * @param links[OUT] array of link information to return
@@ -1960,7 +1957,7 @@ postgres_insert_refresh_commit_links (void *cls,
 static int
 postgres_get_refresh_commit_links (void *cls,
                                    struct TALER_MINTDB_Session *session,
-                                   const struct TALER_SessionPublicKey *refresh_session_pub,
+                                   const struct GNUNET_HashCode *session_hash,
                                    unsigned int i,
                                    unsigned int num_links,
                                    struct RefreshCommitLink *links)
@@ -1970,7 +1967,7 @@ postgres_get_refresh_commit_links (void *cls,
   uint16_t oldcoin_index_nbo = htons (num_links);
 
   struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(session_hash),
     TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
     TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
     TALER_DB_QUERY_PARAM_END
@@ -2017,7 +2014,7 @@ postgres_get_refresh_commit_links (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection
- * @param session_pub refresh session
+ * @param session_hash hash to identify refresh session
  * @param newcoin_index coin index
  * @param ev_sig coin signature
  * @return #GNUNET_OK on success
@@ -2025,7 +2022,7 @@ postgres_get_refresh_commit_links (void *cls,
 static int
 postgres_insert_refresh_collectable (void *cls,
                                      struct TALER_MINTDB_Session *session,
-                                     const struct TALER_SessionPublicKey *session_pub,
+                                     const struct GNUNET_HashCode *session_hash,
                                      uint16_t newcoin_index,
                                      const struct TALER_DenominationSignature *ev_sig)
 {
@@ -2039,7 +2036,7 @@ postgres_insert_refresh_collectable (void *cls,
                                                  &buf);
   {
     struct TALER_DB_QueryParam params[] = {
-      TALER_DB_QUERY_PARAM_PTR(session_pub),
+      TALER_DB_QUERY_PARAM_PTR(session_hash),
       TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
       TALER_DB_QUERY_PARAM_PTR_SIZED(buf, buf_size),
       TALER_DB_QUERY_PARAM_END
diff --git a/src/mint/taler-mint-httpd_db.c b/src/mint/taler-mint-httpd_db.c
index 30585730b..7592403da 100644
--- a/src/mint/taler-mint-httpd_db.c
+++ b/src/mint/taler-mint-httpd_db.c
@@ -481,7 +481,7 @@ TALER_MINT_db_execute_withdraw_sign (struct MHD_Connection *connection,
  * @param connection the connection to send errors to
  * @param session the database connection
  * @param key_state the mint's key state
- * @param session_pub the refresh session's public key
+ * @param session_hash hash identifying the refresh session
  * @param coin_public_info the coin to melt
  * @param coin_details details about the coin being melted
  * @param oldcoin_index what is the number assigned to this coin
@@ -493,7 +493,7 @@ static int
 refresh_accept_melts (struct MHD_Connection *connection,
                       struct TALER_MINTDB_Session *session,
                       const struct MintKeyState *key_state,
-                      const struct GNUNET_HashCode *melt_hash,
+                      const struct GNUNET_HashCode *session_hash,
                       const struct TALER_SessionPublicKey *session_pub,
                       const struct TALER_CoinPublicInfo *coin_public_info,
                       const struct MeltDetails *coin_details,
@@ -563,12 +563,11 @@ refresh_accept_melts (struct MHD_Connection *connection,
 
   melt.coin = *coin_public_info;
   melt.coin_sig = coin_details->melt_sig;
-  melt.melt_hash = *melt_hash;
+  melt.session_hash = *session_hash;
   melt.amount_with_fee = coin_details->melt_amount_with_fee;
   if (GNUNET_OK !=
       plugin->insert_refresh_melt (plugin->cls,
                                    session,
-                                   session_pub,
                                    oldcoin_index,
                                    &melt))
   {
@@ -587,7 +586,7 @@ refresh_accept_melts (struct MHD_Connection *connection,
  * melted and confirm the melting operation to the client.
  *
  * @param connection the MHD connection to handle
- * @param melt_hash hash code of the session the coins are melted into
+ * @param session_hash hash code of the session the coins are melted into
  * @param refresh_session_pub public key of the refresh session
  * @param client_signature signature of the client (matching @a refresh_session_pub)
  *         over the melting request
@@ -606,7 +605,7 @@ refresh_accept_melts (struct MHD_Connection *connection,
  */
 int
 TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
-                                    const struct GNUNET_HashCode *melt_hash,
+                                    const struct GNUNET_HashCode *session_hash,
                                     const struct TALER_SessionPublicKey *refresh_session_pub,
                                     const struct TALER_SessionSignature *client_signature,
                                     unsigned int num_new_denoms,
@@ -639,14 +638,14 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
   }
   res = plugin->get_refresh_session (plugin->cls,
                                      session,
-                                     refresh_session_pub,
+                                     session_hash,
                                      &refresh_session);
   if (GNUNET_YES == res)
   {
     plugin->rollback (plugin->cls,
                       session);
     res = TALER_MINT_reply_refresh_melt_success (connection,
-                                                 &refresh_session.session_hash,
+                                                 session_hash,
                                                  refresh_session.noreveal_index);
     return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
   }
@@ -665,7 +664,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
         (res = refresh_accept_melts (connection,
                                      session,
                                      key_state,
-                                     melt_hash,
+                                     session_hash,
                                      refresh_session_pub,
                                      &coin_public_infos[i],
                                      &coin_melt_details[i],
@@ -683,7 +682,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->insert_refresh_order (plugin->cls,
                                     session,
-                                    refresh_session_pub,
+                                    session_hash,
                                     num_new_denoms,
                                     denom_pubs))
   {
@@ -697,7 +696,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
     if (GNUNET_OK !=
         plugin->insert_refresh_commit_coins (plugin->cls,
                                              session,
-                                             refresh_session_pub,
+                                             session_hash,
                                              i,
                                              num_new_denoms,
                                              commit_coin[i]))
@@ -712,7 +711,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
     if (GNUNET_OK !=
         plugin->insert_refresh_commit_links (plugin->cls,
                                              session,
-                                             refresh_session_pub,
+                                             session_hash,
                                              i,
                                              coin_count,
                                              commit_link[i]))
@@ -726,7 +725,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
 
   /* store 'global' session data */
   refresh_session.melt_sig = *client_signature;
-  refresh_session.session_hash = *melt_hash;
+  refresh_session.refresh_session_pub = *refresh_session_pub;
   refresh_session.num_oldcoins = coin_count;
   refresh_session.num_newcoins = num_new_denoms;
   refresh_session.kappa = KAPPA; // FIXME... (#3711)
@@ -736,7 +735,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       (res = plugin->create_refresh_session (plugin->cls,
                                              session,
-                                             refresh_session_pub,
+                                             session_hash,
                                              &refresh_session)))
   {
     plugin->rollback (plugin->cls,
@@ -754,7 +753,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
     return TALER_MINT_reply_commit_error (connection);
   }
   return TALER_MINT_reply_refresh_melt_success (connection,
-                                                &refresh_session.session_hash,
+                                                session_hash,
                                                 refresh_session.noreveal_index);
 }
 
@@ -767,7 +766,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
  *
  * @param connection the MHD connection to handle
  * @param session database connection to use
- * @param refresh_session session to query
+ * @param session_hash hash of session to query
  * @param off commitment offset to check
  * @param num_oldcoins size of the @a transfer_privs and @a melts arrays
  * @param transfer_privs private transfer keys
@@ -781,7 +780,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
 static int
 check_commitment (struct MHD_Connection *connection,
                   struct TALER_MINTDB_Session *session,
-                  const struct TALER_SessionPublicKey *refresh_session,
+                  const struct GNUNET_HashCode *session_hash,
                   unsigned int off,
                   unsigned int num_oldcoins,
                   const struct TALER_TransferPrivateKey *transfer_privs,
@@ -802,7 +801,7 @@ check_commitment (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->get_refresh_commit_links (plugin->cls,
                                         session,
-                                        refresh_session,
+                                        session_hash,
                                         off,
                                         num_oldcoins,
                                         commit_links))
@@ -901,7 +900,7 @@ check_commitment (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->get_refresh_commit_coins (plugin->cls,
                                         session,
-                                        refresh_session,
+                                        session_hash,
                                         off,
                                         num_newcoins,
                                         commit_coins))
@@ -982,7 +981,7 @@ check_commitment (struct MHD_Connection *connection,
  *
  * @param connection the MHD connection to handle
  * @param session database connection to use
- * @param refresh_session session to query
+ * @param session_hash hash of session to query
  * @param key_state key state to lookup denomination pubs
  * @param denom_pub denomination key for the coin to create
  * @param commit_coin the coin that was committed
@@ -992,7 +991,7 @@ check_commitment (struct MHD_Connection *connection,
 static struct TALER_DenominationSignature
 refresh_mint_coin (struct MHD_Connection *connection,
                    struct TALER_MINTDB_Session *session,
-                   const struct TALER_SessionPublicKey *refresh_session,
+                   const struct GNUNET_HashCode *session_hash,
                    struct MintKeyState *key_state,
                    const struct TALER_DenominationPublicKey *denom_pub,
                    const struct RefreshCommitCoin *commit_coin,
@@ -1021,7 +1020,7 @@ refresh_mint_coin (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->insert_refresh_collectable (plugin->cls,
                                           session,
-                                          refresh_session,
+                                          session_hash,
                                           coin_off,
                                           &ev_sig))
   {
@@ -1041,7 +1040,7 @@ refresh_mint_coin (struct MHD_Connection *connection,
  * coins that was not chosen.
  *
  * @param connection the MHD connection to handle
- * @param refresh_session_pub public key of the refresh session
+ * @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
@@ -1049,7 +1048,7 @@ refresh_mint_coin (struct MHD_Connection *connection,
  */
 int
 TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
-                                      const struct TALER_SessionPublicKey *refresh_session_pub,
+                                      const struct GNUNET_HashCode *session_hash,
                                       unsigned int kappa,
                                       unsigned int num_oldcoins,
                                       struct TALER_TransferPrivateKey **transfer_privs)
@@ -1075,11 +1074,11 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
 
   res = plugin->get_refresh_session (plugin->cls,
                                      session,
-                                     refresh_session_pub,
+                                     session_hash,
                                      &refresh_session);
   if (GNUNET_NO == res)
     return TALER_MINT_reply_arg_invalid (connection,
-                                         "session_pub");
+                                         "session_hash");
   if (GNUNET_SYSERR == res)
     return TALER_MINT_reply_internal_db_error (connection);
   if (0 == refresh_session.num_oldcoins)
@@ -1095,7 +1094,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
     if (GNUNET_OK !=
         plugin->get_refresh_melt (plugin->cls,
                                   session,
-                                  refresh_session_pub,
+                                  session_hash,
                                   j,
                                   &melts[j]))
     {
@@ -1109,7 +1108,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->get_refresh_order (plugin->cls,
                                  session,
-                                 refresh_session_pub,
+                                 session_hash,
                                  refresh_session.num_newcoins,
                                  denom_pubs))
   {
@@ -1129,7 +1128,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
     if (GNUNET_OK !=
         (res = check_commitment (connection,
                                  session,
-                                 refresh_session_pub,
+                                 session_hash,
                                  i + off,
                                  refresh_session.num_oldcoins,
                                  transfer_privs[i + off],
@@ -1163,7 +1162,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
   if (GNUNET_OK !=
       plugin->get_refresh_commit_coins (plugin->cls,
                                         session,
-                                        refresh_session_pub,
+                                        session_hash,
                                         refresh_session.noreveal_index,
                                         refresh_session.num_newcoins,
                                         commit_coins))
@@ -1182,7 +1181,7 @@ TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
   {
     ev_sigs[j] = refresh_mint_coin (connection,
                                     session,
-                                    refresh_session_pub,
+                                    session_hash,
                                     key_state,
                                     &denom_pubs[j],
                                     &commit_coins[j],
diff --git a/src/mint/taler-mint-httpd_db.h b/src/mint/taler-mint-httpd_db.h
index fd420bd9b..edf8248c7 100644
--- a/src/mint/taler-mint-httpd_db.h
+++ b/src/mint/taler-mint-httpd_db.h
@@ -106,11 +106,8 @@ struct MeltDetails
  * required value left and if so, store that they have been
  * melted and confirm the melting operation to the client.
  *
- * FIXME: some arguments are redundant here...
- *
  * @param connection the MHD connection to handle
- * @param melt_hash hash code of the session the coins are melted into
- * @param refresh_session_pub public key of the refresh session
+ * @param session_hash hash code of the session the coins are melted into
  * @param client_signature signature of the client (matching @a refresh_session_pub)
  *         over the melting request
  * @param num_new_denoms number of entries in @a denom_pubs, size of y-dimension of @commit_coin array
@@ -128,7 +125,7 @@ struct MeltDetails
  */
 int
 TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
-                                    const struct GNUNET_HashCode *melt_hash,
+                                    const struct GNUNET_HashCode *session_hash,
                                     const struct TALER_SessionPublicKey *refresh_session_pub,
                                     const struct TALER_SessionSignature *client_signature,
                                     unsigned int num_new_denoms,
@@ -149,7 +146,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
  * coins that was not chosen.
  *
  * @param connection the MHD connection to handle
- * @param refresh_session_pub public key of the refresh session
+ * @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
@@ -157,7 +154,7 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
  */
 int
 TALER_MINT_db_execute_refresh_reveal (struct MHD_Connection *connection,
-                                      const struct TALER_SessionPublicKey *refresh_session_pub,
+                                      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_deposit.c b/src/mint/taler-mint-httpd_deposit.c
index bf8121037..7ecf8bfe6 100644
--- a/src/mint/taler-mint-httpd_deposit.c
+++ b/src/mint/taler-mint-httpd_deposit.c
@@ -131,7 +131,7 @@ static int
 parse_and_handle_deposit_request (struct MHD_Connection *connection,
                                   const json_t *root,
                                   const struct TALER_Amount *amount,
-                                  const json_t *wire)
+                                  json_t *wire)
 {
   int res;
   struct Deposit deposit;
diff --git a/src/mint/taler-mint-httpd_refresh.c b/src/mint/taler-mint-httpd_refresh.c
index e72a77950..775ffd4ce 100644
--- a/src/mint/taler-mint-httpd_refresh.c
+++ b/src/mint/taler-mint-httpd_refresh.c
@@ -72,11 +72,7 @@ handle_refresh_melt_binary (struct MHD_Connection *connection,
 
 {
   unsigned int i;
-  struct GNUNET_HashContext *hash_context;
-  struct GNUNET_HashCode melt_hash;
   struct RefreshMeltSessionSignature body;
-  char *buf;
-  size_t buf_size;
   struct MintKeyState *key_state;
   struct TALER_MINT_DenomKeyIssue *dki;
   struct TALER_Amount cost;
@@ -88,28 +84,9 @@ handle_refresh_melt_binary (struct MHD_Connection *connection,
   struct TALER_Amount total_melt;
 
   /* check that signature from the session public key is ok */
-  hash_context = GNUNET_CRYPTO_hash_context_start ();
-  /* FIXME: also hash session public key here!? #3708 */
-  for (i = 0; i < num_new_denoms; i++)
-  {
-    buf_size = GNUNET_CRYPTO_rsa_public_key_encode (denom_pubs[i].rsa_public_key,
-                                                    &buf);
-    GNUNET_CRYPTO_hash_context_read (hash_context,
-                                     buf,
-                                     buf_size);
-    GNUNET_free (buf);
-  }
-  for (i = 0; i < coin_count; i++)
-    GNUNET_CRYPTO_hash_context_read (hash_context,
-                                     &coin_public_infos[i].coin_pub,
-                                     sizeof (struct GNUNET_CRYPTO_EddsaPublicKey));
-  GNUNET_CRYPTO_hash_context_finish (hash_context,
-                                     &melt_hash);
-  /* FIXME: what about the `commit_hash`? #3708 */
-
   body.purpose.purpose = htonl (TALER_SIGNATURE_REFRESH_MELT_SESSION);
   body.purpose.size = htonl (sizeof (struct RefreshMeltSessionSignature));
-  body.melt_hash = melt_hash;
+  body.melt_hash = *commit_hash;
   TALER_amount_hton (&body.amount_with_fee,
                      &coin_melt_details->melt_amount_with_fee);
 
@@ -197,7 +174,7 @@ handle_refresh_melt_binary (struct MHD_Connection *connection,
                                        "error", "value mismatch");
   }
   return TALER_MINT_db_execute_refresh_melt (connection,
-                                             &melt_hash,
+                                             commit_hash,
                                              refresh_session_pub,
                                              commit_client_sig,
                                              num_new_denoms,
@@ -278,7 +255,7 @@ get_coin_public_info (struct MHD_Connection *connection,
  * be done before the transaction starts.
  *
  * @param connection the connection to send error responses to
- * @param melt_hash hash over refresh session the coin is melted into
+ * @param session_hash hash over refresh session the coin is melted into
  * @param r_public_info the coin's public information
  * @param r_melt_detail details about the coin's melting permission (if valid)
  * @return #GNUNET_YES if coin public info in JSON was valid
@@ -287,7 +264,7 @@ get_coin_public_info (struct MHD_Connection *connection,
  */
 static int
 verify_coin_public_info (struct MHD_Connection *connection,
-                         const struct GNUNET_HashCode *melt_hash,
+                         const struct GNUNET_HashCode *session_hash,
                          const struct TALER_CoinPublicInfo *r_public_info,
                          const struct MeltDetails *r_melt_detail)
 {
@@ -298,7 +275,7 @@ verify_coin_public_info (struct MHD_Connection *connection,
 
   body.purpose.size = htonl (sizeof (struct RefreshMeltCoinSignature));
   body.purpose.purpose = htonl (TALER_SIGNATURE_REFRESH_MELT_COIN);
-  body.melt_hash = *melt_hash;
+  body.session_hash = *session_hash;
   TALER_amount_hton (&body.amount_with_fee,
                      &r_melt_detail->melt_amount_with_fee);
   body.coin_pub = r_public_info->coin_pub;
@@ -449,11 +426,21 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
   struct RefreshCommitLink *commit_link[kappa];
   const struct TALER_SessionSignature commit_client_sig;
 
+  /* For the signature check, we hash most of the inputs together
+     (except for the signatures on the coins). */
+  hash_context = GNUNET_CRYPTO_hash_context_start ();
+  GNUNET_CRYPTO_hash_context_read (hash_context,
+                                   refresh_session_pub,
+                                   sizeof (struct TALER_SessionPublicKey));
+
   num_new_denoms = json_array_size (new_denoms);
   denom_pubs = GNUNET_malloc (num_new_denoms *
                               sizeof (struct TALER_DenominationPublicKey));
   for (i=0;i<num_new_denoms;i++)
   {
+    char *buf;
+    size_t buf_size;
+
     res = GNUNET_MINT_parse_navigate_json (connection,
                                            new_denoms,
                                            JNAV_INDEX, (int) i,
@@ -466,7 +453,13 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       GNUNET_free (denom_pubs);
       return res;
     }
-  }
+    buf_size = GNUNET_CRYPTO_rsa_public_key_encode (denom_pubs[i].rsa_public_key,
+                                                    &buf);
+    GNUNET_CRYPTO_hash_context_read (hash_context,
+                                     buf,
+                                     buf_size);
+    GNUNET_free (buf);
+ }
 
   coin_count = json_array_size (melt_coins);
   /* FIXME: make 'struct TALER_CoinPublicInfo' part of `struct MeltDetails`
@@ -478,6 +471,8 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
   for (i=0;i<coin_count;i++)
   {
     /* decode JSON data on coin to melt */
+    struct TALER_AmountNBO melt_amount;
+
     res = get_coin_public_info (connection,
                                 json_array_get (melt_coins, i),
                                 &coin_public_infos[i],
@@ -518,14 +513,21 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
                                                 "melting same coin twice in same session is not allowed");
       }
     }
-  }
+    TALER_amount_hton (&melt_amount,
+                       &coin_melt_details[i].melt_amount_with_fee);
+    GNUNET_CRYPTO_hash_context_read (hash_context,
+                                     &coin_public_infos[i].coin_pub,
+                                     sizeof (struct TALER_CoinSpendPublicKey));
+    GNUNET_CRYPTO_hash_context_read (hash_context,
+                                     &melt_amount,
+                                     sizeof (struct TALER_AmountNBO));
 
+  }
 
   /* parse JSON arrays into 2d binary arrays and hash everything
      together for the signature check */
   memset (commit_coin, 0, sizeof (commit_coin));
   memset (commit_link, 0, sizeof (commit_link));
-  hash_context = GNUNET_CRYPTO_hash_context_start ();
   for (i = 0; i < kappa; i++)
   {
     commit_coin[i] = GNUNET_malloc (num_newcoins *
@@ -534,14 +536,15 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
     {
       char *link_enc;
       size_t link_enc_size;
+      struct RefreshCommitCoin *rcc = &commit_coin[i][j];
 
       res = GNUNET_MINT_parse_navigate_json (connection,
                                              coin_evs,
                                              JNAV_INDEX, (int) i,
                                              JNAV_INDEX, (int) j,
                                              JNAV_RET_DATA_VAR,
-                                             &commit_coin[i][j].coin_ev,
-                                             &commit_coin[i][j].coin_ev_size);
+                                             &rcc->coin_ev,
+                                             &rcc->coin_ev_size);
 
       if (GNUNET_OK != res)
       {
@@ -550,8 +553,8 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
       GNUNET_CRYPTO_hash_context_read (hash_context,
-                                       commit_coin[i][j].coin_ev,
-                                       commit_coin[i][j].coin_ev_size);
+                                       rcc->coin_ev,
+                                       rcc->coin_ev_size);
       res = GNUNET_MINT_parse_navigate_json (connection,
                                              link_encs,
                                              JNAV_INDEX, (int) i,
@@ -565,9 +568,9 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
         free_commit_coins (commit_coin, kappa, num_newcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
-      commit_coin[i][j].refresh_link = TALER_refresh_link_encrypted_decode (link_enc,
-                                                                            link_enc_size);
-
+      rcc->refresh_link
+        = TALER_refresh_link_encrypted_decode (link_enc,
+                                               link_enc_size);
       GNUNET_CRYPTO_hash_context_read (hash_context,
                                        link_enc,
                                        link_enc_size);
@@ -580,12 +583,14 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
                                     sizeof (struct RefreshCommitLink));
     for (j = 0; j < num_oldcoins; j++)
     {
+      struct RefreshCommitLink *rcl = &commit_link[i][j];
+
       res = GNUNET_MINT_parse_navigate_json (connection,
                                              transfer_pubs,
                                              JNAV_INDEX, (int) i,
                                              JNAV_INDEX, (int) j,
                                              JNAV_RET_DATA,
-                                             &commit_link[i][j].transfer_pub,
+                                             &rcl->transfer_pub,
                                              sizeof (struct TALER_TransferPublicKey));
 
       if (GNUNET_OK != res)
@@ -596,17 +601,12 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
         free_commit_links (commit_link, kappa, num_oldcoins);
         return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
       }
-
-      GNUNET_CRYPTO_hash_context_read (hash_context,
-                                       &commit_link[i][j].transfer_pub,
-                                       sizeof (struct TALER_TransferPublicKey));
-
       res = GNUNET_MINT_parse_navigate_json (connection,
                                              secret_encs,
                                              JNAV_INDEX, (int) i,
                                              JNAV_INDEX, (int) j,
                                              JNAV_RET_DATA,
-                                             &commit_link[i][j].shared_secret_enc,
+                                             &rcl->shared_secret_enc,
                                              sizeof (struct GNUNET_HashCode));
 
       if (GNUNET_OK != res)
@@ -619,12 +619,13 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
       }
 
       GNUNET_CRYPTO_hash_context_read (hash_context,
-                                       &commit_link[i][j].shared_secret_enc,
-                                       sizeof (struct GNUNET_HashCode));
+                                       rcl,
+                                       sizeof (struct RefreshCommitLink));
     }
-  }
-  GNUNET_CRYPTO_hash_context_finish (hash_context, &commit_hash);
 
+  }
+  GNUNET_CRYPTO_hash_context_finish (hash_context,
+                                     &commit_hash);
 
   res = GNUNET_MINT_parse_navigate_json (connection,
                                          commit_signature,
@@ -640,7 +641,7 @@ handle_refresh_melt_json (struct MHD_Connection *connection,
 
   for (i=0;i<coin_count;i++)
   {
-    /* verify signatures ons coin to melt */
+    /* verify signatures on coins to melt */
     res = verify_coin_public_info (connection,
                                    &commit_hash,
                                    &coin_public_infos[i],
@@ -812,7 +813,7 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
  * coins.
  *
  * @param connection the MHD connection to handle
- * @param refresh_session_pub public key of the session
+ * @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
@@ -820,7 +821,7 @@ TALER_MINT_handler_refresh_melt (struct RequestHandler *rh,
   */
 static int
 handle_refresh_reveal_json (struct MHD_Connection *connection,
-                            const struct TALER_SessionPublicKey *refresh_session_pub,
+                            const struct GNUNET_HashCode *session_hash,
                             unsigned int kappa,
                             unsigned int num_oldcoins,
                             const json_t *tp_json)
@@ -855,7 +856,7 @@ handle_refresh_reveal_json (struct MHD_Connection *connection,
     res = (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
   else
     res = TALER_MINT_db_execute_refresh_reveal (connection,
-                                                refresh_session_pub,
+                                                session_hash,
                                                 kappa,
                                                 num_oldcoins,
                                                 transfer_privs);
@@ -888,7 +889,7 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
                                    const char *upload_data,
                                    size_t *upload_data_size)
 {
-  struct TALER_SessionPublicKey refresh_session_pub;
+  struct GNUNET_HashCode session_hash;
   int res;
   unsigned int kappa;
   unsigned int num_oldcoins;
@@ -896,7 +897,7 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
   json_t *root;
   json_t *transfer_privs;
   struct GNUNET_MINT_ParseFieldSpec spec[] = {
-    TALER_MINT_PARSE_FIXED ("session_pub", &refresh_session_pub),
+    TALER_MINT_PARSE_FIXED ("session_hash", &session_hash),
     TALER_MINT_PARSE_ARRAY ("transfer_privs", &transfer_privs),
     TALER_MINT_PARSE_END
   };
@@ -941,7 +942,7 @@ TALER_MINT_handler_refresh_reveal (struct RequestHandler *rh,
   }
   num_oldcoins = json_array_size (reveal_detail);
   res = handle_refresh_reveal_json (connection,
-                                    &refresh_session_pub,
+                                    &session_hash,
                                     kappa,
                                     num_oldcoins,
                                     transfer_privs);
diff --git a/src/mint/taler-mint-httpd_responses.c b/src/mint/taler-mint-httpd_responses.c
index 4f124a15c..00b002842 100644
--- a/src/mint/taler-mint-httpd_responses.c
+++ b/src/mint/taler-mint-httpd_responses.c
@@ -364,7 +364,7 @@ compile_transaction_history (const struct TALER_MINT_DB_TransactionList *tl)
         value = melt->amount_with_fee;
         ms.purpose.purpose = htonl (TALER_SIGNATURE_REFRESH_MELT_COIN);
         ms.purpose.size = htonl (sizeof (struct RefreshMeltCoinSignature));
-        ms.melt_hash = melt->melt_hash;
+        ms.session_hash = melt->session_hash;
         TALER_amount_hton (&ms.amount_with_fee,
                            &melt->amount_with_fee);
         ms.coin_pub = melt->coin.coin_pub;
diff --git a/src/mint/taler_mintdb_plugin.h b/src/mint/taler_mintdb_plugin.h
index 078238515..326737e61 100644
--- a/src/mint/taler_mintdb_plugin.h
+++ b/src/mint/taler_mintdb_plugin.h
@@ -236,18 +236,15 @@ struct Deposit
 struct RefreshSession
 {
   /**
-   * Signature over the commitments by the client,
-   * only valid if @e has_commit_sig is set.
-   *
-   * FIXME: The above comment is clearly confused.
+   * Signature over the commitments by the client.
    */
   struct TALER_SessionSignature commit_sig;
 
   /**
-   * Hash over coins to melt and coins to create of the
-   * refresh session.
+   * Public key the client uses to sign messages in
+   * this exchange.
    */
-  struct GNUNET_HashCode session_hash;
+  struct TALER_SessionPublicKey refresh_session_pub;
 
   /**
    * Signature over the melt by the client.
@@ -296,9 +293,9 @@ struct RefreshMelt
   struct TALER_CoinSpendSignature coin_sig;
 
   /**
-   * Which melting operation should the coin become a part of.
+   * Hash of the refresh session this coin is melted into.
    */
-  struct GNUNET_HashCode melt_hash;
+  struct GNUNET_HashCode session_hash;
 
   /**
    * How much value is being melted?  This amount includes the fees,
@@ -341,6 +338,8 @@ struct RefreshCommitCoin
 };
 
 
+GNUNET_NETWORK_STRUCT_BEGIN
+
 /**
  * For each (old) coin being melted, we have a `struct
  * RefreshCommitLink` that allows the user to find the shared secret
@@ -350,7 +349,9 @@ struct RefreshCommitCoin
 struct RefreshCommitLink
 {
   /**
-   * Transfer public key (FIXME: explain!)
+   * Transfer public key, used to decrypt the @e shared_secret_enc
+   * in combintation with the corresponding private key of the
+   * coin.
    */
   struct TALER_TransferPublicKey transfer_pub;
 
@@ -360,6 +361,9 @@ struct RefreshCommitLink
   struct TALER_EncryptedLinkSecret shared_secret_enc;
 };
 
+GNUNET_NETWORK_STRUCT_END
+
+
 
 /**
  * Linked list of refresh information linked to a coin.
@@ -709,11 +713,11 @@ struct TALER_MINTDB_Plugin
 
 
   /**
-   * Lookup refresh session data under the given public key.
+   * Lookup refresh session data under the given @a session_hash.
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database handle to use
-   * @param refresh_session_pub public key to use for the lookup
+   * @param session_hash hash over the melt to use for the lookup
    * @param refresh_session[OUT] where to store the result
    * @return #GNUNET_YES on success,
    *         #GNUNET_NO if not found,
@@ -722,16 +726,16 @@ struct TALER_MINTDB_Plugin
   int
   (*get_refresh_session) (void *cls,
                           struct TALER_MINTDB_Session *sesssion,
-                          const struct TALER_SessionPublicKey *refresh_session_pub,
+                          const struct GNUNET_HashCode *session_hash,
                           struct RefreshSession *refresh_session);
 
 
   /**
-   * Store new refresh session data under the given public key.
+   * Store new refresh session data under the given @a session_hash.
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database handle to use
-   * @param refresh_session_pub public key to use to locate the session
+   * @param session_hash hash over the melt to use to locate the session
    * @param refresh_session session data to store
    * @return #GNUNET_YES on success,
    *         #GNUNET_SYSERR on DB failure
@@ -739,26 +743,24 @@ struct TALER_MINTDB_Plugin
   int
   (*create_refresh_session) (void *cls,
                              struct TALER_MINTDB_Session *sesssion,
-                             const struct TALER_SessionPublicKey *session_pub,
+                             const struct GNUNET_HashCode *session_hash,
                              const struct RefreshSession *refresh_session);
 
 
-
   /**
    * Store the given /refresh/melt request in the database.
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection
-   * @param refresh_session session key of the melt operation
    * @param oldcoin_index index of the coin to store
-   * @param melt coin melt operation details to store
+   * @param melt coin melt operation details to store; includes
+   *             the session hash of the melt
    * @return #GNUNET_OK on success
    *         #GNUNET_SYSERR on internal error
    */
   int
   (*insert_refresh_melt) (void *cls,
                           struct TALER_MINTDB_Session *sesssion,
-                          const struct TALER_SessionPublicKey *refresh_session,
                           uint16_t oldcoin_index,
                           const struct RefreshMelt *melt);
 
@@ -768,7 +770,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection
-   * @param refresh_session session key of the melt operation
+   * @param session_hash hash to identify refresh session
    * @param oldcoin_index index of the coin to retrieve
    * @param melt melt data to fill in
    * @return #GNUNET_OK on success
@@ -777,7 +779,7 @@ struct TALER_MINTDB_Plugin
   int
   (*get_refresh_melt) (void *cls,
                        struct TALER_MINTDB_Session *sesssion,
-                       const struct TALER_SessionPublicKey *refresh_session,
+                       const struct GNUNET_HashCode *session_hash,
                        uint16_t oldcoin_index,
                        struct RefreshMelt *melt);
 
@@ -788,7 +790,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection
-   * @param session_pub refresh session key
+   * @param session_hash hash to identify refresh session
    * @param num_newcoins number of coins to generate, size of the @a denom_pubs array
    * @param denom_pubs array denominations of the coins to create
    * @return #GNUNET_OK on success
@@ -797,7 +799,7 @@ struct TALER_MINTDB_Plugin
   int
   (*insert_refresh_order) (void *cls,
                            struct TALER_MINTDB_Session *sesssion,
-                           const struct TALER_SessionPublicKey *session_pub,
+                           const struct GNUNET_HashCode *session_hash,
                            uint16_t num_newcoins,
                            const struct TALER_DenominationPublicKey *denom_pubs);
 
@@ -808,7 +810,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection
-   * @param session_pub refresh session key
+   * @param session_hash hash to identify refresh session
    * @param num_newcoins size of the @a denom_pubs array
    * @param denom_pubs[OUT] where to write @a num_newcoins denomination keys
    * @return #GNUNET_OK on success
@@ -817,7 +819,7 @@ struct TALER_MINTDB_Plugin
   int
   (*get_refresh_order) (void *cls,
                         struct TALER_MINTDB_Session *sesssion,
-                        const struct TALER_SessionPublicKey *session_pub,
+                        const struct GNUNET_HashCode *session_hash,
                         uint16_t num_newcoins,
                         struct TALER_DenominationPublicKey *denom_pubs);
 
@@ -828,7 +830,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
-   * @param refresh_session_pub refresh session this commitment belongs to
+   * @param session_hash hash to identify refresh session
    * @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
@@ -838,7 +840,7 @@ struct TALER_MINTDB_Plugin
   int
   (*insert_refresh_commit_coins) (void *cls,
                                   struct TALER_MINTDB_Session *sesssion,
-                                  const struct TALER_SessionPublicKey *refresh_session_pub,
+                                  const struct GNUNET_HashCode *session_hash,
                                   unsigned int i,
                                   unsigned int num_newcoins,
                                   const struct RefreshCommitCoin *commit_coins);
@@ -850,7 +852,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
-   * @param refresh_session_pub refresh session the commitment belongs to
+   * @param session_hash hash to identify refresh session
    * @param i set index (1st dimension)
    * @param num_coins size of the @a commit_coins array
    * @param commit_coin[OUT] array of coin commitments to return
@@ -861,7 +863,7 @@ struct TALER_MINTDB_Plugin
   int
   (*get_refresh_commit_coins) (void *cls,
                                struct TALER_MINTDB_Session *sesssion,
-                               const struct TALER_SessionPublicKey *refresh_session_pub,
+                               const struct GNUNET_HashCode *session_hash,
                                unsigned int i,
                                unsigned int num_coins,
                                struct RefreshCommitCoin *commit_coins);
@@ -873,8 +875,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
-   * @param refresh_session_pub public key of the refresh session this
-   *        commitment belongs with
+   * @param session_hash hash to identify refresh session
    * @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
@@ -883,7 +884,7 @@ struct TALER_MINTDB_Plugin
   int
   (*insert_refresh_commit_links) (void *cls,
                                   struct TALER_MINTDB_Session *sesssion,
-                                  const struct TALER_SessionPublicKey *refresh_session_pub,
+                                  const struct GNUNET_HashCode *session_hash,
                                   unsigned int i,
                                   unsigned int num_links,
                                   const struct RefreshCommitLink *commit_links);
@@ -894,8 +895,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
-   * @param refresh_session_pub public key of the refresh session this
-   *        commitment belongs with
+   * @param session_hash hash to identify refresh session
    * @param i set index (1st dimension)
    * @param num_links size of the @links array to return
    * @param links[OUT] array link information to return
@@ -906,7 +906,7 @@ struct TALER_MINTDB_Plugin
   int
   (*get_refresh_commit_links) (void *cls,
                                struct TALER_MINTDB_Session *sesssion,
-                               const struct TALER_SessionPublicKey *refresh_session_pub,
+                               const struct GNUNET_HashCode *session_hash,
                                unsigned int i,
                                unsigned int num_links,
                                struct RefreshCommitLink *links);
@@ -920,7 +920,7 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection
-   * @param session_pub refresh session
+   * @param session_hash hash to identify refresh session
    * @param newcoin_index coin index
    * @param ev_sig coin signature
    * @return #GNUNET_OK on success
@@ -928,7 +928,7 @@ struct TALER_MINTDB_Plugin
   int
   (*insert_refresh_collectable) (void *cls,
                                  struct TALER_MINTDB_Session *sesssion,
-                                 const struct TALER_SessionPublicKey *session_pub,
+                                 const struct GNUNET_HashCode *session_hash,
                                  uint16_t newcoin_index,
                                  const struct TALER_DenominationSignature *ev_sig);