logic of execute_refresh_commit is now clean

4 files changed, 404 insertions, 317 deletions

diff --git a/src/mint/mint.h b/src/mint/mint.h
index e2d559701..fb4889dbb 100644
--- a/src/mint/mint.h
+++ b/src/mint/mint.h
@@ -26,7 +26,6 @@
 #include <jansson.h>
 #include "taler_util.h"
 
-
 /**
  * For now, we just do EUR.  Should become configurable
  * in the future!
@@ -34,58 +33,4 @@
 #define MINT_CURRENCY "EUR"
 
 
-
-
-
-
-
-
-
-/**
- * For each (old) coin being melted, we have a `struct
- * RefreshCommitLink` that allows the user to find the shared secret
- * to decrypt the respective refresh links for the new coins in the
- * `struct RefreshCommitCoin`.
- */
-struct RefreshCommitLink
-{
-  /**
-   * Transfer public key (FIXME: explain!)
-   */
-  struct GNUNET_CRYPTO_EcdsaPublicKey transfer_pub;
-
-  /**
-   * Encrypted shared secret to decrypt the link.
-   */
-  struct TALER_EncryptedLinkSecret shared_secret_enc;
-};
-
-
-/**
- * We have as many `struct RefreshCommitCoin` as there are new
- * coins being created by the refresh.
- */
-struct RefreshCommitCoin
-{
-
-  /**
-   * Encrypted data allowing those able to decrypt it to derive
-   * the private keys of the new coins created by the refresh.
-   */
-  struct TALER_RefreshLinkEncrypted *refresh_link;
-
-  /**
-   * Blinded message to be signed (in envelope), with @e coin_env_size bytes.
-   */
-  char *coin_ev;
-
-  /**
-   * Number of bytes in @e coin_ev.
-   */
-  size_t coin_ev_size;
-
-};
-
-
-
 #endif /* _MINT_H */
diff --git a/src/mint/mint_db.c b/src/mint/mint_db.c
index 67cf4b352..0e908425d 100644
--- a/src/mint/mint_db.c
+++ b/src/mint/mint_db.c
@@ -818,209 +818,6 @@ TALER_MINT_DB_upsert_known_coin (PGconn *db_conn,
 }
 
 
-/**
- * Store the commitment to the given (encrypted) refresh link data
- * for the given refresh session.
- *
- * @param db_conn database connection to use
- * @param refresh_session_pub public key of the refresh session this
- *        commitment belongs with
- * @param i
- * @param j
- * @param commit_link link information to store
- * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
- */
-int
-TALER_MINT_DB_insert_refresh_commit_link (PGconn *db_conn,
-                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                          int i, int j,
-                                          const struct RefreshCommitLink *commit_link)
-{
-  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(&commit_link->transfer_pub),
-    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR(&commit_link->shared_secret_enc),
-    TALER_DB_QUERY_PARAM_END
-  };
-
-  PGresult *result = TALER_DB_exec_prepared (db_conn,
-                                             "insert_refresh_commit_link",
-                                             params);
-  if (PGRES_COMMAND_OK != PQresultStatus (result))
-  {
-    break_db_err (result);
-    PQclear (result);
-    return GNUNET_SYSERR;
-  }
-
-  if (0 != strcmp ("1", PQcmdTuples (result)))
-  {
-    GNUNET_break (0);
-    return GNUNET_SYSERR;
-  }
-
-  PQclear (result);
-  return GNUNET_OK;
-}
-
-
-int
-TALER_MINT_DB_get_refresh_commit_link (PGconn *db_conn,
-                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                       int cnc_index,
-                                       int oldcoin_index,
-                                       struct RefreshCommitLink *cc)
-{
-  uint16_t cnc_index_nbo = htons (cnc_index);
-  uint16_t oldcoin_index_nbo = htons (oldcoin_index);
-
-  struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
-    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
-    TALER_DB_QUERY_PARAM_END
-  };
-
-  PGresult *result = TALER_DB_exec_prepared (db_conn,
-                                             "get_refresh_commit_link",
-                                             params);
-  if (PGRES_TUPLES_OK != PQresultStatus (result))
-  {
-    break_db_err (result);
-    PQclear (result);
-    return GNUNET_SYSERR;
-  }
-
-  if (0 == PQntuples (result))
-  {
-    PQclear (result);
-    return GNUNET_NO;
-  }
-
-  struct TALER_DB_ResultSpec rs[] = {
-    TALER_DB_RESULT_SPEC("transfer_pub", &cc->transfer_pub),
-    TALER_DB_RESULT_SPEC("link_secret_enc", &cc->shared_secret_enc),
-    TALER_DB_RESULT_SPEC_END
-  };
-
-  if (GNUNET_YES != TALER_DB_extract_result (result, rs, 0))
-  {
-    PQclear (result);
-    GNUNET_free (cc);
-    return GNUNET_SYSERR;
-  }
-
-  PQclear (result);
-  return GNUNET_OK;
-}
-
-
-int
-TALER_MINT_DB_insert_refresh_commit_coin (PGconn *db_conn,
-                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                          int i, int j,
-                                          const struct RefreshCommitCoin *commit_coin)
-{
-  uint16_t cnc_index_nbo = htons (i);
-  uint16_t newcoin_index_nbo = htons (j);
-  struct TALER_DB_QueryParam params[] = {
-    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
-    TALER_DB_QUERY_PARAM_PTR_SIZED(commit_coin->coin_ev, commit_coin->coin_ev_size),
-    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR_SIZED(commit_coin->refresh_link->coin_priv_enc,
-                                   commit_coin->refresh_link->blinding_key_enc_size +
-                                   sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey)),
-    TALER_DB_QUERY_PARAM_END
-  };
-
-  PGresult *result = TALER_DB_exec_prepared (db_conn, "insert_refresh_commit_coin", params);
-
-  if (PGRES_COMMAND_OK != PQresultStatus (result))
-  {
-    break_db_err (result);
-    PQclear (result);
-    return GNUNET_SYSERR;
-  }
-
-  if (0 != strcmp ("1", PQcmdTuples (result)))
-  {
-    GNUNET_break (0);
-    return GNUNET_SYSERR;
-  }
-
-  PQclear (result);
-  return GNUNET_OK;
-}
-
-
-int
-TALER_MINT_DB_get_refresh_commit_coin (PGconn *db_conn,
-                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                       int cnc_index,
-                                       int newcoin_index,
-                                       struct RefreshCommitCoin *cc)
-{
-  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(&cnc_index_nbo),
-    TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
-    TALER_DB_QUERY_PARAM_END
-  };
-  char *c_buf;
-  size_t c_buf_size;
-  char *rl_buf;
-  size_t rl_buf_size;
-  struct TALER_RefreshLinkEncrypted *rl;
-
-  PGresult *result = TALER_DB_exec_prepared (db_conn, "get_refresh_commit_coin", params);
-
-  if (PGRES_TUPLES_OK != PQresultStatus (result))
-  {
-    break_db_err (result);
-    PQclear (result);
-    return GNUNET_SYSERR;
-  }
-
-  if (0 == PQntuples (result))
-  {
-    PQclear (result);
-    return GNUNET_NO;
-  }
-
-  struct TALER_DB_ResultSpec rs[] = {
-    TALER_DB_RESULT_SPEC_VAR("coin_ev", &c_buf, &c_buf_size),
-    TALER_DB_RESULT_SPEC_VAR("link_vector_enc", &rl_buf, &rl_buf_size),
-    TALER_DB_RESULT_SPEC_END
-  };
-  if (GNUNET_YES != TALER_DB_extract_result (result, rs, 0))
-  {
-    PQclear (result);
-    return GNUNET_SYSERR;
-  }
-  PQclear (result);
-  if (rl_buf_size < sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey))
-  {
-    GNUNET_free (c_buf);
-    GNUNET_free (rl_buf);
-    return GNUNET_SYSERR;
-  }
-  rl = TALER_refresh_link_encrypted_decode (rl_buf,
-                                            rl_buf_size);
-  GNUNET_free (rl_buf);
-  cc->refresh_link = rl;
-  cc->coin_ev = c_buf;
-  cc->coin_ev_size = c_buf_size;
-  return GNUNET_YES;
-}
-
-
 struct GNUNET_CRYPTO_rsa_PublicKey *
 TALER_MINT_DB_get_refresh_order (PGconn *db_conn,
                                  uint16_t newcoin_index,
@@ -2029,6 +1826,257 @@ TALER_MINT_DB_get_refresh_melt (PGconn *db_conn,
 
 
 /**
+ * Store information about the commitment of the
+ * given coin for the given refresh session in the database.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub refresh session this commitment belongs to
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to refreshed (new) coins
+ * @param commit_coin coin commitment to store
+ * @return #GNUNET_OK on success
+ *         #GNUNET_SYSERR on error
+ */
+int
+TALER_MINT_DB_insert_refresh_commit_coin (PGconn *db_conn,
+                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                          unsigned int i,
+                                          unsigned int j,
+                                          const struct RefreshCommitCoin *commit_coin)
+{
+  // FIXME: check logic!
+  uint16_t cnc_index_nbo = htons (i);
+  uint16_t newcoin_index_nbo = htons (j);
+  struct TALER_DB_QueryParam params[] = {
+    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR_SIZED(commit_coin->coin_ev, commit_coin->coin_ev_size),
+    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR_SIZED(commit_coin->refresh_link->coin_priv_enc,
+                                   commit_coin->refresh_link->blinding_key_enc_size +
+                                   sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey)),
+    TALER_DB_QUERY_PARAM_END
+  };
+
+  PGresult *result = TALER_DB_exec_prepared (db_conn, "insert_refresh_commit_coin", params);
+
+  if (PGRES_COMMAND_OK != PQresultStatus (result))
+  {
+    break_db_err (result);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+
+  if (0 != strcmp ("1", PQcmdTuples (result)))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+
+  PQclear (result);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Obtain information about the commitment of the
+ * given coin of the given refresh session from the database.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub refresh session the commitment belongs to
+ * @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
+ * @return #GNUNET_OK on success
+ *         #GNUNET_NO if not found
+ *         #GNUNET_SYSERR on error
+ */
+int
+TALER_MINT_DB_get_refresh_commit_coin (PGconn *db_conn,
+                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                       unsigned int cnc_index,
+                                       unsigned int newcoin_index,
+                                       struct RefreshCommitCoin *cc)
+{
+  // FIXME: check logic!
+  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(&cnc_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR(&newcoin_index_nbo),
+    TALER_DB_QUERY_PARAM_END
+  };
+  char *c_buf;
+  size_t c_buf_size;
+  char *rl_buf;
+  size_t rl_buf_size;
+  struct TALER_RefreshLinkEncrypted *rl;
+
+  PGresult *result = TALER_DB_exec_prepared (db_conn, "get_refresh_commit_coin", params);
+
+  if (PGRES_TUPLES_OK != PQresultStatus (result))
+  {
+    break_db_err (result);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+
+  if (0 == PQntuples (result))
+  {
+    PQclear (result);
+    return GNUNET_NO;
+  }
+
+  struct TALER_DB_ResultSpec rs[] = {
+    TALER_DB_RESULT_SPEC_VAR("coin_ev", &c_buf, &c_buf_size),
+    TALER_DB_RESULT_SPEC_VAR("link_vector_enc", &rl_buf, &rl_buf_size),
+    TALER_DB_RESULT_SPEC_END
+  };
+  if (GNUNET_YES != TALER_DB_extract_result (result, rs, 0))
+  {
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+  PQclear (result);
+  if (rl_buf_size < sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey))
+  {
+    GNUNET_free (c_buf);
+    GNUNET_free (rl_buf);
+    return GNUNET_SYSERR;
+  }
+  rl = TALER_refresh_link_encrypted_decode (rl_buf,
+                                            rl_buf_size);
+  GNUNET_free (rl_buf);
+  cc->refresh_link = rl;
+  cc->coin_ev = c_buf;
+  cc->coin_ev_size = c_buf_size;
+  return GNUNET_YES;
+}
+
+
+/**
+ * Store the commitment to the given (encrypted) refresh link data
+ * for the given refresh session.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub public key of the refresh session this
+ *        commitment belongs with
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to melted (old) coins
+ * @param commit_link link information to store
+ * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
+ */
+int
+TALER_MINT_DB_insert_refresh_commit_link (PGconn *db_conn,
+                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                          unsigned int i,
+                                          unsigned int j,
+                                          const struct RefreshCommitLink *commit_link)
+{
+  // FIXME: check logic!
+  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(&commit_link->transfer_pub),
+    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR(&commit_link->shared_secret_enc),
+    TALER_DB_QUERY_PARAM_END
+  };
+
+  PGresult *result = TALER_DB_exec_prepared (db_conn,
+                                             "insert_refresh_commit_link",
+                                             params);
+  if (PGRES_COMMAND_OK != PQresultStatus (result))
+  {
+    break_db_err (result);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+
+  if (0 != strcmp ("1", PQcmdTuples (result)))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+
+  PQclear (result);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Obtain the commited (encrypted) refresh link data
+ * for the given refresh session.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub public key of the refresh session this
+ *        commitment belongs with
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to melted (old) coins
+ * @param cc[OUT] link information to return
+ * @return #GNUNET_SYSERR on internal error,
+ *         #GNUNET_NO if commitment was not found
+ *         #GNUNET_OK on success
+ */
+int
+TALER_MINT_DB_get_refresh_commit_link (PGconn *db_conn,
+                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                       unsigned int cnc_index,
+                                       unsigned int oldcoin_index,
+                                       struct RefreshCommitLink *cc)
+{
+  // FIXME: check logic!
+  uint16_t cnc_index_nbo = htons (cnc_index);
+  uint16_t oldcoin_index_nbo = htons (oldcoin_index);
+
+  struct TALER_DB_QueryParam params[] = {
+    TALER_DB_QUERY_PARAM_PTR(refresh_session_pub),
+    TALER_DB_QUERY_PARAM_PTR(&cnc_index_nbo),
+    TALER_DB_QUERY_PARAM_PTR(&oldcoin_index_nbo),
+    TALER_DB_QUERY_PARAM_END
+  };
+
+  PGresult *result = TALER_DB_exec_prepared (db_conn,
+                                             "get_refresh_commit_link",
+                                             params);
+  if (PGRES_TUPLES_OK != PQresultStatus (result))
+  {
+    break_db_err (result);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+
+  if (0 == PQntuples (result))
+  {
+    PQclear (result);
+    return GNUNET_NO;
+  }
+
+  struct TALER_DB_ResultSpec rs[] = {
+    TALER_DB_RESULT_SPEC("transfer_pub", &cc->transfer_pub),
+    TALER_DB_RESULT_SPEC("link_secret_enc", &cc->shared_secret_enc),
+    TALER_DB_RESULT_SPEC_END
+  };
+
+  if (GNUNET_YES != TALER_DB_extract_result (result, rs, 0))
+  {
+    PQclear (result);
+    GNUNET_free (cc);
+    return GNUNET_SYSERR;
+  }
+
+  PQclear (result);
+  return GNUNET_OK;
+}
+
+
+
+
+
+/**
  * Compile a list of all (historic) transactions performed
  * with the given coin (/refresh/melt and /deposit operations).
  *
diff --git a/src/mint/mint_db.h b/src/mint/mint_db.h
index e53df8ac2..e2bf3bb27 100644
--- a/src/mint/mint_db.h
+++ b/src/mint/mint_db.h
@@ -86,45 +86,8 @@ TALER_MINT_DB_insert_known_coin (PGconn *db_conn,
 
 
 
-/**
- * Store the commitment to the given (encrypted) refresh link data
- * for the given refresh session.
- *
- * @param db_conn database connection to use
- * @param refresh_session_pub public key of the refresh session this
- *        commitment belongs with
- * @param i
- * @param j
- * @param commit_link link information to store
- * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
- */
-int
-TALER_MINT_DB_insert_refresh_commit_link (PGconn *db_conn,
-                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                          int i, int j,
-                                          const struct RefreshCommitLink *commit_link);
 
 
-int
-TALER_MINT_DB_get_refresh_commit_link (PGconn *db_conn,
-                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                       int i, int j,
-                                       struct RefreshCommitLink *cc);
-
-
-int
-TALER_MINT_DB_insert_refresh_commit_coin (PGconn *db_conn,
-                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                          int i,
-                                          int j,
-                                          const struct RefreshCommitCoin *commit_coin);
-
-
-int
-TALER_MINT_DB_get_refresh_commit_coin (PGconn *db_conn,
-                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
-                                       int i, int j,
-                                       struct RefreshCommitCoin *commit_coin);
 
 
 struct GNUNET_CRYPTO_rsa_PublicKey *
@@ -695,6 +658,136 @@ TALER_MINT_DB_get_refresh_melt (PGconn *db_conn,
 
 
 /**
+ * We have as many `struct RefreshCommitCoin` as there are new
+ * 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.
+ */
+struct RefreshCommitCoin
+{
+
+  /**
+   * Encrypted data allowing those able to decrypt it to derive
+   * the private keys of the new coins created by the refresh.
+   */
+  struct TALER_RefreshLinkEncrypted *refresh_link;
+
+  /**
+   * Blinded message to be signed (in envelope), with @e coin_env_size bytes.
+   */
+  char *coin_ev;
+
+  /**
+   * Number of bytes in @e coin_ev.
+   */
+  size_t coin_ev_size;
+
+};
+
+
+/**
+ * Store information about the commitment of the
+ * given coin for the given refresh session in the database.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub refresh session this commitment belongs to
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to refreshed (new) coins
+ * @param commit_coin coin commitment to store
+ * @return #GNUNET_OK on success
+ *         #GNUNET_SYSERR on error
+ */
+int
+TALER_MINT_DB_insert_refresh_commit_coin (PGconn *db_conn,
+                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                          unsigned int i,
+                                          unsigned int j,
+                                          const struct RefreshCommitCoin *commit_coin);
+
+
+/**
+ * Obtain information about the commitment of the
+ * given coin of the given refresh session from the database.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub refresh session the commitment belongs to
+ * @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
+ * @return #GNUNET_OK on success
+ *         #GNUNET_NO if not found
+ *         #GNUNET_SYSERR on error
+ */
+int
+TALER_MINT_DB_get_refresh_commit_coin (PGconn *db_conn,
+                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                       unsigned int i,
+                                       unsigned int j,
+                                       struct RefreshCommitCoin *commit_coin);
+
+
+/**
+ * For each (old) coin being melted, we have a `struct
+ * RefreshCommitLink` that allows the user to find the shared secret
+ * to decrypt the respective refresh links for the new coins in the
+ * `struct RefreshCommitCoin`.
+ */
+struct RefreshCommitLink
+{
+  /**
+   * Transfer public key (FIXME: explain!)
+   */
+  struct GNUNET_CRYPTO_EcdsaPublicKey transfer_pub;
+
+  /**
+   * Encrypted shared secret to decrypt the link.
+   */
+  struct TALER_EncryptedLinkSecret shared_secret_enc;
+};
+
+
+/**
+ * Store the commitment to the given (encrypted) refresh link data
+ * for the given refresh session.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub public key of the refresh session this
+ *        commitment belongs with
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to melted (old) coins
+ * @param commit_link link information to store
+ * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
+ */
+int
+TALER_MINT_DB_insert_refresh_commit_link (PGconn *db_conn,
+                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                          unsigned int i,
+                                          unsigned int j,
+                                          const struct RefreshCommitLink *commit_link);
+
+/**
+ * Obtain the commited (encrypted) refresh link data
+ * for the given refresh session.
+ *
+ * @param db_conn database connection to use
+ * @param refresh_session_pub public key of the refresh session this
+ *        commitment belongs with
+ * @param i set index (1st dimension)
+ * @param j coin index (2nd dimension), corresponds to melted (old) coins
+ * @param cc[OUT] link information to return
+ * @return #GNUNET_SYSERR on internal error,
+ *         #GNUNET_NO if commitment was not found
+ *         #GNUNET_OK on success
+ */
+int
+TALER_MINT_DB_get_refresh_commit_link (PGconn *db_conn,
+                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
+                                       unsigned int i,
+                                       unsigned int j,
+                                       struct RefreshCommitLink *cc);
+
+
+/**
  * Specification for a /lock operation.
  */
 struct Lock
@@ -833,7 +926,4 @@ TALER_MINT_DB_free_coin_transaction_list (struct TALER_MINT_DB_TransactionList *
 
 
 
-
-
-
 #endif /* _NEURO_MINT_DB_H */
diff --git a/src/mint/taler-mint-httpd_db.c b/src/mint/taler-mint-httpd_db.c
index 2f6ca0137..39017409c 100644
--- a/src/mint/taler-mint-httpd_db.c
+++ b/src/mint/taler-mint-httpd_db.c
@@ -713,11 +713,11 @@ TALER_MINT_db_execute_refresh_melt (struct MHD_Connection *connection,
       (res = TALER_MINT_DB_get_refresh_session (db_conn,
                                                 refresh_session_pub,
                                                 &session)))
-    {
-      // FIXME: send internal error
-      GNUNET_break (0);
-      return MHD_NO;
-    }
+  {
+    // FIXME: send internal error
+    GNUNET_break (0);
+    return MHD_NO;
+  }
   return TALER_MINT_reply_refresh_melt_success (connection,
                                                 client_signature,
                                                 refresh_session_pub);
@@ -790,6 +790,14 @@ TALER_MINT_db_execute_refresh_commit (struct MHD_Connection *connection,
     return TALER_MINT_reply_arg_invalid (connection,
                                          "session_pub");
   }
+  if ( (refresh_session.kappa != kappa) ||
+       (refresh_session.num_newcoins != num_newcoins) ||
+       (refresh_session.num_oldcoins != num_oldcoins) )
+  {
+    TALER_MINT_DB_rollback (db_conn);
+    return TALER_MINT_reply_arg_invalid (connection,
+                                         "dimensions");
+  }
   if (GNUNET_YES == refresh_session.has_commit_sig)
   {
     TALER_MINT_DB_rollback (db_conn);
@@ -797,14 +805,9 @@ TALER_MINT_db_execute_refresh_commit (struct MHD_Connection *connection,
                                                    &refresh_session);
     return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
   }
-
-
-  // FIXME: this should check that kappa and num_newcoins match
-  // our expectations from refresh_session!
-
-  for (i = 0; i < refresh_session.kappa; i++)
+  for (i = 0; i < kappa; i++)
   {
-    for (j = 0; j < refresh_session.num_newcoins; j++)
+    for (j = 0; j < num_newcoins; j++)
     {
       if (GNUNET_OK !=
           TALER_MINT_DB_insert_refresh_commit_coin (db_conn,
@@ -813,12 +816,15 @@ TALER_MINT_db_execute_refresh_commit (struct MHD_Connection *connection,
                                                     j,
                                                     &commit_coin[i][j]))
       {
-        // FIXME: return 'internal error'?
-        GNUNET_break (0);
         TALER_MINT_DB_rollback (db_conn);
-        return MHD_NO;
+        return TALER_MINT_reply_internal_db_error (connection);
       }
-
+    }
+  }
+  for (i = 0; i < kappa; i++)
+  {
+    for (j = 0; j < num_oldcoins; j++)
+    {
       if (GNUNET_OK !=
           TALER_MINT_DB_insert_refresh_commit_link (db_conn,
                                                     refresh_session_pub,
@@ -826,10 +832,8 @@ TALER_MINT_db_execute_refresh_commit (struct MHD_Connection *connection,
                                                     j,
                                                     &commit_link[i][j]))
       {
-        // FIXME: return 'internal error'?
-        GNUNET_break (0);
         TALER_MINT_DB_rollback (db_conn);
-        return MHD_NO;
+        return TALER_MINT_reply_internal_db_error (connection);
       }
     }
   }