The tree has got back its original layout (i.e. getting rid of this

'melted' directory) and *a lot* of files from the mint's tree have been
imported there. The main expectation is to cut off from these imported files
as much as source code possible, which is actually not needed; although
presumably, that will regard just a small percentage of that source code.

1 files changed, 1218 insertions, 0 deletions

diff --git a/src/backend/taler_mintdb_plugin.h b/src/backend/taler_mintdb_plugin.h
new file mode 100644
index 00000000..21d83d9d
--- /dev/null
+++ b/src/backend/taler_mintdb_plugin.h
@@ -0,0 +1,1218 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file include/taler_mintdb_plugin.h
+ * @brief Low-level (statement-level) database access for the mint
+ * @author Florian Dold
+ * @author Christian Grothoff
+ */
+#ifndef TALER_MINTDB_PLUGIN_H
+#define TALER_MINTDB_PLUGIN_H
+
+#include <gnunet/gnunet_util_lib.h>
+#include "taler_mintdb_lib.h"
+
+
+/**
+ * @brief Information we keep on bank transfer(s) that established a reserve.
+ */
+struct TALER_MINTDB_BankTransfer
+{
+
+  /**
+   * Public key of the reserve that was filled.
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+  /**
+   * Amount that was transferred to the mint.
+   */
+  struct TALER_Amount amount;
+
+  /**
+   * When did the mint receive the incoming transaction?
+   * (This is the execution date of the mint's database,
+   * the execution date of the bank should be in @e wire).
+   */
+  struct GNUNET_TIME_Absolute execution_date;
+
+  /**
+   * Detailed wire information about the transaction.
+   */
+  json_t *wire;
+
+};
+
+
+/**
+ * @brief A summary of a Reserve
+ */
+struct TALER_MINTDB_Reserve
+{
+  /**
+   * The reserve's public key.  This uniquely identifies the reserve
+   */
+  struct TALER_ReservePublicKeyP pub;
+
+  /**
+   * The balance amount existing in the reserve
+   */
+  struct TALER_Amount balance;
+
+  /**
+   * The expiration date of this reserve
+   */
+  struct GNUNET_TIME_Absolute expiry;
+};
+
+
+/**
+ * @brief Information we keep for a withdrawn coin to reproduce
+ * the /withdraw operation if needed, and to have proof
+ * that a reserve was drained by this amount.
+ */
+struct TALER_MINTDB_CollectableBlindcoin
+{
+
+  /**
+   * Our signature over the (blinded) coin.
+   */
+  struct TALER_DenominationSignature sig;
+
+  /**
+   * Denomination key (which coin was generated).
+   */
+  struct TALER_DenominationPublicKey denom_pub;
+
+  /**
+   * Value of the coin being minted (matching the denomination key)
+   * plus the transaction fee.  We include this in what is being
+   * signed so that we can verify a reserve's remaining total balance
+   * without needing to access the respective denomination key
+   * information each time.
+   */
+  struct TALER_Amount amount_with_fee;
+
+  /**
+   * Withdrawl fee charged by the mint.  This must match the Mint's
+   * denomination key's withdrawl fee.  If the client puts in an
+   * invalid withdrawl fee (too high or too low) that does not match
+   * the Mint's denomination key, the withdraw operation is invalid
+   * and will be rejected by the mint.  The @e amount_with_fee minus
+   * the @e withdraw_fee is must match the value of the generated
+   * coin.  We include this in what is being signed so that we can
+   * verify a mint's accounting without needing to access the
+   * respective denomination key information each time.
+   */
+  struct TALER_Amount withdraw_fee;
+
+  /**
+   * Public key of the reserve that was drained.
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+  /**
+   * Hash over the blinded message, needed to verify
+   * the @e reserve_sig.
+   */
+  struct GNUNET_HashCode h_coin_envelope;
+
+  /**
+   * Signature confirming the withdrawl, matching @e reserve_pub,
+   * @e denom_pub and @e h_coin_envelope.
+   */
+  struct TALER_ReserveSignatureP reserve_sig;
+};
+
+
+
+/**
+ * @brief Types of operations on a reserved.
+ */
+enum TALER_MINTDB_ReserveOperation
+{
+  /**
+   * Money was deposited into the reserve via a bank transfer.
+   */
+  TALER_MINTDB_RO_BANK_TO_MINT = 0,
+
+  /**
+   * A Coin was withdrawn from the reserve using /withdraw.
+   */
+  TALER_MINTDB_RO_WITHDRAW_COIN = 1
+};
+
+
+/**
+ * @brief Reserve history as a linked list.  Lists all of the transactions
+ * associated with this reserve (such as the bank transfers that
+ * established the reserve and all /withdraw operations we have done
+ * since).
+ */
+struct TALER_MINTDB_ReserveHistory
+{
+
+  /**
+   * Next entry in the reserve history.
+   */
+  struct TALER_MINTDB_ReserveHistory *next;
+
+  /**
+   * Type of the event, determins @e details.
+   */
+  enum TALER_MINTDB_ReserveOperation type;
+
+  /**
+   * Details of the operation, depending on @e type.
+   */
+  union
+  {
+
+    /**
+     * Details about a bank transfer to the mint.
+     */
+    struct TALER_MINTDB_BankTransfer *bank;
+
+    /**
+     * Details about a /withdraw operation.
+     */
+    struct TALER_MINTDB_CollectableBlindcoin *withdraw;
+
+  } details;
+
+};
+
+
+/**
+ * @brief Specification for a /deposit operation.  The combination of
+ * the coin's public key, the merchant's public key and the
+ * transaction ID must be unique.  While a coin can (theoretically) be
+ * deposited at the same merchant twice (with partial spending), the
+ * merchant must either use a different public key or a different
+ * transaction ID for the two transactions.  The same coin must not
+ * be used twice at the same merchant for the same transaction
+ * (as determined by transaction ID).  (Note: we might want to
+ * fix #3819 and include at least h_contract as well.)
+ */
+struct TALER_MINTDB_Deposit
+{
+  /**
+   * Information about the coin that is being deposited.
+   */
+  struct TALER_CoinPublicInfo coin;
+
+  /**
+   * ECDSA signature affirming that the customer intends
+   * this coin to be deposited at the merchant identified
+   * by @e h_wire in relation to the contract identified
+   * by @e h_contract.
+   */
+  struct TALER_CoinSpendSignatureP csig;
+
+  /**
+   * Public key of the merchant.  Enables later identification
+   * of the merchant in case of a need to rollback transactions.
+   */
+  struct TALER_MerchantPublicKeyP merchant_pub;
+
+  /**
+   * Hash over the contract between merchant and customer
+   * (remains unknown to the Mint).
+   */
+  struct GNUNET_HashCode h_contract;
+
+  /**
+   * Hash of the (canonical) representation of @e wire, used
+   * to check the signature on the request.  Generated by
+   * the mint from the detailed wire data provided by the
+   * merchant.
+   */
+  struct GNUNET_HashCode h_wire;
+
+  /**
+   * Detailed wire information for executing the transaction.
+   */
+  json_t *wire;
+
+  /**
+   * Merchant-generated transaction ID to detect duplicate
+   * transactions.
+   */
+  uint64_t transaction_id;
+
+  /**
+   * Time when this request was generated.  Used, for example, to
+   * assess when (roughly) the income was achieved for tax purposes.
+   * Note that the Mint will only check that the timestamp is not "too
+   * far" into the future (i.e. several days).  The fact that the
+   * timestamp falls within the validity period of the coin's
+   * denomination key is irrelevant for the validity of the deposit
+   * request, as obviously the customer and merchant could conspire to
+   * set any timestamp.  Also, the Mint must accept very old deposit
+   * requests, as the merchant might have been unable to transmit the
+   * deposit request in a timely fashion (so back-dating is not
+   * prevented).
+   */
+  struct GNUNET_TIME_Absolute timestamp;
+
+  /**
+   * How much time does the merchant have to issue a refund request?
+   * Zero if refunds are not allowed.  After this time, the coin
+   * cannot be refunded.
+   */
+  struct GNUNET_TIME_Absolute refund_deadline;
+
+  /**
+   * Fraction of the coin's remaining value to be deposited, including
+   * depositing fee (if any).  The coin is identified by @e coin_pub.
+   */
+  struct TALER_Amount amount_with_fee;
+
+  /**
+   * Depositing fee.
+   */
+  struct TALER_Amount deposit_fee;
+
+};
+
+
+/**
+ * @brief Global information for a refreshing session.  Includes
+ * dimensions of the operation, security parameters and
+ * client signatures from "/refresh/melt" and "/refresh/commit".
+ */
+struct TALER_MINTDB_RefreshSession
+{
+
+  /**
+   * Number of coins we are melting.
+   */
+  uint16_t num_oldcoins;
+
+  /**
+   * Number of new coins we are creating.
+   */
+  uint16_t num_newcoins;
+
+  /**
+   * Index (smaller #TALER_CNC_KAPPA) which the mint has chosen to not
+   * have revealed during cut and choose.
+   */
+  uint16_t noreveal_index;
+
+};
+
+
+/**
+ * @brief Specification for coin in a /refresh/melt operation.
+ */
+struct TALER_MINTDB_RefreshMelt
+{
+  /**
+   * Information about the coin that is being melted.
+   */
+  struct TALER_CoinPublicInfo coin;
+
+  /**
+   * Signature over the melting operation.
+   */
+  struct TALER_CoinSpendSignatureP coin_sig;
+
+  /**
+   * Hash of the refresh session this coin is melted into.
+   */
+  struct GNUNET_HashCode session_hash;
+
+  /**
+   * How much value is being melted?  This amount includes the fees,
+   * so the final amount contributed to the melt is this value minus
+   * the fee for melting the coin.  We include the fee in what is
+   * being signed so that we can verify a reserve's remaining total
+   * balance without needing to access the respective denomination key
+   * information each time.
+   */
+  struct TALER_Amount amount_with_fee;
+
+  /**
+   * Melting fee charged by the mint.  This must match the Mint's
+   * denomination key's melting fee.  If the client puts in an invalid
+   * melting fee (too high or too low) that does not match the Mint's
+   * denomination key, the melting operation is invalid and will be
+   * rejected by the mint.  The @e amount_with_fee minus the @e
+   * melt_fee is the amount that will be credited to the melting
+   * session.
+   */
+  struct TALER_Amount melt_fee;
+
+};
+
+
+/**
+ * @brief We have as many `struct TALER_MINTDB_RefreshCommitCoin` as there are new
+ * coins being created by the refresh (for each of the #TALER_CNC_KAPPA
+ * sets).  These are the coins we ask the mint to sign if the
+ * respective set is selected.
+ */
+struct TALER_MINTDB_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;
+
+};
+
+
+GNUNET_NETWORK_STRUCT_BEGIN
+
+/**
+ * @brief For each (old) coin being melted, we have a `struct
+ * RefreshCommitLinkP` that allows the user to find the shared secret
+ * to decrypt the respective refresh links for the new coins in the
+ * `struct TALER_MINTDB_RefreshCommitCoin`.
+ */
+struct TALER_MINTDB_RefreshCommitLinkP
+{
+  /**
+   * Transfer public key, used to decrypt the @e shared_secret_enc
+   * in combintation with the corresponding private key of the
+   * coin.
+   */
+  struct TALER_TransferPublicKeyP transfer_pub;
+
+  /**
+   * Encrypted shared secret to decrypt the link.
+   */
+  struct TALER_EncryptedLinkSecretP shared_secret_enc;
+};
+
+GNUNET_NETWORK_STRUCT_END
+
+
+
+/**
+ * @brief Linked list of refresh information linked to a coin.
+ */
+struct TALER_MINTDB_LinkDataList
+{
+  /**
+   * Information is stored in a NULL-terminated linked list.
+   */
+  struct TALER_MINTDB_LinkDataList *next;
+
+  /**
+   * Link data, used to recover the private key of the coin
+   * by the owner of the old coin.
+   */
+  struct TALER_RefreshLinkEncrypted *link_data_enc;
+
+  /**
+   * Denomination public key, determines the value of the coin.
+   */
+  struct TALER_DenominationPublicKey denom_pub;
+
+  /**
+   * Signature over the blinded envelope.
+   */
+  struct TALER_DenominationSignature ev_sig;
+};
+
+
+/**
+ * @brief Specification for a /lock operation.
+ */
+struct TALER_MINTDB_LockOperation
+{
+  /**
+   * Information about the coin that is being locked.
+   */
+  struct TALER_CoinPublicInfo coin;
+
+  /**
+   * Signature over the locking operation.
+   */
+  struct TALER_CoinSpendSignatureP coin_sig;
+
+  /**
+   * How much value is being locked?
+   */
+  struct TALER_Amount amount;
+
+  // FIXME: more needed...
+};
+
+
+/**
+ * @brief Enumeration to classify the different types of transactions
+ * that can be done with a coin.
+ */
+enum TALER_MINTDB_TransactionType
+{
+  /**
+   * /deposit operation.
+   */
+  TALER_MINTDB_TT_DEPOSIT = 0,
+
+  /**
+   * /refresh/melt operation.
+   */
+  TALER_MINTDB_TT_REFRESH_MELT = 1,
+
+  /**
+   * /lock operation.
+   */
+  TALER_MINTDB_TT_LOCK = 2
+};
+
+
+/**
+ * @brief List of transactions we performed for a particular coin.
+ */
+struct TALER_MINTDB_TransactionList
+{
+
+  /**
+   * Next pointer in the NULL-terminated linked list.
+   */
+  struct TALER_MINTDB_TransactionList *next;
+
+  /**
+   * Type of the transaction, determines what is stored in @e details.
+   */
+  enum TALER_MINTDB_TransactionType type;
+
+  /**
+   * Details about the transaction, depending on @e type.
+   */
+  union
+  {
+
+    /**
+     * Details if transaction was a /deposit operation.
+     */
+    struct TALER_MINTDB_Deposit *deposit;
+
+    /**
+     * Details if transaction was a /refresh/melt operation.
+     */
+    struct TALER_MINTDB_RefreshMelt *melt;
+
+    /**
+     * Details if transaction was a /lock operation.
+     */
+    struct TALER_MINTDB_LockOperation *lock;
+
+  } details;
+
+};
+
+
+/**
+ * @brief All of the information from a /refresh/melt commitment.
+ */
+struct TALER_MINTDB_MeltCommitment
+{
+
+  /**
+   * Number of coins we are melting.
+   */
+  uint16_t num_oldcoins;
+
+  /**
+   * Number of new coins we are creating.
+   */
+  uint16_t num_newcoins;
+
+  /**
+   * Array of @e num_oldcoins melt operation details.
+   */
+  struct TALER_MINTDB_RefreshMelt *melts;
+
+  /**
+   * Array of @e num_newcoins denomination keys
+   */
+  struct TALER_DenominationPublicKey *denom_pubs;
+
+  /**
+   * 2D-Array of #TALER_CNC_KAPPA and @e num_newcoins commitments.
+   */
+  struct TALER_MINTDB_RefreshCommitCoin *commit_coins[TALER_CNC_KAPPA];
+
+  /**
+   * 2D-Array of #TALER_CNC_KAPPA and @e new_oldcoins links.
+   */
+  struct TALER_MINTDB_RefreshCommitLinkP *commit_links[TALER_CNC_KAPPA];
+};
+
+
+/**
+ * @brief Handle for a database session (per-thread, for transactions).
+ */
+struct TALER_MINTDB_Session;
+
+
+/**
+ * Function called with the session hashes and transfer secret
+ * information for a given coin.
+ *
+ * @param cls closure
+ * @param session_hash a session the coin was melted in
+ * @param transfer_pub public transfer key for the session
+ * @param shared_secret_enc set to shared secret for the session
+ */
+typedef void
+(*TALER_MINTDB_TransferDataCallback)(void *cls,
+                                     const struct GNUNET_HashCode *session_hash,
+                                     const struct TALER_TransferPublicKeyP *transfer_pub,
+                                     const struct TALER_EncryptedLinkSecretP *shared_secret_enc);
+
+
+/**
+ * @brief The plugin API, returned from the plugin's "init" function.
+ * The argument given to "init" is simply a configuration handle.
+ */
+struct TALER_MINTDB_Plugin
+{
+
+  /**
+   * Closure for all callbacks.
+   */
+  void *cls;
+
+  /**
+   * Name of the library which generated this plugin.  Set by the
+   * plugin loader.
+   */
+  char *library_name;
+
+  /**
+   * Get the thread-local database-handle.
+   * Connect to the db if the connection does not exist yet.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param temporary #GNUNET_YES to use a temporary schema; #GNUNET_NO to use the
+   *        database default one
+   * @param the database connection, or NULL on error
+   */
+  struct TALER_MINTDB_Session *
+  (*get_session) (void *cls,
+                  int temporary);
+
+
+  /**
+   * Drop the temporary taler schema.  This is only useful for testcases.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure
+   */
+  int
+  (*drop_temporary) (void *cls,
+                     struct TALER_MINTDB_Session *db);
+
+
+  /**
+   * Create the necessary tables if they are not present
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param temporary should we use a temporary schema
+   * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure
+   */
+  int
+  (*create_tables) (void *cls,
+                    int temporary);
+
+
+  /**
+   * Start a transaction.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @return #GNUNET_OK on success
+   */
+  int
+  (*start) (void *cls,
+            struct TALER_MINTDB_Session *session);
+
+
+  /**
+   * Commit a transaction.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to use
+   * @return #GNUNET_OK on success
+   */
+  int
+  (*commit) (void *cls,
+             struct TALER_MINTDB_Session *sesssion);
+
+
+  /**
+   * Abort/rollback a transaction.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to use
+   */
+  void
+  (*rollback) (void *cls,
+               struct TALER_MINTDB_Session *sesssion);
+
+
+  /**
+   * Insert information about a denomination key and in particular
+   * the properties (value, fees, expiration times) the coins signed
+   * with this key have.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to use
+   * @param denom_pub the public key used for signing coins of this denomination
+   * @param issue issuing information with value, fees and other info about the coin
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_denomination_info) (void *cls,
+                               struct TALER_MINTDB_Session *session,
+                               const struct TALER_DenominationPublicKey *denom_pub,
+                               const struct TALER_MINTDB_DenominationKeyInformationP *issue);
+
+
+  /**
+   * Fetch information about a denomination key.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to use
+   * @param denom_pub the public key used for signing coins of this denomination
+   * @param[out] issue set to issue information with value, fees and other info about the coin, can be NULL
+   * @return #GNUNET_OK on success; #GNUNET_NO if no record was found, #GNUNET_SYSERR on failure
+   */
+  int
+  (*get_denomination_info) (void *cls,
+                            struct TALER_MINTDB_Session *session,
+                            const struct TALER_DenominationPublicKey *denom_pub,
+                            struct TALER_MINTDB_DenominationKeyInformationP *issue);
+
+
+  /**
+   * Get the summary of a reserve.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param db the database connection handle
+   * @param[in,out] reserve the reserve data.  The public key of the reserve should be set
+   *          in this structure; it is used to query the database.  The balance
+   *          and expiration are then filled accordingly.
+   * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure
+   */
+  int
+  (*reserve_get) (void *cls,
+                  struct TALER_MINTDB_Session *db,
+                  struct TALER_MINTDB_Reserve *reserve);
+
+
+  /**
+   * Insert a incoming transaction into reserves.  New reserves are
+   * also created through this function.  Note that this API call
+   * starts (and stops) its own transaction scope (so the application
+   * must not do so).
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param db the database connection handle
+   * @param reserve_pub public key of the reserve
+   * @param balance the amount that has to be added to the reserve
+   * @param execution_time when was the amount added
+   * @param details bank transaction details justifying the increment,
+   *        must be unique for each incoming transaction
+   * @return #GNUNET_OK upon success; #GNUNET_NO if the given
+   *         @a details are already known for this @a reserve_pub,
+   *         #GNUNET_SYSERR upon failures (DB error, incompatible currency)
+   */
+  int
+  (*reserves_in_insert) (void *cls,
+                         struct TALER_MINTDB_Session *db,
+                         const struct TALER_ReservePublicKeyP *reserve_pub,
+                         const struct TALER_Amount *balance,
+                         struct GNUNET_TIME_Absolute execution_time,
+                         const json_t *details);
+
+
+  /**
+   * Locate the response for a /withdraw request under the
+   * key of the hash of the blinded message.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param h_blind hash of the blinded coin to be signed (will match
+   *                `h_coin_envelope` in the @a collectable to be returned)
+   * @param collectable corresponding collectable coin (blind signature)
+   *                    if a coin is found
+   * @return #GNUNET_SYSERR on internal error
+   *         #GNUNET_NO if the collectable was not found
+   *         #GNUNET_YES on success
+   */
+  int
+  (*get_withdraw_info) (void *cls,
+                        struct TALER_MINTDB_Session *sesssion,
+                        const struct GNUNET_HashCode *h_blind,
+                        struct TALER_MINTDB_CollectableBlindcoin *collectable);
+
+
+  /**
+   * Store collectable bit coin under the corresponding
+   * hash of the blinded message.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param collectable corresponding collectable coin (blind signature)
+   *                    if a coin is found
+   * @return #GNUNET_SYSERR on internal error
+   *         #GNUNET_NO if the collectable was not found
+   *         #GNUNET_YES on success
+   */
+  int
+  (*insert_withdraw_info) (void *cls,
+                           struct TALER_MINTDB_Session *sesssion,
+                           const struct TALER_MINTDB_CollectableBlindcoin *collectable);
+
+
+  /**
+   * Get all of the transaction history associated with the specified
+   * reserve.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to use
+   * @param reserve_pub public key of the reserve
+   * @return known transaction history (NULL if reserve is unknown)
+   */
+  struct TALER_MINTDB_ReserveHistory *
+  (*get_reserve_history) (void *cls,
+                          struct TALER_MINTDB_Session *sesssion,
+                          const struct TALER_ReservePublicKeyP *reserve_pub);
+
+
+  /**
+   * Free memory associated with the given reserve history.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param rh history to free.
+   */
+  void
+  (*free_reserve_history) (void *cls,
+                           struct TALER_MINTDB_ReserveHistory *rh);
+
+
+  /**
+   * Check if we have the specified deposit already in the database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param deposit deposit to search for
+   * @return #GNUNET_YES if we know this operation,
+   *         #GNUNET_NO if this deposit is unknown to us,
+   *         #GNUNET_SYSERR on DB error or if same coin(pub), merchant(pub) and
+   *                        transaction ID are already in DB, but for different
+   *                        other transaction details (contract, wiring details,
+   *                        amount, etc.)
+   */
+  int
+  (*have_deposit) (void *cls,
+                   struct TALER_MINTDB_Session *sesssion,
+                   const struct TALER_MINTDB_Deposit *deposit);
+
+
+  /**
+   * Insert information about deposited coin into the
+   * database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion connection to the database
+   * @param deposit deposit information to store
+   * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+   */
+  int
+  (*insert_deposit) (void *cls,
+                     struct TALER_MINTDB_Session *sesssion,
+                     const struct TALER_MINTDB_Deposit *deposit);
+
+
+  /**
+   * 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 session_hash hash over the melt to use for the lookup
+   * @param[out] refresh_session where to store the result
+   * @return #GNUNET_YES on success,
+   *         #GNUNET_NO if not found,
+   *         #GNUNET_SYSERR on DB failure
+   */
+  int
+  (*get_refresh_session) (void *cls,
+                          struct TALER_MINTDB_Session *sesssion,
+                          const struct GNUNET_HashCode *session_hash,
+                          struct TALER_MINTDB_RefreshSession *refresh_session);
+
+
+  /**
+   * 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 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
+   */
+  int
+  (*create_refresh_session) (void *cls,
+                             struct TALER_MINTDB_Session *sesssion,
+                             const struct GNUNET_HashCode *session_hash,
+                             const struct TALER_MINTDB_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 oldcoin_index index of the coin 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,
+                          uint16_t oldcoin_index,
+                          const struct TALER_MINTDB_RefreshMelt *melt);
+
+
+  /**
+   * Get information about melted coin details from the database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param session_hash hash to identify refresh session
+   * @param oldcoin_index index of the coin to retrieve
+   * @param melt melt data to fill in, can be NULL
+   * @return #GNUNET_OK on success
+   *         #GNUNET_SYSERR on internal error
+   */
+  int
+  (*get_refresh_melt) (void *cls,
+                       struct TALER_MINTDB_Session *sesssion,
+                       const struct GNUNET_HashCode *session_hash,
+                       uint16_t oldcoin_index,
+                       struct TALER_MINTDB_RefreshMelt *melt);
+
+
+  /**
+   * Store in the database which coin(s) we want to create
+   * in a given refresh operation.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @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
+   *         #GNUNET_SYSERR on internal error
+   */
+  int
+  (*insert_refresh_order) (void *cls,
+                           struct TALER_MINTDB_Session *sesssion,
+                           const struct GNUNET_HashCode *session_hash,
+                           uint16_t num_newcoins,
+                           const struct TALER_DenominationPublicKey *denom_pubs);
+
+
+  /**
+   * Lookup in the database for the @a num_newcoins coins that we want to
+   * create in the given refresh operation.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param session_hash hash to identify refresh session
+   * @param num_newcoins size of the @a denom_pubs array
+   * @param[out] denom_pubs where to write @a num_newcoins denomination keys
+   * @return #GNUNET_OK on success
+   *         #GNUNET_SYSERR on internal error
+   */
+  int
+  (*get_refresh_order) (void *cls,
+                        struct TALER_MINTDB_Session *sesssion,
+                        const struct GNUNET_HashCode *session_hash,
+                        uint16_t num_newcoins,
+                        struct TALER_DenominationPublicKey *denom_pubs);
+
+
+  /**
+   * Store information about the commitments of the given index @a i
+   * for the given refresh session in the database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param session_hash hash to identify refresh session
+   * @param cnc_index cut and choose index (1st dimension), relating to #TALER_CNC_KAPPA
+   * @param num_newcoins coin index size of the @a commit_coins array
+   * @param commit_coin array of coin commitments to store
+   * @return #GNUNET_OK on success
+   *         #GNUNET_SYSERR on error
+   */
+  int
+  (*insert_refresh_commit_coins) (void *cls,
+                                  struct TALER_MINTDB_Session *sesssion,
+                                  const struct GNUNET_HashCode *session_hash,
+                                  uint16_t cnc_index,
+                                  uint16_t num_newcoins,
+                                  const struct TALER_MINTDB_RefreshCommitCoin *commit_coins);
+
+
+  /**
+   * Obtain information about the commitment of the
+   * given coin of the given refresh session from the database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param session_hash hash to identify refresh session
+   * @param cnc_index cut and choose set index (1st dimension)
+   * @param num_coins size of the @a commit_coins array
+   * @param[out] commit_coins array of coin commitments to return
+   * @return #GNUNET_OK on success
+   *         #GNUNET_NO if not found
+   *         #GNUNET_SYSERR on error
+   */
+  int
+  (*get_refresh_commit_coins) (void *cls,
+                               struct TALER_MINTDB_Session *sesssion,
+                               const struct GNUNET_HashCode *session_hash,
+                               uint16_t cnc_index,
+                               uint16_t num_coins,
+                               struct TALER_MINTDB_RefreshCommitCoin *commit_coins);
+
+
+  /**
+   * Store the commitment to the given (encrypted) refresh link data
+   * for the given refresh session.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param session_hash hash to identify refresh session
+   * @param cnc_index cut and choose index (1st dimension), relating to #TALER_CNC_KAPPA
+   * @param num_links size of the @a commit_link array
+   * @param commit_links array of link information to store
+   * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
+   */
+  int
+  (*insert_refresh_commit_links) (void *cls,
+                                  struct TALER_MINTDB_Session *sesssion,
+                                  const struct GNUNET_HashCode *session_hash,
+                                  uint16_t cnc_index,
+                                  uint16_t num_links,
+                                  const struct TALER_MINTDB_RefreshCommitLinkP *commit_links);
+
+  /**
+   * Obtain the commited (encrypted) refresh link data
+   * for the given refresh session.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param session_hash hash to identify refresh session
+   * @param cnc_index cut and choose index (1st dimension)
+   * @param num_links size of the @a links array to return
+   * @param[out] links array link information to return
+   * @return #GNUNET_SYSERR on internal error,
+   *         #GNUNET_NO if commitment was not found
+   *         #GNUNET_OK on success
+   */
+  int
+  (*get_refresh_commit_links) (void *cls,
+                               struct TALER_MINTDB_Session *sesssion,
+                               const struct GNUNET_HashCode *session_hash,
+                               uint16_t cnc_index,
+                               uint16_t num_links,
+                               struct TALER_MINTDB_RefreshCommitLinkP *links);
+
+
+  /**
+   * Get all of the information from the given melt commit operation.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection to use
+   * @param session_hash hash to identify refresh session
+   * @return NULL if the @a session_hash does not correspond to any known melt
+   *         operation
+   */
+  struct TALER_MINTDB_MeltCommitment *
+  (*get_melt_commitment) (void *cls,
+                          struct TALER_MINTDB_Session *sesssion,
+                          const struct GNUNET_HashCode *session_hash);
+
+
+  /**
+   * Free information about a melt commitment.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param mc melt commitment data to free
+   */
+  void
+  (*free_melt_commitment) (void *cls,
+                           struct TALER_MINTDB_MeltCommitment *mc);
+
+
+  /**
+   * Insert signature of a new coin generated during refresh into
+   * the database indexed by the refresh session and the index
+   * of the coin.  This data is later used should an old coin
+   * be used to try to obtain the private keys during "/refresh/link".
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param session_hash hash to identify refresh session
+   * @param newcoin_index coin index
+   * @param ev_sig coin signature
+   * @return #GNUNET_OK on success
+   */
+  int
+  (*insert_refresh_out) (void *cls,
+                                 struct TALER_MINTDB_Session *sesssion,
+                                 const struct GNUNET_HashCode *session_hash,
+                                 uint16_t newcoin_index,
+                                 const struct TALER_DenominationSignature *ev_sig);
+
+
+  /**
+   * Obtain the link data of a coin, that is the encrypted link
+   * information, the denomination keys and the signatures.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param session_hash session to get linkage data for
+   * @return all known link data for the session
+   */
+  struct TALER_MINTDB_LinkDataList *
+  (*get_link_data_list) (void *cls,
+                         struct TALER_MINTDB_Session *sesssion,
+                         const struct GNUNET_HashCode *session_hash);
+
+
+  /**
+   * Free memory of the link data list.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param ldl link data list to release
+   */
+  void
+  (*free_link_data_list) (void *cls,
+                          struct TALER_MINTDB_LinkDataList *ldl);
+
+
+  /**
+   * Obtain shared secret and transfer public key from the public key of
+   * the coin.  This information and the link information returned by
+   * @e get_link_data_list() enable the owner of an old coin to determine
+   * the private keys of the new coins after the melt.
+   *
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param coin_pub public key of the coin
+   * @param tdc function to call for each session the coin was melted into
+   * @param tdc_cls closure for @a tdc
+   * @return #GNUNET_OK on success,
+   *         #GNUNET_NO on failure (not found)
+   *         #GNUNET_SYSERR on internal failure (database issue)
+   */
+  int
+  (*get_transfer) (void *cls,
+                   struct TALER_MINTDB_Session *sesssion,
+                   const struct TALER_CoinSpendPublicKeyP *coin_pub,
+                   TALER_MINTDB_TransferDataCallback tdc,
+                   void *tdc_cls);
+
+
+
+  /**
+   * Test if the given /lock request is known to us.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param lock lock operation
+   * @return #GNUNET_YES if known,
+   *         #GNUNET_NO if not,
+   *         #GNUNET_SYSERR on internal error
+   */
+  int
+  (*have_lock) (void *cls,
+                struct TALER_MINTDB_Session *sesssion,
+                const struct TALER_MINTDB_LockOperation *lock);
+
+
+  /**
+   * Store the given /lock request in the database.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param lock lock operation
+   * @return #GNUNET_OK on success
+   *         #GNUNET_SYSERR on internal error
+   */
+  int
+  (*insert_lock) (void *cls,
+                  struct TALER_MINTDB_Session *sesssion,
+                  const struct TALER_MINTDB_LockOperation *lock);
+
+
+  /**
+   * Compile a list of all (historic) transactions performed
+   * with the given coin (/refresh/melt and /deposit operations).
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param sesssion database connection
+   * @param coin_pub coin to investigate
+   * @return list of transactions, NULL if coin is fresh
+   */
+  struct TALER_MINTDB_TransactionList *
+  (*get_coin_transactions) (void *cls,
+                            struct TALER_MINTDB_Session *sesssion,
+                            const struct TALER_CoinSpendPublicKeyP *coin_pub);
+
+
+  /**
+   * Free linked list of transactions.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param list list to free
+   */
+  void
+  (*free_coin_transaction_list) (void *cls,
+                                 struct TALER_MINTDB_TransactionList *list);
+
+
+};
+
+
+#endif /* _NEURO_MINT_DB_H */