Changing configuration structure to enable multiple accounts.

This change enables using multiple wire plugins at the same time.
Also, we now distinguish between the wire plugin (i.e. EBICS or
taler_bank) and the wire method (i.e. SEPA or x-taler-bank) that
the wire plugin is implementing.  The "taler-bank" wire method
was renamed from "test" to "x-taler-bank".

This also changes the format of the /wire response of the exchange,
as we now need to return multiple accounts.  Note that wire fees
are specified per wire method, not per wire account.

taler-exchange-keyup now automatically signs all of the /wire
responses in the location specified by the configuration.

Account identification in wire plugins was changed to use
payto://-URLs instead of method-specific JSON fields.  Signing
and validation of /wire responses was moved from each wire
plugin to a generic validation method in libtalerutil (crypto)
or libtalerjson (for JSON-formatted inputs).
Convenience methods were added to generate JSON for wire accounts
(salting, signing).

Various section and option names were adjusted to streamline the
configuration and make it more consistent overall.  Documentation
was updated as well.

12 files changed, 362 insertions, 166 deletions

diff --git a/src/include/taler_auditordb_plugin.h b/src/include/taler_auditordb_plugin.h
index 80974cca0..cc583e8e7 100644
--- a/src/include/taler_auditordb_plugin.h
+++ b/src/include/taler_auditordb_plugin.h
@@ -382,6 +382,7 @@ struct TALER_AUDITORDB_Plugin
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param session connection to use
    * @param master_pub master key of the exchange
+   * @param account_name name of the wire account we are auditing
    * @param pp where is the auditor in processing
    * @param in_wire_off how far are we in the incoming wire transaction history
    * @param out_wire_off how far are we in the outgoing wire transaction history
@@ -392,6 +393,7 @@ struct TALER_AUDITORDB_Plugin
   (*insert_wire_auditor_progress)(void *cls,
                                   struct TALER_AUDITORDB_Session *session,
                                   const struct TALER_MasterPublicKeyP *master_pub,
+                                  const char *account_name,
                                   const struct TALER_AUDITORDB_WireProgressPoint *pp,
                                   const void *in_wire_off,
                                   const void *out_wire_off,
@@ -405,6 +407,7 @@ struct TALER_AUDITORDB_Plugin
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param session connection to use
    * @param master_pub master key of the exchange
+   * @param account_name name of the wire account we are auditing
    * @param pp where is the auditor in processing
    * @param in_wire_off how far are we in the incoming wire transaction history
    * @param out_wire_off how far are we in the outgoing wire transaction history
@@ -415,6 +418,7 @@ struct TALER_AUDITORDB_Plugin
   (*update_wire_auditor_progress)(void *cls,
                                   struct TALER_AUDITORDB_Session *session,
                                   const struct TALER_MasterPublicKeyP *master_pub,
+                                  const char *account_name,
                                   const struct TALER_AUDITORDB_WireProgressPoint *pp,
                                   const void *in_wire_off,
                                   const void *out_wire_off,
@@ -428,6 +432,7 @@ struct TALER_AUDITORDB_Plugin
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param session connection to use
    * @param master_pub master key of the exchange
+   * @param account_name name of the wire account we are auditing
    * @param[out] pp set to where the auditor is in processing
    * @param[out] in_wire_off how far are we in the incoming wire transaction history
    * @param[out] out_wire_off how far are we in the outgoing wire transaction history
@@ -438,6 +443,7 @@ struct TALER_AUDITORDB_Plugin
   (*get_wire_auditor_progress)(void *cls,
                                struct TALER_AUDITORDB_Session *session,
                                const struct TALER_MasterPublicKeyP *master_pub,
+                               const char *account_name,
                                struct TALER_AUDITORDB_WireProgressPoint *pp,
                                void **in_wire_off,
                                void **out_wire_off,
diff --git a/src/include/taler_bank_service.h b/src/include/taler_bank_service.h
index bfa050336..1cad5710a 100644
--- a/src/include/taler_bank_service.h
+++ b/src/include/taler_bank_service.h
@@ -217,9 +217,9 @@ struct TALER_BANK_TransferDetails
   char *wire_transfer_subject;
 
   /**
-   * The other account that was involved
+   * payto://-URL of the other account that was involved
    */
-  json_t *account_details;
+  char *account_url;
 };
 
 
@@ -347,4 +347,29 @@ void
 TALER_BANK_reject_cancel (struct TALER_BANK_RejectHandle *rh);
 
 
+/**
+ * Convenience method for parsing configuration section with bank
+ * authentication data.  The section must contain an option
+ * "METHOD", plus other options that depend on the METHOD specified.
+ *
+ * @param cfg configuration to parse
+ * @param section the section with the configuration data
+ * @param auth[out] set to the configuration data found
+ * @return #GNUNET_OK on success
+ */
+int
+TALER_BANK_auth_parse_cfg (const struct GNUNET_CONFIGURATION_Handle *cfg,
+                           const char *section,
+                           struct TALER_BANK_AuthenticationData *auth);
+
+
+/**
+ * Free memory inside of @a auth (but not auth itself).
+ * Dual to #TALER_BANK_auth_parse_cfg().
+ *
+ * @param auth authentication data to free
+ */
+void
+TALER_BANK_auth_free (struct TALER_BANK_AuthenticationData *auth);
+
 #endif  /* _TALER_BANK_SERVICE_H */
diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index d45e7bb28..b22c55ce3 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014, 2015, 2016, 2017 Taler Systems SA
+  Copyright (C) 2014-2018 Taler Systems SA
 
   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
@@ -730,4 +730,51 @@ TALER_refresh_get_commitment (struct TALER_RefreshCommitmentP *rc,
                               const struct TALER_Amount *amount_with_fee);
 
 
+/* **************** /wire account offline signing **************** */
+
+
+/**
+ * Compute the hash of the given wire details.   The resulting
+ * hash is what is put into the contract.
+ *
+ * @param payto_url bank account
+ * @param salt salt used to eliminate brute-force inversion
+ * @param hc[out] set to the hash
+ */
+void
+TALER_wire_signature_hash (const char *payto_url,
+                           const char *salt,
+                           struct GNUNET_HashCode *hc);
+
+/**
+ * Check the signature in @a wire_s.
+ *
+ * @param payto_url URL that is signed
+ * @param salt the salt used to salt the @a payto_url when hashing
+ * @param master_pub master public key of the exchange
+ * @param master_sig signature of the exchange
+ * @return #GNUNET_OK if signature is valid
+ */
+int
+TALER_wire_signature_check (const char *payto_url,
+                            const char *salt,
+                            const struct TALER_MasterPublicKeyP *master_pub,
+                            const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Create a signed wire statement for the given account.
+ *
+ * @param payto_url account specification
+ * @param salt the salt used to salt the @a payto_url when hashing
+ * @param master_priv private key to sign with
+ * @param master_sig[out] where to write the signature
+ */
+void
+TALER_wire_signature_make (const char *payto_url,
+                           const char *salt,
+                           const struct TALER_MasterPrivateKeyP *master_priv,
+                           struct TALER_MasterSignatureP *master_sig);
+
+
 #endif
diff --git a/src/include/taler_error_codes.h b/src/include/taler_error_codes.h
index 1a20889d8..dbde04df1 100644
--- a/src/include/taler_error_codes.h
+++ b/src/include/taler_error_codes.h
@@ -165,7 +165,15 @@ enum TALER_ErrorCode
    */
   TALER_EC_INTERNAL_LOGIC_ERROR = 1011,
 
+  /**
+   * The method specified in a payto:// URL is not one we expected.
+   */
+  TALER_EC_PAYTO_WRONG_METHOD = 1012,
 
+  /**
+   * The PAYTO URL is malformed.
+   */
+  TALER_EC_PAYTO_MALFORMED = 1013,
 
   /* ********** request-specific error codes ************* */
 
@@ -1535,6 +1543,20 @@ enum TALER_ErrorCode
    */
   TALER_EC_TEST_RSA_SIGN_ERROR = 4005,
 
+
+  /**
+   * The JSON in the server's response was malformed.  This response
+   * is provided with HTTP status code of 0.
+   */
+  TALER_EC_SERVER_JSON_INVALID = 5000,
+
+  /**
+   * A signature in the server's response was malformed.  This response
+   * is provided with HTTP status code of 0.
+   */
+  TALER_EC_SERVER_SIGNATURE_INVALID = 5001,
+
+
   /* *************** Taler BANK/FAKEBANK error codes *************** */
 
   /**
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index 30ea4ce66..22ca049eb 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -472,40 +472,32 @@ struct TALER_EXCHANGE_WireAggregateFees
 
 
 /**
- * Function called with information about the wire fees
- * for each wire method.
- *
- * @param cls closure
- * @param wire_method name of the wire method (i.e. "sepa")
- * @param fees fee structure for this method
+ * Information about a wire account of the exchange.
  */
-typedef void
-(*TALER_EXCHANGE_WireFeeCallback)(void *cls,
-                                  const char *wire_method,
-                                  const struct TALER_EXCHANGE_WireAggregateFees *fees);
+struct TALER_EXCHANGE_WireAccount
+{
+  /**
+   * payto://-URL of the exchange.
+   */
+  const char *url;
 
+  /**
+   * Salt used to generate @e master_sig.
+   */
+  const char *salt;
 
-/**
- * Obtain information about wire fees encoded in @a obj
- * by wire method.
- *
- * @param master_pub public key to use to verify signatures, NULL to not verify
- * @param obj wire information as encoded in the #TALER_EXCHANGE_WireResultCallback
- * @param cb callback to invoke for the fees
- * @param cb_cls closure for @a cb
- * @return #GNUNET_OK in success, #GNUNET_SYSERR if @a obj is ill-formed
- */
-int
-TALER_EXCHANGE_wire_get_fees (const struct TALER_MasterPublicKeyP *master_pub,
-                              const json_t *obj,
-                              TALER_EXCHANGE_WireFeeCallback cb,
-                              void *cb_cls);
+  /**
+   * Signature of the exchange over the account (was checked by the API).
+   */
+  struct TALER_MasterSignatureP master_sig;
 
+  /**
+   * Linked list of wire fees the exchange charges for
+   * accounts of the wire method matching @e url.
+   */
+  const struct TALER_EXCHANGE_WireAggregateFees *fees;
 
-/**
- * @brief A Wire format inquiry handle
- */
-struct TALER_EXCHANGE_WireHandle;
+};
 
 
 /**
@@ -519,15 +511,21 @@ struct TALER_EXCHANGE_WireHandle;
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful request;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
  * @param ec taler-specific error code, #TALER_EC_NONE on success
- * @param obj the received JSON reply, if successful this should be the wire
- *            format details as provided by /wire, or NULL if the
- *            reply was not in JSON format.
+ * @param accounts_len length of the @a accounts array
+ * @param accounts list of wire accounts of the exchange, NULL on error
  */
 typedef void
 (*TALER_EXCHANGE_WireResultCallback) (void *cls,
                                       unsigned int http_status,
 				      enum TALER_ErrorCode ec,
-                                      const json_t *obj);
+                                      unsigned int accounts_len,
+                                      const struct TALER_EXCHANGE_WireAccount *accounts);
+
+
+/**
+ * @brief A Wire format inquiry handle
+ */
+struct TALER_EXCHANGE_WireHandle;
 
 
 /**
@@ -843,9 +841,9 @@ struct TALER_EXCHANGE_ReserveHistory
      */
     struct {
       /**
-       * Sender account information for the incoming transfer.
+       * Sender account payto://-URL of the incoming transfer.
        */
-      json_t *sender_account_details;
+      char *sender_url;
 
       /**
        * Information that uniquely identifies the wire transfer.
diff --git a/src/include/taler_exchangedb_lib.h b/src/include/taler_exchangedb_lib.h
index e4284c27f..b89dd087d 100644
--- a/src/include/taler_exchangedb_lib.h
+++ b/src/include/taler_exchangedb_lib.h
@@ -406,4 +406,72 @@ TALER_EXCHANGEDB_fees_write (const char *filename,
 void
 TALER_EXCHANGEDB_fees_free (struct TALER_EXCHANGEDB_AggregateFees *af);
 
+
+/**
+ * Information about an account from the configuration.
+ */
+struct TALER_EXCHANGEDB_AccountInfo
+{
+  /**
+   * Section in the configuration file that specifies the
+   * account. Must start with "account-".
+   */
+  const char *section_name;
+
+  /**
+   * Name of the wire plugin that should be used to access
+   * the account.
+   */
+  const char *plugin_name;
+
+  /**
+   * payto://-URL of the account.
+   */
+  const char *payto_url;
+
+  /**
+   * Filename containing the signed /wire response, or NULL
+   * if not given.
+   */
+  const char *wire_response_filename;
+
+  /**
+   * #GNUNET_YES if this account is enabed to be debited
+   * by the taler-exchange-aggregator.
+   */
+  int debit_enabled;
+
+  /**
+   * #GNUNET_YES if this account is enabed to be credited by wallets
+   * and needs to be watched by the taler-exchange-wirewatch.
+   * Also, the account will only be included in /wire if credit
+   * is enabled.
+   */
+  int credit_enabled;
+};
+
+
+/**
+ * Function called with information about a wire account.
+ *
+ * @param cls closure
+ * @param ai account information
+ */
+typedef void
+(*TALER_EXCHANGEDB_AccountCallback)(void *cls,
+                                    const struct TALER_EXCHANGEDB_AccountInfo *ai);
+
+/**
+ * Parse the configuration to find account information.
+ *
+ * @param cfg configuration to use
+ * @param cb callback to invoke
+ * @param cb_cls closure for @a cb
+ */
+void
+TALER_EXCHANGEDB_find_accounts (const struct GNUNET_CONFIGURATION_Handle *cfg,
+                                TALER_EXCHANGEDB_AccountCallback cb,
+                                void *cb_cls);
+
+
 #endif
diff --git a/src/include/taler_exchangedb_plugin.h b/src/include/taler_exchangedb_plugin.h
index 33677559a..0d6f9cd90 100644
--- a/src/include/taler_exchangedb_plugin.h
+++ b/src/include/taler_exchangedb_plugin.h
@@ -21,7 +21,6 @@
  */
 #ifndef TALER_EXCHANGEDB_PLUGIN_H
 #define TALER_EXCHANGEDB_PLUGIN_H
-
 #include <jansson.h>
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_db_lib.h>
@@ -52,9 +51,10 @@ struct TALER_EXCHANGEDB_BankTransfer
   struct GNUNET_TIME_Absolute execution_date;
 
   /**
-   * Detailed wire information about the sending account.
+   * Detailed wire information about the sending account
+   * in "payto://" format.
    */
-  json_t *sender_account_details;
+  char *sender_account_details;
 
   /**
    * Data uniquely identifying the wire transfer (wire transfer-type specific)
@@ -97,9 +97,10 @@ struct TALER_EXCHANGEDB_ClosingTransfer
   struct GNUNET_TIME_Absolute execution_date;
 
   /**
-   * Detailed wire information about the receiving account.
+   * Detailed wire information about the receiving account
+   * in payto://-format.
    */
-  json_t *receiver_account_details;
+  char *receiver_account_details;
 
   /**
    * Detailed wire transfer information that uniquely identifies the
@@ -361,6 +362,7 @@ struct TALER_EXCHANGEDB_Deposit
 
   /**
    * Detailed information about the receiver for executing the transaction.
+   * Includes URL in payto://-format and salt.
    */
   json_t *receiver_wire_account;
 
@@ -638,7 +640,8 @@ struct TALER_EXCHANGEDB_Session;
  * @param h_contract_terms hash of the proposal data known to merchant and customer
  * @param wire_deadline by which the merchant adviced that he would like the
  *        wire transfer to be executed
- * @param receiver_wire_account wire details for the merchant, NULL from iterate_matching_deposits()
+ * @param receiver_wire_account wire details for the merchant, includes
+ *        'url' in payto://-format; NULL from iterate_matching_deposits()
  * @return transaction status code, #GNUNET_DB_STATUS_SUCCESS_ONE_RESULT to continue to iterate
  */
 typedef enum GNUNET_DB_QueryStatus
@@ -687,7 +690,8 @@ typedef void
  *        to get a refund
  * @param wire_deadline by which the merchant adviced that he would like the
  *        wire transfer to be executed
- * @param receiver_wire_account wire details for the merchant, NULL from iterate_matching_deposits()
+ * @param receiver_wire_account wire details for the merchant including 'url' in payto://-format;
+ *        NULL from iterate_matching_deposits()
  * @param done flag set if the deposit was already executed (or not)
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
@@ -837,7 +841,7 @@ typedef int
  * @param rowid unique serial ID for the refresh session in our DB
  * @param reserve_pub public key of the reserve (also the WTID)
  * @param credit amount that was received
- * @param sender_account_details information about the sender's bank account
+ * @param sender_account_details information about the sender's bank account, in payto://-format
  * @param wire_reference unique identifier for the wire transfer (plugin-specific format)
  * @param wire_reference_size number of bytes in @a wire_reference
  * @param execution_date when did we receive the funds
@@ -848,7 +852,7 @@ typedef int
                                       uint64_t rowid,
                                       const struct TALER_ReservePublicKeyP *reserve_pub,
                                       const struct TALER_Amount *credit,
-                                      const json_t *sender_account_details,
+                                      const char *sender_account_details,
                                       const void *wire_reference,
                                       size_t wire_reference_size,
                                       struct GNUNET_TIME_Absolute execution_date);
@@ -923,8 +927,8 @@ typedef void
  * @param cls closure
  * @param rowid which row in the table is the information from (for diagnostics)
  * @param merchant_pub public key of the merchant (should be same for all callbacks with the same @e cls)
- * @param wire_method which wire plugin was used for the transfer?
  * @param h_wire hash of wire transfer details of the merchant (should be same for all callbacks with the same @e cls)
+ * @param account_details which account did the transfer go to?
  * @param exec_time execution time of the wire transfer (should be same for all callbacks with the same @e cls)
  * @param h_contract_terms which proposal was this payment about
  * @param coin_pub which public key was this payment about
@@ -935,8 +939,8 @@ typedef void
 (*TALER_EXCHANGEDB_WireTransferDataCallback)(void *cls,
                                              uint64_t rowid,
                                              const struct TALER_MerchantPublicKeyP *merchant_pub,
-                                             const char *wire_method,
                                              const struct GNUNET_HashCode *h_wire,
+                                             const json_t *account_details,
                                              struct GNUNET_TIME_Absolute exec_time,
                                              const struct GNUNET_HashCode *h_contract_terms,
                                              const struct TALER_CoinSpendPublicKeyP *coin_pub,
@@ -952,7 +956,7 @@ typedef void
  * @param rowid identifier of the respective row in the database
  * @param date timestamp of the wire transfer (roughly)
  * @param wtid wire transfer subject
- * @param wire wire transfer details of the receiver
+ * @param wire wire transfer details of the receiver, including "url" in payto://-format
  * @param amount amount that was wired
  * @return #GNUNET_OK to continue, #GNUNET_SYSERR to stop iteration
  */
@@ -1019,7 +1023,7 @@ typedef int
  * @param amount_with_fee how much did we debit the reserve
  * @param closing_fee how much did we charge for closing the reserve
  * @param reserve_pub public key of the reserve
- * @param receiver_account where did we send the funds
+ * @param receiver_account where did we send the funds, in payto://-format
  * @param wtid identifier used for the wire transfer
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
@@ -1030,7 +1034,7 @@ typedef int
 					  const struct TALER_Amount *amount_with_fee,
 					  const struct TALER_Amount *closing_fee,
 					  const struct TALER_ReservePublicKeyP *reserve_pub,
-					  const json_t *receiver_account,
+					  const char *receiver_account,
 					  const struct TALER_WireTransferIdentifierRawP *wtid);
 
 
@@ -1040,7 +1044,7 @@ typedef int
  * @param cls closure
  * @param reserve_pub public key of the reserve
  * @param left amount left in the reserve
- * @param account_details information about the reserve's bank account
+ * @param account_details information about the reserve's bank account, in payto://-format
  * @param expiration_date when did the reserve expire
  * @return transaction status code to pass on
  */
@@ -1048,7 +1052,7 @@ typedef enum GNUNET_DB_QueryStatus
 (*TALER_EXCHANGEDB_ReserveExpiredCallback)(void *cls,
 					   const struct TALER_ReservePublicKeyP *reserve_pub,
 					   const struct TALER_Amount *left,
-					   const json_t *account_details,
+					   const char *account_details,
 					   struct GNUNET_TIME_Absolute expiration_date);
 
 
@@ -1082,7 +1086,7 @@ typedef void
  * @param rowid deposit table row of the coin's deposit
  * @param coin_pub public key of the coin
  * @param amount value of the deposit, including fee
- * @param wire where should the funds be wired
+ * @param wire where should the funds be wired, including 'url' in payto://-format
  * @param deadline what was the requested wire transfer deadline
  * @param tiny did the exchange defer this transfer because it is too small?
  * @param done did the exchange claim that it made a transfer?
@@ -1259,7 +1263,7 @@ struct TALER_EXCHANGEDB_Plugin
    * @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 sender_account_details information about the sender's bank account
+   * @param sender_account_details information about the sender's bank account, in payto://-format
    * @param wire_reference unique reference identifying the wire transfer (binary blob)
    * @param wire_reference_size number of bytes in @a wire_reference
    * @return transaction status code
@@ -1270,7 +1274,8 @@ struct TALER_EXCHANGEDB_Plugin
                          const struct TALER_ReservePublicKeyP *reserve_pub,
                          const struct TALER_Amount *balance,
                          struct GNUNET_TIME_Absolute execution_time,
-                         const json_t *sender_account_details,
+                         const char *sender_account_details,
+                         const char *exchange_account_name,
                          const void *wire_reference,
                          size_t wire_reference_size);
 
@@ -1287,6 +1292,7 @@ struct TALER_EXCHANGEDB_Plugin
   enum GNUNET_DB_QueryStatus
   (*get_latest_reserve_in_reference)(void *cls,
                                      struct TALER_EXCHANGEDB_Session *db,
+                                     const char *exchange_account_name,
                                      void **wire_reference,
                                      size_t *wire_reference_size);
 
@@ -1781,7 +1787,7 @@ struct TALER_EXCHANGEDB_Plugin
    * @param session database connection
    * @param reserve_pub which reserve is this about?
    * @param execution_date when did we perform the transfer?
-   * @param receiver_account to which account do we transfer?
+   * @param receiver_account to which account do we transfer, in payto://-format
    * @param wtid identifier for the wire transfer
    * @param amount_with_fee amount we charged to the reserve
    * @param closing_fee how high is the closing fee
@@ -1792,7 +1798,7 @@ struct TALER_EXCHANGEDB_Plugin
 			   struct TALER_EXCHANGEDB_Session *session,
 			   const struct TALER_ReservePublicKeyP *reserve_pub,
 			   struct GNUNET_TIME_Absolute execution_date,
-			   const json_t *receiver_account,
+			   const char *receiver_account,
 			   const struct TALER_WireTransferIdentifierRawP *wtid,
 			   const struct TALER_Amount *amount_with_fee,
 			   const struct TALER_Amount *closing_fee);
@@ -1869,7 +1875,8 @@ struct TALER_EXCHANGEDB_Plugin
    * @param session database connection
    * @param date time of the wire transfer
    * @param wtid subject of the wire transfer
-   * @param wire_account details about the receiver account of the wire transfer
+   * @param wire_account details about the receiver account of the wire transfer,
+   *        including 'url' in payto://-format
    * @param amount amount that was transmitted
    * @return transaction status code
    */
diff --git a/src/include/taler_json_lib.h b/src/include/taler_json_lib.h
index 6d019ecca..0504ddfb8 100644
--- a/src/include/taler_json_lib.h
+++ b/src/include/taler_json_lib.h
@@ -126,6 +126,65 @@ enum TALER_ErrorCode
 TALER_JSON_get_error_code (const json_t *json);
 
 
+/* **************** /wire account offline signing **************** */
+
+/**
+ * Compute the hash of the given wire details.   The resulting
+ * hash is what is put into the contract.
+ *
+ * @param wire_s wire details to hash
+ * @param hc[out] set to the hash
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR if @a wire_s is malformed
+ */
+int
+TALER_JSON_wire_signature_hash (const json_t *wire_s,
+                                struct GNUNET_HashCode *hc);
+
+/**
+ * Check the signature in @a wire_s.
+ *
+ * @param wire_s signed wire information of an exchange
+ * @param master_pub master public key of the exchange
+ * @return #GNUNET_OK if signature is valid
+ */
+int
+TALER_JSON_wire_signature_check (const json_t *wire_s,
+                                 const struct TALER_MasterPublicKeyP *master_pub);
+
+
+/**
+ * Create a signed wire statement for the given account.
+ *
+ * @param payto_url account specification
+ * @param master_priv private key to sign with, NULL to not sign
+ */
+json_t *
+TALER_JSON_wire_signature_make (const char *payto_url,
+                                const struct TALER_MasterPrivateKeyP *master_priv);
+
+
+/**
+ * Obtain the wire method associated with the given
+ * wire account details.  @a wire_s must contain a payto://-URL
+ * under 'url'.
+ *
+ * @return NULL on error
+ */
+char *
+TALER_JSON_wire_to_method (const json_t *wire_s);
+
+
+/**
+ * Obtain the payto://-URL associated with the given
+ * wire account details.  @a wire_s must contain a payto://-URL
+ * under 'url'.
+ *
+ * @return NULL on error
+ */
+char *
+TALER_JSON_wire_to_payto (const json_t *wire_s);
+
+
 #endif /* TALER_JSON_LIB_H_ */
 
 /* End of taler_json_lib.h */
diff --git a/src/include/taler_signatures.h b/src/include/taler_signatures.h
index c281d21fd..f1148beb8 100644
--- a/src/include/taler_signatures.h
+++ b/src/include/taler_signatures.h
@@ -62,18 +62,6 @@
 #define TALER_SIGNATURE_MASTER_DENOMINATION_KEY_VALIDITY 1025
 
 /**
- * Signature where the Exchange confirms its SEPA details in
- * the /wire response.
- */
-#define TALER_SIGNATURE_MASTER_SEPA_DETAILS 1026
-
-/**
- * Signature where the Exchange confirms its TEST details in
- * the /wire response.
- */
-#define TALER_SIGNATURE_MASTER_TEST_DETAILS 1027
-
-/**
  * Fees charged per (aggregate) wire transfer to the merchant.
  */
 #define TALER_SIGNATURE_MASTER_WIRE_FEES 1028
@@ -83,6 +71,12 @@
  */
 #define TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED 1029
 
+/**
+ * Signature where the Exchange confirms its SEPA details in
+ * the /wire response.
+ */
+#define TALER_SIGNATURE_MASTER_WIRE_DETAILS 1030
+
 /*********************************************/
 /* Exchange online signatures (with signing key) */
 /*********************************************/
@@ -891,16 +885,15 @@ struct TALER_MasterWireDetailsPS
 {
 
   /**
-   * Purpose is #TALER_SIGNATURE_MASTER_SEPA_DETAILS or
-   * #TALER_SIGNATURE_MASTER_TEST_DETAILS.
+   * Purpose is #TALER_SIGNATURE_MASTER_WIRE_DETAILS.
    */
   struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
 
   /**
-   * Hash over the account holder's name, IBAN and BIC
-   * code (all as 0-terminated strings).
+   * Hash over the account holder's payto:// URL and
+   * the salt, as done by #TALER_wire_signature_hash().
    */
-  struct GNUNET_HashCode h_sepa_details GNUNET_PACKED;
+  struct GNUNET_HashCode h_wire_details GNUNET_PACKED;
 
 };
 
diff --git a/src/include/taler_testing_lib.h b/src/include/taler_testing_lib.h
index 3914208f1..dce92ceae 100644
--- a/src/include/taler_testing_lib.h
+++ b/src/include/taler_testing_lib.h
@@ -66,20 +66,22 @@
 #define TALER_TESTING_MAKE_TRAIT_ROW_ID(data) \
   TALER_TESTING_make_trait_uint64 (3, data)
 
+
 /**
- * Allocate and return a piece of wire-details.  Mostly, it adds
- * the bank_url to the JSON.
+ * Allocate and return a piece of wire-details.  Combines
+ * the @a account_no and the @a bank_url to a
+ * @a payto://-URL and adds some salt to create the JSON.
  *
- * @param template the wire-details template.
+ * @param account_no account number
  * @param bank_url the bank_url
- *
- * @return the filled out and stringified wire-details.  To
- *         be manually free'd.
+ * @return JSON describing the account, including the
+ *         payto://-URL of the account, must be manually decref'd
  */
-char *
-TALER_TESTING_make_wire_details (const char *template,
+json_t *
+TALER_TESTING_make_wire_details (unsigned long long account_no,
                                  const char *bank_url);
 
+
 /**
  * Find denomination key matching the given amount.
  *
@@ -130,10 +132,12 @@ TALER_TESTING_url_port_free (const char *url);
  * If everything is OK, return the configured URL of the fakebank.
  *
  * @param config_filename configuration file to use
+ * @param config_section which account to use (must match x-taler-bank)
  * @return NULL on error, fakebank URL otherwise
  */
 char *
-TALER_TESTING_prepare_fakebank (const char *config_filename);
+TALER_TESTING_prepare_fakebank (const char *config_filename,
+                                const char *config_section);
 
 
 /* ******************* Generic interpreter logic ************ */
@@ -613,8 +617,8 @@ TALER_TESTING_cmd_status (const char *label,
  *        coins, this parameter selects which one in that array
  *        This value is currently ignored, as only one-coin
  *        withdrawals are implemented.
- * @param wire_details bank details of the merchant performing the
- *        deposit
+ * @param wire_details JSON including payto://-URL of the merchant performing the
+ *        deposit, reference is captured by this command
  * @param contract_terms contract terms to be signed over by the
  *        coin
  * @param refund_deadline refund deadline
@@ -625,12 +629,12 @@ TALER_TESTING_cmd_status (const char *label,
  * @return the deposit command to be run by the interpreter
  */
 struct TALER_TESTING_Command
-TALER_TESTING_cmd_deposit 
+TALER_TESTING_cmd_deposit
   (const char *label,
    struct TALER_EXCHANGE_Handle *exchange,
    const char *coin_reference,
    unsigned int coin_index,
-   char *wire_details,
+   json_t *wire_details,
    const char *contract_terms,
    struct GNUNET_TIME_Relative refund_deadline,
    const char *amount,
@@ -1209,7 +1213,7 @@ int
 TALER_TESTING_get_trait_wire_details
   (const struct TALER_TESTING_Command *cmd,
    unsigned int index,
-   const char **wire_details);
+   const json_t **wire_details);
 
 
 /**
@@ -1223,7 +1227,7 @@ TALER_TESTING_get_trait_wire_details
 struct TALER_TESTING_Trait
 TALER_TESTING_make_trait_wire_details
   (unsigned int index,
-   const char *wire_details);
+   const json_t *wire_details);
 
 /**
  * Obtain a private key from a "peer".  Used e.g. to obtain
@@ -1300,11 +1304,11 @@ TALER_TESTING_get_trait_transfer_subject
 
 
 /**
- * Offer wire details in a trait.
+ * Offer wire wire transfer subject in a trait.
  *
  * @param index always (?) zero, as one command sticks
  *        to one bank account
- * @param wire_details wire details to offer
+ * @param transfer_subject wire transfer subject to offer
  * @return the trait, to be put in the traits array of the command
  */
 struct TALER_TESTING_Trait
diff --git a/src/include/taler_wire_lib.h b/src/include/taler_wire_lib.h
index 68c36e889..0cf38d6d1 100644
--- a/src/include/taler_wire_lib.h
+++ b/src/include/taler_wire_lib.h
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2016 GNUnet e.V.
+  Copyright (C) 2016,2018 Taler Systems SA
 
   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
@@ -26,6 +26,16 @@
 
 
 /**
+ * Obtain the payment method from a @a payto_url
+ *
+ * @param payto_url the URL to parse
+ * @return NULL on error (malformed @a payto_url)
+ */
+char *
+TALER_WIRE_payto_get_method (const char *payto_url);
+
+
+/**
  * Load a WIRE plugin.
  *
  * @param cfg configuration to use
@@ -45,28 +55,4 @@ void
 TALER_WIRE_plugin_unload (struct TALER_WIRE_Plugin *plugin);
 
 
-/**
- * Signature of a function to be called on each enabled
- * wire plugin.
- *
- * @param cls closure
- * @param name name of the enabled plugin
- */
-typedef void
-(*TALER_WIRE_EnabledCallback)(void *cls,
-                              const char *name);
-
-
-/**
- * Check which wire plugins are enabled in @a cfg and call @a cb for each one.
- *
- * @param cfg configuration to use
- * @param cb callback to invoke
- * @param cb_cls closure for @a cb
- */
-void
-TALER_WIRE_find_enabled (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                         TALER_WIRE_EnabledCallback cb,
-                         void *cb_cls);
-
 #endif
diff --git a/src/include/taler_wire_plugin.h b/src/include/taler_wire_plugin.h
index c0e29609f..2758d2d2e 100644
--- a/src/include/taler_wire_plugin.h
+++ b/src/include/taler_wire_plugin.h
@@ -22,7 +22,6 @@
 #define TALER_WIRE_PLUGIN_H
 
 #include <gnunet/gnunet_util_lib.h>
-#include <jansson.h>
 #include "taler_util.h"
 #include "taler_error_codes.h"
 #include "taler_bank_service.h" /* for `enum TALER_BANK_Direction` and `struct TALER_BANK_TransferDetails` */
@@ -72,9 +71,9 @@ struct TALER_WIRE_TransferDetails
   char *wtid_s;
 
   /**
-   * The other account that was involved
+   * payto://-URL of the other account that was involved
    */
-  json_t *account_details;
+  char *account_url;
 };
 
 
@@ -161,6 +160,13 @@ struct TALER_WIRE_Plugin
   char *library_name;
 
   /**
+   * Which wire method (payto://METHOD/") is supported by this plugin?
+   * For example, "sepa" or "x-taler-bank".
+   */
+  const char *method;
+
+
+  /**
    * Round amount DOWN to the amount that can be transferred via the wire
    * method.  For example, Taler may support 0.000001 EUR as a unit of
    * payment, but SEPA only supports 0.01 EUR.  This function would
@@ -177,62 +183,27 @@ struct TALER_WIRE_Plugin
 
 
   /**
-   * Obtain wire transfer details in the plugin-specific format
-   * from the configuration.
-   *
-   * @param cls closure
-   * @param cfg configuration with details about wire accounts
-   * @param account_name which section in the configuration should we parse
-   * @return NULL if @a cfg fails to have valid wire details for @a account_name
-   */
-  json_t *
-  (*get_wire_details)(void *cls,
-                      const struct GNUNET_CONFIGURATION_Handle *cfg,
-                      const char *account_name);
-
-
-  /**
-   * Sign wire transfer details in the plugin-specific format.
-   *
-   * @param cls closure
-   * @param in wire transfer details in JSON format
-   * @param key private signing key to use
-   * @param salt salt to add
-   * @param[out] sig where to write the signature
-   * @return #GNUNET_OK on success
-   */
-  int
-  (*sign_wire_details)(void *cls,
-                       const json_t *in,
-                       const struct TALER_MasterPrivateKeyP *key,
-                       const struct GNUNET_HashCode *salt,
-                       struct TALER_MasterSignatureP *sig);
-
-
-  /**
-   * Check if the given wire format JSON object is correctly formatted
+   * Check if the given payto:// URL is correctly formatted for this plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
-   * @param wire the JSON wire format object
-   * @param master_pub public key of the exchange to verify against
-   * @param[out] emsg set to an error message, unless we return #TALER_EC_NONE;
-   *             error message must be freed by the caller using GNUNET_free()
+   * @param account_url the payto:// URL
    * @return #TALER_EC_NONE if correctly formatted
    */
   enum TALER_ErrorCode
   (*wire_validate) (void *cls,
-                    const json_t *wire,
-                    const struct TALER_MasterPublicKeyP *master_pub,
-                    char **emsg);
+                    const char *account_url);
 
 
   /**
    * Prepare for exeuction of a wire transfer.
    *
    * @param cls the @e cls of this struct with the plugin-specific state
-   * @param wire valid wire account information
+   * @param origin_account_section configuration section specifying the origin
+   *        account of the exchange to use
+   * @param destination_account_url payto:// URL identifying where to send the money
    * @param amount amount to transfer, already rounded
-   * @param exchange_base_url base URL of this exchange
+   * @param exchange_base_url base URL of this exchange (included in subject
+   *        to facilitate use of tracking API by merchant backend)
    * @param wtid wire transfer identifier to use
    * @param ptc function to call with the prepared data to persist
    * @param ptc_cls closure for @a ptc
@@ -240,13 +211,15 @@ struct TALER_WIRE_Plugin
    */
   struct TALER_WIRE_PrepareHandle *
   (*prepare_wire_transfer) (void *cls,
-                            const json_t *wire,
+                            const char *origin_account_section,
+                            const char *destination_account_url,
                             const struct TALER_Amount *amount,
                             const char *exchange_base_url,
                             const struct TALER_WireTransferIdentifierRawP *wtid,
                             TALER_WIRE_PrepareTransactionCallback ptc,
                             void *ptc_cls);
 
+
   /**
    * Abort preparation of a wire transfer. For example,
    * because we are shutting down.
@@ -305,6 +278,8 @@ struct TALER_WIRE_Plugin
    * (with negative @a num_results).
    *
    * @param cls the @e cls of this struct with the plugin-specific state
+   * @param account_section specifies the configuration section which
+   *        identifies the account for which we should get the history
    * @param direction what kinds of wire transfers should be returned
    * @param start_off from which row on do we want to get results, use NULL for the latest; exclusive
    * @param start_off_len number of bytes in @a start_off
@@ -316,6 +291,7 @@ struct TALER_WIRE_Plugin
    */
   struct TALER_WIRE_HistoryHandle *
   (*get_history) (void *cls,
+                  const char *account_section,
                   enum TALER_BANK_Direction direction,
                   const void *start_off,
                   size_t start_off_len,
@@ -323,6 +299,7 @@ struct TALER_WIRE_Plugin
                   TALER_WIRE_HistoryResultCallback hres_cb,
                   void *hres_cb_cls);
 
+
   /**
    * Cancel going over the account's history.
    *
@@ -345,6 +322,8 @@ struct TALER_WIRE_Plugin
    * results returned by @e get_history.
    *
    * @param cls plugin's closure
+   * @param account_section specifies the configuration section which
+   *        identifies the account to use to reject the transfer
    * @param start_off offset of the wire transfer in plugin-specific format
    * @param start_off_len number of bytes in @a start_off
    * @param rej_cb function to call with the result of the operation
@@ -353,11 +332,13 @@ struct TALER_WIRE_Plugin
    */
   struct TALER_WIRE_RejectHandle *
   (*reject_transfer)(void *cls,
+                     const char *account_section,
                      const void *start_off,
                      size_t start_off_len,
                      TALER_WIRE_RejectTransferCallback rej_cb,
                      void *rej_cb_cls);
 
+
   /**
    * Cancel ongoing reject operation.  Note that the rejection may still
    * proceed. Basically, if this function is called, the rejection may