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.

1 files changed, 137 insertions, 83 deletions

diff --git a/doc/taler-exchange.texi b/doc/taler-exchange.texi
index 9f5fd103c..72efe391c 100644
--- a/doc/taler-exchange.texi
+++ b/doc/taler-exchange.texi
@@ -13,7 +13,7 @@ This manual is for the GNU Taler Exchange
 (version @value{VERSION}, @value{UPDATED}),
 a payment service provider for GNU Taler.
 
-Copyright @copyright{} 2014-2017 GNUnet e.V. and INRIA
+Copyright @copyright{} 2014-2018 Taler Systems SA
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
@@ -260,7 +260,7 @@ GNU libunistring @geq{} 0.9.3
 libcurl @geq{} 7.26 (or libgnurl @geq{} 7.26)
 
 @item
-GNU libmicrohttpd @geq{} 0.9.52
+GNU libmicrohttpd @geq{} 0.9.59
 
 @item
 GNU libgcrypt @geq{} 1.6
@@ -354,6 +354,8 @@ description of some of the options.
 
 The exchange works with three types of keys:
 
+@c FIXME: explain better!
+
 @itemize
 
 @item
@@ -366,34 +368,18 @@ The exchange works with three types of keys:
 @cite{denomination keys} (see section @cite{Coins})
 @end itemize
 
-@cite{master key}: in section @cite{[exchange]}, edit the two following values:
-
+@c FIXME: text here.
 
 @itemize
-
 @item
-@cite{master_priv_file}: Path to the exchange's master private file.
+@cite{MASTER_PRIV_FILE}: Path to the exchange's master private file.
 
 @item
-@cite{master_public_key}: Must specify the exchange's master public key.
+@cite{MASTER_PUBLIC_KEY}: Must specify the exchange's master public key.
 @end itemize
 
-@cite{sign keys}: the following two options under
-@cite{[exchange_keys]} section control @cite{sign keys}:
-
 
-@itemize
-
-@item
-@cite{signkey_duration}: How long should one signing key be used?
 
-@item
-@cite{lookahead_sign}: How much time we want to cover with our
-@cite{signkeys}? Note that if @cite{signkey_duration} is bigger than
-@cite{lookahead_sign}, @cite{taler-exchange-keyup} will generate a
-quantity of @cite{signkeys} which is sufficient to cover all the
-gap. See keys-duration.
-@end itemize
 
 
 @node Serving
@@ -436,99 +422,148 @@ option @cite{currency} in section @cite{[taler]}.
 @node Bank account
 @section Bank account
 
-@menu
-* Wiremethod-test::
-* Wiremethod-sepa::
-@end menu
+To configure a bank account in Taler, we need to furnish four
+pieces of information:
+@itemize
+@item
+  The @code{payto://} URL of the bank account, which uniquely idenfies
+  the account. Examples for such URLs include
+  @code{payto://sepa/CH9300762011623852957} for a bank account
+  in the single European payment area (SEPA) or
+  @code{payto://x-taler-bank/localhost:8080/2} for the 2nd bank
+  account a the Taler bank demonstrator running at @code{localhost}
+  on port 8080.  The first part of the URL following @code{payto://}
+  (``sepa'' or ``x-taler-bank'') is called the wire method.
+@item
+  A matching wire plugin that implements a protocol to interact
+  with the banking system.  For example, the EBICS plugin can
+  be used for SEPA transfers, or the ``taler-bank'' plugin can
+  interact with the Taler bank demonstrator.  A wire plugin
+  only supports one particular wire method. Thus, you must make
+  sure to pick a plugin that supports the wire method used in the
+  URL.
+@item
+  A file containing the signed JSON-encoded bank account details
+  for the /wire API.  This is necessary as Taler supports offline
+  signing for bank accounts for additional security.
+@item
+  Finally, the plugin needs to be provided resources for
+  authentication to the respective banking service.  The format
+  in which the authentication information must be provided
+  depends on the wire plugin.
+@end itemize
 
-@node Wiremethod-test
-@subsection Wiremethod-test
+You can configure multiple accounts for an exchange by creating
+sections starting with ``account-'' for the section name.  You can
+ENABLE for each account whether it should be used, and for what
+(incoming or outgoing wire transfers):
 
-To enable the wire transfer method ``test'', you need to set
-``ENABLE=YES'' in section @cite{[exchange-wire-test]}.
+@setsyntax ini
+@example
+
+[account-1]
+URL = "payto://sepa/CH9300762011623852957"
+WIRE_RESPONSE = $@{TALER_CONFIG_HOME@}/account-1.json
+PLUGIN = ebics
 
-The bank account where the exchange gets money from customers is
-configured under the section @cite{[exchange-wire-test]}.  It must
-contain the options ``EXCHANGE_ACCOUNT_NO'' and ``BANK_URL''.
-For basic authentication, it must additionally contain the
-``USERNAME'' and ``PASSWORD'' of the exchange's account at the bank.
+# Use for exchange-aggregator (outgoing transfers)
+ENABLE_DEBIT = YES
+# Use for exchange-wirewatch (and listed in /wire)
+ENABLE_CREDIT = YES
 
-For incoming transfers, the section must additional contain the
-option: @cite{test_response_file}, which takes
-the path to a text file containing the exchange's bank account details
-in JSON format.
+# ... add authentication options here
+@end example
 
-The command line tool @cite{taler-exchange-wire} is used to create such a file.
-For example, the utility may be invoked as follows:
+The command line tool @cite{taler-exchange-wire} is used to create
+the @code{account-1.json} file.
+For example, the utility may be invoked as follows to create
+all of the WIRE_RESPONSE files (in the locations specified by the configuration):
 
 @example
-$ taler-exchange-wire -j '@{"name": "The Exchange", "account_number":
-10, "bank_url": "https://bank.demo.taler.net", "type": "test"@}' -t
-test -o exchange.json
+$ taler-exchange-wire
 @end example
 
-Note that the value given to option @cite{-t} must match the value in
-the JSON's field @code{"type"}.
-
 The generated file will be echoed by the exchange when serving
 /wire@footnote{https://api.taler.net/api-exchange.html#wire-req}
 requests.
 
 
-@node Wiremethod-sepa
-@subsection Wiremethod-sepa
+@menu
+* Wire plugin ``taler_bank''::
+* Wire plugin ``ebics''::
+* Wire fee structure::
+@end menu
 
-To enable the wire transfer method ``sepa'', you need to set
-``ENABLE=YES'' in section @cite{[exchange-wire-sepa]}.
+@node Wire plugin ``taler_bank''
+@subsection Wire plugin ``taler_bank''
+@cindex x-taler-bank
+@cindex taler_bank plugin
 
+The @code{taler_bank} plugin implements the wire method ``x-taler-bank''.
 
-This section contains only one option: @cite{sepa_response_file},
-which takes the path to a text file containing the exchange's bank
-account details in JSON format.
+The format of the @code{payto://} URL is @code{payto://x-taler-bank/HOSTNAME:PORT},
+possibly followed by other parameters like the amount and wire transfer subject
+as per the @code{payto://} standard.
 
-The command line tool @cite{taler-exchange-wire} is used to create such a file.
-For example, the utility may be invoked as follows:
+For basic authentication, the @code{taler_bank} plugin only supports
+simple password-based authentication.  For this, the configuration
+must contain the ``USERNAME'' and ``PASSWORD'' of the respective
+account at the bank.
 
+@setsyntax ini
 @example
-$ taler-exchange-wire -j '@{"name": "The Exchange", "account_number":
-10, "bank_url": "https://bank.demo.taler.net", "type": "sepa"@}' -t
-sepa -o exchange.json
+[account-2]
+URL = "payto://test/localhost:8080"
+USERNAME = exchange
+PASSWORD = super-secure
 @end example
 
-Note that the value given to option @cite{-t} must match the value in the JSON's field @code{"type"}.
-
-The generated file will be echoed by the exchange when serving
-/wire@footnote{https://api.taler.net/api-exchange.html#wire-req}
-requests.
-
-This exchange's outgoing bank account is used to give money to merchants, after
-successful
-deposits@footnote{https://api.taler.net/api-exchange.html#deposit-par}
-operations. The outgoing bank account is configured by the following
-options under @cite{[exchange-wire-outgoing-sepa]}: (NOT YET SUPPORTED).
 
-@quotation
-
-
-@itemize
+@node Wire plugin ``ebics''
+@subsection Wire plugin ``ebics''
 
-@item
-@cite{exchange_account_numer}: which bank account number has the exchange
+The ``ebics'' wire plugin is not fully implemented and today
+does not support actual wire transfers.
 
-@item
-@cite{bank_url}: base URL of the bank hosting the exchange bank account
-@end itemize
-@end quotation
 
 @cartouche
 @quotation Note
-The rationale behind having two bank accounts is that the exchange operator, as a security
+The rationale behind having multiple bank accounts is that the exchange operator, as a security
 measure, may want to instruct the bank that the incoming bank account is only supposed to
 @emph{receive} money.
 @end quotation
 @end cartouche
 
 
+@node Wire fee structure
+@subsection Wire fee structure
+@cindex wire fee
+@cindex fee
+
+For each wire method (``sepa'' or ``x-taler-wire'', but not per plugin!) the
+exchange configuration must specify applicable wire fees.  This is done
+in configuration sections of the format @code{fee-METHOD}.  There are two
+types of fees, simple wire fees and closing fees.  Wire fees apply whenever
+the aggregator transfers funds to a merchant.  Closing fees apply whenever
+the exchange closes a reserve (sending back funds to the customer).  The
+fees must be constant for a full year, which is specified as part of the name
+of the option.
+
+@setsyntax ini
+@example
+[fee-iban]
+WIRE-FEE-2018 = EUR:0.01
+WIRE-FEE-2019 = EUR:0.01
+CLOSING-FEE-2018 = EUR:0.01
+CLOSING-FEE-2019 = EUR:0.01
+
+[fee-x-taler-bank]
+WIRE-FEE-2018 = KUDOS:0.01
+WIRE-FEE-2019 = KUDOS:0.01
+CLOSING-FEE-2018 = KUDOS:0.01
+CLOSING-FEE-2019 = KUDOS:0.01
+@end example
+
 
 @node Database
 @section Database
@@ -546,18 +581,18 @@ possible in two ways:
 via an environment variable: @cite{TALER_EXCHANGEDB_POSTGRES_CONFIG}.
 
 @item
-via configuration option @cite{db_conn_str}, under section @cite{[exchangedb-BACKEND]}. For example, the demo exchange is configured as follows:
+via configuration option @cite{CONFIG}, under section @cite{[exchangedb-BACKEND]}. For example, the demo exchange is configured as follows:
 @end itemize
 
 @setsyntax ini
 @example
 [exchange]
 ...
-db = postgres
+DB = postgres
 ...
 
 [exchangedb-postgres]
-db_conn_str = postgres:///talerdemo
+CONFIG = postgres:///talerdemo
 @end example
 
 @node Coins denomination keys
@@ -639,6 +674,25 @@ key will get a starting time of @cite{t}, and the @cite{j}-th key will
 get a starting time of @cite{x + duration_withdraw}, where @cite{x} is
 the starting time of the @cite{(j-1)}-th key.
 
+To change these settings, edit the following
+values in section @cite{[exchange]}:
+
+@itemize
+@item
+@cite{SIGNKEY_DURATION}: How long should one signing key be used?
+
+@item
+@cite{LOOKAHEAD_SIGN}: How much time we want to cover with our
+signing keys? Note that if @cite{SIGNKEY_DURATION} is bigger than
+@cite{LOOKAHEAD_SIGN}, @code{taler-exchange-keyup} will generate a
+quantity of signing keys which is sufficient to cover all the
+gap.
+@end itemize
+
+@c FIXME: LEGAL_DURATION not covered!
+@c FIXME: LOOKAHEAD_PROVIDE not covered!
+
+
 @node Deployment
 @chapter Deployment