[age restriction] progress 14/n - withdraw and deposit

Age restriction support for
  - withdraw is done and tested
  - deposit is done and tested

TODOs:
  - melt/refresh/reveal
  - link

------

Added functions
 - TALER_age_restriction_commit
 - TALER_age_commitment_derive
 - TALER_age_commitment_hash
 - TALER_age_restriction_commitment_free_inside
 - Hash of age commitment passed around API boundaries

Exchangedb adjustments for denominations
 - all prepared statements re: denominations now handle age_mask
 - signature parameters adjusted

Hash and signature verification of /keys adjusted
 - Hashes of (normal) denominations and age-restricted denominations are
   calculated seperately
 - The hash of the age-restricted ones will then be added to the other
   hash
 - The total hash is signed/verified

Tests for withdraw with age restriction added
 - TALER_EXCHANGE_DenomPublickey now carries age_mask
 - TALER_TESTING_cmd_withdraw_amount* takes age parameter
 - TALER_TESTING_find_pk takes boolean age_restricted
 - WithdrawState carries age_commitment and its hash
 - withdraw_run derives new age commitment, if applicable
 - Added age parameter to testing (13 as example)

Various Fixes and changes
 - Fixes of post handler for /management/extensions
 - Fixes for offline tool extensions signing
 - Slight refactoring of extensions
 - Age restriction extension simplified
   - config is now global to extension
   - added global TEH_age_restriction_enabled and TEH_age_mask in
     taler-exchange-httpd
   - helper functions and macros introduced

1 files changed, 16 insertions, 0 deletions

diff --git a/src/exchange/taler-exchange-httpd_extensions.c b/src/exchange/taler-exchange-httpd_extensions.c
index 8edb24d40..6894a0762 100644
--- a/src/exchange/taler-exchange-httpd_extensions.c
+++ b/src/exchange/taler-exchange-httpd_extensions.c
@@ -127,6 +127,16 @@ extension_update_event_cb (void *cls,
       GNUNET_break (0);
     }
   }
+
+  /* Special case age restriction: Update global flag and mask  */
+  if (TALER_Extension_AgeRestriction == type)
+  {
+    TEH_age_mask.mask = 0;
+    TEH_age_restriction_enabled =
+      TALER_extensions_age_restriction_is_enabled ();
+    if (TEH_age_restriction_enabled)
+      TEH_age_mask = TALER_extensions_age_restriction_ageMask ();
+  }
 }
 
 
@@ -151,6 +161,12 @@ TEH_extensions_init ()
     return GNUNET_SYSERR;
   }
 
+  /* FIXME: shall we load the extensions from the config right away?
+   * We do have to for now, as otherwise denominations with age restriction
+   * will not have the age mask set right upon initial generation.
+   */
+  TALER_extensions_load_taler_config (TEH_cfg);
+
   /* Trigger the initial load of configuration from the db */
   for (const struct TALER_Extension *it = TALER_extensions_get_head ();
        NULL != it->next;