[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, 25 insertions, 9 deletions

diff --git a/src/lib/exchange_api_common.c b/src/lib/exchange_api_common.c
index 53a75a934..d03409244 100644
--- a/src/lib/exchange_api_common.c
+++ b/src/lib/exchange_api_common.c
@@ -477,6 +477,7 @@ TALER_EXCHANGE_verify_coin_history (
       struct TALER_MerchantPublicKeyP merchant_pub;
       struct GNUNET_TIME_Timestamp refund_deadline = {0};
       struct TALER_CoinSpendSignatureP sig;
+      struct TALER_AgeCommitmentHash *hac = NULL;
       struct GNUNET_JSON_Specification spec[] = {
         GNUNET_JSON_spec_fixed_auto ("coin_sig",
                                      &sig),
@@ -511,6 +512,7 @@ TALER_EXCHANGE_verify_coin_history (
                                        &fee,
                                        &h_wire,
                                        &h_contract_terms,
+                                       hac,
                                        NULL /* h_extensions! */,
                                        h_denom_pub,
                                        wallet_timestamp,
@@ -543,6 +545,7 @@ TALER_EXCHANGE_verify_coin_history (
     {
       struct TALER_CoinSpendSignatureP sig;
       struct TALER_RefreshCommitmentP rc;
+      struct TALER_AgeCommitmentHash h_age_commitment = {0};
       struct GNUNET_JSON_Specification spec[] = {
         GNUNET_JSON_spec_fixed_auto ("coin_sig",
                                      &sig),
@@ -550,6 +553,9 @@ TALER_EXCHANGE_verify_coin_history (
                                      &rc),
         GNUNET_JSON_spec_fixed_auto ("h_denom_pub",
                                      h_denom_pub),
+        GNUNET_JSON_spec_mark_optional (
+          GNUNET_JSON_spec_fixed_auto ("h_age_commitment",
+                                       &h_age_commitment)),
         TALER_JSON_spec_amount_any ("melt_fee",
                                     &fee),
         GNUNET_JSON_spec_end ()
@@ -563,6 +569,7 @@ TALER_EXCHANGE_verify_coin_history (
         GNUNET_break_op (0);
         return GNUNET_SYSERR;
       }
+
       if (NULL != dk)
       {
         /* check that melt fee matches our expectations from /keys! */
@@ -577,16 +584,25 @@ TALER_EXCHANGE_verify_coin_history (
           return GNUNET_SYSERR;
         }
       }
-      if (GNUNET_OK !=
-          TALER_wallet_melt_verify (&amount,
-                                    &fee,
-                                    &rc,
-                                    h_denom_pub,
-                                    coin_pub,
-                                    &sig))
+
       {
-        GNUNET_break_op (0);
-        return GNUNET_SYSERR;
+        const struct TALER_AgeCommitmentHash *ahc = &h_age_commitment;
+
+        if (TALER_AgeCommitmentHash_isNullOrZero (ahc))
+          ahc = NULL;
+
+        if (GNUNET_OK !=
+            TALER_wallet_melt_verify (&amount,
+                                      &fee,
+                                      &rc,
+                                      h_denom_pub,
+                                      ahc,
+                                      coin_pub,
+                                      &sig))
+        {
+          GNUNET_break_op (0);
+          return GNUNET_SYSERR;
+        }
       }
       add = GNUNET_YES;
     }