slowly implementing age restriction in refresh/reveal

- hash of age commitment passed around API boundaries
- code compiles and tests run
- ready to derive new age commitment

src/lib/exchange_api_refresh_common.c

@@ -79,6 +79,8 @@ serialize_melted_coin (const struct MeltedCoin *mc)
   return GNUNET_JSON_PACK (
     GNUNET_JSON_pack_data_auto ("coin_priv",
                                 &mc->coin_priv),
+    GNUNET_JSON_pack_data_auto ("h_age_commitment",
+                                &mc->h_age_commitment),
     TALER_JSON_pack_denom_sig ("denom_sig",
                                &mc->sig),
     TALER_JSON_pack_denom_pub ("denom_pub",
@@ -113,6 +115,9 @@ deserialize_melted_coin (struct MeltedCoin *mc,
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("coin_priv",
                                  &mc->coin_priv),
+    GNUNET_JSON_spec_mark_optional (
+      GNUNET_JSON_spec_fixed_auto ("h_age_commitment",
+                                   &mc->h_age_commitment)),
     TALER_JSON_spec_denom_sig ("denom_sig",
                                &mc->sig),
     TALER_JSON_spec_denom_pub ("denom_pub",
@@ -367,6 +372,9 @@ TALER_EXCHANGE_refresh_prepare (
   md.melted_coin.original_value = melt_pk->value;
   md.melted_coin.expire_deposit
     = melt_pk->expire_deposit;
+  TALER_age_commitment_hash (age_commitment,
+                             &md.melted_coin.h_age_commitment);
+
   GNUNET_assert (GNUNET_OK ==
                  TALER_amount_set_zero (melt_amount->currency,
                                         &total));
@@ -427,22 +435,36 @@ TALER_EXCHANGE_refresh_prepare (
                                          struct TALER_RefreshCoinData);
 
     md.fresh_ach[i] = GNUNET_new_array (fresh_pks_len,
-                                        struct TALER_AgeCommitment);
+                                        struct TALER_AgeCommitmentHash);
 
     for (unsigned int j = 0; j<fresh_pks_len; j++)
     {
       struct TALER_PlanchetSecretsP *fc = &md.fresh_coins[i][j];
       struct TALER_RefreshCoinData *rcd = &rce[i].new_coins[j];
+      struct TALER_AgeCommitmentHash *ach = &md.fresh_ach[i][j];
       struct TALER_PlanchetDetail pd;
       struct TALER_CoinPubHash c_hash;
 
+      if (NULL == age_commitment)
+      {
+        memset (ach, 0, sizeof(struct TALER_AgeCommitmentHash));
+        ach = NULL;
+      }
+      else
+      {
+        GNUNET_break_op (0);
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Age Commitment provided, but not supported");
+        // FIXME-oec: Fill &md.fresh_ach[i][j];
+      }
+
       TALER_planchet_setup_refresh (&trans_sec[i],
                                     j,
                                     fc);
       if (GNUNET_OK !=
           TALER_planchet_prepare (&md.fresh_pks[j],
                                   fc,
-                                  &md.fresh_ach[j],
+                                  ach,
                                   &c_hash,
                                   &pd))
       {

src/lib/exchange_api_refresh_common.h

@@ -52,6 +52,12 @@ struct MeltedCoin
    */
   struct TALER_Amount original_value;
 
+  /**
+   * The original age commitment hash.  MUST be all zeroes, if no age
+   * commitment was set.
+   */
+  struct TALER_AgeCommitmentHash h_age_commitment;
+
   /**
    * Transfer private keys for each cut-and-choose dimension.
    */

src/lib/exchange_api_refreshes_reveal.c

@@ -136,7 +136,7 @@ refresh_reveal_ok (struct TALER_EXCHANGE_RefreshesRevealHandle *rrh,
   {
     const struct TALER_PlanchetSecretsP *fc;
     struct TALER_DenominationPublicKey *pk;
-    struct TALER_AgeCommitmentHash *ach;
+    struct TALER_AgeCommitmentHash *ach = NULL;
     json_t *jsonai;
     struct TALER_BlindedDenominationSignature blind_sig;
     struct TALER_CoinSpendPublicKeyP coin_pub;
@@ -149,11 +149,16 @@ refresh_reveal_ok (struct TALER_EXCHANGE_RefreshesRevealHandle *rrh,
     struct TALER_FreshCoin coin;
 
     fc = &rrh->md->fresh_coins[rrh->noreveal_index][i];
-    ach = &rrh->md->fresh_ach[rrh->noreveal_index][i];
     pk = &rrh->md->fresh_pks[i];
     jsonai = json_array_get (jsona, i);
     GNUNET_assert (NULL != jsonai);
 
+    if (! TALER_AgeCommitmentHash_isNullOrZero (
+          &rrh->md->melted_coin.h_age_commitment))
+    {
+      ach = &rrh->md->fresh_ach[rrh->noreveal_index][i];
+    }
+
     if (GNUNET_OK !=
         GNUNET_JSON_parse (jsonai,
                            spec,

src/util/crypto.c

@@ -373,7 +373,14 @@ TALER_age_commitment_hash (
 {
   struct GNUNET_HashContext *hash_context;
   struct GNUNET_HashCode hash;
-  GNUNET_assert (NULL != commitment);
+
+  GNUNET_assert (NULL != ahash);
+  if (NULL == commitment)
+  {
+    memset (ahash, 0, sizeof(struct TALER_AgeCommitmentHash));
+    return;
+  }
+
   GNUNET_assert (__builtin_popcount (commitment->mask.mask) ==
                  commitment->num_pub_keys);