diff --git a/ChangeLog b/ChangeLog
index d7d00a5ef..ed46233c5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jun  7 15:13:46 CEST 2016
+        Adding public key of the exchange that was used to sign replies
+        to applicable callbacks of libtalerexchange. (This will eventually
+        be needed by the merchant's backend.) -CG
+
 Mon Jun  6 23:59:05 CEST 2016
 	Minor code cleanup, fixing FTBFS when run with just 'make'
 	or when header installed to a location not included.
diff --git a/src/benchmark/taler-exchange-benchmark.c b/src/benchmark/taler-exchange-benchmark.c
index 7e19d8318..939fc58ec 100644
--- a/src/benchmark/taler-exchange-benchmark.c
+++ b/src/benchmark/taler-exchange-benchmark.c
@@ -75,7 +75,13 @@ struct Coin {
    * use.  Otherwise, this will be set (by the interpreter) to the
    * denomination PK matching @e amount.
    */
-  struct TALER_EXCHANGE_DenomPublicKey *pk;
+  const struct TALER_EXCHANGE_DenomPublicKey *pk;
+
+  /**
+   * Array of denomination keys needed in case this coin is to be
+   * refreshed
+   */
+  const struct TALER_EXCHANGE_DenomPublicKey **refresh_pk;
 
   /**
    * Set (by the interpreter) to the exchange's signature over the
@@ -103,6 +109,16 @@ struct Coin {
    */
   struct TALER_EXCHANGE_DepositHandle *dh;
 
+  /**
+   * Refresh melt handle
+   */
+  struct TALER_EXCHANGE_RefreshMeltHandle *rmh;
+
+  /**
+   * Refresh reveal handle
+   */
+  struct TALER_EXCHANGE_RefreshRevealHandle *rrh;
+
 };
 
 /**
@@ -173,17 +189,34 @@ static struct TALER_MerchantPrivateKeyP merchant_priv;
  */
 #define COINS_PER_RESERVE 12
 
+/**
+ * Used currency (to be preferably gotten via config file, together
+ * exchange URI and other needed values)
+ */
+#define CURRENCY "PUDOS"
+
+
 /**
  * Large enough value to allow having 12 coins per reserve without parsing
  * /keys in the first place
  */
-#define RESERVE_AMOUNT "PUDOS:1000"
+#define RESERVE_AMOUNT CURRENCY":1000"
 
 /**
  * Probability a coin can be spent
  */
 #define SPEND_PROBABILITY 0.1
 
+/**
+ * Probability a coin can be refreshed
+ */
+#define REFRESH_PROBABILITY 0.1
+
+/**
+ * Refreshed once. For each batch of deposits, only one
+ * coin will be refreshed, according to #REFRESH_PROBABILITY
+ */
+static unsigned int refreshed_once = GNUNET_NO;
 
 static unsigned int
 eval_probability (float probability)
@@ -216,18 +249,74 @@ fail (const char *msg)
 }
 
 
+/**
+ * Find denomination key matching the given amount.
+ *
+ * @param keys array of keys to search
+ * @param amount coin value to look for
+ * @return NULL if no matching key was found
+ */
+static const struct TALER_EXCHANGE_DenomPublicKey *
+find_pk (const struct TALER_EXCHANGE_Keys *keys,
+         const struct TALER_Amount *amount)
+{
+  unsigned int i;
+  struct GNUNET_TIME_Absolute now;
+  struct TALER_EXCHANGE_DenomPublicKey *pk;
+  char *str;
+
+  now = GNUNET_TIME_absolute_get ();
+  for (i=0;i<keys->num_denom_keys;i++)
+  {
+    pk = &keys->denom_keys[i];
+    if ( (0 == TALER_amount_cmp (amount,
+                                 &pk->value)) &&
+         (now.abs_value_us >= pk->valid_from.abs_value_us) &&
+         (now.abs_value_us < pk->withdraw_valid_until.abs_value_us) )
+      return pk;
+  }
+  /* do 2nd pass to check if expiration times are to blame for failure */
+  str = TALER_amount_to_string (amount);
+  for (i=0;i<keys->num_denom_keys;i++)
+  {
+    pk = &keys->denom_keys[i];
+    if ( (0 == TALER_amount_cmp (amount,
+                                 &pk->value)) &&
+         ( (now.abs_value_us < pk->valid_from.abs_value_us) ||
+           (now.abs_value_us > pk->withdraw_valid_until.abs_value_us) ) )
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Have denomination key for `%s', but with wrong expiration range %llu vs [%llu,%llu)\n",
+                  str,
+                  (unsigned long long) now.abs_value_us,
+                  (unsigned long long) pk->valid_from.abs_value_us,
+                  (unsigned long long) pk->withdraw_valid_until.abs_value_us);
+      GNUNET_free (str);
+      return NULL;
+    }
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+              "No denomination key for amount %s found\n",
+              str);
+  GNUNET_free (str);
+  return NULL;
+}
+
+
 /**
  * Function called with the result of a /deposit operation.
  *
  * @param cls closure with the interpreter state
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param exchange_pub public key used by the exchange for signing
  * @param obj the received JSON reply, should be kept as proof (and, in case of errors,
  *            be forwarded to the customer)
  */
 static void
 deposit_cb (void *cls,
             unsigned int http_status,
+            const struct TALER_ExchangePublicKeyP *exchange_pub,
             const json_t *obj)
 {
   unsigned int coin_index = (unsigned int) (long) cls;
@@ -241,6 +330,13 @@ deposit_cb (void *cls,
   GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Coin #%d correctly spent!\n", coin_index);
   GNUNET_array_append (spent_coins, spent_coins_size, coin_index);
   spent_coins_size++;
+  if (GNUNET_YES == eval_probability (REFRESH_PROBABILITY)
+      && GNUNET_NO == refreshed_once)
+  {
+    /* TODO: all the refresh logic here */
+    refreshed_once = GNUNET_YES;
+  
+  }
 }
 
 /**
@@ -294,7 +390,7 @@ reserve_withdraw_cb (void *cls,
     GNUNET_TIME_round_abs (&timestamp);
     GNUNET_TIME_round_abs (&wire_deadline);
     GNUNET_TIME_round_abs (&refund_deadline);
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Spending %d-th coin\n", coin_index);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Spending %d-th coin\n", coin_index);
     TALER_amount_subtract (&amount,
                            &coins[coin_index].pk->value,
                            &coins[coin_index].pk->fee_deposit);
@@ -355,6 +451,7 @@ reserve_withdraw_cb (void *cls,
 
 /**
  * Function called upon completion of our /admin/add/incoming request.
+ * Its duty is withdrawing coins on the freshly created reserve.
  *
  * @param cls closure with the interpreter state
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
@@ -370,6 +467,7 @@ add_incoming_cb (void *cls,
   struct GNUNET_CRYPTO_EddsaPrivateKey *coin_priv;
   unsigned int i;
   unsigned int coin_index;
+  struct TALER_Amount amount;
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "/admin/add/incoming callback called on %d-th reserve\n",
@@ -384,8 +482,8 @@ add_incoming_cb (void *cls,
     coin_index = reserve_index * COINS_PER_RESERVE + i;
     coins[coin_index].coin_priv.eddsa_priv = *coin_priv;
     coins[coin_index].reserve_index = reserve_index;
-    /* Just pick the first denom key (the reserve is rich enough) */
-    coins[coin_index].pk = &keys->denom_keys[0];
+    TALER_string_to_amount (CURRENCY":5", &amount);
+    GNUNET_assert (NULL != (coins[coin_index].pk = find_pk (keys, &amount)));
     GNUNET_free (coin_priv);
     coins[coin_index].wsh =
       TALER_EXCHANGE_reserve_withdraw (exchange,
@@ -400,7 +498,7 @@ add_incoming_cb (void *cls,
 
 
 /**
- * Run the main interpreter loop that performs exchange operations.
+ * Benchmark runner.
  *
  * @param cls closure for benchmark_run()
  */
@@ -445,7 +543,6 @@ benchmark_run (void *cls)
   coins = GNUNET_new_array (COINS_PER_RESERVE * nreserves,
                             struct Coin);
 
-  /* reserves */
   for (i=0;i < nreserves && 0 < nreserves;i++)
   {
     priv = GNUNET_CRYPTO_eddsa_key_create ();
@@ -500,7 +597,6 @@ cert_cb (void *cls,
               _keys->num_denom_keys);
 #undef ERR
 
-  /* run actual tests via interpreter-loop */
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
 	      "Certificate callback invoked, invoking benchmark_run()\n");
   keys = _keys;
@@ -510,7 +606,7 @@ cert_cb (void *cls,
 
 
 /**
- * Function run when the test terminates (good or bad).
+ * Function run when the benchmark terminates (good or bad).
  * Cleans up our state.
  *
  * @param cls the interpreter state.
@@ -549,6 +645,21 @@ do_shutdown (void *cls)
       TALER_EXCHANGE_deposit_cancel(coins[i].dh);
       coins[i].dh = NULL;
     }
+    if (NULL != coins[i].rmh)
+    {
+      TALER_EXCHANGE_refresh_melt_cancel(coins[i].rmh);
+      coins[i].rmh = NULL;    
+    }
+    if (NULL != coins[i].rrh)
+    {
+      TALER_EXCHANGE_refresh_reveal_cancel(coins[i].rrh);
+      coins[i].rmh = NULL;    
+    }
+    if (NULL != coins[i].refresh_pk)
+    {
+      GNUNET_free (coins[i].refresh_pk);
+    }
+
   }
 
   GNUNET_free_non_null (reserves);
@@ -570,8 +681,6 @@ do_shutdown (void *cls)
     GNUNET_CURL_gnunet_rc_destroy (rc);
     rc = NULL;
   }
-
-
 }
 
 
diff --git a/src/exchange-lib/exchange_api_deposit.c b/src/exchange-lib/exchange_api_deposit.c
index 4d13febf4..e65684acf 100644
--- a/src/exchange-lib/exchange_api_deposit.c
+++ b/src/exchange-lib/exchange_api_deposit.c
@@ -94,18 +94,20 @@ struct TALER_EXCHANGE_DepositHandle
  *
  * @param dh deposit handle
  * @param json json reply with the signature
+ * @param exchange_pub set to the exchange's public key
  * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
  */
 static int
 verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
-                             const json_t *json)
+                             const json_t *json,
+                             struct TALER_ExchangePublicKeyP *exchange_pub)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
-  struct TALER_ExchangePublicKeyP exchange_pub;
+
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
-    GNUNET_JSON_spec_fixed_auto ("pub", &exchange_pub),
+    GNUNET_JSON_spec_fixed_auto ("pub", exchange_pub),
     GNUNET_JSON_spec_end()
   };
 
@@ -120,7 +122,7 @@ verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
   key_state = TALER_EXCHANGE_get_keys (dh->exchange);
   if (GNUNET_OK !=
       TALER_EXCHANGE_test_signing_key (key_state,
-                                   &exchange_pub))
+                                       exchange_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -129,7 +131,7 @@ verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_DEPOSIT,
                                   &dh->depconf.purpose,
                                   &exchange_sig.eddsa_signature,
-                                  &exchange_pub.eddsa_pub))
+                                  &exchange_pub->eddsa_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -200,6 +202,8 @@ handle_deposit_finished (void *cls,
                          const json_t *json)
 {
   struct TALER_EXCHANGE_DepositHandle *dh = cls;
+  struct TALER_ExchangePublicKeyP exchange_pub;
+  struct TALER_ExchangePublicKeyP *ep = NULL;
 
   dh->job = NULL;
   switch (response_code)
@@ -209,11 +213,16 @@ handle_deposit_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_deposit_signature_ok (dh,
-                                     json))
+                                     json,
+                                     &exchange_pub))
     {
       GNUNET_break_op (0);
       response_code = 0;
     }
+    else
+    {
+      ep = &exchange_pub;
+    }
     break;
   case MHD_HTTP_BAD_REQUEST:
     /* This should never happen, either us or the exchange is buggy
@@ -253,6 +262,7 @@ handle_deposit_finished (void *cls,
   }
   dh->cb (dh->cb_cls,
           response_code,
+          ep,
           json);
   TALER_EXCHANGE_deposit_cancel (dh);
 }
diff --git a/src/exchange-lib/exchange_api_deposit_wtid.c b/src/exchange-lib/exchange_api_deposit_wtid.c
index 073ce2b35..66b91413c 100644
--- a/src/exchange-lib/exchange_api_deposit_wtid.c
+++ b/src/exchange-lib/exchange_api_deposit_wtid.c
@@ -84,18 +84,19 @@ struct TALER_EXCHANGE_DepositWtidHandle
  *
  * @param dwh deposit wtid handle
  * @param json json reply with the signature
+ * @param[out] exchange_pub set to the exchange's public key
  * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
  */
 static int
 verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_DepositWtidHandle *dwh,
-                                  const json_t *json)
+                                  const json_t *json,
+                                  struct TALER_ExchangePublicKeyP *exchange_pub)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
-  struct TALER_ExchangePublicKeyP exchange_pub;
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
-    GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
+    GNUNET_JSON_spec_fixed_auto ("exchange_pub", exchange_pub),
     GNUNET_JSON_spec_end()
   };
 
@@ -110,7 +111,7 @@ verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_DepositWtidHandle
   key_state = TALER_EXCHANGE_get_keys (dwh->exchange);
   if (GNUNET_OK !=
       TALER_EXCHANGE_test_signing_key (key_state,
-                                       &exchange_pub))
+                                       exchange_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -119,7 +120,7 @@ verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_DepositWtidHandle
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_WIRE,
                                   &dwh->depconf.purpose,
                                   &exchange_sig.eddsa_signature,
-                                  &exchange_pub.eddsa_pub))
+                                  &exchange_pub->eddsa_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -146,6 +147,8 @@ handle_deposit_wtid_finished (void *cls,
   struct GNUNET_TIME_Absolute execution_time = GNUNET_TIME_UNIT_FOREVER_ABS;
   const struct TALER_Amount *coin_contribution = NULL;
   struct TALER_Amount coin_contribution_s;
+  struct TALER_ExchangePublicKeyP exchange_pub;
+  struct TALER_ExchangePublicKeyP *ep = NULL;
 
   dwh->job = NULL;
   switch (response_code)
@@ -177,11 +180,16 @@ handle_deposit_wtid_finished (void *cls,
       coin_contribution = &coin_contribution_s;
       if (GNUNET_OK !=
           verify_deposit_wtid_signature_ok (dwh,
-                                            json))
+                                            json,
+                                            &exchange_pub))
       {
         GNUNET_break_op (0);
         response_code = 0;
       }
+      else
+      {
+        ep = &exchange_pub;
+      }
     }
     break;
   case MHD_HTTP_ACCEPTED:
@@ -231,6 +239,7 @@ handle_deposit_wtid_finished (void *cls,
   }
   dwh->cb (dwh->cb_cls,
            response_code,
+           ep,
            json,
            wtid,
            execution_time,
diff --git a/src/exchange-lib/exchange_api_refresh.c b/src/exchange-lib/exchange_api_refresh.c
index 7e207d795..b86e58362 100644
--- a/src/exchange-lib/exchange_api_refresh.c
+++ b/src/exchange-lib/exchange_api_refresh.c
@@ -951,20 +951,21 @@ struct TALER_EXCHANGE_RefreshMeltHandle
  *
  * @param rmh melt handle
  * @param json json reply with the signature
+ * @param[out] exchange_pub public key of the exchange used for the signature
  * @param[out] noreveal_index set to the noreveal index selected by the exchange
  * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
  */
 static int
 verify_refresh_melt_signature_ok (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
                                   const json_t *json,
+                                  struct TALER_ExchangePublicKeyP *exchange_pub,
                                   uint16_t *noreveal_index)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
-  struct TALER_ExchangePublicKeyP exchange_pub;
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
-    GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
+    GNUNET_JSON_spec_fixed_auto ("exchange_pub", exchange_pub),
     GNUNET_JSON_spec_uint16 ("noreveal_index", noreveal_index),
     GNUNET_JSON_spec_end()
   };
@@ -983,7 +984,7 @@ verify_refresh_melt_signature_ok (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
   key_state = TALER_EXCHANGE_get_keys (rmh->exchange);
   if (GNUNET_OK !=
       TALER_EXCHANGE_test_signing_key (key_state,
-                                   &exchange_pub))
+                                       exchange_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -1006,7 +1007,7 @@ verify_refresh_melt_signature_ok (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_MELT,
                                   &confirm.purpose,
                                   &exchange_sig.eddsa_signature,
-                                  &exchange_pub.eddsa_pub))
+                                  &exchange_pub->eddsa_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -1126,6 +1127,7 @@ handle_refresh_melt_finished (void *cls,
 {
   struct TALER_EXCHANGE_RefreshMeltHandle *rmh = cls;
   uint16_t noreveal_index = TALER_CNC_KAPPA; /* invalid value */
+  struct TALER_ExchangePublicKeyP exchange_pub;
 
   rmh->job = NULL;
   switch (response_code)
@@ -1136,6 +1138,7 @@ handle_refresh_melt_finished (void *cls,
     if (GNUNET_OK !=
         verify_refresh_melt_signature_ok (rmh,
                                           json,
+                                          &exchange_pub,
                                           &noreveal_index))
     {
       GNUNET_break_op (0);
@@ -1146,6 +1149,7 @@ handle_refresh_melt_finished (void *cls,
       rmh->melt_cb (rmh->melt_cb_cls,
                     response_code,
                     noreveal_index,
+                    (0 == response_code) ? NULL : &exchange_pub,
                     json);
       rmh->melt_cb = NULL;
     }
@@ -1190,6 +1194,7 @@ handle_refresh_melt_finished (void *cls,
     rmh->melt_cb (rmh->melt_cb_cls,
                   response_code,
                   UINT16_MAX,
+                  NULL,
                   json);
   TALER_EXCHANGE_refresh_melt_cancel (rmh);
 }
@@ -1731,7 +1736,7 @@ TALER_EXCHANGE_refresh_reveal (struct TALER_EXCHANGE_Handle *exchange,
   struct GNUNET_CURL_Context *ctx;
   struct MeltData *md;
   unsigned int j;
-  
+
   GNUNET_assert (GNUNET_YES ==
 		 MAH_handle_is_ready (exchange));
   md = deserialize_melt_data (refresh_data,
diff --git a/src/exchange-lib/exchange_api_refund.c b/src/exchange-lib/exchange_api_refund.c
index d622ddc75..fff03acf9 100644
--- a/src/exchange-lib/exchange_api_refund.c
+++ b/src/exchange-lib/exchange_api_refund.c
@@ -83,18 +83,19 @@ struct TALER_EXCHANGE_RefundHandle
  *
  * @param rh refund handle
  * @param json json reply with the signature
+ * @param[out] exchange_pub set to the exchange's public key
  * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
  */
 static int
 verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
-                             const json_t *json)
+                            const json_t *json,
+                            struct TALER_ExchangePublicKeyP *exchange_pub)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
-  struct TALER_ExchangePublicKeyP exchange_pub;
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
-    GNUNET_JSON_spec_fixed_auto ("pub", &exchange_pub),
+    GNUNET_JSON_spec_fixed_auto ("pub", exchange_pub),
     GNUNET_JSON_spec_end()
   };
 
@@ -109,7 +110,7 @@ verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
   key_state = TALER_EXCHANGE_get_keys (rh->exchange);
   if (GNUNET_OK !=
       TALER_EXCHANGE_test_signing_key (key_state,
-				       &exchange_pub))
+				       exchange_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -118,7 +119,7 @@ verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND,
                                   &rh->depconf.purpose,
                                   &exchange_sig.eddsa_signature,
-                                  &exchange_pub.eddsa_pub))
+                                  &exchange_pub->eddsa_pub))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -141,6 +142,8 @@ handle_refund_finished (void *cls,
                         const json_t *json)
 {
   struct TALER_EXCHANGE_RefundHandle *rh = cls;
+  struct TALER_ExchangePublicKeyP exchange_pub;
+  struct TALER_ExchangePublicKeyP *ep = NULL;
 
   rh->job = NULL;
   switch (response_code)
@@ -150,11 +153,16 @@ handle_refund_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_refund_signature_ok (rh,
-				    json))
+				    json,
+                                    &exchange_pub))
     {
       GNUNET_break_op (0);
       response_code = 0;
     }
+    else
+    {
+      ep = &exchange_pub;
+    }
     break;
   case MHD_HTTP_BAD_REQUEST:
     /* This should never happen, either us or the exchange is buggy
@@ -188,6 +196,7 @@ handle_refund_finished (void *cls,
   }
   rh->cb (rh->cb_cls,
           response_code,
+          ep,
           json);
   TALER_EXCHANGE_refund_cancel (rh);
 }
diff --git a/src/exchange-lib/exchange_api_wire_deposits.c b/src/exchange-lib/exchange_api_wire_deposits.c
index 0601f9b4a..91e2aef7b 100644
--- a/src/exchange-lib/exchange_api_wire_deposits.c
+++ b/src/exchange-lib/exchange_api_wire_deposits.c
@@ -186,6 +186,7 @@ handle_wire_deposits_finished (void *cls,
           break;
         wdh->cb (wdh->cb_cls,
                  response_code,
+                 &exchange_pub,
                  json,
                  &h_wire,
                  &total_amount,
@@ -224,6 +225,7 @@ handle_wire_deposits_finished (void *cls,
   }
   wdh->cb (wdh->cb_cls,
            response_code,
+           NULL,
            json,
            NULL, NULL, 0, NULL);
   TALER_EXCHANGE_wire_deposits_cancel (wdh);
diff --git a/src/exchange-lib/test_exchange_api.c b/src/exchange-lib/test_exchange_api.c
index 75a9cfbd9..83fb0eb32 100644
--- a/src/exchange-lib/test_exchange_api.c
+++ b/src/exchange-lib/test_exchange_api.c
@@ -1028,12 +1028,14 @@ reserve_withdraw_cb (void *cls,
  * @param cls closure with the interpreter state
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param exchange_pub public key the exchange used for signing
  * @param obj the received JSON reply, should be kept as proof (and, in case of errors,
  *            be forwarded to the customer)
  */
 static void
 deposit_cb (void *cls,
             unsigned int http_status,
+            const struct TALER_ExchangePublicKeyP *exchange_pub,
             const json_t *obj)
 {
   struct InterpreterState *is = cls;
@@ -1062,12 +1064,14 @@ deposit_cb (void *cls,
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
  * @param noreveal_index choice by the exchange in the cut-and-choose protocol,
  *                    UINT16_MAX on error
+ * @param exchange_pub public key the exchange used for signing
  * @param full_response full response from the exchange (for logging, in case of errors)
  */
 static void
 melt_cb (void *cls,
          unsigned int http_status,
          uint16_t noreveal_index,
+         const struct TALER_ExchangePublicKeyP *exchange_pub,
          const json_t *full_response)
 {
   struct InterpreterState *is = cls;
@@ -1388,6 +1392,7 @@ wire_cb (void *cls,
  *
  * @param cls closure
  * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param exchange_pub public key the exchange used for signing
  * @param json original json reply (may include signatures, those have then been
  *        validated already)
  * @param wtid extracted wire transfer identifier, or NULL if the exchange could
@@ -1400,6 +1405,7 @@ wire_cb (void *cls,
 static void
 wire_deposits_cb (void *cls,
                   unsigned int http_status,
+                  const struct TALER_ExchangePublicKeyP *exchange_pub,
                   const json_t *json,
                   const struct GNUNET_HashCode *h_wire,
                   const struct TALER_Amount *total_amount,
@@ -1515,6 +1521,7 @@ wire_deposits_cb (void *cls,
  *
  * @param cls closure
  * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param exchange_pub public key the exchange used for signing
  * @param json original json reply (may include signatures, those have then been
  *        validated already)
  * @param wtid wire transfer identifier used by the exchange, NULL if exchange did not
@@ -1527,6 +1534,7 @@ wire_deposits_cb (void *cls,
 static void
 deposit_wtid_cb (void *cls,
                  unsigned int http_status,
+                 const struct TALER_ExchangePublicKeyP *exchange_pub,
                  const json_t *json,
                  const struct TALER_WireTransferIdentifierRawP *wtid,
                  struct GNUNET_TIME_Absolute execution_time,
@@ -1580,12 +1588,14 @@ deposit_wtid_cb (void *cls,
  * @param cls closure
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param exchange_pub public key the exchange used for signing @a obj
  * @param obj the received JSON reply, should be kept as proof (and, in particular,
  *            be forwarded to the customer)
  */
 static void
 refund_cb (void *cls,
            unsigned int http_status,
+           const struct TALER_ExchangePublicKeyP *exchange_pub,
            const json_t *obj)
 {
   struct InterpreterState *is = cls;
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index e65a9faee..5f79b9bee 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -416,12 +416,14 @@ struct TALER_EXCHANGE_DepositHandle;
  * @param cls closure
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param sign_key exchange key used to sign @a obj, or NULL
  * @param obj the received JSON reply, should be kept as proof (and, in case of errors,
  *            be forwarded to the customer)
  */
 typedef void
 (*TALER_EXCHANGE_DepositResultCallback) (void *cls,
                                          unsigned int http_status,
+                                         const struct TALER_ExchangePublicKeyP *sign_key,
                                          const json_t *obj);
 
 
@@ -502,12 +504,14 @@ struct TALER_EXCHANGE_RefundHandle;
  * @param cls closure
  * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param sign_key exchange key used to sign @a obj, or NULL
  * @param obj the received JSON reply, should be kept as proof (and, in particular,
  *            be forwarded to the customer)
  */
 typedef void
 (*TALER_EXCHANGE_RefundResultCallback) (void *cls,
 					unsigned int http_status,
+                                        const struct TALER_ExchangePublicKeyP *sign_key,
 					const json_t *obj);
 
 
@@ -833,12 +837,14 @@ struct TALER_EXCHANGE_RefreshMeltHandle;
  *                    0 if the exchange's reply is bogus (fails to follow the protocol)
  * @param noreveal_index choice by the exchange in the cut-and-choose protocol,
  *                    UINT16_MAX on error
+ * @param sign_key exchange key used to sign @a full_response, or NULL
  * @param full_response full response from the exchange (for logging, in case of errors)
  */
 typedef void
 (*TALER_EXCHANGE_RefreshMeltCallback) (void *cls,
                                        unsigned int http_status,
                                        uint16_t noreveal_index,
+                                       const struct TALER_ExchangePublicKeyP *sign_key,
                                        const json_t *full_response);
 
 
@@ -1135,6 +1141,7 @@ struct TALER_WireDepositDetails
  *
  * @param cls closure
  * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param sign_key exchange key used to sign @a json, or NULL
  * @param json original json reply (may include signatures, those have then been
  *        validated already)
  * @param wtid extracted wire transfer identifier, or NULL if the exchange could
@@ -1147,6 +1154,7 @@ struct TALER_WireDepositDetails
 typedef void
 (*TALER_EXCHANGE_WireDepositsCallback)(void *cls,
                                        unsigned int http_status,
+                                       const struct TALER_ExchangePublicKeyP *sign_key,
                                        const json_t *json,
                                        const struct GNUNET_HashCode *h_wire,
                                        const struct TALER_Amount *total_amount,
@@ -1195,6 +1203,7 @@ struct TALER_EXCHANGE_DepositWtidHandle;
  *
  * @param cls closure
  * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param sign_key exchange key used to sign @a json, or NULL
  * @param json original json reply (may include signatures, those have then been
  *        validated already)
  * @param wtid wire transfer identifier used by the exchange, NULL if exchange did not
@@ -1205,6 +1214,7 @@ struct TALER_EXCHANGE_DepositWtidHandle;
 typedef void
 (*TALER_EXCHANGE_DepositWtidCallback)(void *cls,
                                       unsigned int http_status,
+                                      const struct TALER_ExchangePublicKeyP *sign_key,
                                       const json_t *json,
                                       const struct TALER_WireTransferIdentifierRawP *wtid,
                                       struct GNUNET_TIME_Absolute execution_time,