[age-withdraw] added library function for age-withdraw

- Added TALER_EXCHANGE_age_withdraw
- Also: Change TALER_EXCHANGE_batch_withdraw and related functions to
  use GNUNET_CURL_ctx, TALER_EXCHANGE_keys and const char *echange_url

20 files changed, 1354 insertions, 102 deletions

diff --git a/src/exchange/taler-exchange-httpd_age-withdraw.c b/src/exchange/taler-exchange-httpd_age-withdraw.c
index c451e5266..2f30ad8f6 100644
--- a/src/exchange/taler-exchange-httpd_age-withdraw.c
+++ b/src/exchange/taler-exchange-httpd_age-withdraw.c
@@ -69,6 +69,7 @@ struct AgeWithdrawContext
 
   /**
    * kappa * #num_coins hashes of blinded coin planchets.
+   * FIXME[oec]: Make the [][] structure more explicit.
    */
   struct TALER_BlindedPlanchet *coin_evs;
 
diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 3af5d326d..3ad441cb9 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -439,7 +439,9 @@ struct TALER_AgeCommitmentPublicKeyP
 
 
 /*
- * @brief Hash to represent the commitment to n*kappa blinded keys during a age-withdrawal.
+ * @brief Hash to represent the commitment to n*kappa blinded keys during a
+ * age-withdrawal. It is the running SHA512 hash over the hashes of the blinded
+ * envelopes of n*kappa coins.
  */
 struct TALER_AgeWithdrawCommitmentHashP
 {
@@ -3726,7 +3728,7 @@ TALER_wallet_withdraw_verify (
 /**
  * Sign age-withdraw request.
  *
- * @param h_commitment hash all n*kappa blinded coins in the commitment for the age-withdraw
+ * @param h_commitment hash over all n*kappa blinded coins in the commitment for the age-withdraw
  * @param amount_with_fee amount to debit the reserve for
  * @param mask the mask that defines the age groups
  * @param max_age maximum age from which the age group is derived, that the withdrawn coins must be restricted to.
@@ -3762,7 +3764,6 @@ TALER_wallet_age_withdraw_verify (
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const struct TALER_ReserveSignatureP *reserve_sig);
 
-
 /**
  * Verify exchange melt confirmation.
  *
@@ -4871,6 +4872,22 @@ TALER_exchange_online_age_withdraw_confirmation_sign (
   struct TALER_ExchangeSignatureP *sig);
 
 
+/**
+ * Verfiy an exchange age-withdraw confirmation
+ *
+ * @param h_commitment Commitment over all n*kappa coin candidates from the original request to age-withdraw
+ * @param noreveal_index The index returned by the exchange
+ * @param exchange_pub The public key used for signing
+ * @param exchange_sig The signature from the exchange
+ */
+enum GNUNET_GenericReturnValue
+TALER_exchange_online_age_withdraw_confirmation_verify (
+  const struct TALER_AgeWithdrawCommitmentHashP *h_commitment,
+  uint32_t noreveal_index,
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_ExchangeSignatureP *exchange_sig);
+
+
 /* ********************* offline signing ************************** */
 
 
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index bc6a230b6..d4efc15d5 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -18,6 +18,7 @@
  * @brief C interface of libtalerexchange, a C library to use exchange's HTTP API
  * @author Sree Harsha Totakura <sreeharsha@totakura.in>
  * @author Christian Grothoff
+ * @author Özgür Kesim
  */
 #ifndef _TALER_EXCHANGE_SERVICE_H
 #define _TALER_EXCHANGE_SERVICE_H
@@ -1618,7 +1619,8 @@ typedef void
 /**
  * Get a CS R using a /csr-withdraw request.
  *
- * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param curl_ctx The curl context to use for the requests
+ * @param exchange_url Base-URL to the excnange
  * @param pk Which denomination key is the /csr request for
  * @param nonce client nonce for the request
  * @param res_cb the callback to call when the final result for this request is available
@@ -1629,7 +1631,8 @@ typedef void
  */
 struct TALER_EXCHANGE_CsRWithdrawHandle *
 TALER_EXCHANGE_csr_withdraw (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
   const struct TALER_EXCHANGE_DenomPublicKey *pk,
   const struct TALER_CsNonce *nonce,
   TALER_EXCHANGE_CsRWithdrawCallback res_cb,
@@ -2448,7 +2451,9 @@ typedef void
  * disk before calling, and be ready to repeat the request with the
  * same arguments in case of failures.
  *
- * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param curl_ctx The curl context to use
+ * @param exchange_url The base-URL of the exchange
+ * @param keys The /keys material from the exchange
  * @param reserve_priv private key of the reserve to withdraw from
  * @param wci inputs that determine the planchet
  * @param res_cb the callback to call when the final result for this request is available
@@ -2459,7 +2464,9 @@ typedef void
  */
 struct TALER_EXCHANGE_WithdrawHandle *
 TALER_EXCHANGE_withdraw (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_EXCHANGE_WithdrawCoinInput *wci,
   TALER_EXCHANGE_WithdrawCallback res_cb,
@@ -2575,7 +2582,9 @@ typedef void
  * disk before calling, and be ready to repeat the request with the
  * same arguments in case of failures.
  *
- * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param curl_ctx The curl context to use
+ * @param exchange_url The base-URL of the exchange
+ * @param keys The /keys material from the exchange
  * @param reserve_priv private key of the reserve to withdraw from
  * @param wcis inputs that determine the planchets
  * @param wci_length number of entries in @a wcis
@@ -2587,7 +2596,9 @@ typedef void
  */
 struct TALER_EXCHANGE_BatchWithdrawHandle *
 TALER_EXCHANGE_batch_withdraw (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  const struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_EXCHANGE_WithdrawCoinInput *wcis,
   unsigned int wci_length,
@@ -2668,7 +2679,9 @@ struct TALER_EXCHANGE_Withdraw2Handle;
  * disk before calling, and be ready to repeat the request with the
  * same arguments in case of failures.
  *
- * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param curl_ctx The curl-context to use
+ * @param exchange_url The base-URL of the exchange
+ * @param keys The /keys material from the exchange
  * @param pd planchet details of the planchet to withdraw
  * @param reserve_priv private key of the reserve to withdraw from
  * @param res_cb the callback to call when the final result for this request is available
@@ -2679,7 +2692,9 @@ struct TALER_EXCHANGE_Withdraw2Handle;
  */
 struct TALER_EXCHANGE_Withdraw2Handle *
 TALER_EXCHANGE_withdraw2 (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_PlanchetDetail *pd,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   TALER_EXCHANGE_Withdraw2Callback res_cb,
@@ -2765,7 +2780,9 @@ struct TALER_EXCHANGE_BatchWithdraw2Handle;
  * disk before calling, and be ready to repeat the request with the
  * same arguments in case of failures.
  *
- * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param curl_ctx The curl context to use
+ * @param exchange_url The base-URL of the exchange
+ * @param keys The /keys material from the exchange
  * @param pds array of planchet details of the planchet to withdraw
  * @param pds_length number of entries in the @a pds array
  * @param reserve_priv private key of the reserve to withdraw from
@@ -2777,7 +2794,9 @@ struct TALER_EXCHANGE_BatchWithdraw2Handle;
  */
 struct TALER_EXCHANGE_BatchWithdraw2Handle *
 TALER_EXCHANGE_batch_withdraw2 (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  const struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_PlanchetDetail *pds,
   unsigned int pds_length,
@@ -2796,6 +2815,119 @@ TALER_EXCHANGE_batch_withdraw2_cancel (
   struct TALER_EXCHANGE_BatchWithdraw2Handle *wh);
 
 
+/* ********************* /reserve/$RESERVE_PUB/age-withdraw *************** */
+
+/**
+ * @brief Information needed to withdraw age restricted coins.
+ */
+struct TALER_EXCHANGE_AgeWithdrawCoinInput
+{
+  /* The master secret from which we derive all other relevant values for
+   * the coin: private key, nonces (if applicable) and age restriction
+   */
+  const struct TALER_PlanchetMasterSecretP secret[TALER_CNC_KAPPA];
+
+  /* The denomination of the coin.  Must support age restriction, i.e
+   * its .keys.age_mask MUST not be 0 */
+  const struct TALER_EXCHANGE_DenomPublicKey *denom_pub;
+};
+
+/**
+ * @brief A handle to a /reserves/$RESERVE_PUB/age-withdraw request
+ */
+struct TALER_EXCHANGE_AgeWithdrawHandle;
+
+/**
+ * @brief Details about the response for a age withdraw request.
+ */
+struct TALER_EXCHANGE_AgeWithdrawResponse
+{
+  /**
+   * HTTP response data.
+   */
+  struct TALER_EXCHANGE_HttpResponse hr;
+
+  /**
+   * Details about the response
+   */
+  union
+  {
+    /**
+     * Details if the status is #MHD_HTTP_OK.
+     */
+    struct
+    {
+      /**
+       * Index that should not be revealed during the age-withdraw reveal phase.
+       * The struct TALER_PlanchetMasterSecretP * from the request
+       * with this index are the ones to keep.
+       */
+      uint8_t noreveal_index;
+
+      /**
+       * Signature of the exchange over the origina TALER_AgeWithdrawRequestPS
+       */
+      struct TALER_ExchangeSignatureP exchange_sig;
+
+      /**
+       * Key used by the exchange for @e exchange_sig
+       */
+      struct TALER_ExchangePublicKeyP exchange_pub;
+
+    } ok;
+    /* FIXME[oec]: error cases */
+  } details;
+};
+
+typedef void
+(*TALER_EXCHANGE_AgeWithdrawCallback)(
+  void *cls,
+  const struct TALER_EXCHANGE_AgeWithdrawResponse *awr);
+
+/**
+ * Submit an age-withdraw request to the exchange and get the exchange's
+ * response.
+ *
+ * This API is typically used by a wallet.  Note that to ensure that
+ * no money is lost in case of hardware failures, the provided
+ * argument @a rd should be committed to persistent storage
+ * prior to calling this function.
+ *
+ * @param curl_ctx The curl context
+ * @param exchange_url The base url of the exchange
+ * @parm keys The denomination keys from the exchange
+ * @param reserve_priv The pivate key to the reserve
+ * @param coin_inputs The input for the coins to withdraw
+ * @param num_coins The number of elements in @e coin_inputs
+ * @param max_age The maximum age we commit to.
+ * @param res_cb A callback for the result, maybe NULL
+ * @param res_cb_cls A closure for @e res_cb, maybe NULL
+ * @return a handle for this request; NULL if the argument was invalid.
+ *         In this case, the callback will not be called.
+ */
+struct TALER_EXCHANGE_AgeWithdrawHandle *
+TALER_EXCHANGE_age_withdraw (
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
+  const struct TALER_ReservePrivateKeyP *reserve_priv,
+  const struct TALER_EXCHANGE_AgeWithdrawCoinInput *coin_inputs,
+  size_t num_coins,
+  uint8_t max_age,
+  TALER_EXCHANGE_AgeWithdrawCallback res_cb,
+  void *res_cb_cls);
+
+/**
+ * Cancel a age-withdraw request.  This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param awh the age-withdraw handle
+ */
+void
+TALER_EXCHANGE_age_withdraw_cancel (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh);
+
+
 /* ********************* /refresh/melt+reveal ***************************** */
 
 
@@ -3565,7 +3697,7 @@ TALER_EXCHANGE_verify_coin_history (
  */
 enum GNUNET_GenericReturnValue
 TALER_EXCHANGE_parse_reserve_history (
-  struct TALER_EXCHANGE_Keys *keys,
+  const struct TALER_EXCHANGE_Keys *keys,
   const json_t *history,
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const char *currency,
diff --git a/src/include/taler_exchangedb_plugin.h b/src/include/taler_exchangedb_plugin.h
index c4fcad562..1b1a657c2 100644
--- a/src/include/taler_exchangedb_plugin.h
+++ b/src/include/taler_exchangedb_plugin.h
@@ -1215,8 +1215,7 @@ struct TALER_EXCHANGEDB_AgeWithdraw
 
   /**
    * Signature confirming the age withdrawal commitment, matching @e
-   * reserve_pub, @e maximum_age_group and @e h_commitment and @e
-   * total_amount_with_fee.
+   * reserve_pub, @e max_age and @e h_commitment and @e amount_with_fee.
    */
   struct TALER_ReserveSignatureP reserve_sig;
 
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 53190bc5b..762a3f805 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -22,6 +22,7 @@ libtalerexchange_la_LDFLAGS = \
   -no-undefined
 libtalerexchange_la_SOURCES = \
   exchange_api_add_aml_decision.c \
+  exchange_api_age_withdraw.c \
   exchange_api_auditor_add_denomination.c \
   exchange_api_batch_deposit.c \
   exchange_api_batch_withdraw.c \
diff --git a/src/lib/exchange_api_age_withdraw.c b/src/lib/exchange_api_age_withdraw.c
new file mode 100644
index 000000000..4e146c15c
--- /dev/null
+++ b/src/lib/exchange_api_age_withdraw.c
@@ -0,0 +1,1033 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2023 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file lib/exchange_api_age_withdraw.c
+ * @brief Implementation of /reserves/$RESERVE_PUB/age-withdraw requests
+ * @author Özgür Kesim
+ */
+
+#include "platform.h"
+#include <gnunet/gnunet_common.h>
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP status codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_curl_lib.h"
+#include "taler_json_lib.h"
+#include "taler_exchange_service.h"
+#include "exchange_api_common.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+struct CoinCandidate
+{
+  /**
+   * Master key material for the coin candidates.
+   */
+  struct TALER_PlanchetMasterSecretP secret;
+
+  /**
+   * Age commitment for the coin candidates, calculated from the @e ps and a
+   * given maximum age
+   */
+  struct TALER_AgeCommitmentProof age_commitment_proof;
+
+  /**
+   * Age commitment for the coin.
+   */
+  struct TALER_AgeCommitmentHash h_age_commitment;
+
+  /**
+   *  blinding secret
+   */
+  union TALER_DenominationBlindingKeyP blinding_key;
+
+  /**
+   * Private key of the coin we are withdrawing.
+   */
+  struct TALER_CoinSpendPrivateKeyP coin_priv;
+
+  /**
+   * Details of the planchet.
+   */
+  struct TALER_PlanchetDetail planchet_detail;
+
+  /**
+   * Values of the @cipher selected
+   */
+  struct TALER_ExchangeWithdrawValues alg_values;
+
+  /**
+   * Hash of the public key of the coin we are signing.
+   */
+  struct TALER_CoinPubHashP h_coin_pub;
+
+  /* Blinded hash of the coin */
+  struct TALER_BlindedCoinHashP blinded_coin_h;
+
+  /**
+   * The following fields are needed as closure for the call to /csr-withdrwaw
+   * per coin-candidate.
+   */
+
+  /* Denomination information, needed for CS coins for the step after /csr-withdraw */
+  struct TALER_EXCHANGE_DenomPublicKey *denom_pub;
+
+  /**
+   * Handler for the CS R request (only used for TALER_DENOMINATION_CS denominations)
+   */
+  struct TALER_EXCHANGE_CsRWithdrawHandle *csr_withdraw_handle;
+
+  /* Needed in the closure for csr-withdraw calls */
+  struct TALER_EXCHANGE_AgeWithdrawHandle *age_withdraw_handle;
+
+};
+
+
+/**
+ * Data we keep per coin in the batch.
+ */
+struct CoinData
+{
+
+  /**
+   * Denomination key we are withdrawing.
+   */
+  struct TALER_EXCHANGE_DenomPublicKey denom_pub;
+
+  /**
+   * The Candidates for the coin
+   */
+  struct CoinCandidate coin_candidates[TALER_CNC_KAPPA];
+
+};
+
+
+/**
+ * @brief A /reserves/$RESERVE_PUB/age-withdraw request-handle
+ */
+struct TALER_EXCHANGE_AgeWithdrawHandle
+{
+
+  /**
+   * Reserve private key.
+   */
+  const struct TALER_ReservePrivateKeyP *reserve_priv;
+
+  /**
+   * Reserve public key, calculated
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+  /**
+   * Signature of the reserve for the request, calculated after all
+   * parameters for the coins are collected.
+   */
+  struct TALER_ReserveSignatureP reserve_sig;
+
+  /*
+   * The denomination keys of the exchange
+   */
+  struct TALER_EXCHANGE_Keys *keys;
+
+  /**
+   * The base-URL of the exchange.
+   */
+  const char *exchange_url;
+
+  /**
+   * The age mask, extacted from the denominations.
+   * MUST be the same for all denominations
+   *
+   */
+  struct TALER_AgeMask age_mask;
+
+  /**
+   * Maximum age to commit to.
+   */
+  uint8_t max_age;
+
+  /**
+   * Length of the @e coin_data Array
+   */
+  size_t num_coins;
+
+  /**
+   * Array of per-coin data
+   */
+  struct CoinData *coin_data;
+
+  /**
+   * The commitment calculated as SHA512 hash over all blinded_coin_h
+   */
+  struct TALER_AgeWithdrawCommitmentHashP h_commitment;
+
+  /**
+   * Total amount requested (value plus withdraw fee).
+   */
+  struct TALER_Amount amount_with_fee;
+
+  /**
+   * Number of /csr-withdraw requests still pending.
+   */
+  unsigned int csr_pending;
+
+  /**
+   * The url for this request.
+   */
+  char *request_url;
+
+  /**
+   * Context for curl.
+   */
+  struct GNUNET_CURL_Context *curl_ctx;
+
+  /**
+   * CURL handle for the request job.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Post Context
+   */
+  struct TALER_CURL_PostContext post_ctx;
+
+  /**
+   * Function to call with age-withdraw response results.
+   */
+  TALER_EXCHANGE_AgeWithdrawCallback callback;
+
+  /**
+   * Closure for @e age_withdraw_cb
+   */
+  void *callback_cls;
+
+};
+
+/**
+ * We got a 200 OK response for the /reserves/$RESERVE_PUB/age-withdraw operation.
+ * Extract the noreveal_index and return it to the caller.
+ *
+ * @param awh operation handle
+ * @param j_response reply from the exchange
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
+ */
+static enum GNUNET_GenericReturnValue
+reserve_age_withdraw_ok (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh,
+  const json_t *j_response)
+{
+  struct TALER_EXCHANGE_AgeWithdrawResponse response = {
+    .hr.reply = j_response,
+    .hr.http_status = MHD_HTTP_OK
+  };
+  struct GNUNET_JSON_Specification spec[] = {
+    GNUNET_JSON_spec_uint8 ("noreaveal_index",
+                            &response.details.ok.noreveal_index),
+    GNUNET_JSON_spec_fixed_auto ("exchange_sig",
+                                 &response.details.ok.exchange_sig),
+    GNUNET_JSON_spec_fixed_auto ("exchange_pub",
+                                 &response.details.ok.exchange_pub)
+  };
+
+  if (GNUNET_OK!=
+      GNUNET_JSON_parse (j_response,
+                         spec,
+                         NULL, NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+
+  if (GNUNET_OK !=
+      TALER_exchange_online_age_withdraw_confirmation_verify (
+        &awh->h_commitment,
+        response.details.ok.noreveal_index,
+        &response.details.ok.exchange_pub,
+        &response.details.ok.exchange_sig))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+
+  }
+  awh->callback (awh->callback_cls,
+                 &response);
+  /* make sure the callback isn't called again */
+  awh->callback = NULL;
+
+  return GNUNET_OK;
+}
+
+
+/**
+ * FIXME: This function should be common to batch- and age-withdraw
+ *
+ * We got a 409 CONFLICT response for the /reserves/$RESERVE_PUB/age-withdraw operation.
+ * Check the signatures on the batch withdraw transactions in the provided
+ * history and that the balances add up.  We don't do anything directly
+ * with the information, as the JSON will be returned to the application.
+ * However, our job is ensuring that the exchange followed the protocol, and
+ * this in particular means checking all of the signatures in the history.
+ *
+ * @param keys The denomination keys from the exchange
+ * @param reserve_pub The reserve's public key
+ * @param requested_amount The requested amount
+ * @param json reply from the exchange
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
+ */
+static enum GNUNET_GenericReturnValue
+reserve_age_withdraw_payment_required (
+  struct TALER_EXCHANGE_Keys *keys,
+  const struct TALER_ReservePublicKeyP *reserve_pub,
+  const struct TALER_Amount *requested_amount,
+  const json_t *json)
+{
+  struct TALER_Amount balance;
+  struct TALER_Amount total_in_from_history;
+  struct TALER_Amount total_out_from_history;
+  json_t *history;
+  size_t len;
+  struct GNUNET_JSON_Specification spec[] = {
+    TALER_JSON_spec_amount_any ("balance",
+                                &balance),
+    GNUNET_JSON_spec_end ()
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_JSON_parse (json,
+                         spec,
+                         NULL, NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  history = json_object_get (json,
+                             "history");
+  if (NULL == history)
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+
+  /* go over transaction history and compute
+     total incoming and outgoing amounts */
+  len = json_array_size (history);
+  {
+    struct TALER_EXCHANGE_ReserveHistoryEntry *rhistory;
+
+    /* Use heap allocation as "len" may be very big and thus this may
+       not fit on the stack. Use "GNUNET_malloc_large" as a malicious
+       exchange may theoretically try to crash us by giving a history
+       that does not fit into our memory. */
+    rhistory = GNUNET_malloc_large (
+      sizeof (struct TALER_EXCHANGE_ReserveHistoryEntry)
+      * len);
+    if (NULL == rhistory)
+    {
+      GNUNET_break (0);
+      return GNUNET_SYSERR;
+    }
+
+    if (GNUNET_OK !=
+        TALER_EXCHANGE_parse_reserve_history (
+          keys,
+          history,
+          reserve_pub,
+          balance.currency,
+          &total_in_from_history,
+          &total_out_from_history,
+          len,
+          rhistory))
+    {
+      GNUNET_break_op (0);
+      TALER_EXCHANGE_free_reserve_history (rhistory,
+                                           len);
+      return GNUNET_SYSERR;
+    }
+    TALER_EXCHANGE_free_reserve_history (rhistory,
+                                         len);
+  }
+
+  /* Check that funds were really insufficient */
+  if (0 >= TALER_amount_cmp (requested_amount,
+                             &balance))
+  {
+    /* Requested amount is smaller or equal to reported balance,
+       so this should not have failed. */
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /reserves/$RESERVE_PUB/age-withdraw request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_AgeWithdrawHandle`
+ * @param aw2r response data
+ */
+static void
+handle_reserve_age_withdraw_finished (
+  void *cls,
+  long response_code,
+  const void *response)
+{
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh = cls;
+  const json_t *j_response = response;
+  struct TALER_EXCHANGE_AgeWithdrawResponse awr = {
+    .hr.reply = j_response,
+    .hr.http_status = (unsigned int) response_code
+  };
+
+  awh->job = NULL;
+  switch (response_code)
+  {
+  case 0:
+    awr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
+    break;
+  case MHD_HTTP_OK:
+    if (GNUNET_OK !=
+        reserve_age_withdraw_ok (awh,
+                                 j_response))
+    {
+      GNUNET_break_op (0);
+      awr.hr.http_status = 0;
+      awr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+      break;
+    }
+    GNUNET_assert (NULL == awh->callback);
+    TALER_EXCHANGE_age_withdraw_cancel (awh);
+    return;
+  case MHD_HTTP_UNAVAILABLE_FOR_LEGAL_REASONS:
+    /* only validate reply is well-formed */
+    {
+      uint64_t ptu;
+      struct GNUNET_JSON_Specification spec[] = {
+        GNUNET_JSON_spec_uint64 ("legitimization_uuid",
+                                 &ptu),
+        GNUNET_JSON_spec_end ()
+      };
+
+      if (GNUNET_OK !=
+          GNUNET_JSON_parse (j_response,
+                             spec,
+                             NULL, NULL))
+      {
+        GNUNET_break_op (0);
+        awr.hr.http_status = 0;
+        awr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+        break;
+      }
+    }
+  case MHD_HTTP_BAD_REQUEST:
+    /* This should never happen, either us or the exchange is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    break;
+  case MHD_HTTP_FORBIDDEN:
+    GNUNET_break_op (0);
+    /* Nothing really to verify, exchange says one of the signatures is
+       invalid; as we checked them, this should never happen, we
+       should pass the JSON reply to the application */
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    /* Nothing really to verify, the exchange basically just says
+       that it doesn't know this reserve.  Can happen if we
+       query before the wire transfer went through.
+       We should simply pass the JSON reply to the application. */
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    break;
+  case MHD_HTTP_CONFLICT:
+    /* The exchange says that the reserve has insufficient funds;
+       check the signatures in the history... */
+    if (GNUNET_OK !=
+        reserve_age_withdraw_payment_required (awh->keys,
+                                               &awh->reserve_pub,
+                                               &awh->amount_with_fee,
+                                               j_response))
+    {
+      GNUNET_break_op (0);
+      awr.hr.http_status = 0;
+      awr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+    }
+    else
+    {
+      awr.hr.ec = TALER_JSON_get_error_code (j_response);
+      awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    }
+    break;
+  case MHD_HTTP_GONE:
+    /* could happen if denomination was revoked */
+    /* Note: one might want to check /keys for revocation
+       signature here, alas tricky in case our /keys
+       is outdated => left to clients */
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    break;
+  case MHD_HTTP_INTERNAL_SERVER_ERROR:
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    break;
+  default:
+    /* unexpected response code */
+    GNUNET_break_op (0);
+    awr.hr.ec = TALER_JSON_get_error_code (j_response);
+    awr.hr.hint = TALER_JSON_get_error_hint (j_response);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u/%d for exchange age-withdraw\n",
+                (unsigned int) response_code,
+                (int) awr.hr.ec);
+    break;
+  }
+  awh->callback (awh->callback_cls,
+                 &awr);
+  TALER_EXCHANGE_age_withdraw_cancel (awh);
+}
+
+
+/**
+ * Runs the actual age-withdraw operation. If there were CS-denominations
+ * involved, started once the all calls to /csr-withdraw are done.
+ *
+ * @param[in,out] awh age withdraw handler
+ */
+static void
+perform_protocol (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh)
+{
+#define FAIL_IF(cond) \
+  do { \
+    if ((cond)) \
+    { \
+      GNUNET_break (! (cond)); \
+      goto ERROR; \
+    } \
+  } while(0)
+
+  struct GNUNET_HashContext *coins_hctx;
+  json_t *j_denoms = NULL;
+  json_t *j_array_candidates = NULL;
+  json_t *j_request_body = NULL;
+  CURL *curlh = NULL;
+
+
+  GNUNET_assert (0 == awh->csr_pending);
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Attempting to age-withdraw from reserve %s with maximum age %d\n",
+              TALER_B2S (&awh->reserve_pub),
+              awh->max_age);
+
+  coins_hctx = GNUNET_CRYPTO_hash_context_start ();
+  FAIL_IF (NULL == coins_hctx);
+
+
+  j_denoms = json_array ();
+  j_array_candidates = json_array ();
+  FAIL_IF ((NULL == j_denoms) ||
+           (NULL == j_array_candidates));
+
+  for (size_t i  = 0; i< awh->num_coins; i++)
+  {
+    /* Build the denomination array */
+    {
+      struct TALER_EXCHANGE_DenomPublicKey *denom =
+        &awh->coin_data[i].denom_pub;
+      json_t *jdenom = GNUNET_JSON_PACK (
+        TALER_JSON_pack_denom_pub (NULL,
+                                   &denom->key));
+
+      FAIL_IF (NULL == jdenom);
+      FAIL_IF (0 < json_array_append_new (j_denoms,
+                                          jdenom));
+
+      /* Build the candidate array */
+      {
+        const struct CoinCandidate *can = awh->coin_data[i].coin_candidates;
+        json_t *j_can = json_array ();
+        FAIL_IF (NULL == j_can);
+
+        for (size_t k = 0; k < TALER_CNC_KAPPA; k++)
+        {
+          json_t *jc = GNUNET_JSON_PACK (
+            TALER_JSON_pack_blinded_planchet (
+              NULL,
+              &can->planchet_detail.blinded_planchet));
+
+          FAIL_IF (NULL == jc);
+          FAIL_IF (0 < json_array_append_new (j_can,
+                                              jc));
+
+          GNUNET_CRYPTO_hash_context_read (coins_hctx,
+                                           &can->blinded_coin_h,
+                                           sizeof(can->blinded_coin_h));
+        }
+      }
+    }
+  }
+
+  /* Sign the request */
+  {
+    struct TALER_AgeWithdrawCommitmentHashP coins_commitment_h;
+
+    GNUNET_CRYPTO_hash_context_finish (coins_hctx,
+                                       &coins_commitment_h.hash);
+
+    TALER_wallet_age_withdraw_sign (&coins_commitment_h,
+                                    &awh->amount_with_fee,
+                                    &awh->age_mask,
+                                    awh->max_age,
+                                    awh->reserve_priv,
+                                    &awh->reserve_sig);
+  }
+
+  /* Initiate the POST-request */
+  j_request_body = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_array_steal ("denoms_h", j_denoms),
+    GNUNET_JSON_pack_array_steal ("blinded_coin_evs", j_array_candidates),
+    GNUNET_JSON_pack_uint64 ("max_age", awh->max_age),
+    GNUNET_JSON_pack_data_auto ("reserve_sig", &awh->reserve_sig));
+  FAIL_IF (NULL == j_request_body);
+
+  curlh = TALER_EXCHANGE_curl_easy_get_ (awh->request_url);
+  FAIL_IF (NULL == curlh);
+  FAIL_IF (GNUNET_OK !=
+           TALER_curl_easy_post (&awh->post_ctx,
+                                 curlh,
+                                 j_request_body));
+  json_decref (j_request_body);
+  j_request_body = NULL;
+
+  awh->job = GNUNET_CURL_job_add2 (awh->curl_ctx,
+                                   curlh,
+                                   awh->post_ctx.headers,
+                                   &handle_reserve_age_withdraw_finished,
+                                   awh);
+  FAIL_IF (NULL == awh->job);
+
+  /* No errors, return */
+  return;
+
+ERROR:
+  if (NULL != j_denoms)
+    json_decref (j_denoms);
+  if (NULL != j_array_candidates)
+    json_decref (j_array_candidates);
+  if (NULL != j_request_body)
+    json_decref (j_request_body);
+  if (NULL != curlh)
+    curl_easy_cleanup (curlh);
+  TALER_EXCHANGE_age_withdraw_cancel (awh);
+  return;
+#undef FAIL_IF
+}
+
+
+/**
+ * Prepares the request URL for the age-withdraw request
+ *
+ * @param awh The handler
+ */
+static
+enum GNUNET_GenericReturnValue
+prepare_url (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh,
+  const char *exchange_url)
+{
+  char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
+  char pub_str[sizeof (struct TALER_ReservePublicKeyP) * 2];
+  char *end;
+
+  end = GNUNET_STRINGS_data_to_string (
+    &awh->reserve_pub,
+    sizeof (awh->reserve_pub),
+    pub_str,
+    sizeof (pub_str));
+  *end = '\0';
+  GNUNET_snprintf (arg_str,
+                   sizeof (arg_str),
+                   "reserves/%s/age-withdraw",
+                   pub_str);
+
+  awh->request_url = TALER_url_join (exchange_url,
+                                     arg_str,
+                                     NULL);
+  if (NULL == awh->request_url)
+  {
+    GNUNET_break (0);
+    TALER_EXCHANGE_age_withdraw_cancel (awh);
+    return GNUNET_SYSERR;
+  }
+
+  return GNUNET_OK;
+}
+
+
+/**
+ * @brief Function called when CSR withdraw retrieval is finished
+ *
+ * @param cls the `struct CoinCandidate *`
+ * @param csrr replies from the /csr-withdraw request
+ */
+static void
+csr_withdraw_done (
+  void *cls,
+  const struct TALER_EXCHANGE_CsRWithdrawResponse *csrr)
+{
+  struct CoinCandidate *can = cls;
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh = can->age_withdraw_handle;
+  struct TALER_EXCHANGE_AgeWithdrawResponse awr = { .hr = csrr->hr };
+
+  can->csr_withdraw_handle = NULL;
+
+  switch (csrr->hr.http_status)
+  {
+  case MHD_HTTP_OK:
+    {
+      bool success = true;
+      /* Complete the initialization of the coin with CS denomination */
+      can->alg_values = csrr->details.ok.alg_values;
+      TALER_planchet_setup_coin_priv (&can->secret,
+                                      &can->alg_values,
+                                      &can->coin_priv);
+      TALER_planchet_blinding_secret_create (&can->secret,
+                                             &can->alg_values,
+                                             &can->blinding_key);
+      /* This initializes the 2nd half of the
+         can->planchet_detail.blinded_planchet! */
+      if (GNUNET_OK !=
+          TALER_planchet_prepare (&can->denom_pub->key,
+                                  &can->alg_values,
+                                  &can->blinding_key,
+                                  &can->coin_priv,
+                                  &can->h_age_commitment,
+                                  &can->h_coin_pub,
+                                  &can->planchet_detail))
+      {
+        GNUNET_break (0);
+        success = false;
+        TALER_EXCHANGE_age_withdraw_cancel (awh);
+      }
+
+      if (GNUNET_OK !=
+          TALER_coin_ev_hash (&can->planchet_detail.blinded_planchet,
+                              &can->planchet_detail.denom_pub_hash,
+                              &can->blinded_coin_h))
+      {
+        GNUNET_break (0);
+        success = false;
+        TALER_EXCHANGE_age_withdraw_cancel (awh);
+      }
+
+      awh->csr_pending--;
+
+      /* No more pending requests to /csr-withdraw, we can now perform the
+       * actual age-withdraw operation */
+      if (0 == awh->csr_pending && success)
+        perform_protocol (awh);
+      return;
+    }
+  default:
+    break;
+  }
+
+  awh->callback (awh->callback_cls,
+                 &awr);
+  TALER_EXCHANGE_age_withdraw_cancel (awh);
+}
+
+
+/**
+ * @brief Prepare the coins for the call to age-withdraw and calculates
+ * the total amount with fees.
+ *
+ * For denomination with CS as cipher, initiates the preflight to retrieve the
+ * csr-parameter via /csr-withdraw.
+ *
+ * @param awh The handler to the age-withdraw
+ * @param coin_inputs The input for the individial coin(-candidates)
+ * @param num_coins The number of coins in @e coin_inputs
+ *
+ * @return GNUNET_OK on success, GNUNET_SYSERR on failure
+ */
+static
+enum GNUNET_GenericReturnValue
+prepare_coins (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh,
+  const struct TALER_EXCHANGE_AgeWithdrawCoinInput *coin_inputs,
+  size_t num_coins)
+{
+
+  if (GNUNET_OK != TALER_amount_set_zero (
+        awh->keys->currency,
+        &awh->amount_with_fee))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+
+  awh->coin_data = GNUNET_new_array (awh->num_coins,
+                                     struct CoinData);
+
+  GNUNET_assert (0 < num_coins);
+  awh->age_mask = coin_inputs[0].denom_pub->key.age_mask;
+
+  for (size_t i = 0; i < num_coins; i++)
+  {
+    struct CoinData *cd = &awh->coin_data[i];
+    const struct TALER_EXCHANGE_AgeWithdrawCoinInput *input = &coin_inputs[i];
+    cd->denom_pub = *input->denom_pub;
+
+    /* The mask must be the same for all coins */
+    if (awh->age_mask.bits != input->denom_pub->key.age_mask.bits)
+    {
+      GNUNET_break (0);
+      TALER_EXCHANGE_age_withdraw_cancel (awh);
+      return GNUNET_SYSERR;
+    }
+
+    TALER_denom_pub_deep_copy (&cd->denom_pub.key,
+                               &input->denom_pub->key);
+
+    /* Accumulate total value with fees */
+    {
+      struct TALER_Amount coin_total;
+
+      if (0 >
+          TALER_amount_add (&coin_total,
+                            &cd->denom_pub.fees.withdraw,
+                            &cd->denom_pub.value))
+      {
+        GNUNET_break (0);
+        TALER_EXCHANGE_age_withdraw_cancel (awh);
+        return GNUNET_SYSERR;
+      }
+
+      if (0 >
+          TALER_amount_add (&awh->amount_with_fee,
+                            &awh->amount_with_fee,
+                            &coin_total))
+      {
+        /* Overflow here? Very strange, our CPU must be fried... */
+        GNUNET_break (0);
+        TALER_EXCHANGE_age_withdraw_cancel (awh);
+        return GNUNET_SYSERR;
+      }
+    }
+
+    for (uint8_t k = 0; k < TALER_CNC_KAPPA; k++)
+    {
+      struct CoinCandidate *can = &cd->coin_candidates[k];
+
+      can->secret = input->secret[k];
+
+      /* Derive the age restriction from the given secret and
+       * the maximum age */
+      GNUNET_assert (GNUNET_OK ==
+                     TALER_age_restriction_from_secret (
+                       &can->secret,
+                       &input->denom_pub->key.age_mask,
+                       awh->max_age,
+                       &can->age_commitment_proof));
+      TALER_age_commitment_hash (&can->age_commitment_proof.commitment,
+                                 &can->h_age_commitment);
+
+      switch (input->denom_pub->key.cipher)
+      {
+      case TALER_DENOMINATION_RSA:
+        {
+          can->alg_values.cipher = TALER_DENOMINATION_RSA;
+          TALER_planchet_setup_coin_priv (&can->secret,
+                                          &can->alg_values,
+                                          &can->coin_priv);
+          TALER_planchet_blinding_secret_create (&can->secret,
+                                                 &can->alg_values,
+                                                 &can->blinding_key);
+          if (GNUNET_OK !=
+              TALER_planchet_prepare (&cd->denom_pub.key,
+                                      &can->alg_values,
+                                      &can->blinding_key,
+                                      &can->coin_priv,
+                                      &can->h_age_commitment,
+                                      &can->h_coin_pub,
+                                      &can->planchet_detail))
+          {
+            GNUNET_break (0);
+            TALER_EXCHANGE_age_withdraw_cancel (awh);
+            return GNUNET_SYSERR;
+          }
+          if (GNUNET_OK !=
+              TALER_coin_ev_hash (&can->planchet_detail.blinded_planchet,
+                                  &can->planchet_detail.denom_pub_hash,
+                                  &can->blinded_coin_h))
+          {
+            GNUNET_break (0);
+            TALER_EXCHANGE_age_withdraw_cancel (awh);
+            return GNUNET_SYSERR;
+          }
+          break;
+        }
+      case TALER_DENOMINATION_CS:
+        {
+          /**
+           * Save the handler and the denomination for the callback
+           * after the call to csr-withdraw */
+          can->age_withdraw_handle = awh;
+          can->denom_pub = &cd->denom_pub;
+
+          TALER_cs_withdraw_nonce_derive (
+            &can->secret,
+            &can->planchet_detail
+            .blinded_planchet
+            .details
+            .cs_blinded_planchet
+            .nonce);
+
+          /* Note that we only initialize the first half
+             of the blinded_planchet here; the other part
+             will be done after the /csr-withdraw request! */
+          can->planchet_detail.blinded_planchet.cipher = TALER_DENOMINATION_CS;
+          can->csr_withdraw_handle = NULL;
+          TALER_EXCHANGE_csr_withdraw (
+            awh->curl_ctx,
+            awh->exchange_url,
+            &cd->denom_pub,
+            &can->planchet_detail
+            .blinded_planchet
+            .details
+            .cs_blinded_planchet
+            .nonce,
+            &csr_withdraw_done,
+            &can);
+          if (NULL == can->csr_withdraw_handle)
+          {
+            GNUNET_break (0);
+            TALER_EXCHANGE_age_withdraw_cancel (awh);
+            return GNUNET_SYSERR;
+          }
+
+          awh->csr_pending++;
+          break;
+        }
+      default:
+        GNUNET_break (0);
+        TALER_EXCHANGE_age_withdraw_cancel (awh);
+        return GNUNET_SYSERR;
+      }
+    }
+  }
+  return GNUNET_OK;
+};
+
+struct TALER_EXCHANGE_AgeWithdrawHandle *
+TALER_EXCHANGE_age_withdraw (
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
+  const struct TALER_ReservePrivateKeyP *reserve_priv,
+  const struct TALER_EXCHANGE_AgeWithdrawCoinInput *coin_inputs,
+  size_t num_coins,
+  uint8_t max_age,
+  TALER_EXCHANGE_AgeWithdrawCallback res_cb,
+  void *res_cb_cls)
+{
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh;
+
+  awh = GNUNET_new (struct TALER_EXCHANGE_AgeWithdrawHandle);
+  awh->exchange_url = exchange_url;
+  awh->keys = TALER_EXCHANGE_keys_incref (keys);
+  awh->curl_ctx = curl_ctx;
+  awh->reserve_priv = reserve_priv;
+  awh->callback = res_cb;
+  awh->callback_cls = res_cb_cls;
+  awh->num_coins = num_coins;
+  awh->max_age = max_age;
+
+  GNUNET_CRYPTO_eddsa_key_get_public (&awh->reserve_priv->eddsa_priv,
+                                      &awh->reserve_pub.eddsa_pub);
+
+
+  if (GNUNET_OK != prepare_url (awh,
+                                exchange_url))
+    return NULL;
+
+  if (GNUNET_OK != prepare_coins (awh,
+                                  coin_inputs,
+                                  num_coins))
+    return NULL;
+
+  /* If there were no CS denominations, we can now perform the actual
+   * age-withdraw protocol.  Otherwise, there are calls to /csr-withdraw
+   * in flight and once they finish, the age-withdraw-protocol will be
+   * called from within the csr_withdraw_done-function.
+   */
+  if (0 == awh->csr_pending)
+    perform_protocol (awh);
+
+  return awh;
+}
+
+
+void
+TALER_EXCHANGE_age_withdraw_cancel (
+  struct TALER_EXCHANGE_AgeWithdrawHandle *awh)
+{
+  /* Cleanup coin data */
+  for (unsigned int i = 0; i<awh->num_coins; i++)
+  {
+    struct CoinData *cd = &awh->coin_data[i];
+
+    for (uint8_t k = 0; k < TALER_CNC_KAPPA; k++)
+    {
+      struct CoinCandidate *can = &cd->coin_candidates[k];
+
+      if (NULL != can->csr_withdraw_handle)
+      {
+        TALER_EXCHANGE_csr_withdraw_cancel (can->csr_withdraw_handle);
+        can->csr_withdraw_handle = NULL;
+      }
+      TALER_blinded_planchet_free (&can->planchet_detail.blinded_planchet);
+    }
+    TALER_denom_pub_free (&cd->denom_pub.key);
+  }
+  GNUNET_free (awh->coin_data);
+
+  /* Cleanup CURL job data */
+  if (NULL != awh->job)
+  {
+    GNUNET_CURL_job_cancel (awh->job);
+    awh->job = NULL;
+  }
+  TALER_curl_easy_post_finished (&awh->post_ctx);
+  TALER_EXCHANGE_keys_decref (awh->keys);
+  GNUNET_free (awh->request_url);
+  GNUNET_free (awh);
+
+}
+
+
+/* exchange_api_age_withdraw.c */
diff --git a/src/lib/exchange_api_batch_withdraw.c b/src/lib/exchange_api_batch_withdraw.c
index 4817ae403..07ad37f63 100644
--- a/src/lib/exchange_api_batch_withdraw.c
+++ b/src/lib/exchange_api_batch_withdraw.c
@@ -97,9 +97,20 @@ struct TALER_EXCHANGE_BatchWithdrawHandle
 {
 
   /**
-   * The connection to exchange this request handle will use
+   * The curl context to use
    */
-  struct TALER_EXCHANGE_Handle *exchange;
+  struct GNUNET_CURL_Context *curl_ctx;
+
+  /**
+   * The base URL to the exchange
+   */
+  const char *exchange_url;
+
+  /**
+   * The /keys information from the exchange
+   */
+  const struct TALER_EXCHANGE_Keys *keys;
+
 
   /**
    * Handle for the actual (internal) batch withdraw operation.
@@ -255,7 +266,9 @@ phase_two (struct TALER_EXCHANGE_BatchWithdrawHandle *wh)
     pds[i] = cd->pd;
   }
   wh->wh2 = TALER_EXCHANGE_batch_withdraw2 (
-    wh->exchange,
+    wh->curl_ctx,
+    wh->exchange_url,
+    wh->keys,
     wh->reserve_priv,
     pds,
     wh->num_coins,
@@ -322,7 +335,9 @@ withdraw_cs_stage_two_callback (
 
 struct TALER_EXCHANGE_BatchWithdrawHandle *
 TALER_EXCHANGE_batch_withdraw (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  const struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_EXCHANGE_WithdrawCoinInput *wcis,
   unsigned int wci_length,
@@ -332,7 +347,9 @@ TALER_EXCHANGE_batch_withdraw (
   struct TALER_EXCHANGE_BatchWithdrawHandle *wh;
 
   wh = GNUNET_new (struct TALER_EXCHANGE_BatchWithdrawHandle);
-  wh->exchange = exchange;
+  wh->curl_ctx = curl_ctx;
+  wh->exchange_url = exchange_url;
+  wh->keys = keys;
   wh->cb = res_cb;
   wh->cb_cls = res_cb_cls;
   wh->reserve_priv = reserve_priv;
@@ -386,7 +403,8 @@ TALER_EXCHANGE_batch_withdraw (
            will be done after the /csr-withdraw request! */
         cd->pd.blinded_planchet.cipher = TALER_DENOMINATION_CS;
         cd->csrh = TALER_EXCHANGE_csr_withdraw (
-          exchange,
+          curl_ctx,
+          exchange_url,
           &cd->pk,
           &cd->pd.blinded_planchet.details.cs_blinded_planchet.nonce,
           &withdraw_cs_stage_two_callback,
diff --git a/src/lib/exchange_api_batch_withdraw2.c b/src/lib/exchange_api_batch_withdraw2.c
index 6dd421cea..a855fc57e 100644
--- a/src/lib/exchange_api_batch_withdraw2.c
+++ b/src/lib/exchange_api_batch_withdraw2.c
@@ -39,14 +39,14 @@ struct TALER_EXCHANGE_BatchWithdraw2Handle
 {
 
   /**
-   * The connection to exchange this request handle will use
+   * The url for this request.
    */
-  struct TALER_EXCHANGE_Handle *exchange;
+  char *url;
 
   /**
-   * The url for this request.
+   * The /keys material from the exchange
    */
-  char *url;
+  const struct TALER_EXCHANGE_Keys *keys;
 
   /**
    * Handle for the request.
@@ -219,7 +219,7 @@ reserve_batch_withdraw_payment_required (
 
     if (GNUNET_OK !=
         TALER_EXCHANGE_parse_reserve_history (
-          TALER_EXCHANGE_get_keys (wh->exchange),
+          wh->keys,
           history,
           &wh->reserve_pub,
           balance.currency,
@@ -387,7 +387,9 @@ handle_reserve_batch_withdraw_finished (void *cls,
 
 struct TALER_EXCHANGE_BatchWithdraw2Handle *
 TALER_EXCHANGE_batch_withdraw2 (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  const struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_PlanchetDetail *pds,
   unsigned int pds_length,
@@ -395,21 +397,15 @@ TALER_EXCHANGE_batch_withdraw2 (
   void *res_cb_cls)
 {
   struct TALER_EXCHANGE_BatchWithdraw2Handle *wh;
-  const struct TALER_EXCHANGE_Keys *keys;
   const struct TALER_EXCHANGE_DenomPublicKey *dk;
   struct TALER_ReserveSignatureP reserve_sig;
   char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
   struct TALER_BlindedCoinHashP bch;
   json_t *jc;
 
-  keys = TALER_EXCHANGE_get_keys (exchange);
-  if (NULL == keys)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  GNUNET_assert (NULL != keys);
   wh = GNUNET_new (struct TALER_EXCHANGE_BatchWithdraw2Handle);
-  wh->exchange = exchange;
+  wh->keys = keys;
   wh->cb = res_cb;
   wh->cb_cls = res_cb_cls;
   wh->num_coins = pds_length;
@@ -430,14 +426,15 @@ TALER_EXCHANGE_batch_withdraw2 (
     *end = '\0';
     GNUNET_snprintf (arg_str,
                      sizeof (arg_str),
-                     "/reserves/%s/batch-withdraw",
+                     "reserves/%s/batch-withdraw",
                      pub_str);
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Attempting to batch-withdraw from reserve %s\n",
               TALER_B2S (&wh->reserve_pub));
-  wh->url = TEAH_path_to_url (exchange,
-                              arg_str);
+  wh->url = TALER_url_join (exchange_url,
+                            arg_str,
+                            NULL);
   if (NULL == wh->url)
   {
     GNUNET_break (0);
@@ -513,13 +510,11 @@ TALER_EXCHANGE_batch_withdraw2 (
   }
   {
     CURL *eh;
-    struct GNUNET_CURL_Context *ctx;
     json_t *req;
 
     req = GNUNET_JSON_PACK (
       GNUNET_JSON_pack_array_steal ("planchets",
                                     jc));
-    ctx = TEAH_handle_to_context (exchange);
     eh = TALER_EXCHANGE_curl_easy_get_ (wh->url);
     if ( (NULL == eh) ||
          (GNUNET_OK !=
@@ -535,7 +530,7 @@ TALER_EXCHANGE_batch_withdraw2 (
       return NULL;
     }
     json_decref (req);
-    wh->job = GNUNET_CURL_job_add2 (ctx,
+    wh->job = GNUNET_CURL_job_add2 (curl_ctx,
                                     eh,
                                     wh->post_ctx.headers,
                                     &handle_reserve_batch_withdraw_finished,
diff --git a/src/lib/exchange_api_common.c b/src/lib/exchange_api_common.c
index f43673d76..77a5cf816 100644
--- a/src/lib/exchange_api_common.c
+++ b/src/lib/exchange_api_common.c
@@ -36,7 +36,7 @@ struct HistoryParseContext
   /**
    * Keys of the exchange we use.
    */
-  struct TALER_EXCHANGE_Keys *keys;
+  const struct TALER_EXCHANGE_Keys *keys;
 
   /**
    * Our reserve public key.
@@ -647,7 +647,7 @@ parse_close (struct TALER_EXCHANGE_ReserveHistoryEntry *rh,
 
 enum GNUNET_GenericReturnValue
 TALER_EXCHANGE_parse_reserve_history (
-  struct TALER_EXCHANGE_Keys *keys,
+  const struct TALER_EXCHANGE_Keys *keys,
   const json_t *history,
   const struct TALER_ReservePublicKeyP *reserve_pub,
   const char *currency,
diff --git a/src/lib/exchange_api_csr_withdraw.c b/src/lib/exchange_api_csr_withdraw.c
index fca3fff8e..4c1d83a9a 100644
--- a/src/lib/exchange_api_csr_withdraw.c
+++ b/src/lib/exchange_api_csr_withdraw.c
@@ -39,11 +39,6 @@
 struct TALER_EXCHANGE_CsRWithdrawHandle
 {
   /**
-   * The connection to exchange this request handle will use
-   */
-  struct TALER_EXCHANGE_Handle *exchange;
-
-  /**
    * Function to call with the result.
    */
   TALER_EXCHANGE_CsRWithdrawCallback cb;
@@ -204,11 +199,13 @@ handle_csr_finished (void *cls,
 
 
 struct TALER_EXCHANGE_CsRWithdrawHandle *
-TALER_EXCHANGE_csr_withdraw (struct TALER_EXCHANGE_Handle *exchange,
-                             const struct TALER_EXCHANGE_DenomPublicKey *pk,
-                             const struct TALER_CsNonce *nonce,
-                             TALER_EXCHANGE_CsRWithdrawCallback res_cb,
-                             void *res_cb_cls)
+TALER_EXCHANGE_csr_withdraw (
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  const struct TALER_EXCHANGE_DenomPublicKey *pk,
+  const struct TALER_CsNonce *nonce,
+  TALER_EXCHANGE_CsRWithdrawCallback res_cb,
+  void *res_cb_cls)
 {
   struct TALER_EXCHANGE_CsRWithdrawHandle *csrh;
 
@@ -218,11 +215,11 @@ TALER_EXCHANGE_csr_withdraw (struct TALER_EXCHANGE_Handle *exchange,
     return NULL;
   }
   csrh = GNUNET_new (struct TALER_EXCHANGE_CsRWithdrawHandle);
-  csrh->exchange = exchange;
   csrh->cb = res_cb;
   csrh->cb_cls = res_cb_cls;
-  csrh->url = TEAH_path_to_url (exchange,
-                                "/csr-withdraw");
+  csrh->url = TALER_url_join (exchange_url,
+                              "csr-withdraw",
+                              NULL);
   if (NULL == csrh->url)
   {
     GNUNET_free (csrh);
@@ -231,7 +228,6 @@ TALER_EXCHANGE_csr_withdraw (struct TALER_EXCHANGE_Handle *exchange,
 
   {
     CURL *eh;
-    struct GNUNET_CURL_Context *ctx;
     json_t *req;
 
     req = GNUNET_JSON_PACK (
@@ -242,7 +238,6 @@ TALER_EXCHANGE_csr_withdraw (struct TALER_EXCHANGE_Handle *exchange,
                                      &pk->h_key,
                                      sizeof(struct TALER_DenominationHashP)));
     GNUNET_assert (NULL != req);
-    ctx = TEAH_handle_to_context (exchange);
     eh = TALER_EXCHANGE_curl_easy_get_ (csrh->url);
     if ( (NULL == eh) ||
          (GNUNET_OK !=
@@ -259,7 +254,7 @@ TALER_EXCHANGE_csr_withdraw (struct TALER_EXCHANGE_Handle *exchange,
       return NULL;
     }
     json_decref (req);
-    csrh->job = GNUNET_CURL_job_add2 (ctx,
+    csrh->job = GNUNET_CURL_job_add2 (curl_ctx,
                                       eh,
                                       csrh->post_ctx.headers,
                                       &handle_csr_finished,
diff --git a/src/lib/exchange_api_curl_defaults.h b/src/lib/exchange_api_curl_defaults.h
index 009d72ab8..c4ba04fc5 100644
--- a/src/lib/exchange_api_curl_defaults.h
+++ b/src/lib/exchange_api_curl_defaults.h
@@ -25,7 +25,6 @@
 #define _TALER_CURL_DEFAULTS_H
 
 
-#include "platform.h"
 #include <gnunet/gnunet_curl_lib.h>
 
 
diff --git a/src/lib/exchange_api_handle.c b/src/lib/exchange_api_handle.c
index fe73f0504..0bb3c2085 100644
--- a/src/lib/exchange_api_handle.c
+++ b/src/lib/exchange_api_handle.c
@@ -1229,6 +1229,8 @@ TALER_EXCHANGE_check_keys_current (struct TALER_EXCHANGE_Handle *exchange,
   bool force_download = 0 != (flags & TALER_EXCHANGE_CKF_FORCE_DOWNLOAD);
   bool pull_all_keys = 0 != (flags & TALER_EXCHANGE_CKF_PULL_ALL_KEYS);
 
+  GNUNET_assert (NULL != exchange);
+
   if ( (NULL != cb) &&
        ( (exchange->cert_cb != cb) ||
          (exchange->cert_cb_cls != cb_cls) ) )
diff --git a/src/lib/exchange_api_melt.c b/src/lib/exchange_api_melt.c
index 1da4184d2..f19f98c54 100644
--- a/src/lib/exchange_api_melt.c
+++ b/src/lib/exchange_api_melt.c
@@ -504,6 +504,7 @@ csr_cb (void *cls,
 }
 
 
+/* FIXME: refactor this to use struct TALER_EXCHANGE_Handle */
 struct TALER_EXCHANGE_MeltHandle *
 TALER_EXCHANGE_melt (
   struct GNUNET_CURL_Context *ctx,
diff --git a/src/lib/exchange_api_refreshes_reveal.c b/src/lib/exchange_api_refreshes_reveal.c
index 9b6f9b19c..e698a2977 100644
--- a/src/lib/exchange_api_refreshes_reveal.c
+++ b/src/lib/exchange_api_refreshes_reveal.c
@@ -303,6 +303,7 @@ handle_refresh_reveal_finished (void *cls,
 }
 
 
+/* FIXME: refactor this to use struct TALER_EXCHANGE_Handle */
 struct TALER_EXCHANGE_RefreshesRevealHandle *
 TALER_EXCHANGE_refreshes_reveal (
   struct GNUNET_CURL_Context *ctx,
diff --git a/src/lib/exchange_api_withdraw.c b/src/lib/exchange_api_withdraw.c
index 2a3c095a6..87218989a 100644
--- a/src/lib/exchange_api_withdraw.c
+++ b/src/lib/exchange_api_withdraw.c
@@ -39,9 +39,19 @@ struct TALER_EXCHANGE_WithdrawHandle
 {
 
   /**
-   * The connection to exchange this request handle will use
+   * The curl context to use
    */
-  struct TALER_EXCHANGE_Handle *exchange;
+  struct GNUNET_CURL_Context *curl_ctx;
+
+  /**
+   * The base-URL to the exchange
+   */
+  const char *exchange_url;
+
+  /**
+   * The /keys material from the exchange
+   */
+  struct TALER_EXCHANGE_Keys *keys;
 
   /**
    * Handle for the actual (internal) withdraw operation.
@@ -232,7 +242,9 @@ withdraw_cs_stage_two_callback (
       GNUNET_break (0);
       break;
     }
-    wh->wh2 = TALER_EXCHANGE_withdraw2 (wh->exchange,
+    wh->wh2 = TALER_EXCHANGE_withdraw2 (wh->curl_ctx,
+                                        wh->exchange_url,
+                                        wh->keys,
                                         &wh->pd,
                                         wh->reserve_priv,
                                         &handle_reserve_withdraw_finished,
@@ -249,7 +261,9 @@ withdraw_cs_stage_two_callback (
 
 struct TALER_EXCHANGE_WithdrawHandle *
 TALER_EXCHANGE_withdraw (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   const struct TALER_EXCHANGE_WithdrawCoinInput *wci,
   TALER_EXCHANGE_WithdrawCallback res_cb,
@@ -258,7 +272,9 @@ TALER_EXCHANGE_withdraw (
   struct TALER_EXCHANGE_WithdrawHandle *wh;
 
   wh = GNUNET_new (struct TALER_EXCHANGE_WithdrawHandle);
-  wh->exchange = exchange;
+  wh->keys = TALER_EXCHANGE_keys_incref (keys);
+  wh->exchange_url = exchange_url;
+  wh->curl_ctx = curl_ctx;
   wh->cb = res_cb;
   wh->cb_cls = res_cb_cls;
   wh->reserve_priv = reserve_priv;
@@ -292,7 +308,9 @@ TALER_EXCHANGE_withdraw (
         GNUNET_free (wh);
         return NULL;
       }
-      wh->wh2 = TALER_EXCHANGE_withdraw2 (exchange,
+      wh->wh2 = TALER_EXCHANGE_withdraw2 (curl_ctx,
+                                          exchange_url,
+                                          keys,
                                           &wh->pd,
                                           wh->reserve_priv,
                                           &handle_reserve_withdraw_finished,
@@ -309,7 +327,8 @@ TALER_EXCHANGE_withdraw (
          will be done after the /csr-withdraw request! */
       wh->pd.blinded_planchet.cipher = TALER_DENOMINATION_CS;
       wh->csrh = TALER_EXCHANGE_csr_withdraw (
-        exchange,
+        curl_ctx,
+        exchange_url,
         &wh->pk,
         &wh->pd.blinded_planchet.details.cs_blinded_planchet.nonce,
         &withdraw_cs_stage_two_callback,
@@ -339,6 +358,7 @@ TALER_EXCHANGE_withdraw_cancel (struct TALER_EXCHANGE_WithdrawHandle *wh)
     TALER_EXCHANGE_withdraw2_cancel (wh->wh2);
     wh->wh2 = NULL;
   }
+  TALER_EXCHANGE_keys_decref (wh->keys);
   TALER_denom_pub_free (&wh->pk.key);
   GNUNET_free (wh);
 }
diff --git a/src/lib/exchange_api_withdraw2.c b/src/lib/exchange_api_withdraw2.c
index daac429c7..11028ed5b 100644
--- a/src/lib/exchange_api_withdraw2.c
+++ b/src/lib/exchange_api_withdraw2.c
@@ -39,9 +39,9 @@ struct TALER_EXCHANGE_Withdraw2Handle
 {
 
   /**
-   * The connection to exchange this request handle will use
+   * The /keys material from the exchange
    */
-  struct TALER_EXCHANGE_Handle *exchange;
+  struct TALER_EXCHANGE_Keys *keys;
 
   /**
    * The url for this request.
@@ -192,8 +192,7 @@ reserve_withdraw_payment_required (
     }
 
     if (GNUNET_OK !=
-        TALER_EXCHANGE_parse_reserve_history (TALER_EXCHANGE_get_keys (
-                                                wh->exchange),
+        TALER_EXCHANGE_parse_reserve_history (wh->keys,
                                               history,
                                               &wh->reserve_pub,
                                               balance.currency,
@@ -361,25 +360,21 @@ handle_reserve_withdraw_finished (void *cls,
 
 struct TALER_EXCHANGE_Withdraw2Handle *
 TALER_EXCHANGE_withdraw2 (
-  struct TALER_EXCHANGE_Handle *exchange,
+  struct GNUNET_CURL_Context *curl_ctx,
+  const char *exchange_url,
+  struct TALER_EXCHANGE_Keys *keys,
   const struct TALER_PlanchetDetail *pd,
   const struct TALER_ReservePrivateKeyP *reserve_priv,
   TALER_EXCHANGE_Withdraw2Callback res_cb,
   void *res_cb_cls)
 {
   struct TALER_EXCHANGE_Withdraw2Handle *wh;
-  const struct TALER_EXCHANGE_Keys *keys;
   const struct TALER_EXCHANGE_DenomPublicKey *dk;
   struct TALER_ReserveSignatureP reserve_sig;
   char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
   struct TALER_BlindedCoinHashP bch;
 
-  keys = TALER_EXCHANGE_get_keys (exchange);
-  if (NULL == keys)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
+  GNUNET_assert (NULL != keys);
   dk = TALER_EXCHANGE_get_denomination_key_by_hash (keys,
                                                     &pd->denom_pub_hash);
   if (NULL == dk)
@@ -388,7 +383,7 @@ TALER_EXCHANGE_withdraw2 (
     return NULL;
   }
   wh = GNUNET_new (struct TALER_EXCHANGE_Withdraw2Handle);
-  wh->exchange = exchange;
+  wh->keys = TALER_EXCHANGE_keys_incref (keys);
   wh->cb = res_cb;
   wh->cb_cls = res_cb_cls;
   /* Compute how much we expected to charge to the reserve */
@@ -418,7 +413,7 @@ TALER_EXCHANGE_withdraw2 (
     *end = '\0';
     GNUNET_snprintf (arg_str,
                      sizeof (arg_str),
-                     "/reserves/%s/withdraw",
+                     "reserves/%s/withdraw",
                      pub_str);
   }
 
@@ -448,8 +443,9 @@ TALER_EXCHANGE_withdraw2 (
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Attempting to withdraw from reserve %s\n",
                 TALER_B2S (&wh->reserve_pub));
-    wh->url = TEAH_path_to_url (exchange,
-                                arg_str);
+    wh->url = TALER_url_join (exchange_url,
+                              arg_str,
+                              NULL);
     if (NULL == wh->url)
     {
       json_decref (withdraw_obj);
@@ -458,9 +454,7 @@ TALER_EXCHANGE_withdraw2 (
     }
     {
       CURL *eh;
-      struct GNUNET_CURL_Context *ctx;
 
-      ctx = TEAH_handle_to_context (exchange);
       eh = TALER_EXCHANGE_curl_easy_get_ (wh->url);
       if ( (NULL == eh) ||
            (GNUNET_OK !=
@@ -477,7 +471,7 @@ TALER_EXCHANGE_withdraw2 (
         return NULL;
       }
       json_decref (withdraw_obj);
-      wh->job = GNUNET_CURL_job_add2 (ctx,
+      wh->job = GNUNET_CURL_job_add2 (curl_ctx,
                                       eh,
                                       wh->post_ctx.headers,
                                       &handle_reserve_withdraw_finished,
@@ -498,5 +492,6 @@ TALER_EXCHANGE_withdraw2_cancel (struct TALER_EXCHANGE_Withdraw2Handle *wh)
   }
   GNUNET_free (wh->url);
   TALER_curl_easy_post_finished (&wh->post_ctx);
+  TALER_EXCHANGE_keys_decref (wh->keys);
   GNUNET_free (wh);
 }
diff --git a/src/testing/testing_api_cmd_batch_withdraw.c b/src/testing/testing_api_cmd_batch_withdraw.c
index e0b8285ae..9283f0325 100644
--- a/src/testing/testing_api_cmd_batch_withdraw.c
+++ b/src/testing/testing_api_cmd_batch_withdraw.c
@@ -321,12 +321,15 @@ batch_withdraw_run (void *cls,
     wci->ps = &cs->ps;
     wci->ach = cs->h_age_commitment;
   }
-  ws->wsh = TALER_EXCHANGE_batch_withdraw (exchange,
-                                           rp,
-                                           wcis,
-                                           ws->num_coins,
-                                           &reserve_batch_withdraw_cb,
-                                           ws);
+  ws->wsh = TALER_EXCHANGE_batch_withdraw (
+    TALER_TESTING_interpreter_get_context (is),
+    TALER_TESTING_get_exchange_url (is),
+    TALER_TESTING_get_keys (is),
+    rp,
+    wcis,
+    ws->num_coins,
+    &reserve_batch_withdraw_cb,
+    ws);
   if (NULL == ws->wsh)
   {
     GNUNET_break (0);
diff --git a/src/testing/testing_api_cmd_withdraw.c b/src/testing/testing_api_cmd_withdraw.c
index 8188eeae9..a6315f91e 100644
--- a/src/testing/testing_api_cmd_withdraw.c
+++ b/src/testing/testing_api_cmd_withdraw.c
@@ -410,7 +410,7 @@ withdraw_run (void *cls,
 
   if (NULL == ws->pk)
   {
-    dpk = TALER_TESTING_find_pk (TALER_EXCHANGE_get_keys (exchange),
+    dpk = TALER_TESTING_find_pk (TALER_TESTING_get_keys (is),
                                  &ws->amount,
                                  ws->age > 0);
     if (NULL == dpk)
@@ -443,11 +443,14 @@ withdraw_run (void *cls,
       .ps = &ws->ps,
       .ach = ws->h_age_commitment
     };
-    ws->wsh = TALER_EXCHANGE_withdraw (exchange,
-                                       rp,
-                                       &wci,
-                                       &reserve_withdraw_cb,
-                                       ws);
+    ws->wsh = TALER_EXCHANGE_withdraw (
+      TALER_TESTING_interpreter_get_context (is),
+      TALER_TESTING_get_exchange_url (is),
+      TALER_TESTING_get_keys (is),
+      rp,
+      &wci,
+      &reserve_withdraw_cb,
+      ws);
   }
   if (NULL == ws->wsh)
   {
diff --git a/src/util/exchange_signatures.c b/src/util/exchange_signatures.c
index 6f8ebdaff..3aa464aa7 100644
--- a/src/util/exchange_signatures.c
+++ b/src/util/exchange_signatures.c
@@ -413,6 +413,34 @@ TALER_exchange_online_age_withdraw_confirmation_sign (
 }
 
 
+enum GNUNET_GenericReturnValue
+TALER_exchange_online_age_withdraw_confirmation_verify (
+  const struct TALER_AgeWithdrawCommitmentHashP *h_commitment,
+  uint32_t noreveal_index,
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_ExchangeSignatureP *exchange_sig)
+{
+  struct TALER_AgeWithdrawConfirmationPS confirm = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_AGE_WITHDRAW),
+    .purpose.size = htonl (sizeof (confirm)),
+    .h_commitment = *h_commitment,
+    .noreveal_index = htonl (noreveal_index)
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_eddsa_verify (
+        TALER_SIGNATURE_EXCHANGE_CONFIRM_AGE_WITHDRAW,
+        &confirm,
+        &exchange_sig->eddsa_signature,
+        &exchange_pub->eddsa_pub))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
 /* TODO:oec: add signature for age-withdraw, age-reveal */
 
 
diff --git a/src/util/wallet_signatures.c b/src/util/wallet_signatures.c
index 34d097d77..823641ed4 100644
--- a/src/util/wallet_signatures.c
+++ b/src/util/wallet_signatures.c
@@ -22,6 +22,7 @@
 #include "platform.h"
 #include "taler_util.h"
 #include "taler_signatures.h"
+#include <gnunet/gnunet_common.h>
 
 
 GNUNET_NETWORK_STRUCT_BEGIN
@@ -621,9 +622,9 @@ struct TALER_AgeWithdrawRequestPS
   struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
 
   /**
-   * Hash of the commitment of n*kappa coins
+   * The reserve's public key
    */
-  struct TALER_AgeWithdrawCommitmentHashP h_commitment GNUNET_PACKED;
+  struct TALER_ReservePublicKeyP reserve_pub;
 
   /**
    * Value of the coin being exchanged (matching the denomination key)
@@ -635,7 +636,12 @@ struct TALER_AgeWithdrawRequestPS
   struct TALER_AmountNBO amount_with_fee;
 
   /**
-   * The mask that defines the age groups
+   * Running SHA512 hash of the commitment of n*kappa coins
+   */
+  struct TALER_AgeWithdrawCommitmentHashP h_commitment;
+
+  /**
+   * The mask that defines the age groups.  MUST be the same for all denominations.
    */
   struct TALER_AgeMask mask;
 
@@ -665,6 +671,8 @@ TALER_wallet_age_withdraw_sign (
     .max_age_group = TALER_get_age_group (mask, max_age)
   };
 
+  GNUNET_CRYPTO_eddsa_key_get_public (&reserve_priv->eddsa_priv,
+                                      &req.reserve_pub.eddsa_pub);
   TALER_amount_hton (&req.amount_with_fee,
                      amount_with_fee);
   GNUNET_CRYPTO_eddsa_sign (&reserve_priv->eddsa_priv,
@@ -685,6 +693,7 @@ TALER_wallet_age_withdraw_verify (
   struct TALER_AgeWithdrawRequestPS awsrd = {
     .purpose.size = htonl (sizeof (awsrd)),
     .purpose.purpose = htonl (TALER_SIGNATURE_WALLET_RESERVE_AGE_WITHDRAW),
+    .reserve_pub = *reserve_pub,
     .h_commitment = *h_commitment,
     .mask = *mask,
     .max_age_group = TALER_get_age_group (mask, max_age)