renaming mint->exchange

1 files changed, 1039 insertions, 0 deletions

diff --git a/src/exchange-tools/taler-exchange-keyup.c b/src/exchange-tools/taler-exchange-keyup.c
new file mode 100644
index 000000000..779e3a3d3
--- /dev/null
+++ b/src/exchange-tools/taler-exchange-keyup.c
@@ -0,0 +1,1039 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015 GNUnet e.V.
+
+  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, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-exchange-keyup.c
+ * @brief Update the exchange's keys for coins and signatures,
+ *        using the exchange's offline master key.
+ * @author Florian Dold
+ * @author Benedikt Mueller
+ * @author Christian Grothoff
+ */
+#include <platform.h>
+#include "taler_exchangedb_lib.h"
+
+/**
+ * When generating filenames from a cryptographic hash, we do not use
+ * all 512 bits but cut off after this number of characters (in
+ * base32-encoding).  Base32 is 5 bit per character, and given that we
+ * have very few coin types we hash, at 100 bits the chance of
+ * collision (by accident over tiny set -- birthday paradox does not
+ * apply here!) is negligible.
+ */
+#define HASH_CUTOFF 20
+
+
+GNUNET_NETWORK_STRUCT_BEGIN
+
+/**
+ * Struct with all of the key information for a kind of coin.  Hashed
+ * to generate a unique directory name per coin type.
+ */
+struct CoinTypeNBOP
+{
+  /**
+   * How long are the signatures legally valid?
+   */
+  struct GNUNET_TIME_RelativeNBO duration_legal;
+
+  /**
+   * How long can the coin be spend?
+   */
+  struct GNUNET_TIME_RelativeNBO duration_spend;
+
+  /**
+   * How long can the coin be withdrawn (generated)?
+   */
+  struct GNUNET_TIME_RelativeNBO duration_withdraw;
+
+  /**
+   * What is the value of the coin?
+   */
+  struct TALER_AmountNBO value;
+
+  /**
+   * What is the fee charged for withdrawl?
+   */
+  struct TALER_AmountNBO fee_withdraw;
+
+  /**
+   * What is the fee charged for deposits?
+   */
+  struct TALER_AmountNBO fee_deposit;
+
+  /**
+   * What is the fee charged for melting?
+   */
+  struct TALER_AmountNBO fee_refresh;
+
+  /**
+   * Key size in NBO.
+   */
+  uint32_t rsa_keysize;
+};
+
+GNUNET_NETWORK_STRUCT_END
+
+/**
+ * Set of all of the parameters that chracterize a coin.
+ */
+struct CoinTypeParams
+{
+
+  /**
+   * How long are the signatures legally valid?  Should be
+   * significantly larger than @e duration_spend (i.e. years).
+   */
+  struct GNUNET_TIME_Relative duration_legal;
+
+
+  /**
+   * How long can the coin be spend?  Should be significantly
+   * larger than @e duration_withdraw (i.e. years).
+   */
+  struct GNUNET_TIME_Relative duration_spend;
+
+  /**
+   * How long can the coin be withdrawn (generated)?  Should be small
+   * enough to limit how many coins will be signed into existence with
+   * the same key, but large enough to still provide a reasonable
+   * anonymity set.
+   */
+  struct GNUNET_TIME_Relative duration_withdraw;
+
+  /**
+   * How much should coin creation (@e duration_withdraw) duration
+   * overlap with the next coin?  Basically, the starting time of two
+   * coins is always @e duration_withdraw - @e duration_overlap apart.
+   */
+  struct GNUNET_TIME_Relative duration_overlap;
+
+  /**
+   * What is the value of the coin?
+   */
+  struct TALER_Amount value;
+
+  /**
+   * What is the fee charged for withdrawl?
+   */
+  struct TALER_Amount fee_withdraw;
+
+  /**
+   * What is the fee charged for deposits?
+   */
+  struct TALER_Amount fee_deposit;
+
+  /**
+   * What is the fee charged for melting?
+   */
+  struct TALER_Amount fee_refresh;
+
+  /**
+   * Time at which this coin is supposed to become valid.
+   */
+  struct GNUNET_TIME_Absolute anchor;
+
+  /**
+   * Length of the RSA key in bits.
+   */
+  uint32_t rsa_keysize;
+};
+
+
+/**
+ * Filename of the master private key.
+ */
+static char *masterkeyfile;
+
+/**
+ * Filename where to write denomination key signing
+ * requests for the auditor (optional, can be NULL).
+ */
+static char *auditorrequestfile;
+
+/**
+ * Handle for writing the output for the auditor.
+ */
+static FILE *auditor_output_file;
+
+/**
+ * Director of the exchange, containing the keys.
+ */
+static char *exchange_directory;
+
+/**
+ * Time to pretend when the key update is executed.
+ */
+static char *pretend_time_str;
+
+/**
+ * Handle to the exchange's configuration
+ */
+static struct GNUNET_CONFIGURATION_Handle *kcfg;
+
+/**
+ * Time when the key update is executed.  Either the actual current time, or a
+ * pretended time.
+ */
+static struct GNUNET_TIME_Absolute now;
+
+/**
+ * Master private key of the exchange.
+ */
+static struct TALER_MasterPrivateKeyP master_priv;
+
+/**
+ * Master public key of the exchange.
+ */
+static struct TALER_MasterPublicKeyP master_public_key;
+
+/**
+ * Until what time do we provide keys?
+ */
+static struct GNUNET_TIME_Absolute lookahead_sign_stamp;
+
+
+/**
+ * Obtain the name of the directory we use to store signing
+ * keys created at time @a start.
+ *
+ * @param start time at which we create the signing key
+ * @return name of the directory we should use, basically "$EXCHANGEDIR/$TIME/";
+ *         (valid until next call to this function)
+ */
+static const char *
+get_signkey_file (struct GNUNET_TIME_Absolute start)
+{
+  static char dir[4096];
+
+  GNUNET_snprintf (dir,
+                   sizeof (dir),
+                   "%s" DIR_SEPARATOR_STR TALER_EXCHANGEDB_DIR_SIGNING_KEYS DIR_SEPARATOR_STR "%llu",
+                   exchange_directory,
+                   (unsigned long long) start.abs_value_us);
+  return dir;
+}
+
+
+/**
+ * Hash the data defining the coin type.  Exclude information that may
+ * not be the same for all instances of the coin type (i.e. the
+ * anchor, overlap).
+ *
+ * @param p coin parameters to convert to a hash
+ * @param[out] hash set to the hash matching @a p
+ */
+static void
+hash_coin_type (const struct CoinTypeParams *p,
+                struct GNUNET_HashCode *hash)
+{
+  struct CoinTypeNBOP p_nbo;
+
+  memset (&p_nbo,
+          0,
+          sizeof (struct CoinTypeNBOP));
+  p_nbo.duration_spend = GNUNET_TIME_relative_hton (p->duration_spend);
+  p_nbo.duration_legal = GNUNET_TIME_relative_hton (p->duration_legal);
+  p_nbo.duration_withdraw = GNUNET_TIME_relative_hton (p->duration_withdraw);
+  TALER_amount_hton (&p_nbo.value,
+                     &p->value);
+  TALER_amount_hton (&p_nbo.fee_withdraw,
+                     &p->fee_withdraw);
+  TALER_amount_hton (&p_nbo.fee_deposit,
+                     &p->fee_deposit);
+  TALER_amount_hton (&p_nbo.fee_refresh,
+                     &p->fee_refresh);
+  p_nbo.rsa_keysize = htonl (p->rsa_keysize);
+  GNUNET_CRYPTO_hash (&p_nbo,
+                      sizeof (struct CoinTypeNBOP),
+                      hash);
+}
+
+
+/**
+ * Obtain the name of the directory we should use to store coins of
+ * the given type.  The directory name has the format
+ * "$EXCHANGEDIR/$VALUE/$HASH/" where "$VALUE" represents the value of the
+ * coin and "$HASH" encodes all of the coin's parameters, generating a
+ * unique string for each type of coin.  Note that the "$HASH"
+ * includes neither the absolute creation time nor the key of the
+ * coin, thus the files in the subdirectory really just refer to the
+ * same type of coins, not the same coin.
+ *
+ * @param p coin parameters to convert to a directory name
+ * @return directory name (valid until next call to this function)
+ */
+static const char *
+get_cointype_dir (const struct CoinTypeParams *p)
+{
+  static char dir[4096];
+  struct GNUNET_HashCode hash;
+  char *hash_str;
+  char *val_str;
+  size_t i;
+
+  hash_coin_type (p, &hash);
+  hash_str = GNUNET_STRINGS_data_to_string_alloc (&hash,
+                                                  sizeof (struct GNUNET_HashCode));
+  GNUNET_assert (NULL != hash_str);
+  GNUNET_assert (HASH_CUTOFF <= strlen (hash_str) + 1);
+  hash_str[HASH_CUTOFF] = 0;
+
+  val_str = TALER_amount_to_string (&p->value);
+  for (i = 0; i < strlen (val_str); i++)
+    if ( (':' == val_str[i]) ||
+         ('.' == val_str[i]) )
+      val_str[i] = '_';
+
+  GNUNET_snprintf (dir,
+                   sizeof (dir),
+                   "%s" DIR_SEPARATOR_STR TALER_EXCHANGEDB_DIR_DENOMINATION_KEYS DIR_SEPARATOR_STR "%s-%s",
+                   exchange_directory,
+                   val_str,
+                   hash_str);
+  GNUNET_free (hash_str);
+  GNUNET_free (val_str);
+  return dir;
+}
+
+
+/**
+ * Obtain the name of the file we would use to store the key
+ * information for a coin of the given type @a p and validity
+ * start time @a start
+ *
+ * @param p parameters for the coin
+ * @param start when would the coin begin to be issued
+ * @return name of the file to use for this coin
+ *         (valid until next call to this function)
+ */
+static const char *
+get_cointype_file (const struct CoinTypeParams *p,
+                   struct GNUNET_TIME_Absolute start)
+{
+  static char filename[4096];
+  const char *dir;
+
+  dir = get_cointype_dir (p);
+  GNUNET_snprintf (filename,
+                   sizeof (filename),
+                   "%s" DIR_SEPARATOR_STR "%llu",
+                   dir,
+                   (unsigned long long) start.abs_value_us);
+  return filename;
+}
+
+
+/**
+ * Get the latest key file from a past run of the key generation
+ * tool.  Used to calculate the starting time for the keys we
+ * generate during this invocation.  This function is used to
+ * handle both signing keys and coin keys, as in both cases
+ * the filenames correspond to the timestamps we need.
+ *
+ * @param cls closure, a `struct GNUNET_TIME_Absolute *`, updated
+ *                     to contain the highest timestamp (below #now)
+ *                     that was found
+ * @param filename complete filename (absolute path)
+ * @return #GNUNET_OK (to continue to iterate)
+ */
+static int
+get_anchor_iter (void *cls,
+                 const char *filename)
+{
+  struct GNUNET_TIME_Absolute *anchor = cls;
+  struct GNUNET_TIME_Absolute stamp;
+  const char *base;
+  char *end = NULL;
+
+  base = GNUNET_STRINGS_get_short_name (filename);
+  stamp.abs_value_us = strtol (base,
+                               &end,
+                               10);
+  if ((NULL == end) || (0 != *end))
+  {
+    fprintf(stderr,
+            "Ignoring unexpected file `%s'.\n",
+            filename);
+    return GNUNET_OK;
+  }
+  *anchor = GNUNET_TIME_absolute_max (stamp,
+                                      *anchor);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Get the timestamp where the first new key should be generated.
+ * Relies on correctly named key files (as we do not parse them,
+ * but just look at the filenames to "guess" at their contents).
+ *
+ * @param dir directory that should contain the existing keys
+ * @param duration how long is one key valid (for signing)?
+ * @param overlap what's the overlap between the keys validity period?
+ * @param[out] anchor the timestamp where the first new key should be generated
+ */
+static void
+get_anchor (const char *dir,
+            struct GNUNET_TIME_Relative duration,
+            struct GNUNET_TIME_Relative overlap,
+            struct GNUNET_TIME_Absolute *anchor)
+{
+  GNUNET_assert (0 == duration.rel_value_us % 1000000);
+  GNUNET_assert (0 == overlap.rel_value_us % 1000000);
+  if (GNUNET_YES !=
+      GNUNET_DISK_directory_test (dir,
+                                  GNUNET_YES))
+  {
+    *anchor = now;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "No existing keys found, starting with fresh key set.\n");
+    return;
+  }
+  *anchor = GNUNET_TIME_UNIT_ZERO_ABS;
+  if (-1 ==
+      GNUNET_DISK_directory_scan (dir,
+                                  &get_anchor_iter,
+                                  anchor))
+  {
+    *anchor = now;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "No existing keys found, starting with fresh key set.\n");
+    return;
+  }
+
+  if ((GNUNET_TIME_absolute_add (*anchor,
+                                 duration)).abs_value_us < now.abs_value_us)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "Existing keys are way too old, starting with fresh key set.\n");
+    *anchor = now;
+  }
+  else if (anchor->abs_value_us != now.abs_value_us)
+  {
+    /* Real starting time is the last start time + duration - overlap */
+    *anchor = GNUNET_TIME_absolute_add (*anchor,
+                                        duration);
+    *anchor = GNUNET_TIME_absolute_subtract (*anchor,
+                                             overlap);
+  }
+  /* anchor is now the stamp where we need to create a new key */
+}
+
+
+/**
+ * Create a exchange signing key (for signing exchange messages, not for coins)
+ * and assert its correctness by signing it with the master key.
+ *
+ * @param start start time of the validity period for the key
+ * @param duration how long should the key be valid
+ * @param end when do all signatures by this key expire
+ * @param[out] pi set to the signing key information
+ */
+static void
+create_signkey_issue_priv (struct GNUNET_TIME_Absolute start,
+                           struct GNUNET_TIME_Relative duration,
+                           struct GNUNET_TIME_Absolute end,
+                           struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP *pi)
+{
+  struct GNUNET_CRYPTO_EddsaPrivateKey *priv;
+  struct TALER_ExchangeSigningKeyValidityPS *issue = &pi->issue;
+
+  priv = GNUNET_CRYPTO_eddsa_key_create ();
+  pi->signkey_priv.eddsa_priv = *priv;
+  GNUNET_free (priv);
+  issue->master_public_key = master_public_key;
+  issue->start = GNUNET_TIME_absolute_hton (start);
+  issue->expire = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_add (start,
+                                                                       duration));
+  issue->end = GNUNET_TIME_absolute_hton (end);
+  GNUNET_CRYPTO_eddsa_key_get_public (&pi->signkey_priv.eddsa_priv,
+                                      &issue->signkey_pub.eddsa_pub);
+  issue->purpose.purpose = htonl (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY);
+  issue->purpose.size = htonl (sizeof (struct TALER_ExchangeSigningKeyValidityPS) -
+                               offsetof (struct TALER_ExchangeSigningKeyValidityPS,
+                                         purpose));
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CRYPTO_eddsa_sign (&master_priv.eddsa_priv,
+                                           &issue->purpose,
+                                           &issue->signature.eddsa_signature));
+}
+
+
+/**
+ * Generate signing keys starting from the last key found to
+ * the lookahead time.
+ *
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+static int
+exchange_keys_update_signkeys ()
+{
+  struct GNUNET_TIME_Relative signkey_duration;
+  struct GNUNET_TIME_Relative legal_duration;
+  struct GNUNET_TIME_Absolute anchor;
+  char *signkey_dir;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           "exchange_keys",
+                                           "signkey_duration",
+                                           &signkey_duration))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange_keys",
+                               "signkey_duration");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           "exchange_keys",
+                                           "legal_duration",
+                                           &legal_duration))
+  {
+    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange_keys",
+                               "legal_duration",
+                               "fails to specify valid timeframe");
+    return GNUNET_SYSERR;
+  }
+  if (signkey_duration.rel_value_us > legal_duration.rel_value_us)
+  {
+    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange_keys",
+                               "legal_duration",
+                               "must be longer than signkey_duration");
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&signkey_duration);
+  GNUNET_asprintf (&signkey_dir,
+                   "%s" DIR_SEPARATOR_STR TALER_EXCHANGEDB_DIR_SIGNING_KEYS,
+                   exchange_directory);
+  /* make sure the directory exists */
+  if (GNUNET_OK !=
+      GNUNET_DISK_directory_create (signkey_dir))
+  {
+    fprintf (stderr,
+             "Failed to create signing key directory\n");
+    return GNUNET_SYSERR;
+  }
+
+  get_anchor (signkey_dir,
+              signkey_duration,
+              GNUNET_TIME_UNIT_ZERO /* no overlap for signing keys */,
+              &anchor);
+
+  while (anchor.abs_value_us < lookahead_sign_stamp.abs_value_us)
+  {
+    const char *skf;
+    struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP signkey_issue;
+    ssize_t nwrite;
+    struct GNUNET_TIME_Absolute end;
+
+    skf = get_signkey_file (anchor);
+    end = GNUNET_TIME_absolute_add (anchor,
+                                    legal_duration);
+    GNUNET_break (GNUNET_YES !=
+                  GNUNET_DISK_file_test (skf));
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Generating signing key for %s.\n",
+                GNUNET_STRINGS_absolute_time_to_string (anchor));
+    create_signkey_issue_priv (anchor,
+                               signkey_duration,
+                               end,
+                               &signkey_issue);
+    nwrite = GNUNET_DISK_fn_write (skf,
+                                   &signkey_issue,
+                                   sizeof (struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP),
+                                   GNUNET_DISK_PERM_USER_WRITE | GNUNET_DISK_PERM_USER_READ);
+    if (sizeof (struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP) != nwrite)
+    {
+      fprintf (stderr,
+               "Failed to write to file `%s': %s\n",
+               skf,
+               STRERROR (errno));
+      return GNUNET_SYSERR;
+    }
+    anchor = GNUNET_TIME_absolute_add (anchor,
+                                       signkey_duration);
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Parse configuration for coin type parameters.  Also determines
+ * our anchor by looking at the existing coins of the same type.
+ *
+ * @param ct section in the configuration file giving the coin type parameters
+ * @param[out] params set to the coin parameters from the configuration
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR if the configuration is invalid
+ */
+static int
+get_cointype_params (const char *ct,
+                     struct CoinTypeParams *params)
+{
+  const char *dir;
+  unsigned long long rsa_keysize;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           ct,
+                                           "duration_withdraw",
+                                           &params->duration_withdraw))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "duration_withdraw");
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&params->duration_withdraw);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           ct,
+                                           "duration_spend",
+                                           &params->duration_spend))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "duration_spend");
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&params->duration_spend);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           ct,
+                                           "duration_legal",
+                                           &params->duration_legal))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "duration_legal");
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&params->duration_legal);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           ct,
+                                           "duration_overlap",
+                                           &params->duration_overlap))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "exchange_denom_duration_overlap");
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&params->duration_overlap);
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (kcfg,
+                                             ct,
+                                             "rsa_keysize",
+                                             &rsa_keysize))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "rsa_keysize");
+    return GNUNET_SYSERR;
+  }
+  if ( (rsa_keysize > 4 * 2048) ||
+       (rsa_keysize < 1024) )
+  {
+    fprintf (stderr,
+             "Given RSA keysize %llu outside of permitted range\n",
+             rsa_keysize);
+    return GNUNET_SYSERR;
+  }
+  params->rsa_keysize = (unsigned int) rsa_keysize;
+  if (GNUNET_OK !=
+      TALER_config_get_denom (kcfg,
+                              ct,
+                              "value",
+                              &params->value))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "value");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_config_get_denom (kcfg,
+                              ct,
+                              "fee_withdraw",
+                              &params->fee_withdraw))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "fee_withdraw");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_config_get_denom (kcfg,
+                              ct,
+                              "fee_deposit",
+                              &params->fee_deposit))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "fee_deposit");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_config_get_denom (kcfg,
+                              ct,
+                              "fee_refresh",
+                              &params->fee_refresh))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               ct,
+                               "fee_refresh");
+    return GNUNET_SYSERR;
+  }
+
+  dir = get_cointype_dir (params);
+  get_anchor (dir,
+              params->duration_withdraw,
+              params->duration_overlap,
+              &params->anchor);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Initialize the private and public key information structure for
+ * signing coins into existence.  Generates the private signing key
+ * and signes it together with the coin's meta data using the master
+ * signing key.
+ *
+ * @param params parameters used to initialize the @a dki
+ * @param[out] dki initialized according to @a params
+ */
+static void
+create_denomkey_issue (const struct CoinTypeParams *params,
+                       struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dki)
+{
+  dki->denom_priv.rsa_private_key
+    = GNUNET_CRYPTO_rsa_private_key_create (params->rsa_keysize);
+  GNUNET_assert (NULL != dki->denom_priv.rsa_private_key);
+  dki->denom_pub.rsa_public_key
+    = GNUNET_CRYPTO_rsa_private_key_get_public (dki->denom_priv.rsa_private_key);
+  GNUNET_CRYPTO_rsa_public_key_hash (dki->denom_pub.rsa_public_key,
+                                     &dki->issue.properties.denom_hash);
+  dki->issue.properties.master = master_public_key;
+  dki->issue.properties.start = GNUNET_TIME_absolute_hton (params->anchor);
+  dki->issue.properties.expire_withdraw =
+      GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_add (params->anchor,
+                                                           params->duration_withdraw));
+  dki->issue.properties.expire_spend =
+    GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_add (params->anchor,
+                                                         params->duration_spend));
+  dki->issue.properties.expire_legal =
+    GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_add (params->anchor,
+                                                         params->duration_legal));
+  TALER_amount_hton (&dki->issue.properties.value,
+                     &params->value);
+  TALER_amount_hton (&dki->issue.properties.fee_withdraw,
+                     &params->fee_withdraw);
+  TALER_amount_hton (&dki->issue.properties.fee_deposit,
+                     &params->fee_deposit);
+  TALER_amount_hton (&dki->issue.properties.fee_refresh,
+                     &params->fee_refresh);
+  dki->issue.properties.purpose.purpose
+    = htonl (TALER_SIGNATURE_MASTER_DENOMINATION_KEY_VALIDITY);
+  dki->issue.properties.purpose.size
+    = htonl (sizeof (struct TALER_DenominationKeyValidityPS));
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CRYPTO_eddsa_sign (&master_priv.eddsa_priv,
+                                           &dki->issue.properties.purpose,
+                                           &dki->issue.signature.eddsa_signature));
+}
+
+
+/**
+ * Generate new coin signing keys for the coin type of the given @a
+ * coin_alias.
+ *
+ * @param cls a `int *`, to be set to #GNUNET_SYSERR on failure
+ * @param coin_alias name of the coin's section in the configuration
+ */
+static void
+exchange_keys_update_cointype (void *cls,
+                           const char *coin_alias)
+{
+  int *ret = cls;
+  struct CoinTypeParams p;
+  const char *dkf;
+  struct TALER_EXCHANGEDB_DenominationKeyIssueInformation denomkey_issue;
+
+  if (0 != strncasecmp (coin_alias,
+                        "coin_",
+                        strlen ("coin_")))
+    return; /* not a coin definition */
+  if (GNUNET_OK !=
+      get_cointype_params (coin_alias,
+                           &p))
+  {
+    *ret = GNUNET_SYSERR;
+    return;
+  }
+  if (GNUNET_OK !=
+      GNUNET_DISK_directory_create (get_cointype_dir (&p)))
+  {
+    *ret = GNUNET_SYSERR;
+    return;
+  }
+
+  while (p.anchor.abs_value_us < lookahead_sign_stamp.abs_value_us)
+  {
+    dkf = get_cointype_file (&p,
+                             p.anchor);
+    GNUNET_break (GNUNET_YES != GNUNET_DISK_file_test (dkf));
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Generating denomination key for type `%s', start %s at %s\n",
+                coin_alias,
+                GNUNET_STRINGS_absolute_time_to_string (p.anchor),
+                dkf);
+    create_denomkey_issue (&p,
+                           &denomkey_issue);
+    if (GNUNET_OK !=
+        TALER_EXCHANGEDB_denomination_key_write (dkf,
+                                             &denomkey_issue))
+    {
+      fprintf (stderr,
+               "Failed to write denomination key information to file `%s'.\n",
+               dkf);
+      *ret = GNUNET_SYSERR;
+      GNUNET_CRYPTO_rsa_private_key_free (denomkey_issue.denom_priv.rsa_private_key);
+      return;
+    }
+    if ( (NULL != auditor_output_file) &&
+         (sizeof (denomkey_issue.issue.properties) !=
+          fwrite (&denomkey_issue.issue.properties,
+                  sizeof (struct TALER_DenominationKeyValidityPS),
+                  1,
+                  auditor_output_file)) )
+    {
+      fprintf (stderr,
+               "Failed to write denomination key information to %s: %s\n",
+               auditorrequestfile,
+               STRERROR (errno));
+      *ret = GNUNET_SYSERR;
+      return;
+    }
+    GNUNET_CRYPTO_rsa_private_key_free (denomkey_issue.denom_priv.rsa_private_key);
+    p.anchor = GNUNET_TIME_absolute_add (p.anchor,
+                                         p.duration_spend);
+    p.anchor = GNUNET_TIME_absolute_subtract (p.anchor,
+                                              p.duration_overlap);
+  }
+}
+
+
+/**
+ * Update all of the denomination keys of the exchange.
+ *
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+static int
+exchange_keys_update_denomkeys ()
+{
+  int ok;
+
+  ok = GNUNET_OK;
+  GNUNET_CONFIGURATION_iterate_sections (kcfg,
+                                         &exchange_keys_update_cointype,
+                                         &ok);
+  return ok;
+}
+
+
+/**
+ * The main function of the taler-exchange-keyup tool.  This tool is used
+ * to create the signing and denomination keys for the exchange.  It uses
+ * the long-term offline private key and writes the (additional) key
+ * files to the respective exchange directory (from where they can then be
+ * copied to the online server).  Note that we need (at least) the
+ * most recent generated previous keys so as to align the validity
+ * periods.
+ *
+ * @param argc number of arguments from the command line
+ * @param argv command line arguments
+ * @return 0 ok, 1 on error
+ */
+int
+main (int argc,
+      char *const *argv)
+{
+  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
+    {'d', "exchange-dir", "DIR",
+     "exchange directory with keys to update", 1,
+     &GNUNET_GETOPT_set_filename, &exchange_directory},
+    TALER_GETOPT_OPTION_HELP ("Setup signing and denomination keys for a Taler exchange"),
+    {'m', "master-key", "FILE",
+     "master key file (private key)", 1,
+     &GNUNET_GETOPT_set_filename, &masterkeyfile},
+    {'o', "output", "FILE",
+     "auditor denomination key signing request file to create", 1,
+     &GNUNET_GETOPT_set_filename, &auditorrequestfile},
+    {'t', "time", "TIMESTAMP",
+     "pretend it is a different time for the update", 0,
+     &GNUNET_GETOPT_set_string, &pretend_time_str},
+    GNUNET_GETOPT_OPTION_VERSION (VERSION "-" VCS_VERSION),
+    GNUNET_GETOPT_OPTION_END
+  };
+  struct GNUNET_TIME_Relative lookahead_sign;
+  struct GNUNET_CRYPTO_EddsaPrivateKey *eddsa_priv;
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_log_setup ("taler-exchange-keyup",
+                                   "WARNING",
+                                   NULL));
+
+  if (GNUNET_GETOPT_run ("taler-exchange-keyup",
+                         options,
+                         argc, argv) < 0)
+    return 1;
+  if (NULL == exchange_directory)
+  {
+    fprintf (stderr,
+             "Exchange directory not given\n");
+    return 1;
+  }
+  if (NULL != pretend_time_str)
+  {
+    if (GNUNET_OK !=
+        GNUNET_STRINGS_fancy_time_to_absolute (pretend_time_str,
+                                               &now))
+    {
+      fprintf (stderr,
+               "timestamp `%s' invalid\n",
+               pretend_time_str);
+      return 1;
+    }
+  }
+  else
+  {
+    now = GNUNET_TIME_absolute_get ();
+  }
+  TALER_round_abs_time (&now);
+
+  kcfg = TALER_config_load (exchange_directory);
+  if (NULL == kcfg)
+  {
+    fprintf (stderr,
+             "Failed to load exchange configuration\n");
+    return 1;
+  }
+  if (NULL == masterkeyfile)
+  {
+    fprintf (stderr,
+             "Master key file not given\n");
+    return 1;
+  }
+  eddsa_priv = GNUNET_CRYPTO_eddsa_key_create_from_file (masterkeyfile);
+  if (NULL == eddsa_priv)
+  {
+    fprintf (stderr,
+             "Failed to initialize master key from file `%s'\n",
+             masterkeyfile);
+    return 1;
+  }
+  master_priv.eddsa_priv = *eddsa_priv;
+  GNUNET_free (eddsa_priv);
+  GNUNET_CRYPTO_eddsa_key_get_public (&master_priv.eddsa_priv,
+                                      &master_public_key.eddsa_pub);
+
+  if (NULL != auditorrequestfile)
+  {
+    auditor_output_file = FOPEN (auditorrequestfile,
+                                 "w");
+    if (NULL == auditor_output_file)
+    {
+      fprintf (stderr,
+               "Failed to open `%s' for writing: %s\n",
+               auditorrequestfile,
+               STRERROR (errno));
+      return 1;
+    }
+  }
+
+  /* check if key from file matches the one from the configuration */
+  {
+    struct GNUNET_CRYPTO_EddsaPublicKey master_public_key_from_cfg;
+
+    if (GNUNET_OK !=
+        GNUNET_CONFIGURATION_get_data (kcfg,
+                                       "exchange",
+                                       "master_public_key",
+                                       &master_public_key_from_cfg,
+                                       sizeof (struct GNUNET_CRYPTO_EddsaPublicKey)))
+    {
+      GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                                 "exchange",
+                                 "master_public_key");
+      return 1;
+    }
+    if (0 !=
+        memcmp (&master_public_key,
+                &master_public_key_from_cfg,
+                sizeof (struct GNUNET_CRYPTO_EddsaPublicKey)))
+    {
+      GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                                 "exchange",
+                                 "master_public_key",
+                                 _("does not match with private key"));
+      return 1;
+    }
+  }
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (kcfg,
+                                           "exchange_keys",
+                                           "lookahead_sign",
+                                           &lookahead_sign))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange_keys",
+                               "lookahead_sign");
+    return GNUNET_SYSERR;
+  }
+  if (0 == lookahead_sign.rel_value_us)
+  {
+    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange_keys",
+                               "lookahead_sign",
+                               _("must not be zero"));
+    return GNUNET_SYSERR;
+  }
+  TALER_round_rel_time (&lookahead_sign);
+  lookahead_sign_stamp = GNUNET_TIME_absolute_add (now,
+                                                   lookahead_sign);
+
+
+  /* finally, do actual work */
+  if (GNUNET_OK != exchange_keys_update_signkeys ())
+    return 1;
+
+  if (GNUNET_OK != exchange_keys_update_denomkeys ())
+    return 1;
+  if (NULL != auditor_output_file)
+  {
+    FCLOSE (auditor_output_file);
+    auditor_output_file = NULL;
+  }
+  return 0;
+}
+
+/* end of taler-exchange-keyup.c */