messenger_api_handle.c

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/*
   This file is part of GNUnet.
   Copyright (C) 2020--2026 GNUnet e.V.
 
   GNUnet is free software: you can redistribute it and/or modify it
   under the terms of the GNU Affero General Public License as published
   by the Free Software Foundation, either version 3 of the License,
   or (at your option) any later version.
 
   GNUnet 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
   Affero General Public License for more details.
 
   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
   SPDX-License-Identifier: AGPL3.0-or-later
 */
#include "messenger_api_handle.h"
 
#include "gnu_name_system_record_types.h"
#include "gnunet_common.h"
#include "gnunet_messenger_service.h"
#include "gnunet_util_lib.h"
#include "messenger_api_epoch.h"
#include "messenger_api_epoch_announcement.h"
#include "messenger_api_epoch_group.h"
#include "messenger_api_message.h"
#include "messenger_api_room.h"
#include "messenger_api_util.h"
 
#include <ctype.h>
 
struct GNUNET_MESSENGER_Handle*
create_handle (const struct GNUNET_CONFIGURATION_Handle *config,
               const struct GNUNET_HashCode *secret,
               GNUNET_MESSENGER_MessageCallback msg_callback,
               void *msg_cls)
{
  struct GNUNET_MESSENGER_Handle *handle;
 
  GNUNET_assert (config);
 
  handle = GNUNET_new (struct GNUNET_MESSENGER_Handle);
 
  handle->config = config;
  handle->mq = NULL;
 
  handle->group_keys = GNUNET_CONFIGURATION_get_value_yesno (
    handle->config,
    GNUNET_MESSENGER_SERVICE_NAME,
    "MESSENGER_GROUP_KEYS");
 
  if (handle->config)
    handle->namestore = GNUNET_NAMESTORE_connect (handle->config);
 
  if (secret)
    GNUNET_memcpy (&(handle->secret), secret, sizeof (handle->secret));
  else
    memset (&(handle->secret), 0, sizeof (handle->secret));
 
  handle->msg_callback = msg_callback;
  handle->msg_cls = msg_cls;
 
  handle->name = NULL;
  handle->key = NULL;
  handle->pubkey = NULL;
 
  handle->reconnect_time = GNUNET_TIME_relative_get_zero_ ();
  handle->reconnect_task = NULL;
 
  handle->key_monitor = NULL;
 
  handle->rooms = GNUNET_CONTAINER_multihashmap_create (8, GNUNET_NO);
 
  init_contact_store (get_handle_contact_store (handle));
 
  return handle;
}
 
 
static enum GNUNET_GenericReturnValue
iterate_destroy_room (void *cls,
                      const struct GNUNET_HashCode *key,
                      void *value)
{
  struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert (value);
 
  room = value;
 
  destroy_room (room);
  return GNUNET_YES;
}
 
 
void
destroy_handle (struct GNUNET_MESSENGER_Handle *handle)
{
  GNUNET_assert (handle);
 
  clear_contact_store (get_handle_contact_store (handle));
 
  if (handle->rooms)
  {
    GNUNET_CONTAINER_multihashmap_iterate (
      handle->rooms, iterate_destroy_room, NULL);
 
    GNUNET_CONTAINER_multihashmap_destroy (handle->rooms);
  }
 
  if (handle->key_monitor)
    GNUNET_NAMESTORE_zone_monitor_stop (handle->key_monitor);
 
  if (handle->reconnect_task)
    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
 
  if (handle->mq)
    GNUNET_MQ_destroy (handle->mq);
 
  if (handle->namestore)
    GNUNET_NAMESTORE_disconnect (handle->namestore);
 
  if (handle->name)
    GNUNET_free (handle->name);
 
  if (handle->key)
    GNUNET_free (handle->key);
 
  if (handle->pubkey)
    GNUNET_free (handle->pubkey);
 
  GNUNET_free (handle);
}
 
 
void
set_handle_name (struct GNUNET_MESSENGER_Handle *handle,
                 const char *name)
{
  GNUNET_assert (handle);
 
  if (handle->name)
    GNUNET_free (handle->name);
 
  handle->name = name ? GNUNET_strdup (name) : NULL;
}
 
 
const char*
get_handle_name (const struct GNUNET_MESSENGER_Handle *handle)
{
  GNUNET_assert (handle);
 
  return handle->name;
}
 
 
static void
cb_key_error (void *cls)
{
  struct GNUNET_MESSENGER_Handle *handle;
  const char *name;
 
  GNUNET_assert (cls);
 
  handle = cls;
  name = get_handle_name (handle);
 
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Error on monitoring records: %s\n",
              name);
}
 
 
static void
read_handle_epoch_key (struct GNUNET_MESSENGER_Handle *handle,
                       const struct GNUNET_CRYPTO_BlindablePrivateKey *zone,
                       const struct GNUNET_MESSENGER_RoomEpochKeyRecord *record)
{
  struct GNUNET_MESSENGER_Room *room;
  const struct GNUNET_HashCode *room_key;
  struct GNUNET_MESSENGER_Epoch *epoch;
  union GNUNET_MESSENGER_EpochIdentifier identifier;
  enum GNUNET_GenericReturnValue valid;
  struct GNUNET_CRYPTO_SymmetricSessionKey shared_key;
 
  GNUNET_assert ((handle) && (zone) && (record));
 
  room = get_handle_room (handle, &(record->key), GNUNET_YES);
 
  if (! room)
    return;
 
  room_key = get_room_key (room);
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Monitor epoch key record of room: %s\n",
              GNUNET_h2s (room_key));
 
  epoch = get_room_epoch (room, &(record->hash), GNUNET_NO);
 
  if (! epoch)
    return;
 
  GNUNET_memcpy (
    &identifier,
    &(record->identifier),
    sizeof (record->identifier));
  valid = (GNUNET_MESSENGER_FLAG_EPOCH_VALID & record->flags? GNUNET_YES :
           GNUNET_NO);
 
  {
    struct GNUNET_CRYPTO_SymmetricSessionKey skey;
    struct GNUNET_CRYPTO_SymmetricInitializationVector iv [2];
    int32_t checksum;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &skey, sizeof (skey),
          GNUNET_MESSENGER_SALT_EPOCH_KEY,
          sizeof (GNUNET_MESSENGER_SALT_EPOCH_KEY),
          &(handle->secret),
          sizeof (handle->secret),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (zone),
          GNUNET_CRYPTO_kdf_arg_auto (&epoch->hash),
          GNUNET_CRYPTO_kdf_arg_auto (&identifier.hash)))
      return;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &iv, sizeof (iv),
          GNUNET_MESSENGER_SALT_EPOCH_IV,
          sizeof (GNUNET_MESSENGER_SALT_EPOCH_IV),
          &skey,
          sizeof (skey),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (&epoch->hash),
          GNUNET_CRYPTO_kdf_arg_auto (&identifier.hash)))
      return;
 
    if (-1 == GNUNET_CRYPTO_symmetric_decrypt (&(record->shared_key),
                                               sizeof (record->shared_key),
                                               &skey,
                                               &iv[0],
                                               &shared_key))
      return;
 
    if (-1 == GNUNET_CRYPTO_symmetric_decrypt (&(record->checksum),
                                               sizeof (record->checksum),
                                               &skey,
                                               &iv[1],
                                               &checksum))
      return;
 
    GNUNET_CRYPTO_zero_keys (&skey, sizeof (skey));
 
    if (checksum != GNUNET_CRYPTO_crc32_n (&shared_key, sizeof (shared_key)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Epoch key record failed checksum: %s\n",
                  GNUNET_h2s (&(record->key)));
      goto clear_key;
    }
  }
 
  if (identifier.code.group_bit)
  {
    struct GNUNET_MESSENGER_EpochGroup *group;
 
    group = get_epoch_group (epoch, &identifier, valid);
 
    if (! group)
      goto clear_key;
 
    set_epoch_group_key (group, &shared_key, GNUNET_NO);
  }
  else
  {
    struct GNUNET_MESSENGER_EpochAnnouncement *announcement;
 
    announcement = get_epoch_announcement (epoch, &identifier, valid);
 
    if (! announcement)
      goto clear_key;
 
    set_epoch_announcement_key (announcement, &shared_key, GNUNET_NO);
  }
 
clear_key:
  GNUNET_CRYPTO_zero_keys (&shared_key, sizeof (shared_key));
}
 
 
static void
read_handle_encryption_key (struct GNUNET_MESSENGER_Handle *handle,
                            const struct GNUNET_CRYPTO_BlindablePrivateKey
                            *zone,
                            const struct GNUNET_MESSENGER_EncryptionKeyRecord
                            *record)
{
  struct GNUNET_MESSENGER_Room *room;
  const struct GNUNET_HashCode *room_key;
  struct GNUNET_CRYPTO_HpkePrivateKey encryption_key;
 
  GNUNET_assert ((handle) && (zone) && (record));
 
  room = get_handle_room (handle, &(record->key), GNUNET_YES);
 
  if (! room)
    return;
 
  room_key = get_room_key (room);
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Monitor encryption key record of room: %s\n",
              GNUNET_h2s (room_key));
 
  {
    struct GNUNET_CRYPTO_SymmetricSessionKey skey;
    struct GNUNET_CRYPTO_SymmetricInitializationVector iv [2];
    uint8_t encryption_key_data[GNUNET_MESSENGER_ENCRYPTION_KEY_DATA_BYTES];
    size_t encryption_key_len;
    int32_t encrypted_key_checksum;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &skey, sizeof (skey),
          GNUNET_MESSENGER_SALT_ENCRYPTION_KEY,
          sizeof (GNUNET_MESSENGER_SALT_ENCRYPTION_KEY),
          &(handle->secret),
          sizeof (handle->secret),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (zone),
          GNUNET_CRYPTO_kdf_arg (record->nonce_data,
                                 sizeof (record->nonce_data))))
      return;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &iv, sizeof (iv),
          GNUNET_MESSENGER_SALT_ENCRYPTION_IV,
          sizeof (GNUNET_MESSENGER_SALT_ENCRYPTION_IV),
          &skey,
          sizeof skey,
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg (record->nonce_data, sizeof (record->nonce_data))))
      return;
 
 
    if (-1 == GNUNET_CRYPTO_symmetric_decrypt (record->encrypted_key_data,
                                               sizeof (encryption_key_data),
                                               &skey,
                                               &iv[0],
                                               encryption_key_data))
      return;
 
    if (-1 == GNUNET_CRYPTO_symmetric_decrypt (&(record->encrypted_key_checksum)
                                               ,
                                               sizeof (encrypted_key_checksum),
                                               &skey,
                                               &iv[1],
                                               &encrypted_key_checksum))
      return;
 
    GNUNET_CRYPTO_zero_keys (&skey, sizeof (skey));
 
    if (encrypted_key_checksum != GNUNET_CRYPTO_crc32_n (encryption_key_data,
                                                         sizeof (
                                                           encryption_key_data))
        )
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Encryption key record failed checksum: %s\n",
                  GNUNET_h2s (&(record->key)));
      return;
    }
 
    if (GNUNET_OK != GNUNET_CRYPTO_read_hpke_sk_from_buffer (
          encryption_key_data, record->encrypted_key_length, &encryption_key, &
          encryption_key_len))
      return;
 
    if (encryption_key_len < record->encrypted_key_length)
      goto clear_key;
  }
 
  add_room_encryption_key (room, &encryption_key);
 
clear_key:
  GNUNET_CRYPTO_hpke_sk_clear (&encryption_key);
}
 
 
static void
cb_key_monitor (void *cls,
                const struct GNUNET_CRYPTO_BlindablePrivateKey *zone,
                const char *label,
                unsigned int rd_count,
                const struct GNUNET_GNSRECORD_Data *rd,
                struct GNUNET_TIME_Absolute expiry)
{
  struct GNUNET_MESSENGER_Handle *handle;
 
  GNUNET_assert (
    (cls) && (zone) && (label) && (rd_count) && (rd));
 
  handle = cls;
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Monitor record with label: %s\n",
              label);
 
  switch (rd->record_type)
  {
  case GNUNET_GNSRECORD_TYPE_MESSENGER_ROOM_EPOCH_KEY:
    if ((sizeof (struct GNUNET_MESSENGER_RoomEpochKeyRecord) == rd->data_size)
        && (rd->data))
      read_handle_epoch_key (handle, zone, rd->data);
 
    break;
  case GNUNET_GNSRECORD_TYPE_MESSENGER_ENCRYPTION_KEY:
    if ((sizeof (struct GNUNET_MESSENGER_EncryptionKeyRecord) == rd->data_size)
        && (rd->data))
      read_handle_encryption_key (handle, zone, rd->data);
 
    break;
  default:
    break;
  }
 
  GNUNET_NAMESTORE_zone_monitor_next (handle->key_monitor, 1);
}
 
 
static enum GNUNET_GenericReturnValue
it_announcement_store_key (void *cls,
                           GNUNET_UNUSED const struct GNUNET_ShortHashCode *key,
                           void *value)
{
  struct GNUNET_MESSENGER_EpochAnnouncement *announcement;
 
  GNUNET_assert (value);
 
  announcement = value;
 
  if ((cls) && (GNUNET_YES != announcement->stored))
    write_epoch_announcement_record (announcement, GNUNET_NO);
  else if (! cls)
    announcement->stored = GNUNET_NO;
 
  return GNUNET_YES;
}
 
 
static enum GNUNET_GenericReturnValue
it_group_store_key (void *cls,
                    GNUNET_UNUSED const struct GNUNET_ShortHashCode *key,
                    void *value)
{
  struct GNUNET_MESSENGER_EpochGroup *group;
 
  GNUNET_assert (value);
 
  group = value;
 
  if ((cls) && (GNUNET_YES != group->stored))
    write_epoch_group_record (group, GNUNET_NO);
  else if (! cls)
    group->stored = GNUNET_NO;
 
  return GNUNET_YES;
}
 
 
static enum GNUNET_GenericReturnValue
it_epoch_store_keys (void *cls,
                     GNUNET_UNUSED const struct GNUNET_HashCode *key,
                     void *value)
{
  const struct GNUNET_MESSENGER_Epoch *epoch;
 
  GNUNET_assert (value);
 
  epoch = value;
 
  GNUNET_CONTAINER_multishortmap_iterate (epoch->announcements,
                                          it_announcement_store_key, cls);
  GNUNET_CONTAINER_multishortmap_iterate (epoch->groups, it_group_store_key,
                                          cls);
  return GNUNET_YES;
}
 
 
static enum GNUNET_GenericReturnValue
it_room_store_keys (void *cls,
                    GNUNET_UNUSED const struct GNUNET_HashCode *key,
                    void *value)
{
  const struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert (value);
 
  room = value;
 
  GNUNET_CONTAINER_multihashmap_iterate (
    room->epochs,
    it_epoch_store_keys,
    cls);
  return GNUNET_YES;
}
 
 
static void
cb_key_sync (void *cls)
{
  struct GNUNET_MESSENGER_Handle *handle;
  const char *name;
 
  GNUNET_assert (cls);
 
  handle = cls;
  name = get_handle_name (handle);
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Syncing keys from records completed: %s\n",
              name);
 
  GNUNET_CONTAINER_multihashmap_iterate (
    handle->rooms, it_room_store_keys, handle);
}
 
 
void
set_handle_key (struct GNUNET_MESSENGER_Handle *handle,
                const struct GNUNET_CRYPTO_BlindablePrivateKey *key)
{
  GNUNET_assert (handle);
 
  if (handle->key_monitor)
  {
    GNUNET_NAMESTORE_zone_monitor_stop (handle->key_monitor);
    handle->key_monitor = NULL;
  }
 
  if (! key)
  {
    if (handle->key)
      GNUNET_free (handle->key);
 
    if (handle->pubkey)
      GNUNET_free (handle->pubkey);
 
    handle->key = NULL;
    handle->pubkey = NULL;
    return;
  }
 
  if (! handle->key)
    handle->key = GNUNET_new (struct GNUNET_CRYPTO_BlindablePrivateKey);
 
  if (! handle->pubkey)
    handle->pubkey = GNUNET_new (struct GNUNET_CRYPTO_BlindablePublicKey);
 
  GNUNET_memcpy (handle->key, key, sizeof(*key));
  GNUNET_CRYPTO_blindable_key_get_public (key, handle->pubkey);
 
  // Resets epoch and group keys as not stored yet
  GNUNET_CONTAINER_multihashmap_iterate (
    handle->rooms, it_room_store_keys, NULL);
 
  handle->key_monitor = GNUNET_NAMESTORE_zone_monitor_start2 (
    handle->config,
    handle->key,
    GNUNET_YES,
    cb_key_error,
    handle,
    cb_key_monitor,
    handle,
    cb_key_sync,
    handle,
    GNUNET_GNSRECORD_FILTER_NONE);
}
 
 
const struct GNUNET_CRYPTO_BlindablePrivateKey*
get_handle_key (const struct GNUNET_MESSENGER_Handle *handle)
{
  GNUNET_assert (handle);
 
  if (handle->key)
    return handle->key;
 
  return get_anonymous_private_key ();
}
 
 
const struct GNUNET_CRYPTO_BlindablePublicKey*
get_handle_pubkey (const struct GNUNET_MESSENGER_Handle *handle)
{
  GNUNET_assert (handle);
 
  if (handle->pubkey)
    return handle->pubkey;
 
  return get_anonymous_public_key ();
}
 
 
struct GNUNET_MESSENGER_ContactStore*
get_handle_contact_store (struct GNUNET_MESSENGER_Handle *handle)
{
  GNUNET_assert (handle);
 
  return &(handle->contact_store);
}
 
 
struct GNUNET_MESSENGER_Contact*
get_handle_contact (struct GNUNET_MESSENGER_Handle *handle,
                    const struct GNUNET_HashCode *key)
{
  struct GNUNET_MESSENGER_Room *room;
  const struct GNUNET_ShortHashCode *contact_id;
 
  GNUNET_assert ((handle) && (key));
 
  room = GNUNET_CONTAINER_multihashmap_get (handle->rooms, key);
 
  if (! room)
    return NULL;
 
  contact_id = get_room_sender_id (room);
 
  if (! contact_id)
    return NULL;
 
  {
    struct GNUNET_HashCode context;
    get_context_from_member (key, contact_id, &context);
 
    return get_store_contact (get_handle_contact_store (handle),
                              &context,
                              get_handle_pubkey (handle));
  }
}
 
 
void
open_handle_room (struct GNUNET_MESSENGER_Handle *handle,
                  const struct GNUNET_HashCode *key)
{
  struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert ((handle) && (key));
 
  room = get_handle_room (handle, key, GNUNET_YES);
 
  if (room)
    room->opened = GNUNET_YES;
}
 
 
void
entry_handle_room_at (struct GNUNET_MESSENGER_Handle *handle,
                      const struct GNUNET_PeerIdentity *door,
                      const struct GNUNET_HashCode *key)
{
  struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert ((handle) && (door) && (key));
 
  room = get_handle_room (handle, key, GNUNET_YES);
 
  if (room)
    add_to_list_tunnels (&(room->entries), door, NULL);
}
 
 
void
close_handle_room (struct GNUNET_MESSENGER_Handle *handle,
                   const struct GNUNET_HashCode *key)
{
  struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert ((handle) && (key));
 
  room = get_handle_room (handle, key, GNUNET_YES);
 
  if ((room) && (GNUNET_YES == GNUNET_CONTAINER_multihashmap_remove (
                   handle->rooms, key, room)))
    destroy_room (room);
}
 
 
struct GNUNET_MESSENGER_Room*
get_handle_room (struct GNUNET_MESSENGER_Handle *handle,
                 const struct GNUNET_HashCode *key,
                 enum GNUNET_GenericReturnValue init)
{
  struct GNUNET_MESSENGER_Room *room;
 
  GNUNET_assert ((handle) && (key));
 
  room = GNUNET_CONTAINER_multihashmap_get (handle->rooms, key);
 
  if ((! room) && (GNUNET_YES == init))
  {
    union GNUNET_MESSENGER_RoomKey room_key;
    GNUNET_memcpy (&(room_key.hash), key, sizeof (struct GNUNET_HashCode));
 
    room = create_room (handle, &room_key);
 
    if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put (
          handle->rooms, key, room,
          GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
    {
      destroy_room (room);
      return NULL;
    }
  }
 
  return room;
}
 
 
enum GNUNET_GenericReturnValue
store_handle_epoch_key (const struct GNUNET_MESSENGER_Handle *handle,
                        const struct GNUNET_MESSENGER_Room *room,
                        const struct GNUNET_HashCode *hash,
                        const struct GNUNET_ShortHashCode *identifier,
                        const struct GNUNET_CRYPTO_SymmetricSessionKey *
                        shared_key,
                        uint32_t flags,
                        GNUNET_NAMESTORE_ContinuationWithStatus cont,
                        void *cont_cls,
                        struct GNUNET_NAMESTORE_QueueEntry **query)
{
  const struct GNUNET_CRYPTO_BlindablePrivateKey *zone;
  struct GNUNET_TIME_Absolute expiration;
  const struct GNUNET_HashCode *room_key;
  struct GNUNET_GNSRECORD_Data data;
  struct GNUNET_MESSENGER_RoomEpochKeyRecord record;
  char *label;
 
  GNUNET_assert ((handle) && (room) && (hash) && (identifier) && (query));
 
  if (! handle->namestore)
    return GNUNET_SYSERR;
 
  zone = get_handle_key (handle);
 
  if (! zone)
    return GNUNET_SYSERR;
 
  expiration = GNUNET_TIME_absolute_get_forever_ ();
 
  memset (&data, 0, sizeof (data));
  memset (&record, 0, sizeof (record));
 
  room_key = get_room_key (room);
 
  if (shared_key)
  {
    struct GNUNET_CRYPTO_SymmetricSessionKey skey;
    struct GNUNET_CRYPTO_SymmetricInitializationVector iv [2];
    int32_t checksum;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &skey, sizeof (skey),
          GNUNET_MESSENGER_SALT_EPOCH_KEY,
          sizeof (GNUNET_MESSENGER_SALT_EPOCH_KEY),
          &(handle->secret),
          sizeof (handle->secret),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (zone),
          GNUNET_CRYPTO_kdf_arg_auto (hash),
          GNUNET_CRYPTO_kdf_arg_auto (identifier)))
      return GNUNET_SYSERR;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &iv, sizeof (iv),
          GNUNET_MESSENGER_SALT_EPOCH_IV,
          sizeof (GNUNET_MESSENGER_SALT_EPOCH_IV),
          &skey,
          sizeof (skey),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (hash),
          GNUNET_CRYPTO_kdf_arg_auto (identifier)))
      return GNUNET_SYSERR;
 
    GNUNET_memcpy (&(record.key), room_key, sizeof (record.key));
    GNUNET_memcpy (&(record.hash), hash, sizeof (record.hash));
    GNUNET_memcpy (
      &(record.identifier),
      identifier,
      sizeof (record.identifier));
 
    if (-1 == GNUNET_CRYPTO_symmetric_encrypt (shared_key,
                                               sizeof (*shared_key),
                                               &skey,
                                               &iv[0],
                                               &(record.shared_key)))
      return GNUNET_SYSERR;
 
    checksum = GNUNET_CRYPTO_crc32_n (shared_key, sizeof (*shared_key));
 
    if (-1 == GNUNET_CRYPTO_symmetric_encrypt (&checksum,
                                               sizeof (checksum),
                                               &skey,
                                               &iv[1],
                                               &(record.checksum)))
      return GNUNET_SYSERR;
 
    record.flags = flags;
 
    data.record_type = GNUNET_GNSRECORD_TYPE_MESSENGER_ROOM_EPOCH_KEY;
    data.data = &record;
    data.data_size = sizeof (record);
    data.expiration_time = expiration.abs_value_us;
    data.flags = GNUNET_GNSRECORD_RF_PRIVATE;
 
    GNUNET_CRYPTO_zero_keys (&skey, sizeof (skey));
  }
 
  {
    char lower_key [9];
    char lower_hash [9];
    char lower_id [7];
    const char *s;
 
    memset (lower_key, 0, sizeof (lower_key));
    memset (lower_hash, 0, sizeof (lower_hash));
    memset (lower_id, 0, sizeof (lower_id));
 
    s = GNUNET_h2s (room_key);
    for (size_t i=0; '\0' != s[i]; i++)
    {
      GNUNET_assert (i < sizeof (lower_key));
      lower_key[i] = (char) tolower ((int) s[i]);
    }
    s = GNUNET_h2s (hash);
    for (size_t i=0; '\0' != s[i]; i++)
    {
      GNUNET_assert (i < sizeof (lower_hash));
      lower_hash[i] = (char) tolower ((int) s[i]);
    }
 
    s = GNUNET_sh2s (identifier);
    for (size_t i=0; '\0' != s[i]; i++)
    {
      GNUNET_assert (i < sizeof (lower_id));
      lower_id[i] = (char) tolower ((int) s[i]);
    }
 
    GNUNET_asprintf (
      &label,
      "epoch_key_%s%s%s",
      lower_key,
      lower_hash,
      lower_id);
  }
 
  if (! label)
    return GNUNET_SYSERR;
 
  if (*query)
    GNUNET_NAMESTORE_cancel (*query);
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Store epoch key record with label: %s [%d]\n",
              label,
              shared_key? 1 : 0);
 
  *query = GNUNET_NAMESTORE_record_set_store (
    handle->namestore,
    zone,
    label,
    shared_key? 1 : 0,
    &data,
    cont,
    cont_cls);
 
  GNUNET_free (label);
  return GNUNET_OK;
}
 
 
enum GNUNET_GenericReturnValue
store_handle_encryption_key (const struct GNUNET_MESSENGER_Handle *handle,
                             const struct GNUNET_MESSENGER_Room *room,
                             const struct GNUNET_CRYPTO_HpkePrivateKey
                             *encryption_key,
                             GNUNET_NAMESTORE_ContinuationWithStatus cont,
                             void *cont_cls,
                             struct GNUNET_NAMESTORE_QueueEntry **query)
{
  const struct GNUNET_CRYPTO_BlindablePrivateKey *zone;
  struct GNUNET_TIME_Absolute expiration;
  const struct GNUNET_HashCode *room_key;
  struct GNUNET_GNSRECORD_Data data;
  struct GNUNET_MESSENGER_EncryptionKeyRecord record;
  struct GNUNET_HashCode nonce_hash;
  char *label;
 
  GNUNET_assert ((handle) && (room) && (encryption_key) && (query));
 
  if (! handle->namestore)
    return GNUNET_SYSERR;
 
  zone = get_handle_key (handle);
 
  if (! zone)
    return GNUNET_SYSERR;
 
  expiration = GNUNET_TIME_absolute_get_forever_ ();
  room_key = get_room_key (room);
 
  memset (&data, 0, sizeof (data));
 
  {
    struct GNUNET_CRYPTO_SymmetricSessionKey skey;
    struct GNUNET_CRYPTO_SymmetricInitializationVector iv [2];
    uint8_t encryption_key_data [GNUNET_MESSENGER_ENCRYPTION_KEY_DATA_BYTES];
    int32_t encryption_key_checksum;
    size_t encryption_key_len;
    ssize_t offset;
 
    encryption_key_len = GNUNET_CRYPTO_hpke_sk_get_length (encryption_key);
 
    if ((0 > encryption_key_len) || (encryption_key_len >
                                     GNUNET_MESSENGER_ENCRYPTION_KEY_DATA_BYTES)
        )
      return GNUNET_SYSERR;
 
    GNUNET_memcpy (&(record.key), room_key, sizeof (record.key));
    GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE, record.nonce_data,
                                GNUNET_MESSENGER_ENCRYPTION_KEY_NONCE_BYTES);
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &skey, sizeof (skey),
          GNUNET_MESSENGER_SALT_ENCRYPTION_KEY,
          sizeof (GNUNET_MESSENGER_SALT_ENCRYPTION_KEY),
          &(handle->secret),
          sizeof (handle->secret),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg_auto (zone),
          GNUNET_CRYPTO_kdf_arg (record.nonce_data,
                                 sizeof (record.nonce_data))))
      return GNUNET_SYSERR;
 
    if (GNUNET_YES != GNUNET_CRYPTO_hkdf_gnunet (
          &iv, sizeof (iv),
          GNUNET_MESSENGER_SALT_ENCRYPTION_IV,
          sizeof (GNUNET_MESSENGER_SALT_ENCRYPTION_IV),
          &skey,
          sizeof (skey),
          GNUNET_CRYPTO_kdf_arg_auto (room_key),
          GNUNET_CRYPTO_kdf_arg (record.nonce_data,
                                sizeof record.nonce_data)))
      return GNUNET_SYSERR;
 
    offset = GNUNET_CRYPTO_write_hpke_sk_to_buffer (
      encryption_key, encryption_key_data, encryption_key_len);
 
    if (offset < 0)
      return GNUNET_SYSERR;
 
    if (offset < encryption_key_len)
      encryption_key_len = offset;
 
    record.encrypted_key_length = encryption_key_len;
 
    GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_WEAK, encryption_key_data
                                + encryption_key_len,
                                sizeof (encryption_key_data)
                                - encryption_key_len);
 
    encryption_key_checksum = GNUNET_CRYPTO_crc32_n (encryption_key_data,
                                                     sizeof (encryption_key_data
                                                             ));
 
    if (-1 == GNUNET_CRYPTO_symmetric_encrypt (encryption_key_data,
                                               sizeof (encryption_key_data),
                                               &skey,
                                               &iv[0],
                                               record.encrypted_key_data))
      return GNUNET_SYSERR;
 
    if (-1 == GNUNET_CRYPTO_symmetric_encrypt (&encryption_key_checksum,
                                               sizeof (encryption_key_checksum),
                                               &skey,
                                               &iv[1],
                                               &(record.encrypted_key_checksum))
        )
      return GNUNET_SYSERR;
 
    GNUNET_CRYPTO_hash (record.nonce_data, sizeof (record.nonce_data), &
                        nonce_hash);
 
    data.record_type = GNUNET_GNSRECORD_TYPE_MESSENGER_ENCRYPTION_KEY;
    data.data = &record;
    data.data_size = sizeof (record);
    data.expiration_time = expiration.abs_value_us;
    data.flags = GNUNET_GNSRECORD_RF_PRIVATE;
 
    GNUNET_CRYPTO_zero_keys (&skey, sizeof (skey));
  }
 
  {
    char *lower_key;
    char *lower_nonce;
    const char *s;
 
    s = GNUNET_h2s (room_key);
    lower_key = GNUNET_STRINGS_utf8_tolower (s);
    if (! lower_key)
      lower_key = GNUNET_strdup (s);
 
    s = GNUNET_h2s (&nonce_hash);
    lower_nonce = GNUNET_STRINGS_utf8_tolower (s);
    if (! lower_nonce)
      lower_nonce = GNUNET_strdup (s);
 
    GNUNET_asprintf (
      &label,
      "encryption_key_%s%s",
      lower_key,
      lower_nonce);
 
    if (lower_nonce)
      GNUNET_free (lower_nonce);
    if (lower_key)
      GNUNET_free (lower_key);
  }
 
  if (! label)
    return GNUNET_SYSERR;
 
  if (*query)
    GNUNET_NAMESTORE_cancel (*query);
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Store encryption key record with label: %s [%d]\n",
              label,
              encryption_key? 1 : 0);
 
  *query = GNUNET_NAMESTORE_record_set_store (
    handle->namestore,
    zone,
    label,
    encryption_key? 1 : 0,
    &data,
    cont,
    cont_cls);
 
  GNUNET_free (label);
  return GNUNET_OK;
}