diff --git a/src/core/ddsi/CMakeLists.txt b/src/core/ddsi/CMakeLists.txt
index ccb6a25..fb8785f 100644
--- a/src/core/ddsi/CMakeLists.txt
+++ b/src/core/ddsi/CMakeLists.txt
@@ -18,6 +18,7 @@ PREPEND(srcs_ddsi "${CMAKE_CURRENT_LIST_DIR}/src"
     ddsi_raweth.c
     ddsi_ipaddr.c
     ddsi_mcgroup.c
+    ddsi_security_omg.c
     ddsi_serdata.c
     ddsi_serdata_default.c
     ddsi_sertopic.c
@@ -70,6 +71,7 @@ PREPEND(hdrs_private_ddsi "${CMAKE_CURRENT_LIST_DIR}/include/dds/ddsi"
     ddsi_ipaddr.h
     ddsi_mcgroup.h
     ddsi_plist_generic.h
+    ddsi_security_omg.h
     ddsi_serdata.h
     ddsi_sertopic.h
     ddsi_serdata_default.h
diff --git a/src/core/ddsi/include/dds/ddsi/ddsi_security_omg.h b/src/core/ddsi/include/dds/ddsi/ddsi_security_omg.h
new file mode 100644
index 0000000..298370f
--- /dev/null
+++ b/src/core/ddsi/include/dds/ddsi/ddsi_security_omg.h
@@ -0,0 +1,152 @@
+/*
+ * Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+#ifndef DDSI_OMG_SECURITY_H
+#define DDSI_OMG_SECURITY_H
+
+#include "dds/ddsi/q_entity.h"
+#include "dds/ddsi/q_plist.h"
+#include "dds/ddsi/q_globals.h"
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+#ifdef DDSI_INCLUDE_SECURITY
+
+/**
+ * @brief Check if security is enabled for the participant.
+ *
+ * @param[in] pp  Participant to check if it is secure.
+ *
+ * @returns bool
+ * @retval true   Participant is secure
+ * @retval false  Participant is not secure
+ */
+bool q_omg_participant_is_secure(const struct participant *pp);
+
+/**
+ * @brief Get security info flags of the given writer.
+ *
+ * @param[in]  wr    Writer to get the security info from.
+ * @param[out] info  The security info.
+ *
+ * @returns bool
+ * @retval true   Security info set.
+ * @retval false  Security info not set (probably unsecure writer).
+ */
+bool q_omg_get_writer_security_info(const struct writer *wr, nn_security_info_t *info);
+
+/**
+ * @brief Get security info flags of the given reader.
+ *
+ * @param[in]  rd    Reader to get the security info from.
+ * @param[out] info  The security info.
+ *
+ * @returns bool
+ * @retval true   Security info set.
+ * @retval false  Security info not set (probably unsecure reader).
+ */
+bool q_omg_get_reader_security_info(const struct reader *rd, nn_security_info_t *info);
+
+/**
+ * @brief Return the builtin writer id for this readers' discovery.
+ *
+ * Return builtin entity id of the writer to use for the subscription
+ * discovery information.
+ * Depending on whether the discovery is protected or not (for the
+ * given reader), either the default writer or protected writer needs
+ * to be used.
+ *
+ * @param[in] rd Reader to determine the subscription writer from.
+ *
+ * @returns unsigned
+ * @retval NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER
+ * @retval NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER
+ */
+unsigned determine_subscription_writer(const struct reader *rd);
+
+/**
+ * @brief Return the builtin writer id for this writers' discovery.
+ *
+ * Return builtin entity id of the writer to use for the publication
+ * discovery information.
+ * Depending on whether the discovery is protected or not (for the
+ * given writer), either the default writer or protected writer needs
+ * to be used.
+ *
+ * @param[in] wr Writer to determine the publication writer from.
+ *
+ * @returns unsigned
+ * @retval NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER
+ * @retval NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER
+ */
+unsigned determine_publication_writer(const struct writer *wr);
+
+/**
+ * @brief Determine if the proxy participant is allowed to be deleted
+ *        by the given writer.
+ *
+ * If an proxy participant is authenticated, it is only allowed to
+ * to deleted when a dispose is received from the proper protected
+ * discovery writer.
+ *
+ * @param[in] gv           Used for tracing.
+ * @param[in] guid         Guid of the proxy participant to be deleted.
+ * @param[in] pwr_entityid Writer that send the dispose.
+ *
+ * @returns bool
+ * @retval true   The proxy participant may be deleted.
+ * @retval false  The proxy participant may not be deleted by this writer.
+ */
+bool allow_proxy_participant_deletion(struct q_globals * const gv, const struct ddsi_guid *guid, const ddsi_entityid_t pwr_entityid);
+
+#else /* DDSI_INCLUDE_SECURITY */
+
+#include "dds/ddsi/q_unused.h"
+
+inline bool
+q_omg_participant_is_secure(
+  UNUSED_ARG(const struct participant *pp))
+{
+  return false;
+}
+
+inline unsigned
+determine_subscription_writer(
+  UNUSED_ARG(const struct reader *rd))
+{
+  return NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER;
+}
+
+inline unsigned
+determine_publication_writer(
+  UNUSED_ARG(const struct writer *wr))
+{
+  return NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER;
+}
+
+inline bool
+allow_proxy_participant_deletion(
+  UNUSED_ARG(struct q_globals * const gv),
+  UNUSED_ARG(const struct ddsi_guid *guid),
+  UNUSED_ARG(const ddsi_entityid_t pwr_entityid))
+{
+  return true;
+}
+
+#endif /* DDSI_INCLUDE_SECURITY */
+
+#if defined (__cplusplus)
+}
+#endif
+
+#endif /* DDSI_OMG_SECURITY_H */
diff --git a/src/core/ddsi/include/dds/ddsi/q_globals.h b/src/core/ddsi/include/dds/ddsi/q_globals.h
index c14b490..c5cff1a 100644
--- a/src/core/ddsi/include/dds/ddsi/q_globals.h
+++ b/src/core/ddsi/include/dds/ddsi/q_globals.h
@@ -237,6 +237,10 @@ struct q_globals {
   dds_qos_t spdp_endpoint_xqos;
   dds_qos_t builtin_endpoint_xqos_rd;
   dds_qos_t builtin_endpoint_xqos_wr;
+#ifdef DDSI_INCLUDE_SECURITY
+  dds_qos_t builtin_stateless_xqos_rd;
+  dds_qos_t builtin_stateless_xqos_wr;
+#endif
 
   /* SPDP packets get very special treatment (they're the only packets
      we accept from writers we don't know) and have their very own
diff --git a/src/core/ddsi/include/dds/ddsi/q_plist.h b/src/core/ddsi/include/dds/ddsi/q_plist.h
index 5f82529..561bdbf 100644
--- a/src/core/ddsi/include/dds/ddsi/q_plist.h
+++ b/src/core/ddsi/include/dds/ddsi/q_plist.h
@@ -172,6 +172,9 @@ typedef struct nn_security_info
 #define NN_PLUGIN_PARTICIPANT_SECURITY_ATTRIBUTES_FLAG_IS_RTPS_AUTHENTICATED           (1u <<  3)
 #define NN_PLUGIN_PARTICIPANT_SECURITY_ATTRIBUTES_FLAG_IS_DISCOVERY_AUTHENTICATED      (1u <<  4)
 #define NN_PLUGIN_PARTICIPANT_SECURITY_ATTRIBUTES_FLAG_IS_LIVELINESS_AUTHENTICATED     (1u <<  5)
+#else
+struct nn_security_info;
+typedef struct nn_security_info nn_security_info_t;
 #endif
 
 
diff --git a/src/core/ddsi/include/dds/ddsi/q_protocol.h b/src/core/ddsi/include/dds/ddsi/q_protocol.h
index 9ebf7c5..0fbbc64 100644
--- a/src/core/ddsi/include/dds/ddsi/q_protocol.h
+++ b/src/core/ddsi/include/dds/ddsi/q_protocol.h
@@ -89,6 +89,19 @@ typedef struct {
 #define NN_DISC_BUILTIN_ENDPOINT_TOPIC_ANNOUNCER (1u << 12)
 #define NN_DISC_BUILTIN_ENDPOINT_TOPIC_DETECTOR (1u << 13)
 
+/* Security extensions: */
+#define NN_BUILTIN_ENDPOINT_PUBLICATION_MESSAGE_SECURE_ANNOUNCER (1u<<16)
+#define NN_BUILTIN_ENDPOINT_PUBLICATION_MESSAGE_SECURE_DETECTOR (1u<<17)
+#define NN_BUILTIN_ENDPOINT_SUBSCRIPTION_MESSAGE_SECURE_ANNOUNCER (1u<<18)
+#define NN_BUILTIN_ENDPOINT_SUBSCRIPTION_MESSAGE_SECURE_DETECTOR (1u<<19)
+#define NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_ANNOUNCER (1u<<20)
+#define NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_DETECTOR (1u<<21)
+#define NN_BUILTIN_ENDPOINT_PARTICIPANT_STATELESS_MESSAGE_ANNOUNCER (1u<<22)
+#define NN_BUILTIN_ENDPOINT_PARTICIPANT_STATELESS_MESSAGE_DETECTOR (1u<<23)
+/* TODO: ENDPOINT_PARTICIPANT_VOLATILE */
+#define NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_ANNOUNCER (1u << 26)
+#define NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_DETECTOR (1u << 27)
+
 /* PrismTech extensions: */
 #define NN_DISC_BUILTIN_ENDPOINT_CM_PARTICIPANT_WRITER (1u << 0)
 #define NN_DISC_BUILTIN_ENDPOINT_CM_PARTICIPANT_READER (1u << 1)
diff --git a/src/core/ddsi/include/dds/ddsi/q_rtps.h b/src/core/ddsi/include/dds/ddsi/q_rtps.h
index dfe0d39..71382f4 100644
--- a/src/core/ddsi/include/dds/ddsi/q_rtps.h
+++ b/src/core/ddsi/include/dds/ddsi/q_rtps.h
@@ -44,6 +44,19 @@ typedef int64_t seqno_t;
 #define NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_READER 0x100c7
 #define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_WRITER 0x200c2
 #define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_READER 0x200c7
+
+#define NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER 0xff0003c2
+#define NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER 0xff0003c7
+#define NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER 0xff0004c2
+#define NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER 0xff0004c7
+#define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER 0x201c3
+#define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_READER 0x201c4
+#define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER 0xff0200c2
+#define NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER 0xff0200c7
+/* TODO: ENDPOINT_PARTICIPANT_VOLATILE */
+#define NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER 0xff0101c2
+#define NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER 0xff0101c7
+
 #define NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_WRITER 0x142
 #define NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_READER 0x147
 #define NN_ENTITYID_SEDP_BUILTIN_CM_PUBLISHER_WRITER 0x242
diff --git a/src/core/ddsi/src/ddsi_security_omg.c b/src/core/ddsi/src/ddsi_security_omg.c
new file mode 100644
index 0000000..8e04eb3
--- /dev/null
+++ b/src/core/ddsi/src/ddsi_security_omg.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ */
+#ifdef DDSI_INCLUDE_SECURITY
+
+#include <string.h>
+
+#include "dds/ddsrt/misc.h"
+
+#include "dds/ddsi/q_unused.h"
+#include "dds/ddsi/ddsi_security_omg.h"
+
+bool
+q_omg_participant_is_secure(
+  const struct participant *pp)
+{
+  /* TODO: Register local participant. */
+  DDSRT_UNUSED_ARG(pp);
+  return false;
+}
+
+static bool
+q_omg_writer_is_discovery_protected(
+  const struct writer *wr)
+{
+  /* TODO: Register local writer. */
+  DDSRT_UNUSED_ARG(wr);
+  return false;
+}
+
+static bool
+q_omg_reader_is_discovery_protected(
+  const struct reader *rd)
+{
+  /* TODO: Register local reader. */
+  DDSRT_UNUSED_ARG(rd);
+  return false;
+}
+
+bool
+q_omg_get_writer_security_info(
+  const struct writer *wr,
+  nn_security_info_t *info)
+{
+  assert(wr);
+  assert(info);
+  /* TODO: Register local writer. */
+  DDSRT_UNUSED_ARG(wr);
+  info->plugin_security_attributes = 0;
+  info->security_attributes = 0;
+  return false;
+}
+
+bool
+q_omg_get_reader_security_info(
+  const struct reader *rd,
+  nn_security_info_t *info)
+{
+  assert(rd);
+  assert(info);
+  /* TODO: Register local reader. */
+  DDSRT_UNUSED_ARG(rd);
+  info->plugin_security_attributes = 0;
+  info->security_attributes = 0;
+  return false;
+}
+
+static bool
+q_omg_proxyparticipant_is_authenticated(
+  struct proxy_participant *proxypp)
+{
+  /* TODO: Handshake */
+  DDSRT_UNUSED_ARG(proxypp);
+  return false;
+}
+
+unsigned
+determine_subscription_writer(
+  const struct reader *rd)
+{
+  if (q_omg_reader_is_discovery_protected(rd))
+  {
+    return NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER;
+  }
+  return NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER;
+}
+
+unsigned
+determine_publication_writer(
+  const struct writer *wr)
+{
+  if (q_omg_writer_is_discovery_protected(wr))
+  {
+    return NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER;
+  }
+  return NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER;
+}
+
+bool
+allow_proxy_participant_deletion(
+  struct q_globals * const gv,
+  const struct ddsi_guid *guid,
+  const ddsi_entityid_t pwr_entityid)
+{
+  struct proxy_participant *proxypp;
+
+  assert(gv);
+  assert(guid);
+
+  /* Always allow deletion from a secure proxy writer. */
+  if (pwr_entityid.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER)
+    return true;
+
+  /* Not from a secure proxy writer.
+   * Only allow deletion when proxy participant is not authenticated. */
+  proxypp = ephash_lookup_proxy_participant_guid(gv->guid_hash, guid);
+  if (!proxypp)
+  {
+    GVLOGDISC (" unknown");
+    return false;
+  }
+  return (!q_omg_proxyparticipant_is_authenticated(proxypp));
+}
+
+
+#else /* DDSI_INCLUDE_SECURITY */
+
+#include "dds/ddsi/ddsi_security_omg.h"
+
+extern inline bool q_omg_participant_is_secure(UNUSED_ARG(const struct participant *pp));
+
+extern inline unsigned determine_subscription_writer(UNUSED_ARG(const struct reader *rd));
+extern inline unsigned determine_publication_writer(UNUSED_ARG(const struct writer *wr));
+
+extern inline bool allow_proxy_participant_deletion(
+  UNUSED_ARG(struct q_globals * const gv),
+  UNUSED_ARG(const struct ddsi_guid *guid),
+  UNUSED_ARG(const ddsi_entityid_t pwr_entityid));
+
+#endif /* DDSI_INCLUDE_SECURITY */
diff --git a/src/core/ddsi/src/q_ddsi_discovery.c b/src/core/ddsi/src/q_ddsi_discovery.c
index 74d025a..d6f2137 100644
--- a/src/core/ddsi/src/q_ddsi_discovery.c
+++ b/src/core/ddsi/src/q_ddsi_discovery.c
@@ -43,6 +43,7 @@
 #include "dds/ddsi/q_lease.h"
 #include "dds/ddsi/ddsi_serdata_default.h"
 #include "dds/ddsi/q_feature_check.h"
+#include "dds/ddsi/ddsi_security_omg.h"
 
 static int get_locator (const struct q_globals *gv, nn_locator_t *loc, const nn_locators_t *locs, int uc_same_subnet)
 {
@@ -327,16 +328,18 @@ int spdp_write (struct participant *pp)
   return ret;
 }
 
-int spdp_dispose_unregister (struct participant *pp)
+static int spdp_dispose_unregister_with_wr (struct participant *pp, unsigned entityid)
 {
   struct nn_xmsg *mpayload;
   nn_plist_t ps;
   struct writer *wr;
   int ret;
 
-  if ((wr = get_builtin_writer (pp, NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER)) == NULL)
+  if ((wr = get_builtin_writer (pp, entityid)) == NULL)
   {
-    ETRACE (pp, "spdp_dispose_unregister("PGUIDFMT") - builtin participant writer not found\n", PGUID (pp->e.guid));
+    ETRACE (pp, "spdp_dispose_unregister("PGUIDFMT") - builtin participant %s writer not found\n",
+            PGUID (pp->e.guid),
+            entityid == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER ? "secure" : "");
     return 0;
   }
 
@@ -353,6 +356,21 @@ int spdp_dispose_unregister (struct participant *pp)
   return ret;
 }
 
+int spdp_dispose_unregister (struct participant *pp)
+{
+  /*
+   * When disposing a participant, it should be announced on both the
+   * non-secure and secure writers.
+   * The receiver will decide from which writer it accepts the dispose.
+   */
+  int ret = spdp_dispose_unregister_with_wr(pp, NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER);
+  if ((ret > 0) && q_omg_participant_is_secure(pp))
+  {
+    ret = spdp_dispose_unregister_with_wr(pp, NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER);
+  }
+  return ret;
+}
+
 static unsigned pseudo_random_delay (const ddsi_guid_t *x, const ddsi_guid_t *y, nn_mtime_t tnow)
 {
   /* You know, an ordinary random generator would be even better, but
@@ -407,7 +425,7 @@ static void respond_to_spdp (const struct q_globals *gv, const ddsi_guid_t *dest
   ephash_enum_participant_fini (&est);
 }
 
-static int handle_SPDP_dead (const struct receiver_state *rst, nn_wctime_t timestamp, const nn_plist_t *datap, unsigned statusinfo)
+static int handle_SPDP_dead (const struct receiver_state *rst, ddsi_entityid_t pwr_entityid, nn_wctime_t timestamp, const nn_plist_t *datap, unsigned statusinfo)
 {
   struct q_globals * const gv = rst->gv;
   ddsi_guid_t guid;
@@ -419,13 +437,20 @@ static int handle_SPDP_dead (const struct receiver_state *rst, nn_wctime_t times
     guid = datap->participant_guid;
     GVLOGDISC (" %"PRIx32":%"PRIx32":%"PRIx32":%"PRIx32, PGUID (guid));
     assert (guid.entityid.u == NN_ENTITYID_PARTICIPANT);
-    if (delete_proxy_participant_by_guid (gv, &guid, timestamp, 0) < 0)
+    if (allow_proxy_participant_deletion(gv, &guid, pwr_entityid))
     {
-      GVLOGDISC (" unknown");
+      if (delete_proxy_participant_by_guid (gv, &guid, timestamp, 0) < 0)
+      {
+        GVLOGDISC (" unknown");
+      }
+      else
+      {
+        GVLOGDISC (" delete");
+      }
     }
     else
     {
-      GVLOGDISC (" delete");
+      GVLOGDISC (" not allowed");
     }
   }
   else
@@ -793,7 +818,7 @@ static int handle_SPDP_alive (const struct receiver_state *rst, seqno_t seq, nn_
   return 1;
 }
 
-static void handle_SPDP (const struct receiver_state *rst, seqno_t seq, nn_wctime_t timestamp, unsigned statusinfo, const void *vdata, uint32_t len)
+static void handle_SPDP (const struct receiver_state *rst, ddsi_entityid_t pwr_entityid, seqno_t seq, nn_wctime_t timestamp, unsigned statusinfo, const void *vdata, uint32_t len)
 {
   struct q_globals * const gv = rst->gv;
   const struct CDRHeader *data = vdata; /* built-ins not deserialized (yet) */
@@ -832,7 +857,7 @@ static void handle_SPDP (const struct receiver_state *rst, seqno_t seq, nn_wctim
       case NN_STATUSINFO_DISPOSE:
       case NN_STATUSINFO_UNREGISTER:
       case (NN_STATUSINFO_DISPOSE | NN_STATUSINFO_UNREGISTER):
-        interesting = handle_SPDP_dead (rst, timestamp, &decoded_data, statusinfo);
+        interesting = handle_SPDP_dead (rst, pwr_entityid, timestamp, &decoded_data, statusinfo);
         break;
     }
 
@@ -888,7 +913,7 @@ static int sedp_write_endpoint
 (
    struct writer *wr, int alive, const ddsi_guid_t *epguid,
    const struct entity_common *common, const struct endpoint_common *epcommon,
-   const dds_qos_t *xqos, struct addrset *as)
+   const dds_qos_t *xqos, struct addrset *as, nn_security_info_t *security)
 {
   struct q_globals * const gv = wr->e.gv;
   const dds_qos_t *defqos = is_writer_entityid (epguid->entityid) ? &gv->default_xqos_wr : &gv->default_xqos_rd;
@@ -908,6 +933,17 @@ static int sedp_write_endpoint
     ps.entity_name = common->name;
   }
 
+#ifdef DDSI_INCLUDE_SECURITY
+  if (security)
+  {
+    ps.present |= PP_ENDPOINT_SECURITY_INFO;
+    memcpy(&ps.endpoint_security_info, security, sizeof(nn_security_info_t));
+  }
+#else
+  (void)security;
+  assert(security == NULL);
+#endif
+
   if (!alive)
   {
     assert (xqos == NULL);
@@ -987,13 +1023,22 @@ int sedp_write_writer (struct writer *wr)
 {
   if ((!is_builtin_entityid(wr->e.guid.entityid, NN_VENDORID_ECLIPSE)) && (!wr->e.onlylocal))
   {
-    struct writer *sedp_wr = get_sedp_writer (wr->c.pp, NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER);
+    unsigned entityid = determine_publication_writer(wr);
+    struct writer *sedp_wr = get_sedp_writer (wr->c.pp, entityid);
+    nn_security_info_t *security = NULL;
 #ifdef DDSI_INCLUDE_SSM
     struct addrset *as = wr->ssm_as;
 #else
     struct addrset *as = NULL;
 #endif
-    return sedp_write_endpoint (sedp_wr, 1, &wr->e.guid, &wr->e, &wr->c, wr->xqos, as);
+#ifdef DDSI_INCLUDE_SECURITY
+    nn_security_info_t tmp;
+    if (q_omg_get_writer_security_info(wr, &tmp))
+    {
+      security = &tmp;
+    }
+#endif
+    return sedp_write_endpoint (sedp_wr, 1, &wr->e.guid, &wr->e, &wr->c, wr->xqos, as, security);
   }
   return 0;
 }
@@ -1002,13 +1047,22 @@ int sedp_write_reader (struct reader *rd)
 {
   if ((!is_builtin_entityid (rd->e.guid.entityid, NN_VENDORID_ECLIPSE)) && (!rd->e.onlylocal))
   {
-    struct writer *sedp_wr = get_sedp_writer (rd->c.pp, NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER);
+    unsigned entityid = determine_subscription_writer(rd);
+    struct writer *sedp_wr = get_sedp_writer (rd->c.pp, entityid);
+    nn_security_info_t *security = NULL;
 #ifdef DDSI_INCLUDE_NETWORK_PARTITIONS
     struct addrset *as = rd->as;
 #else
     struct addrset *as = NULL;
 #endif
-    return sedp_write_endpoint (sedp_wr, 1, &rd->e.guid, &rd->e, &rd->c, rd->xqos, as);
+#ifdef DDSI_INCLUDE_SECURITY
+    nn_security_info_t tmp;
+    if (q_omg_get_reader_security_info(rd, &tmp))
+    {
+      security = &tmp;
+    }
+#endif
+    return sedp_write_endpoint (sedp_wr, 1, &rd->e.guid, &rd->e, &rd->c, rd->xqos, as, security);
   }
   return 0;
 }
@@ -1017,8 +1071,9 @@ int sedp_dispose_unregister_writer (struct writer *wr)
 {
   if ((!is_builtin_entityid(wr->e.guid.entityid, NN_VENDORID_ECLIPSE)) && (!wr->e.onlylocal))
   {
-    struct writer *sedp_wr = get_sedp_writer (wr->c.pp, NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER);
-    return sedp_write_endpoint (sedp_wr, 0, &wr->e.guid, NULL, NULL, NULL, NULL);
+    unsigned entityid = determine_publication_writer(wr);
+    struct writer *sedp_wr = get_sedp_writer (wr->c.pp, entityid);
+    return sedp_write_endpoint (sedp_wr, 0, &wr->e.guid, NULL, NULL, NULL, NULL, NULL);
   }
   return 0;
 }
@@ -1027,8 +1082,9 @@ int sedp_dispose_unregister_reader (struct reader *rd)
 {
   if ((!is_builtin_entityid(rd->e.guid.entityid, NN_VENDORID_ECLIPSE)) && (!rd->e.onlylocal))
   {
-    struct writer *sedp_wr = get_sedp_writer (rd->c.pp, NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER);
-    return sedp_write_endpoint (sedp_wr, 0, &rd->e.guid, NULL, NULL, NULL, NULL);
+    unsigned entityid = determine_subscription_writer(rd);
+    struct writer *sedp_wr = get_sedp_writer (rd->c.pp, entityid);
+    return sedp_write_endpoint (sedp_wr, 0, &rd->e.guid, NULL, NULL, NULL, NULL, NULL);
   }
   return 0;
 }
@@ -1594,7 +1650,13 @@ int builtins_dqueue_handler (const struct nn_rsample_info *sampleinfo, const str
 
   pwr = sampleinfo->pwr;
   if (pwr == NULL)
-    assert (srcguid.entityid.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER);
+  {
+    /* NULL with NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER is normal. It is possible that
+     * NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER has NULL as well if there
+     * is a security mismatch being handled. */
+    assert ((srcguid.entityid.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER) ||
+            (srcguid.entityid.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER));
+  }
   else
   {
     assert (is_builtin_entityid (pwr->e.guid.entityid, pwr->c.vendor));
@@ -1690,6 +1752,7 @@ int builtins_dqueue_handler (const struct nn_rsample_info *sampleinfo, const str
       {
         case NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER:
         case NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_WRITER:
+        case NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER:
           pid = PID_PARTICIPANT_GUID;
           break;
         case NN_ENTITYID_SEDP_BUILTIN_CM_PUBLISHER_WRITER:
@@ -1698,6 +1761,8 @@ int builtins_dqueue_handler (const struct nn_rsample_info *sampleinfo, const str
           break;
         case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER:
         case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER:
+        case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER:
+        case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER:
           pid = PID_ENDPOINT_GUID;
           break;
         case NN_ENTITYID_SEDP_BUILTIN_TOPIC_WRITER:
@@ -1736,18 +1801,27 @@ int builtins_dqueue_handler (const struct nn_rsample_info *sampleinfo, const str
   switch (srcguid.entityid.u)
   {
     case NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER:
-      handle_SPDP (sampleinfo->rst, sampleinfo->seq, timestamp, statusinfo, datap, datasz);
+    case NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER:
+      handle_SPDP (sampleinfo->rst, srcguid.entityid, sampleinfo->seq, timestamp, statusinfo, datap, datasz);
       break;
     case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER:
     case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER:
+    case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER:
+    case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER:
       handle_SEDP (sampleinfo->rst, sampleinfo->seq, timestamp, statusinfo, datap, datasz);
       break;
     case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_WRITER:
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER:
       handle_PMD (sampleinfo->rst, timestamp, statusinfo, datap, datasz);
       break;
     case NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_WRITER:
       handle_SEDP_CM (sampleinfo->rst, srcguid.entityid, timestamp, statusinfo, datap, datasz);
       break;
+#ifdef DDSI_INCLUDE_SECURITY
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER:
+      /* TODO: Handshake */
+      break;
+#endif
     default:
       GVLOGDISC ("data(builtin, vendor %u.%u): "PGUIDFMT" #%"PRId64": not handled\n",
                  sampleinfo->rst->vendor.id[0], sampleinfo->rst->vendor.id[1],
diff --git a/src/core/ddsi/src/q_entity.c b/src/core/ddsi/src/q_entity.c
index d2a4fed..e4c020d 100644
--- a/src/core/ddsi/src/q_entity.c
+++ b/src/core/ddsi/src/q_entity.c
@@ -48,6 +48,7 @@
 #include "dds__whc.h"
 #include "dds/ddsi/ddsi_iid.h"
 #include "dds/ddsi/ddsi_tkmap.h"
+#include "dds/ddsi/ddsi_security_omg.h"
 
 struct deleted_participant {
   ddsrt_avl_node_t avlnode;
@@ -461,6 +462,76 @@ static void pp_release_entityid(struct participant *pp, ddsi_entityid_t id)
   ddsrt_mutex_unlock (&pp->e.lock);
 }
 
+static void force_as_disc_address(struct q_globals *gv, const ddsi_guid_t *subguid)
+{
+  struct writer *wr = ephash_lookup_writer_guid (gv->guid_hash, subguid);
+  assert (wr != NULL);
+  ddsrt_mutex_lock (&wr->e.lock);
+  unref_addrset (wr->as);
+  unref_addrset (wr->as_group);
+  wr->as = ref_addrset (gv->as_disc);
+  wr->as_group = ref_addrset (gv->as_disc_group);
+  ddsrt_mutex_unlock (&wr->e.lock);
+}
+
+#ifdef DDSI_INCLUDE_SECURITY
+static void add_security_builtin_endpoints(struct participant *pp, ddsi_guid_t *subguid, const ddsi_guid_t *group_guid, struct q_globals *gv, bool add_writers, bool add_readers)
+{
+  if (add_writers)
+  {
+    subguid->entityid = to_entityid (NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER);
+    new_writer_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_wr, whc_new(gv, 1, 1, 1), NULL, NULL);
+    /* But we need the as_disc address set for SPDP, because we need to
+       send it to everyone regardless of the existence of readers. */
+    force_as_disc_address(gv, subguid);
+    pp->bes |= NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_ANNOUNCER;
+
+    subguid->entityid = to_entityid (NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER);
+    new_writer_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_stateless_xqos_wr, whc_new(gv, 0, 1, 1), NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_PARTICIPANT_STATELESS_MESSAGE_ANNOUNCER;
+
+    subguid->entityid = to_entityid (NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER);
+    new_writer_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_wr, whc_new(gv, 1, 1, 1), NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_ANNOUNCER;
+
+    subguid->entityid = to_entityid (NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER);
+    new_writer_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_wr, whc_new(gv, 1, 1, 1), NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_PUBLICATION_MESSAGE_SECURE_ANNOUNCER;
+
+    subguid->entityid = to_entityid (NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER);
+    new_writer_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_wr, whc_new(gv, 1, 1, 1), NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_SUBSCRIPTION_MESSAGE_SECURE_ANNOUNCER;
+  }
+
+  if (add_readers)
+  {
+    subguid->entityid = to_entityid (NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER);
+    new_reader_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_rd, NULL, NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_SUBSCRIPTION_MESSAGE_SECURE_DETECTOR;
+
+    subguid->entityid = to_entityid (NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER);
+    new_reader_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_rd, NULL, NULL, NULL);
+    pp->bes |= NN_BUILTIN_ENDPOINT_PUBLICATION_MESSAGE_SECURE_DETECTOR;
+  }
+
+  /*
+   * When security is enabled configure the associated necessary builtin readers independent of the
+   * besmode flag setting, because all participant do require authentication.
+   */
+  subguid->entityid = to_entityid (NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER);
+  new_reader_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_rd, NULL, NULL, NULL);
+  pp->bes |= NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_DETECTOR;
+
+  subguid->entityid = to_entityid (NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_READER);
+  new_reader_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_stateless_xqos_rd, NULL, NULL, NULL);
+  pp->bes |= NN_BUILTIN_ENDPOINT_PARTICIPANT_STATELESS_MESSAGE_DETECTOR;
+
+  subguid->entityid = to_entityid (NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER);
+  new_reader_guid (NULL, subguid, group_guid, pp, NULL, &gv->builtin_endpoint_xqos_rd, NULL, NULL, NULL);
+  pp->bes |= NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_DETECTOR;
+}
+#endif
+
 dds_return_t new_participant_guid (const ddsi_guid_t *ppguid, struct q_globals *gv, unsigned flags, const nn_plist_t *plist)
 {
   struct participant *pp;
@@ -591,16 +662,7 @@ dds_return_t new_participant_guid (const ddsi_guid_t *ppguid, struct q_globals *
     new_writer_guid (NULL, &subguid, &group_guid, pp, NULL, &gv->spdp_endpoint_xqos, whc_new(gv, 1, 1, 1), LAST_WR_PARAMS);
     /* But we need the as_disc address set for SPDP, because we need to
        send it to everyone regardless of the existence of readers. */
-    {
-      struct writer *wr = ephash_lookup_writer_guid (gv->guid_hash, &subguid);
-      assert (wr != NULL);
-      ddsrt_mutex_lock (&wr->e.lock);
-      unref_addrset (wr->as);
-      unref_addrset (wr->as_group);
-      wr->as = ref_addrset (gv->as_disc);
-      wr->as_group = ref_addrset (gv->as_disc_group);
-      ddsrt_mutex_unlock (&wr->e.lock);
-    }
+    force_as_disc_address(gv, &subguid);
     pp->bes |= NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_ANNOUNCER;
   }
 
@@ -679,6 +741,14 @@ dds_return_t new_participant_guid (const ddsi_guid_t *ppguid, struct q_globals *
     pp->prismtech_bes |= NN_DISC_BUILTIN_ENDPOINT_CM_SUBSCRIBER_READER;
 
   }
+
+#ifdef DDSI_INCLUDE_SECURITY
+  if (q_omg_participant_is_secure(pp))
+  {
+    add_security_builtin_endpoints(pp, &subguid, &group_guid, gv, !(flags & RTPS_PF_NO_BUILTIN_WRITERS), !(flags & RTPS_PF_NO_BUILTIN_READERS));
+  }
+#endif
+
 #undef LAST_WR_PARAMS
 
   /* If the participant doesn't have the full set of builtin writers
@@ -830,6 +900,17 @@ static void unref_participant (struct participant *pp, const struct ddsi_guid *g
     NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_READER,
     NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_READER,
     NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_READER,
+    /* Security ones: */
+    NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER,
+    NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER,
+    NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER,
+    NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER,
+    NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER,
+    NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER,
+    NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER,
+    NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_READER,
+    NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER,
+    NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER,
     /* PrismTech ones: */
     NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_WRITER,
     NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_READER,
@@ -913,7 +994,7 @@ static void unref_participant (struct participant *pp, const struct ddsi_guid *g
           (pp->prismtech_bes & prismtech_builtin_writers_besmask) != prismtech_builtin_writers_besmask)
       {
         /* Participant doesn't have a full complement of built-in
-           writers, therefore, it relies on gv.privileged_pp, and
+           writers, therefore, it relies on gv->privileged_pp, and
            therefore we must decrement the reference count of that one.
 
            Why read it with the lock held, only to release it and use it
@@ -1002,9 +1083,15 @@ struct writer *get_builtin_writer (const struct participant *pp, unsigned entity
     case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_WRITER:
       bes_mask = NN_DISC_BUILTIN_ENDPOINT_SUBSCRIPTION_ANNOUNCER;
       break;
+    case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER:
+      bes_mask = NN_BUILTIN_ENDPOINT_SUBSCRIPTION_MESSAGE_SECURE_ANNOUNCER;
+      break;
     case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_WRITER:
       bes_mask = NN_DISC_BUILTIN_ENDPOINT_PUBLICATION_ANNOUNCER;
       break;
+    case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER:
+      bes_mask = NN_BUILTIN_ENDPOINT_PUBLICATION_MESSAGE_SECURE_ANNOUNCER;
+      break;
     case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_WRITER:
       bes_mask = NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_DATA_WRITER;
       break;
@@ -1020,6 +1107,15 @@ struct writer *get_builtin_writer (const struct participant *pp, unsigned entity
     case NN_ENTITYID_SEDP_BUILTIN_TOPIC_WRITER:
       bes_mask = NN_DISC_BUILTIN_ENDPOINT_TOPIC_ANNOUNCER;
       break;
+    case NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER:
+      bes_mask = NN_DISC_BUILTIN_ENDPOINT_PARTICIPANT_SECURE_ANNOUNCER;
+      break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER:
+      bes_mask = NN_BUILTIN_ENDPOINT_PARTICIPANT_STATELESS_MESSAGE_ANNOUNCER;
+      break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER:
+      bes_mask = NN_BUILTIN_ENDPOINT_PARTICIPANT_MESSAGE_SECURE_ANNOUNCER;
+      break;
     default:
       DDS_FATAL ("get_builtin_writer called with entityid %x\n", entityid);
       return NULL;
@@ -1385,7 +1481,7 @@ void rebuild_or_clear_writer_addrsets (struct q_globals *gv, int rebuild)
     else
     {
       /* SPDP writers have no matched readers, instead they all use the same address space,
-         gv.as_disc. Keep as_disc unchanged, and instead make the participants point to the
+         gv->as_disc. Keep as_disc unchanged, and instead make the participants point to the
          empty one. */
       unref_addrset(wr->as);
       if (rebuild)
@@ -2112,6 +2208,13 @@ static ddsi_entityid_t builtin_entityid_match (ddsi_entityid_t x)
       res.u = NN_ENTITYID_UNKNOWN;
       break;
 
+    case NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER:
+      res.u = NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER;
+      break;
+    case NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_READER:
+      res.u = NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER;
+      break;
+
     case NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_READER:
       res.u = NN_ENTITYID_SEDP_BUILTIN_CM_PARTICIPANT_WRITER;
       break;
@@ -2130,6 +2233,30 @@ static ddsi_entityid_t builtin_entityid_match (ddsi_entityid_t x)
     case NN_ENTITYID_SEDP_BUILTIN_CM_SUBSCRIBER_WRITER:
       res.u = NN_ENTITYID_SEDP_BUILTIN_CM_SUBSCRIBER_READER;
       break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER:
+      res.u = NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_READER;
+      break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_READER:
+      res.u = NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER;
+      break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER:
+      res.u = NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER;
+      break;
+    case NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_READER:
+      res.u = NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_MESSAGE_SECURE_WRITER;
+      break;
+    case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER:
+      res.u = NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER;
+      break;
+    case NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_READER:
+      res.u = NN_ENTITYID_SEDP_BUILTIN_PUBLICATIONS_SECURE_WRITER;
+      break;
+    case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER:
+      res.u = NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER;
+      break;
+    case NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_READER:
+      res.u = NN_ENTITYID_SEDP_BUILTIN_SUBSCRIPTIONS_SECURE_WRITER;
+      break;
 
     default:
       assert (0);
@@ -2815,7 +2942,8 @@ static void new_writer_guid_common_init (struct writer *wr, const struct ddsi_se
   if (is_builtin_entityid (wr->e.guid.entityid, NN_VENDORID_ECLIPSE))
   {
     assert (wr->xqos->history.kind == DDS_HISTORY_KEEP_LAST);
-    assert (wr->xqos->durability.kind == DDS_DURABILITY_TRANSIENT_LOCAL);
+    assert (wr->xqos->durability.kind == DDS_DURABILITY_TRANSIENT_LOCAL ||
+            wr->e.guid.entityid.u == NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER);
   }
   wr->handle_as_transient_local = (wr->xqos->durability.kind == DDS_DURABILITY_TRANSIENT_LOCAL);
   wr->include_keyhash =
@@ -3614,6 +3742,158 @@ void proxy_participant_reassign_lease (struct proxy_participant *proxypp, struct
   ddsrt_mutex_unlock (&proxypp->e.lock);
 }
 
+struct bestab {
+  unsigned besflag;
+  unsigned prismtech_besflag;
+  unsigned entityid;
+};
+
+static void create_proxy_builtin_endpoints(
+  struct q_globals *gv,
+  const struct bestab *bestab,
+  int nbes,
+  const struct ddsi_guid *ppguid,
+  struct proxy_participant *proxypp,
+  nn_wctime_t timestamp,
+  dds_qos_t *xqos_wr,
+  dds_qos_t *xqos_rd)
+{
+  nn_plist_t plist_rd, plist_wr;
+  int i;
+  /* Note: no entity name or group GUID supplied, but that shouldn't
+   * matter, as these are internal to DDSI and don't use group
+   * coherency
+   */
+  nn_plist_init_empty (&plist_wr);
+  nn_plist_init_empty (&plist_rd);
+  nn_xqos_copy (&plist_wr.qos, xqos_wr);
+  nn_xqos_copy (&plist_rd.qos, xqos_rd);
+  for (i = 0; i < nbes; i++)
+  {
+    const struct bestab *te = &bestab[i];
+    if ((proxypp->bes & te->besflag) || (proxypp->prismtech_bes & te->prismtech_besflag))
+    {
+      ddsi_guid_t guid1;
+      guid1.prefix = proxypp->e.guid.prefix;
+      guid1.entityid.u = te->entityid;
+      assert (is_builtin_entityid (guid1.entityid, proxypp->vendor));
+      if (is_writer_entityid (guid1.entityid))
+      {
+        new_proxy_writer (gv, ppguid, &guid1, proxypp->as_meta, &plist_wr, gv->builtins_dqueue, gv->xevents, timestamp, 0);
+      }
+      else
+      {
+#ifdef DDSI_INCLUDE_SSM
+        const int ssm = addrset_contains_ssm (gv, proxypp->as_meta);
+#else
+        const int ssm = 0;
+#endif
+        new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, 0, ssm);
+      }
+    }
+  }
+  nn_plist_fini (&plist_wr);
+  nn_plist_fini (&plist_rd);
+}
+
+
+static void add_proxy_builtin_endpoints(
+  struct q_globals *gv,
+  const struct ddsi_guid *ppguid,
+  struct proxy_participant *proxypp,
+  nn_wctime_t timestamp)
+{
+  /* Add proxy endpoints based on the advertised (& possibly augmented
+     ...) built-in endpoint set. */
+#define PT_TE(ap_, a_, bp_, b_) { 0, NN_##ap_##BUILTIN_ENDPOINT_##a_, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
+#define TE(ap_, a_, bp_, b_) { NN_##ap_##BUILTIN_ENDPOINT_##a_, 0, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
+#define LTE(a_, bp_, b_) { NN_##BUILTIN_ENDPOINT_##a_, 0, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
+
+  /* 'Default' proxy endpoints. */
+  static const struct bestab bestab_default[] = {
+#if 0
+    /* SPDP gets special treatment => no need for proxy
+       writers/readers */
+    TE (DISC_, PARTICIPANT_ANNOUNCER, SPDP, PARTICIPANT_WRITER),
+#endif
+    TE (DISC_, PARTICIPANT_DETECTOR, SPDP, PARTICIPANT_READER),
+    TE (DISC_, PUBLICATION_ANNOUNCER, SEDP, PUBLICATIONS_WRITER),
+    TE (DISC_, PUBLICATION_DETECTOR, SEDP, PUBLICATIONS_READER),
+    TE (DISC_, SUBSCRIPTION_ANNOUNCER, SEDP, SUBSCRIPTIONS_WRITER),
+    TE (DISC_, SUBSCRIPTION_DETECTOR, SEDP, SUBSCRIPTIONS_READER),
+    LTE (PARTICIPANT_MESSAGE_DATA_WRITER, P2P, PARTICIPANT_MESSAGE_WRITER),
+    LTE (PARTICIPANT_MESSAGE_DATA_READER, P2P, PARTICIPANT_MESSAGE_READER),
+    TE (DISC_, TOPIC_ANNOUNCER, SEDP, TOPIC_WRITER),
+    TE (DISC_, TOPIC_DETECTOR, SEDP, TOPIC_READER),
+    PT_TE (DISC_, CM_PARTICIPANT_READER, SEDP, CM_PARTICIPANT_READER),
+    PT_TE (DISC_, CM_PARTICIPANT_WRITER, SEDP, CM_PARTICIPANT_WRITER),
+    PT_TE (DISC_, CM_PUBLISHER_READER, SEDP, CM_PUBLISHER_READER),
+    PT_TE (DISC_, CM_PUBLISHER_WRITER, SEDP, CM_PUBLISHER_WRITER),
+    PT_TE (DISC_, CM_SUBSCRIBER_READER, SEDP, CM_SUBSCRIBER_READER),
+    PT_TE (DISC_, CM_SUBSCRIBER_WRITER, SEDP, CM_SUBSCRIBER_WRITER)
+  };
+  create_proxy_builtin_endpoints(gv,
+                                 bestab_default,
+                                 (int)(sizeof (bestab_default) / sizeof (*bestab_default)),
+                                 ppguid,
+                                 proxypp,
+                                 timestamp,
+                                 &gv->builtin_endpoint_xqos_wr,
+                                 &gv->builtin_endpoint_xqos_rd);
+
+#ifdef DDSI_INCLUDE_SECURITY
+  /* Security 'default' proxy endpoints. */
+  static const struct bestab bestab_security[] = {
+    LTE (PUBLICATION_MESSAGE_SECURE_ANNOUNCER, SEDP, PUBLICATIONS_SECURE_WRITER),
+    LTE (PUBLICATION_MESSAGE_SECURE_DETECTOR, SEDP, PUBLICATIONS_SECURE_READER),
+    LTE (SUBSCRIPTION_MESSAGE_SECURE_ANNOUNCER, SEDP, SUBSCRIPTIONS_SECURE_WRITER),
+    LTE (SUBSCRIPTION_MESSAGE_SECURE_DETECTOR, SEDP, SUBSCRIPTIONS_SECURE_READER),
+    LTE (PARTICIPANT_MESSAGE_SECURE_ANNOUNCER, P2P, PARTICIPANT_MESSAGE_SECURE_WRITER),
+    LTE (PARTICIPANT_MESSAGE_SECURE_DETECTOR, P2P, PARTICIPANT_MESSAGE_SECURE_READER),
+    TE (DISC_, PARTICIPANT_SECURE_ANNOUNCER, SPDP_RELIABLE, PARTICIPANT_SECURE_WRITER),
+    TE (DISC_, PARTICIPANT_SECURE_DETECTOR, SPDP_RELIABLE, PARTICIPANT_SECURE_READER)
+  };
+  create_proxy_builtin_endpoints(gv,
+                                 bestab_security,
+                                 (int)(sizeof (bestab_security) / sizeof (*bestab_security)),
+                                 ppguid,
+                                 proxypp,
+                                 timestamp,
+                                 &gv->builtin_endpoint_xqos_wr,
+                                 &gv->builtin_endpoint_xqos_rd);
+
+  /* Security 'stateless' proxy endpoints. */
+  static const struct bestab bestab_stateless[] = {
+    LTE (PARTICIPANT_STATELESS_MESSAGE_ANNOUNCER, P2P, PARTICIPANT_STATELESS_MESSAGE_WRITER),
+    LTE (PARTICIPANT_STATELESS_MESSAGE_DETECTOR, P2P, PARTICIPANT_STATELESS_MESSAGE_READER)
+  };
+  create_proxy_builtin_endpoints(gv,
+                                 bestab_stateless,
+                                 (int)(sizeof (bestab_stateless) / sizeof (*bestab_stateless)),
+                                 ppguid,
+                                 proxypp,
+                                 timestamp,
+                                 &gv->builtin_stateless_xqos_wr,
+                                 &gv->builtin_stateless_xqos_rd);
+#endif
+
+  /* Register lease, but be careful not to accidentally re-register
+     DDSI2's lease, as we may have become dependent on DDSI2 any time
+     after ephash_insert_proxy_participant_guid even if
+     privileged_pp_guid was NULL originally */
+  ddsrt_mutex_lock (&proxypp->e.lock);
+
+  if (proxypp->owns_lease)
+    lease_register (ddsrt_atomic_ldvoidp (&proxypp->lease));
+
+  builtintopic_write (gv->builtin_topic_interface, &proxypp->e, timestamp, true);
+  ddsrt_mutex_unlock (&proxypp->e.lock);
+
+#undef PT_TE
+#undef TE
+#undef LTE
+}
+
 void new_proxy_participant
 (
   struct q_globals *gv,
@@ -3720,89 +4000,8 @@ void new_proxy_participant
      new_proxy_{writer,reader} to work */
   ephash_insert_proxy_participant_guid (gv->guid_hash, proxypp);
 
-  /* Add proxy endpoints based on the advertised (& possibly augmented
-     ...) built-in endpoint set. */
-  {
-#define PT_TE(ap_, a_, bp_, b_) { 0, NN_##ap_##BUILTIN_ENDPOINT_##a_, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
-#define TE(ap_, a_, bp_, b_) { NN_##ap_##BUILTIN_ENDPOINT_##a_, 0, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
-#define LTE(a_, bp_, b_) { NN_##BUILTIN_ENDPOINT_##a_, 0, NN_ENTITYID_##bp_##_BUILTIN_##b_ }
-    static const struct bestab {
-      unsigned besflag;
-      unsigned prismtech_besflag;
-      unsigned entityid;
-    } bestab[] = {
-#if 0
-      /* SPDP gets special treatment => no need for proxy
-         writers/readers */
-      TE (DISC_, PARTICIPANT_ANNOUNCER, SPDP, PARTICIPANT_WRITER),
-#endif
-      TE (DISC_, PARTICIPANT_DETECTOR, SPDP, PARTICIPANT_READER),
-      TE (DISC_, PUBLICATION_ANNOUNCER, SEDP, PUBLICATIONS_WRITER),
-      TE (DISC_, PUBLICATION_DETECTOR, SEDP, PUBLICATIONS_READER),
-      TE (DISC_, SUBSCRIPTION_ANNOUNCER, SEDP, SUBSCRIPTIONS_WRITER),
-      TE (DISC_, SUBSCRIPTION_DETECTOR, SEDP, SUBSCRIPTIONS_READER),
-      LTE (PARTICIPANT_MESSAGE_DATA_WRITER, P2P, PARTICIPANT_MESSAGE_WRITER),
-      LTE (PARTICIPANT_MESSAGE_DATA_READER, P2P, PARTICIPANT_MESSAGE_READER),
-      TE (DISC_, TOPIC_ANNOUNCER, SEDP, TOPIC_WRITER),
-      TE (DISC_, TOPIC_DETECTOR, SEDP, TOPIC_READER),
-      PT_TE (DISC_, CM_PARTICIPANT_READER, SEDP, CM_PARTICIPANT_READER),
-      PT_TE (DISC_, CM_PARTICIPANT_WRITER, SEDP, CM_PARTICIPANT_WRITER),
-      PT_TE (DISC_, CM_PUBLISHER_READER, SEDP, CM_PUBLISHER_READER),
-      PT_TE (DISC_, CM_PUBLISHER_WRITER, SEDP, CM_PUBLISHER_WRITER),
-      PT_TE (DISC_, CM_SUBSCRIBER_READER, SEDP, CM_SUBSCRIBER_READER),
-      PT_TE (DISC_, CM_SUBSCRIBER_WRITER, SEDP, CM_SUBSCRIBER_WRITER)
-    };
-#undef PT_TE
-#undef TE
-#undef LTE
-    nn_plist_t plist_rd, plist_wr;
-    int i;
-    /* Note: no entity name or group GUID supplied, but that shouldn't
-       matter, as these are internal to DDSI and don't use group
-       coherency */
-    nn_plist_init_empty (&plist_wr);
-    nn_plist_init_empty (&plist_rd);
-    nn_xqos_copy (&plist_wr.qos, &gv->builtin_endpoint_xqos_wr);
-    nn_xqos_copy (&plist_rd.qos, &gv->builtin_endpoint_xqos_rd);
-    for (i = 0; i < (int) (sizeof (bestab) / sizeof (*bestab)); i++)
-    {
-      const struct bestab *te = &bestab[i];
-      if ((proxypp->bes & te->besflag) || (proxypp->prismtech_bes & te->prismtech_besflag))
-      {
-        ddsi_guid_t guid1;
-        guid1.prefix = proxypp->e.guid.prefix;
-        guid1.entityid.u = te->entityid;
-        assert (is_builtin_entityid (guid1.entityid, proxypp->vendor));
-        if (is_writer_entityid (guid1.entityid))
-        {
-          new_proxy_writer (gv, ppguid, &guid1, proxypp->as_meta, &plist_wr, gv->builtins_dqueue, gv->xevents, timestamp, 0);
-        }
-        else
-        {
-#ifdef DDSI_INCLUDE_SSM
-          const int ssm = addrset_contains_ssm (gv, proxypp->as_meta);
-          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, 0, ssm);
-#else
-          new_proxy_reader (gv, ppguid, &guid1, proxypp->as_meta, &plist_rd, timestamp, 0);
-#endif
-        }
-      }
-    }
-    nn_plist_fini (&plist_wr);
-    nn_plist_fini (&plist_rd);
-  }
-
-  /* Register lease, but be careful not to accidentally re-register
-     DDSI2's lease, as we may have become dependent on DDSI2 any time
-     after ephash_insert_proxy_participant_guid even if
-     privileged_pp_guid was NULL originally */
-  ddsrt_mutex_lock (&proxypp->e.lock);
-
-  if (proxypp->owns_lease)
-    lease_register (ddsrt_atomic_ldvoidp (&proxypp->lease));
-
-  builtintopic_write (gv->builtin_topic_interface, &proxypp->e, timestamp, true);
-  ddsrt_mutex_unlock (&proxypp->e.lock);
+  /* TODO: Do security checks on the proxy participant. Either add the endpoints or delete the proxy. */
+  add_proxy_builtin_endpoints(gv, ppguid, proxypp, timestamp);
 }
 
 int update_proxy_participant_plist_locked (struct proxy_participant *proxypp, seqno_t seq, const struct nn_plist *datap, enum update_proxy_participant_source source, nn_wctime_t timestamp)
@@ -4104,12 +4303,27 @@ static void proxy_endpoint_common_fini (struct entity_common *e, struct proxy_en
 
 /* PROXY-WRITER ----------------------------------------------------- */
 
+static enum nn_reorder_mode
+get_proxy_writer_reorder_mode(const ddsi_entityid_t pwr_entityid, int isreliable)
+{
+  if (isreliable)
+  {
+    return NN_REORDER_MODE_NORMAL;
+  }
+  if (pwr_entityid.u == NN_ENTITYID_P2P_BUILTIN_PARTICIPANT_STATELESS_MESSAGE_WRITER)
+  {
+    return NN_REORDER_MODE_ALWAYS_DELIVER;
+  }
+  return NN_REORDER_MODE_MONOTONICALLY_INCREASING;
+}
+
 int new_proxy_writer (struct q_globals *gv, const struct ddsi_guid *ppguid, const struct ddsi_guid *guid, struct addrset *as, const nn_plist_t *plist, struct nn_dqueue *dqueue, struct xeventq *evq, nn_wctime_t timestamp, seqno_t seq)
 {
   struct proxy_participant *proxypp;
   struct proxy_writer *pwr;
   int isreliable;
   nn_mtime_t tnow = now_mt ();
+  enum nn_reorder_mode reorder_mode;
 
   assert (is_writer_entityid (guid->entityid));
   assert (ephash_lookup_proxy_writer_guid (gv->guid_hash, guid) == NULL);
@@ -4168,13 +4382,13 @@ int new_proxy_writer (struct q_globals *gv, const struct ddsi_guid *ppguid, cons
   if (isreliable)
   {
     pwr->defrag = nn_defrag_new (&gv->logconfig, NN_DEFRAG_DROP_LATEST, gv->config.defrag_reliable_maxsamples);
-    pwr->reorder = nn_reorder_new (&gv->logconfig, NN_REORDER_MODE_NORMAL, gv->config.primary_reorder_maxsamples, gv->config.late_ack_mode);
   }
   else
   {
     pwr->defrag = nn_defrag_new (&gv->logconfig, NN_DEFRAG_DROP_OLDEST, gv->config.defrag_unreliable_maxsamples);
-    pwr->reorder = nn_reorder_new (&gv->logconfig, NN_REORDER_MODE_MONOTONICALLY_INCREASING, gv->config.primary_reorder_maxsamples, gv->config.late_ack_mode);
   }
+  reorder_mode = get_proxy_writer_reorder_mode(pwr->e.guid.entityid, isreliable);
+  pwr->reorder = nn_reorder_new (&gv->logconfig, reorder_mode, gv->config.primary_reorder_maxsamples, gv->config.late_ack_mode);
   pwr->dqueue = dqueue;
   pwr->evq = evq;
   pwr->ddsi2direct_cb = 0;
diff --git a/src/core/ddsi/src/q_init.c b/src/core/ddsi/src/q_init.c
index f2bb0d9..0e2442a 100644
--- a/src/core/ddsi/src/q_init.c
+++ b/src/core/ddsi/src/q_init.c
@@ -1013,6 +1013,12 @@ int rtps_init (struct q_globals *gv)
   gv->spdp_endpoint_xqos.durability.kind = DDS_DURABILITY_TRANSIENT_LOCAL;
   make_builtin_endpoint_xqos (&gv->builtin_endpoint_xqos_rd, &gv->default_xqos_rd);
   make_builtin_endpoint_xqos (&gv->builtin_endpoint_xqos_wr, &gv->default_xqos_wr);
+#ifdef DDSI_INCLUDE_SECURITY
+  nn_xqos_copy (&gv->builtin_stateless_xqos_rd, &gv->default_xqos_rd);
+  nn_xqos_copy (&gv->builtin_stateless_xqos_wr, &gv->default_xqos_wr);
+  gv->builtin_stateless_xqos_wr.reliability.kind = DDS_RELIABILITY_BEST_EFFORT;
+  gv->builtin_stateless_xqos_wr.durability.kind = DDS_DURABILITY_VOLATILE;
+#endif
 
   make_special_topics (gv);
 
@@ -1329,6 +1335,10 @@ err_unicast_sockets:
   ddsrt_cond_destroy (&gv->participant_set_cond);
   ddsrt_mutex_destroy (&gv->participant_set_lock);
   free_special_topics (gv);
+#ifdef DDSI_INCLUDE_SECURITY
+  nn_xqos_fini (&gv->builtin_stateless_xqos_wr);
+  nn_xqos_fini (&gv->builtin_stateless_xqos_rd);
+#endif
   nn_xqos_fini (&gv->builtin_endpoint_xqos_wr);
   nn_xqos_fini (&gv->builtin_endpoint_xqos_rd);
   nn_xqos_fini (&gv->spdp_endpoint_xqos);
@@ -1657,6 +1667,10 @@ void rtps_fini (struct q_globals *gv)
   ddsrt_cond_destroy (&gv->participant_set_cond);
   free_special_topics (gv);
 
+#ifdef DDSI_INCLUDE_SECURITY
+  nn_xqos_fini (&gv->builtin_stateless_xqos_wr);
+  nn_xqos_fini (&gv->builtin_stateless_xqos_rd);
+#endif
   nn_xqos_fini (&gv->builtin_endpoint_xqos_wr);
   nn_xqos_fini (&gv->builtin_endpoint_xqos_rd);
   nn_xqos_fini (&gv->spdp_endpoint_xqos);
diff --git a/src/core/ddsi/src/q_receive.c b/src/core/ddsi/src/q_receive.c
index ada45a0..352c611 100644
--- a/src/core/ddsi/src/q_receive.c
+++ b/src/core/ddsi/src/q_receive.c
@@ -2305,7 +2305,8 @@ static void drop_oversize (struct receiver_state *rst, struct nn_rmsg *rmsg, con
     /* No proxy writer means nothing really gets done with, unless it
        is SPDP.  SPDP is periodic, so oversize discovery packets would
        cause periodic warnings. */
-    if (msg->writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER)
+    if ((msg->writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER) ||
+        (msg->writerId.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER))
     {
       DDS_CWARNING (&rst->gv->logconfig, "dropping oversize (%"PRIu32" > %"PRIu32") SPDP sample %"PRId64" from remote writer "PGUIDFMT"\n",
                     sampleinfo->size, rst->gv->config.max_sample_size, sampleinfo->seq,
@@ -2374,7 +2375,8 @@ static int handle_Data (struct receiver_state *rst, nn_etime_t tnow, struct nn_r
     }
     rdata = nn_rdata_new (rmsg, 0, sampleinfo->size, submsg_offset, payload_offset);
 
-    if (msg->x.writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER)
+    if ((msg->x.writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER) ||
+        (msg->x.writerId.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER))
       /* SPDP needs special treatment: there are no proxy writers for it
          and we accept data from unknown sources */
     {
@@ -2409,7 +2411,8 @@ static int handle_DataFrag (struct receiver_state *rst, nn_etime_t tnow, struct
     struct nn_rdata *rdata;
     unsigned submsg_offset, payload_offset;
     uint32_t begin, endp1;
-    if (msg->x.writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER)
+    if ((msg->x.writerId.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER) ||
+        (msg->x.writerId.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER))
     {
       DDS_CWARNING (&rst->gv->logconfig, "DATAFRAG("PGUIDFMT" #%"PRId64" -> "PGUIDFMT") - fragmented builtin data not yet supported\n",
                     PGUIDPREFIX (rst->src_guid_prefix), msg->x.writerId.u, fromSN (msg->x.writerSN),
diff --git a/src/core/ddsi/src/q_transmit.c b/src/core/ddsi/src/q_transmit.c
index 0a99fc9..b0061fe 100644
--- a/src/core/ddsi/src/q_transmit.c
+++ b/src/core/ddsi/src/q_transmit.c
@@ -884,7 +884,9 @@ static int insert_sample_in_whc (struct writer *wr, seqno_t seq, struct nn_plist
     res = 1;
 
 #ifndef NDEBUG
-  if (wr->e.guid.entityid.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER && !is_local_orphan_endpoint (&wr->e))
+  if (((wr->e.guid.entityid.u == NN_ENTITYID_SPDP_BUILTIN_PARTICIPANT_WRITER) ||
+       (wr->e.guid.entityid.u == NN_ENTITYID_SPDP_RELIABLE_BUILTIN_PARTICIPANT_SECURE_WRITER)) &&
+       !is_local_orphan_endpoint (&wr->e))
   {
     struct whc_state whcst;
     whc_get_state(wr->whc, &whcst);