diff --git a/rmw_dds_common/CMakeLists.txt b/rmw_dds_common/CMakeLists.txt
index b930cc3..a85bbeb 100644
--- a/rmw_dds_common/CMakeLists.txt
+++ b/rmw_dds_common/CMakeLists.txt
@@ -17,6 +17,7 @@ find_package(rcpputils REQUIRED)
 find_package(rcutils REQUIRED)
 find_package(rmw REQUIRED)
 find_package(rosidl_default_generators REQUIRED)
+find_package(rosidl_runtime_c REQUIRED)
 
 ament_add_default_options()
 ament_export_dependencies(ament_cmake_core)
@@ -44,7 +45,8 @@ target_link_libraries(${PROJECT_NAME}_library PUBLIC
   rcutils::rcutils
   rmw::rmw)
 target_link_libraries(${PROJECT_NAME}_library PRIVATE
-  rcpputils::rcpputils)
+  rcpputils::rcpputils
+  rosidl_runtime_c::rosidl_runtime_c)
 target_include_directories(${PROJECT_NAME}_library
   PUBLIC
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
@@ -95,7 +97,8 @@ if(BUILD_TESTING)
 
   ament_add_gmock(test_graph_cache test/test_graph_cache.cpp)
   if(TARGET test_graph_cache)
-    target_link_libraries(test_graph_cache ${PROJECT_NAME}_library osrf_testing_tools_cpp::memory_tools)
+    target_link_libraries(test_graph_cache
+      ${PROJECT_NAME}_library osrf_testing_tools_cpp::memory_tools rosidl_runtime_c::rosidl_runtime_c)
     target_compile_definitions(test_graph_cache PUBLIC RCUTILS_ENABLE_FAULT_INJECTION)
   endif()
 
@@ -106,7 +109,7 @@ if(BUILD_TESTING)
 
   ament_add_gmock(test_qos test/test_qos.cpp)
   if(TARGET test_qos)
-    target_link_libraries(test_qos ${PROJECT_NAME}_library osrf_testing_tools_cpp::memory_tools)
+    target_link_libraries(test_qos ${PROJECT_NAME}_library osrf_testing_tools_cpp::memory_tools rcpputils::rcpputils)
   endif()
 
   ament_add_gmock(test_time_utils test/test_time_utils.cpp)
@@ -123,7 +126,7 @@ if(BUILD_TESTING)
 
   add_performance_test(benchmark_graph_cache test/benchmark/benchmark_graph_cache.cpp)
   if(TARGET benchmark_graph_cache)
-    target_link_libraries(benchmark_graph_cache ${PROJECT_NAME}_library)
+    target_link_libraries(benchmark_graph_cache ${PROJECT_NAME}_library rosidl_runtime_c::rosidl_runtime_c)
   endif()
 endif()
 
diff --git a/rmw_dds_common/include/rmw_dds_common/graph_cache.hpp b/rmw_dds_common/include/rmw_dds_common/graph_cache.hpp
index 30802e6..bc08ecf 100644
--- a/rmw_dds_common/include/rmw_dds_common/graph_cache.hpp
+++ b/rmw_dds_common/include/rmw_dds_common/graph_cache.hpp
@@ -78,11 +78,12 @@ class GraphCache
    * @{
    */
 
-  /// Add a data writer.
+  /// Add a data writer based on discovery.
   /**
    * \param writer_gid GUID of the data writer.
    * \param topic_name Name of the DDS topic for this data writer.
    * \param type_name Type name of the DDS topic for this data writer.
+   * \param type_hash Hash of the description of the topic type.
    * \param participant_gid GUID of the participant.
    * \param qos QoS profile of the data writer.
    * \return `true` if the cache was updated, `false` if the data writer
@@ -90,6 +91,22 @@ class GraphCache
    */
   RMW_DDS_COMMON_PUBLIC
   bool
+  add_writer(
+    const rmw_gid_t & writer_gid,
+    const std::string & topic_name,
+    const std::string & type_name,
+    const rosidl_type_hash_t & type_hash,
+    const rmw_gid_t & participant_gid,
+    const rmw_qos_profile_t & qos);
+
+  /// Add a data writer based on discovery.
+  /**
+   * See add_reader with rosidl_type_hash_t, whose other parameters match these.
+   */
+  RMW_DDS_COMMON_PUBLIC
+    RCUTILS_DEPRECATED_WITH_MSG(
+    "Migrate to using the version of this function taking a type hash.")
+  bool
   add_writer(
     const rmw_gid_t & writer_gid,
     const std::string & topic_name,
@@ -102,6 +119,7 @@ class GraphCache
    * \param reader_gid GUID of the The data reader.
    * \param topic_name Name of the DDS topic for this data reader.
    * \param type_name Type name of the DDS topic for this data reader.
+   * \param type_hash Hash of the description of the topic type.
    * \param participant_gid GUID of the participant.
    * \param qos QoS profile of the data reader.
    * \return `true` if the cache was updated, `false` if the data reader
@@ -109,6 +127,22 @@ class GraphCache
    */
   RMW_DDS_COMMON_PUBLIC
   bool
+  add_reader(
+    const rmw_gid_t & reader_gid,
+    const std::string & topic_name,
+    const std::string & type_name,
+    const rosidl_type_hash_t & type_hash,
+    const rmw_gid_t & participant_gid,
+    const rmw_qos_profile_t & qos);
+
+  /// Add a data reader based on discovery.
+  /**
+   * See add_reader with rosidl_type_hash_t, whose other parameters match these.
+   */
+  RMW_DDS_COMMON_PUBLIC
+    RCUTILS_DEPRECATED_WITH_MSG(
+    "Migrate to using the version of this function taking a type hash.")
+  bool
   add_reader(
     const rmw_gid_t & reader_gid,
     const std::string & topic_name,
@@ -121,6 +155,7 @@ class GraphCache
    * \param gid GUID of the entity.
    * \param topic_name Name of the DDS topic for this data reader.
    * \param type_name Type name of the DDS topic for this entity
+   * \param type_hash Hash of the description of the topic type.
    * \param participant_gid GUID of the participant.
    * \param qos QoS profile of the entity.
    * \param is_reader Whether the entity is a data reader or a writer.
@@ -129,6 +164,23 @@ class GraphCache
    */
   RMW_DDS_COMMON_PUBLIC
   bool
+  add_entity(
+    const rmw_gid_t & gid,
+    const std::string & topic_name,
+    const std::string & type_name,
+    const rosidl_type_hash_t & type_hash,
+    const rmw_gid_t & participant_gid,
+    const rmw_qos_profile_t & qos,
+    bool is_reader);
+
+  /// Add a data reader or writer.
+  /**
+   * See add_entity with rosidl_type_hash_t, whose other parameters match these.
+   */
+  RMW_DDS_COMMON_PUBLIC
+    RCUTILS_DEPRECATED_WITH_MSG(
+    "Migrate to using the version of this function taking a type hash.")
+  bool
   add_entity(
     const rmw_gid_t & gid,
     const std::string & topic_name,
@@ -541,8 +593,10 @@ struct EntityInfo
 {
   /// Topic name.
   std::string topic_name;
-  /// Topic type.
+  /// Topic type name.
   std::string topic_type;
+  /// Topic type hash.
+  rosidl_type_hash_t topic_type_hash;
   /// Participant gid.
   rmw_gid_t participant_gid;
   /// Quality of service of the topic.
@@ -552,10 +606,12 @@ struct EntityInfo
   EntityInfo(
     const std::string & topic_name,
     const std::string & topic_type,
+    const rosidl_type_hash_t & topic_type_hash,
     const rmw_gid_t & participant_gid,
     const rmw_qos_profile_t & qos)
   : topic_name(topic_name),
     topic_type(topic_type),
+    topic_type_hash(topic_type_hash),
     participant_gid(participant_gid),
     qos(qos)
   {}
diff --git a/rmw_dds_common/include/rmw_dds_common/qos.hpp b/rmw_dds_common/include/rmw_dds_common/qos.hpp
index 3f0b128..63e94f7 100644
--- a/rmw_dds_common/include/rmw_dds_common/qos.hpp
+++ b/rmw_dds_common/include/rmw_dds_common/qos.hpp
@@ -16,6 +16,7 @@
 #define RMW_DDS_COMMON__QOS_HPP_
 
 #include <functional>
+#include <string>
 
 #include "rmw/qos_profiles.h"
 #include "rmw/topic_endpoint_info_array.h"
@@ -224,6 +225,36 @@ RMW_DDS_COMMON_PUBLIC
 rmw_qos_profile_t
 qos_profile_update_best_available_for_services(const rmw_qos_profile_t & qos_profile);
 
+/// Parse USER_DATA "key=value;key=value;"" encoding, finding value of key "typehash"
+/**
+ * \param[in] user_data USER_DATA qos raw bytes
+ * \param[in] user_data_size Length of user_data
+ * \param[out] type_hash_out Filled with type hash data if found, or to zero value if key not found
+ * \return RMW_RET_OK if key parsed successfully, or if key not found
+ * \return RMW_RET_INVALID_ARGUMENT if user_data is null
+ * \return RMW_RET_ERROR if typehash key found, but value could not be parsed
+ */
+RMW_DDS_COMMON_PUBLIC
+rmw_ret_t
+parse_type_hash_from_user_data(
+  const uint8_t * user_data,
+  size_t user_data_size,
+  rosidl_type_hash_t & type_hash_out);
+
+/// Encode type hash as "typehash=hash_string;" for use in USER_DATA QoS
+/**
+ * \param[in] type_hash Type hash value to encode
+ * \param[out] string_out On success, will be set to "typehash=stringified_type_hash;"
+ *   If type_hash's version is 0, string_out will be set to empty
+ * \return RMW_RET_OK on success, including empty string for unset version
+ * \return RMW_RET_BAD_ALLOC if memory allocation fails
+ */
+RMW_DDS_COMMON_PUBLIC
+rmw_ret_t
+encode_type_hash_for_user_data_qos(
+  const rosidl_type_hash_t & type_hash,
+  std::string & string_out);
+
 }  // namespace rmw_dds_common
 
 #endif  // RMW_DDS_COMMON__QOS_HPP_
diff --git a/rmw_dds_common/package.xml b/rmw_dds_common/package.xml
index b0b57a7..8257e50 100644
--- a/rmw_dds_common/package.xml
+++ b/rmw_dds_common/package.xml
@@ -20,6 +20,7 @@
   <depend>rcutils</depend>
   <depend>rcpputils</depend>
   <depend>rmw</depend>
+  <depend>rosidl_runtime_c</depend>
   <depend>rosidl_runtime_cpp</depend>
 
   <test_depend>ament_cmake_gmock</test_depend>
diff --git a/rmw_dds_common/src/graph_cache.cpp b/rmw_dds_common/src/graph_cache.cpp
index 551bb1b..52f6b20 100644
--- a/rmw_dds_common/src/graph_cache.cpp
+++ b/rmw_dds_common/src/graph_cache.cpp
@@ -67,6 +67,7 @@ GraphCache::add_writer(
   const rmw_gid_t & gid,
   const std::string & topic_name,
   const std::string & type_name,
+  const rosidl_type_hash_t & type_hash,
   const rmw_gid_t & participant_gid,
   const rmw_qos_profile_t & qos)
 {
@@ -74,16 +75,34 @@ GraphCache::add_writer(
   auto pair = data_writers_.emplace(
     std::piecewise_construct,
     std::forward_as_tuple(gid),
-    std::forward_as_tuple(topic_name, type_name, participant_gid, qos));
+    std::forward_as_tuple(topic_name, type_name, type_hash, participant_gid, qos));
   GRAPH_CACHE_CALL_ON_CHANGE_CALLBACK_IF(this, pair.second);
   return pair.second;
 }
 
+bool
+GraphCache::add_writer(
+  const rmw_gid_t & gid,
+  const std::string & topic_name,
+  const std::string & type_name,
+  const rmw_gid_t & participant_gid,
+  const rmw_qos_profile_t & qos)
+{
+  return this->add_writer(
+    gid,
+    topic_name,
+    type_name,
+    rosidl_get_zero_initialized_type_hash(),
+    participant_gid,
+    qos);
+}
+
 bool
 GraphCache::add_reader(
   const rmw_gid_t & gid,
   const std::string & topic_name,
   const std::string & type_name,
+  const rosidl_type_hash_t & type_hash,
   const rmw_gid_t & participant_gid,
   const rmw_qos_profile_t & qos)
 {
@@ -91,16 +110,34 @@ GraphCache::add_reader(
   auto pair = data_readers_.emplace(
     std::piecewise_construct,
     std::forward_as_tuple(gid),
-    std::forward_as_tuple(topic_name, type_name, participant_gid, qos));
+    std::forward_as_tuple(topic_name, type_name, type_hash, participant_gid, qos));
   GRAPH_CACHE_CALL_ON_CHANGE_CALLBACK_IF(this, pair.second);
   return pair.second;
 }
 
+bool
+GraphCache::add_reader(
+  const rmw_gid_t & gid,
+  const std::string & topic_name,
+  const std::string & type_name,
+  const rmw_gid_t & participant_gid,
+  const rmw_qos_profile_t & qos)
+{
+  return this->add_reader(
+    gid,
+    topic_name,
+    type_name,
+    rosidl_get_zero_initialized_type_hash(),
+    participant_gid,
+    qos);
+}
+
 bool
 GraphCache::add_entity(
   const rmw_gid_t & gid,
   const std::string & topic_name,
   const std::string & type_name,
+  const rosidl_type_hash_t & type_hash,
   const rmw_gid_t & participant_gid,
   const rmw_qos_profile_t & qos,
   bool is_reader)
@@ -110,6 +147,7 @@ GraphCache::add_entity(
       gid,
       topic_name,
       type_name,
+      type_hash,
       participant_gid,
       qos);
   }
@@ -117,10 +155,30 @@ GraphCache::add_entity(
     gid,
     topic_name,
     type_name,
+    type_hash,
     participant_gid,
     qos);
 }
 
+bool
+GraphCache::add_entity(
+  const rmw_gid_t & gid,
+  const std::string & topic_name,
+  const std::string & type_name,
+  const rmw_gid_t & participant_gid,
+  const rmw_qos_profile_t & qos,
+  bool is_reader)
+{
+  return this->add_entity(
+    gid,
+    topic_name,
+    type_name,
+    rosidl_get_zero_initialized_type_hash(),
+    participant_gid,
+    qos,
+    is_reader);
+}
+
 bool
 GraphCache::remove_writer(const rmw_gid_t & gid)
 {
@@ -570,6 +628,13 @@ __get_entities_info_by_topic(
       return ret;
     }
 
+    ret = rmw_topic_endpoint_info_set_topic_type_hash(
+      &endpoint_info,
+      &entity_pair.second.topic_type_hash);
+    if (RMW_RET_OK != ret) {
+      return ret;
+    }
+
     ret = rmw_topic_endpoint_info_set_endpoint_type(
       &endpoint_info,
       is_reader ? RMW_ENDPOINT_SUBSCRIPTION : RMW_ENDPOINT_PUBLISHER);
diff --git a/rmw_dds_common/src/qos.cpp b/rmw_dds_common/src/qos.cpp
index da1a8da..7604cb1 100644
--- a/rmw_dds_common/src/qos.cpp
+++ b/rmw_dds_common/src/qos.cpp
@@ -16,9 +16,14 @@
 
 #include <cstdarg>
 #include <cstring>
+#include <string>
+#include <vector>
 
+#include "rcpputils/scope_exit.hpp"
+#include "rcutils/error_handling.h"
 #include "rcutils/snprintf.h"
 #include "rmw/error_handling.h"
+#include "rmw/impl/cpp/key_value.hpp"
 #include "rmw/get_topic_endpoint_info.h"
 #include "rmw/qos_profiles.h"
 #include "rmw/qos_string_conversions.h"
@@ -664,4 +669,48 @@ qos_profile_update_best_available_for_services(const rmw_qos_profile_t & qos_pro
   return result;
 }
 
+rmw_ret_t
+parse_type_hash_from_user_data(
+  const uint8_t * user_data,
+  size_t user_data_size,
+  rosidl_type_hash_t & type_hash_out)
+{
+  RMW_CHECK_ARGUMENT_FOR_NULL(user_data, RMW_RET_INVALID_ARGUMENT);
+  std::vector<uint8_t> udvec(user_data, user_data + user_data_size);
+  auto key_value = rmw::impl::cpp::parse_key_value(udvec);
+  auto typehash_it = key_value.find("typehash");
+  if (typehash_it == key_value.end()) {
+    type_hash_out = rosidl_get_zero_initialized_type_hash();
+    return RMW_RET_OK;
+  }
+  std::string type_hash_str(typehash_it->second.begin(), typehash_it->second.end());
+  if (RCUTILS_RET_OK != rosidl_parse_type_hash_string(type_hash_str.c_str(), &type_hash_out)) {
+    return RMW_RET_ERROR;
+  }
+  return RMW_RET_OK;
+}
+
+rmw_ret_t
+encode_type_hash_for_user_data_qos(
+  const rosidl_type_hash_t & type_hash,
+  std::string & string_out)
+{
+  if (type_hash.version == ROSIDL_TYPE_HASH_VERSION_UNSET) {
+    string_out.clear();
+    return RMW_RET_OK;
+  }
+  auto allocator = rcutils_get_default_allocator();
+  char * type_hash_c_str = nullptr;
+  rcutils_ret_t stringify_ret = rosidl_stringify_type_hash(&type_hash, allocator, &type_hash_c_str);
+  if (RCUTILS_RET_BAD_ALLOC == stringify_ret) {
+    return RMW_RET_BAD_ALLOC;
+  }
+  if (RCUTILS_RET_OK != stringify_ret) {
+    return RMW_RET_ERROR;
+  }
+  RCPPUTILS_SCOPE_EXIT(allocator.deallocate(type_hash_c_str, &allocator.state));
+  string_out = "typehash=" + std::string(type_hash_c_str) + ";";
+  return RMW_RET_OK;
+}
+
 }  // namespace rmw_dds_common
diff --git a/rmw_dds_common/test/benchmark/benchmark_graph_cache.cpp b/rmw_dds_common/test/benchmark/benchmark_graph_cache.cpp
index 349bb7a..1fe8b55 100644
--- a/rmw_dds_common/test/benchmark/benchmark_graph_cache.cpp
+++ b/rmw_dds_common/test/benchmark/benchmark_graph_cache.cpp
@@ -24,6 +24,8 @@
 #include "rmw_dds_common/gid_utils.hpp"
 #include "rmw_dds_common/graph_cache.hpp"
 
+#include "rosidl_runtime_c/type_hash.h"
+
 using performance_test_fixture::PerformanceTest;
 using rmw_dds_common::GraphCache;
 
@@ -120,6 +122,7 @@ add_entities(
       gid_from_string(elem.gid),
       elem.name,
       elem.type,
+      rosidl_get_zero_initialized_type_hash(),
       gid_from_string(elem.participant_gid),
       rmw_qos_profile_default,
       elem.is_reader);
diff --git a/rmw_dds_common/test/test_graph_cache.cpp b/rmw_dds_common/test/test_graph_cache.cpp
index b4c4206..c9927ad 100644
--- a/rmw_dds_common/test/test_graph_cache.cpp
+++ b/rmw_dds_common/test/test_graph_cache.cpp
@@ -303,6 +303,7 @@ add_entities(
         gid_from_string(elem.gid),
         elem.name,
         elem.type,
+        rosidl_get_zero_initialized_type_hash(),
         gid_from_string(elem.participant_gid),
         rmw_qos_profile_default,
         elem.is_reader));
diff --git a/rmw_dds_common/test/test_qos.cpp b/rmw_dds_common/test/test_qos.cpp
index c8aedbb..1074ce7 100644
--- a/rmw_dds_common/test/test_qos.cpp
+++ b/rmw_dds_common/test/test_qos.cpp
@@ -17,6 +17,7 @@
 #include <cstring>
 
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
+#include "rcpputils/scope_exit.hpp"
 #include "rmw/error_handling.h"
 #include "rmw/qos_profiles.h"
 #include "rmw/types.h"
@@ -1072,3 +1073,60 @@ TEST(test_qos, test_qos_profile_update_best_available_for_services)
       rmw_qos_profile_services_default.liveliness_lease_duration,
       output_profile.liveliness_lease_duration));
 }
+
+TEST(test_qos, test_parse_type_hash_from_user_data)
+{
+  const auto zero_val = rosidl_get_zero_initialized_type_hash();
+
+  std::string bad_value = "something that isn't key equals value semicolon";
+  rosidl_type_hash_t result_type_hash;
+  rmw_ret_t ret = rmw_dds_common::parse_type_hash_from_user_data(
+    reinterpret_cast<uint8_t *>(bad_value.data()), bad_value.size(), result_type_hash);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_EQ(0, memcmp(&result_type_hash, &zero_val, sizeof(rosidl_type_hash_t)))
+    << "Non-ros 2 user_data should result in zero hash struct.";
+
+  std::string no_key = "key1=value1;key2=value2;key3=value3;";
+  ret = rmw_dds_common::parse_type_hash_from_user_data(
+    reinterpret_cast<uint8_t *>(no_key.data()), no_key.size(), result_type_hash);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_EQ(0, memcmp(&result_type_hash, &zero_val, sizeof(rosidl_type_hash_t)))
+    << "No typehash key should result in zero hash struct.";
+
+  rosidl_type_hash_t input_type_hash;
+  input_type_hash.version = 1;
+  for (uint8_t i = 0; i < ROSIDL_TYPE_HASH_SIZE; i++) {
+    input_type_hash.value[i] = i;
+  }
+  char * type_hash_c_str;
+  auto allocator = rcutils_get_default_allocator();
+  ret = rosidl_stringify_type_hash(&input_type_hash, allocator, &type_hash_c_str);
+  ASSERT_EQ(ret, RCUTILS_RET_OK);
+  RCPPUTILS_SCOPE_EXIT(allocator.deallocate(type_hash_c_str, &allocator.state));
+  std::string type_hash_string(type_hash_c_str);
+  std::string good_data = "foo=bar;typehash=" + type_hash_string + ";key=value;";
+  ret = rmw_dds_common::parse_type_hash_from_user_data(
+    reinterpret_cast<uint8_t *>(good_data.data()), good_data.size(), result_type_hash);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_EQ(0, memcmp(&result_type_hash, &input_type_hash, sizeof(rosidl_type_hash_t)));
+}
+
+TEST(test_qos, test_encode_type_hash_for_user_data_qos)
+{
+  rosidl_type_hash_t test_hash = rosidl_get_zero_initialized_type_hash();
+  std::string hash_string;
+  rmw_ret_t ret = rmw_dds_common::encode_type_hash_for_user_data_qos(test_hash, hash_string);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_EQ(hash_string, "");
+
+  test_hash.version = 1;
+  for (uint8_t i = 0; i < ROSIDL_TYPE_HASH_SIZE; i++) {
+    test_hash.value[i] = i;
+  }
+  hash_string.clear();
+  ret = rmw_dds_common::encode_type_hash_for_user_data_qos(test_hash, hash_string);
+  EXPECT_EQ(ret, RMW_RET_OK);
+  EXPECT_EQ(
+    hash_string,
+    "typehash=RIHS01_000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f;");
+}