diff --git a/doc/dev_ref/oids.rst b/doc/dev_ref/oids.rst
index f8ea9446a8e..11a774ef4d2 100644
--- a/doc/dev_ref/oids.rst
+++ b/doc/dev_ref/oids.rst
@@ -66,6 +66,8 @@ Values currently assigned are::
   SphincsPlus-haraka-256s-r3.1 OBJECT IDENTIFIER ::= { SphincsPlus-haraka 5 }
   SphincsPlus-haraka-256f-r3.1  OBJECT IDENTIFIER ::= { SphincsPlus-haraka 6 }
 
+  HSS-LMS-Private-Key OBJECT IDENTIFIER ::= { publicKey 13 }
+
   symmetricKey OBJECT IDENTIFIER ::= { randombit 3 }
 
   ocbModes OBJECT IDENTIFIER ::= { symmetricKey 2 }
diff --git a/src/lib/pubkey/hss_lms/hss_lms_utils.h b/src/lib/pubkey/hss_lms/hss_lms_utils.h
index d4469320a83..e89d3d9e090 100644
--- a/src/lib/pubkey/hss_lms/hss_lms_utils.h
+++ b/src/lib/pubkey/hss_lms/hss_lms_utils.h
@@ -64,9 +64,13 @@ class PseudorandomKeyGeneration {
       void gen(std::span<uint8_t> out, HashFunction& hash, std::span<const uint8_t> seed) const;
 
    private:
+      /// Input buffer containing the prefix: 'identifier || u32str(q) || u16str(i) || u8str(j)'
       std::vector<uint8_t> m_input_buffer;
+      /// Subspan of m_input_buffer representing 'u32str(q)'
       std::span<uint8_t> m_q;
+      /// Subspan of m_input_buffer representing 'u26str(i)'
       std::span<uint8_t> m_i;
+      /// Pointer to m_input_buffer at 'u8str(j)'
       uint8_t* m_j;
 };
 
diff --git a/src/lib/pubkey/hss_lms/info.txt b/src/lib/pubkey/hss_lms/info.txt
index 70dcb9cfcf8..17946ed2557 100644
--- a/src/lib/pubkey/hss_lms/info.txt
+++ b/src/lib/pubkey/hss_lms/info.txt
@@ -22,4 +22,5 @@ rng
 sha2_32
 shake
 trunc_hash
+tree_hash
 </requires>
diff --git a/src/lib/pubkey/hss_lms/lm_ots.h b/src/lib/pubkey/hss_lms/lm_ots.h
index 8bde0b72aa7..f781c4178b6 100644
--- a/src/lib/pubkey/hss_lms/lm_ots.h
+++ b/src/lib/pubkey/hss_lms/lm_ots.h
@@ -57,7 +57,10 @@ using LMS_Message = Strong<std::vector<uint8_t>, struct LMS_Message_>;
 /**
  * @brief Enum of available LM-OTS algorithm types.
  *
- * See RFC 8554 Section 4.1.
+ * The supported parameter sets are defined in RFC 8554 Section 4.1. and
+ * draft-fluhrer-lms-more-parm-sets-11 Section 4. HSS/LMS typecodes are
+ * introduced in RFC 8554 Section 3.2. and their format specified in
+ * Section 3.3.
  */
 enum class LMOTS_Algorithm_Type : uint32_t {
    // --- RFC 8554 ---
diff --git a/src/lib/pubkey/hss_lms/lms.h b/src/lib/pubkey/hss_lms/lms.h
index 0312dc2f20d..2016a8bd1ab 100644
--- a/src/lib/pubkey/hss_lms/lms.h
+++ b/src/lib/pubkey/hss_lms/lms.h
@@ -21,7 +21,10 @@ namespace Botan {
 /**
  * @brief Enum of available LMS algorithm types.
  *
- * See RFC 8554 Section 5.1.
+ * The supported parameter sets are defined in RFC 8554 Section 5.1. and
+ * draft-fluhrer-lms-more-parm-sets-11 Section 5. HSS/LMS typecodes are
+ * introduced in RFC 8554 Section 3.2. and their format specified in
+ * Section 3.3.
  */
 enum class LMS_Algorithm_Type : uint32_t {
    // --- RFC 8554 ---
diff --git a/src/lib/utils/concepts.h b/src/lib/utils/concepts.h
index 0222ed4dfa7..fa586dd22fc 100644
--- a/src/lib/utils/concepts.h
+++ b/src/lib/utils/concepts.h
@@ -29,18 +29,6 @@ struct is_strong_type<Strong<Ts...>> : std::true_type {};
 template <typename... Ts>
 constexpr bool is_strong_type_v = is_strong_type<std::remove_const_t<Ts>...>::value;
 
-/**
- * Checks whether a strong type has the @p Capability included in its @p Tags type pack.
- */
-template <typename Capability, typename T, typename... Tags>
-constexpr auto strong_type_has_capability(Strong<T, Tags...>) {
-   if constexpr((std::is_same_v<Capability, Tags> || ...)) {
-      return std::true_type();
-   } else {
-      return std::false_type();
-   }
-}
-
 namespace concepts {
 
 // TODO: C++20 use std::convertible_to<> that was not available in Android NDK
@@ -130,9 +118,8 @@ template <class T>
 concept contiguous_strong_type = strong_type<T> && contiguous_container<T>;
 
 template <typename T, typename Capability>
-concept strong_type_with_capability = requires(T a) {
-                                         { strong_type_has_capability<Capability>(a) } -> std::same_as<std::true_type>;
-                                      };
+concept strong_type_with_capability = T::template
+has_capability<Capability>();
 
 // std::integral is a concept that is shipped with C++20 but Android NDK is not
 // yet there.
diff --git a/src/lib/utils/info.txt b/src/lib/utils/info.txt
index cf13472cabd..20b874b7dc6 100644
--- a/src/lib/utils/info.txt
+++ b/src/lib/utils/info.txt
@@ -45,7 +45,6 @@ safeint.h
 scan_name.h
 stl_util.h
 timer.h
-tree_hash.h
 </header:internal>
 
 <requires>
diff --git a/src/lib/utils/stl_util.h b/src/lib/utils/stl_util.h
index d5d7662fa3a..d9b3d99c979 100644
--- a/src/lib/utils/stl_util.h
+++ b/src/lib/utils/stl_util.h
@@ -157,6 +157,11 @@ class BufferSlicer final {
          return load_be<T>(take(sizeof(T)).data(), 0);
       }
 
+      template <typename T>
+      auto copy_le() {
+         return load_le<T>(take(sizeof(T)).data(), 0);
+      }
+
       void skip(const size_t count) { take(count); }
 
       size_t remaining() const { return m_remaining.size(); }
diff --git a/src/lib/utils/strong_type.h b/src/lib/utils/strong_type.h
index dda41492da6..b6a2d0069c9 100644
--- a/src/lib/utils/strong_type.h
+++ b/src/lib/utils/strong_type.h
@@ -157,6 +157,11 @@ class Strong : public detail::Strong_Adapter<T> {
    public:
       using detail::Strong_Adapter<T>::Strong_Adapter;
 
+      template <typename CapabilityT>
+      constexpr static bool has_capability() {
+         return (std::is_same_v<CapabilityT, Capabilities> || ...);
+      }
+
    private:
       using Tag = TagTypeT;
 };
diff --git a/src/lib/utils/tree_hash/info.txt b/src/lib/utils/tree_hash/info.txt
new file mode 100644
index 00000000000..ddbcded3f24
--- /dev/null
+++ b/src/lib/utils/tree_hash/info.txt
@@ -0,0 +1,12 @@
+<defines>
+TREE_HASH -> 20231006
+</defines>
+
+<module_info>
+name -> "Tree Hash"
+</module_info>
+
+<header:internal>
+tree_hash.h
+</header:internal>
+
diff --git a/src/lib/utils/tree_hash.h b/src/lib/utils/tree_hash/tree_hash.h
similarity index 99%
rename from src/lib/utils/tree_hash.h
rename to src/lib/utils/tree_hash/tree_hash.h
index 6c2f1014f9f..db1e4c94a42 100644
--- a/src/lib/utils/tree_hash.h
+++ b/src/lib/utils/tree_hash/tree_hash.h
@@ -43,9 +43,6 @@ concept tree_node_index = strong_type_with_capability<T, EnableArithmeticWithPla
 template <typename T>
 concept tree_layer_index = strong_type_with_capability<T, EnableArithmeticWithPlainNumber>;
 
-template <strong_type S>
-struct strong_span_type {};
-
 /**
  * @brief An adress in a Tree.
  */