Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/security/v2/secured_message.hpp

@@ -0,0 +1,128 @@
+#ifndef SECURED_MESSAGE_HPP_MO3HBSXG
+#define SECURED_MESSAGE_HPP_MO3HBSXG
+
+#include <vanetza/common/its_aid.hpp>
+#include <vanetza/security/v2/header_field.hpp>
+#include <vanetza/security/v2/trailer_field.hpp>
+#include <vanetza/security/v2/payload.hpp>
+#include <cstdint>
+#include <list>
+
+namespace vanetza
+{
+namespace security
+{
+namespace v2
+{
+
+/// SecuredMessage as specified in TS 103 097 v1.2.1, section 5.1
+struct SecuredMessage
+{
+    std::list<HeaderField> header_fields;
+    std::list<TrailerField> trailer_fields;
+    Payload payload;
+
+    uint8_t protocol_version() const { return 2; }
+
+    /**
+     * Fetch pointer to first matching header field
+     * \param type HeaderField has to match given type
+     * \return matching HeaderField or nullptr
+     */
+    HeaderField* header_field(HeaderFieldType);
+
+    /**
+     * Fetch read-only pointer to first machting header field
+     * \param type requested header field type
+     * \return matching header field or nullptr
+     */
+    const HeaderField* header_field(HeaderFieldType type) const;
+
+    /**
+     * Fetch pointer to first matching trailer field
+     * \param type TrailerField has to match given type
+     * \return matching TrailerField or nullptr
+     */
+    TrailerField* trailer_field(TrailerFieldType);
+
+    /**
+     * Fetch read-only pointer of first matching trailer field
+     * \param type request trailer field type
+     * \return matching trailer field or nullptr
+     */
+    const TrailerField* trailer_field(TrailerFieldType type) const;
+
+    template<HeaderFieldType T>
+    typename header_field_type<T>::type* header_field()
+    {
+        using field_type = typename header_field_type<T>::type;
+        HeaderField* field = header_field(T);
+        return boost::get<field_type>(field);
+    }
+
+    template<HeaderFieldType T>
+    const typename header_field_type<T>::type* header_field() const
+    {
+        using field_type = typename header_field_type<T>::type;
+        const HeaderField* field = header_field(T);
+        return boost::get<field_type>(field);
+    }
+
+    template<TrailerFieldType T>
+    typename trailer_field_type<T>::type* trailer_field()
+    {
+        using field_type = typename trailer_field_type<T>::type;
+        TrailerField* field = trailer_field(T);
+        return boost::get<field_type>(field);
+    }
+
+    template<TrailerFieldType T>
+    const typename trailer_field_type<T>::type* trailer_field() const
+    {
+        using field_type = typename trailer_field_type<T>::type;
+        const TrailerField* field = trailer_field(T);
+        return boost::get<field_type>(field);
+    }
+};
+
+/**
+ * \brief Calculates size of a SecuredMessage object
+ * \return size_t containing the number of octets needed to serialize the object
+ */
+size_t get_size(const SecuredMessage&);
+
+/**
+ * \brief Serializes a SecuredMessage into a binary archive
+ */
+void serialize(OutputArchive& ar, const SecuredMessage& message);
+
+/**
+ * \brief Deserializes a SecuredMessage from a binary archive
+ * \return size of deserialized SecuredMessage
+ */
+size_t deserialize(InputArchive& ar, SecuredMessage& message);
+
+/**
+ * \brief Create ByteBuffer equivalent of SecuredMessage suitable for signature creation
+ *
+ * ByteBuffer contains message's version, header_fields and payload.
+ * Additionally, the length of trailer fields and the type of the signature is appended.
+ *
+ * \param message
+ * \param trailer_fields only trailer fields up to signature will be included in byte buffer
+ * \return serialized data fields relevant for signature creation
+ */
+ByteBuffer convert_for_signing(const SecuredMessage& message, const std::list<TrailerField>& trailer_fields);
+
+/**
+ * \brief Get ITS-AID from message
+ * \param msg secured message object
+ * \return found ITS-AID or 0
+ */
+ItsAid get_its_aid(const SecuredMessage& msg);
+
+} // namespace v2
+} // namespace security
+} // namespace vanetza
+
+#endif /* SECURED_MESSAGE_HPP_MO3HBSXG */