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/tools/certify/commands/extract-public-key.cpp

@@ -0,0 +1,85 @@
+#include "extract-public-key.hpp"
+#include <boost/program_options.hpp>
+#include <iostream>
+#include <stdexcept>
+#include <vanetza/security/backend.hpp>
+#include <vanetza/security/v2/basic_elements.hpp>
+#include <vanetza/security/v2/persistence.hpp>
+
+namespace po = boost::program_options;
+using namespace vanetza::security;
+
+bool ExtractPublicKeyCommand::parse(const std::vector<std::string>& opts)
+{
+    po::options_description desc("Available options");
+    desc.add_options()
+        ("help", "Print out available options.")
+        ("output", po::value<std::string>(&output)->required(), "Output file.")
+        ("certificate", po::value<std::string>(&certificate_path), "Certificate file to extract public key from.")
+        ("private-key", po::value<std::string>(&private_key_path), "Private key file to extract public key from.")
+    ;
+
+    po::positional_options_description pos;
+    pos.add("output", 1);
+
+    po::variables_map vm;
+    po::store(po::command_line_parser(opts).options(desc).positional(pos).run(), vm);
+
+    if (vm.count("help")) {
+        std::cerr << desc << std::endl;
+
+        return false;
+    }
+
+    try {
+        po::notify(vm);
+
+        if (!(vm.count("certificate") ^ vm.count("private-key"))) {
+            std::cerr << "Error: One of certificate / private-key parameters must be present." << std::endl;
+
+            return false;
+        }
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << std::endl << std::endl << desc << std::endl;
+
+        return false;
+    }
+
+    return true;
+}
+
+int ExtractPublicKeyCommand::execute()
+{
+    std::cout << "Loading key... ";
+
+    std::unique_ptr<Backend> backend = create_backend("default");
+    ecdsa256::PublicKey public_key;
+    if (certificate_path.length() > 0) {
+        auto certificate = v2::load_certificate_from_file(certificate_path);
+        auto certificate_key = get_public_key(certificate, *backend);
+
+        if (!certificate_key) {
+            std::cerr << "Reading public key from certificate failed." << std::endl;
+        }
+
+        public_key = *certificate_key;
+    } else {
+        auto private_key = v2::load_private_key_from_file(private_key_path);
+        public_key = private_key.public_key;
+    }
+
+    std::cout << "OK" << std::endl;
+
+    Uncompressed coordinates;
+    coordinates.x.assign(public_key.x.begin(), public_key.x.end());
+    coordinates.y.assign(public_key.y.begin(), public_key.y.end());
+
+    v2::ecdsa_nistp256_with_sha256 public_key_etsi;
+    public_key_etsi.public_key = coordinates;
+
+    std::cout << "Writing public key to '" << output << "'... ";
+    v2::save_public_key_to_file(output, public_key_etsi);
+    std::cout << "OK" << std::endl;
+
+    return 0;
+}