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/pki/ea_request.cpp

@@ -0,0 +1,119 @@
+#include "ea_request.hpp"
+#include "asn1.hpp"
+#include "certificate.hpp"
+#include "encrypted_data.hpp"
+#include "exception.hpp"
+#include "psid_ssp.hpp"
+#include "security_module.hpp"
+#include "signed_builder.hpp"
+#include "signed_data.hpp"
+#include <vanetza/asn1/security/InnerEcRequest.h>
+#include <vanetza/common/its_aid.hpp>
+#include <stdexcept>
+
+namespace vanetza
+{
+namespace pki
+{
+
+namespace
+{
+
+class InnerEcRequest : public asn1::asn1c_oer_wrapper<Vanetza_Security_InnerEcRequest_t>
+{
+public:
+    using wrapper = asn1::asn1c_oer_wrapper<Vanetza_Security_InnerEcRequest_t>;
+
+    InnerEcRequest() : wrapper(asn_DEF_Vanetza_Security_InnerEcRequest)
+    {
+        m_struct->certificateFormat = Vanetza_Security_CertificateFormat_ts103097v131;
+    }
+
+    void set_its_id(const std::string& id)
+    {
+        if (OCTET_STRING_fromBuf(&m_struct->itsId, id.data(), id.size()) != 0) {
+            throw std::runtime_error("setting ITS ID failed");
+        }
+    }
+
+    void set_verification_key(const PublicKey& pubkey)
+    {
+        pki::set_verification_key(m_struct->publicKeys.verificationKey, pubkey);
+    }
+
+    void add_permission(const PsidSsp& perm)
+    {
+        if (m_struct->requestedSubjectAttributes.appPermissions == nullptr) {
+            m_struct->requestedSubjectAttributes.appPermissions =
+                asn1::allocate<Vanetza_Security_SequenceOfPsidSsp_t>();
+        }
+
+        auto psid_ssp = asn1::allocate<Vanetza_Security_PsidSsp_t>();
+        psid_ssp->psid = perm.psid;
+        if (!perm.ssp.empty()) {
+            psid_ssp->ssp = asn1::allocate<Vanetza_Security_ServiceSpecificPermissions_t>();
+            psid_ssp->ssp->present = Vanetza_Security_ServiceSpecificPermissions_PR_bitmapSsp;
+            copy(perm.ssp, psid_ssp->ssp->choice.bitmapSsp);
+        }
+
+        auto* perms = m_struct->requestedSubjectAttributes.appPermissions;
+        if (asn_sequence_add(perms, psid_ssp) != 0) {
+            throw std::runtime_error("adding app permission to InnerEcRequest failed");
+        }
+    }
+};
+
+} // namespace
+
+ByteBuffer build_signed_enrolment_request(SecurityModule& security, const EnrolmentRequestParameters& params)
+{
+    if (params.its_id.empty()) {
+        throw std::invalid_argument("EnrolmentRequest: its_id must not be empty");
+    }
+
+    // 1. InnerEcRequest
+    InnerEcRequest inner;
+    inner.set_its_id(params.its_id);
+    inner.set_verification_key(params.verification_key);
+    inner.add_permission(PsidSsp { aid::SCR, { 0x01, 0xC0 } });
+    if (!inner.validate()) {
+        throw std::runtime_error("EnrolmentRequest: constructed InnerEcRequest is invalid");
+    }
+
+    // 2. InnerEcRequestSignedForPop wrapped in EtsiTs102941Data
+    MgmtData pop_data;
+    pop_data->version = Vanetza_Security_Version_v1;
+    pop_data->content.present = Vanetza_Security_EtsiTs102941DataContent_PR_enrolmentRequest;
+    // Inner PoP is always signer = self (TS 102 941 §6.2.3.2.1)
+    create_signed(inner.encode(), security, params.verification_key, params.hash_algo, nullptr)
+        .move_into(pop_data->content.choice.enrolmentRequest);
+
+    // 3. Outer EtsiTs103097Data-Signed: signer = self for initial enrolment or
+    //    signer = digest(outer_signer_certificate) for a re-keying renewal.
+    SignedData outer = create_signed(pop_data.encode(), security, params.outer_signer_key, params.hash_algo,
+        params.outer_signer_certificate);
+    return outer.encode();
+}
+
+EncryptedData build_enrolment_request(SecurityModule& security, const EnrolmentRequestParameters& params,
+    const Certificate& ea_certificate)
+{
+    boost::optional<PublicKey> ea_enckey = ea_certificate.get_encryption_key();
+    if (!ea_enckey) {
+        throw DecodingFailure("EnrolmentRequest: EA certificate has no encryption key");
+    }
+
+    ByteBuffer signed_request = build_signed_enrolment_request(security, params);
+
+    Sha256Hash ea_cert_sha256 = calculate_sha256_hash(security, ea_certificate);
+    auto ecies_unique = security.create_ecies_context(*ea_enckey, ea_cert_sha256);
+    std::shared_ptr<SecurityModule::EciesContext> ecies { std::move(ecies_unique) };
+    EncryptedData encrypted { ecies };
+    encrypted.generate_ciphertext(signed_request);
+    encrypted.add_recipient_info(ea_certificate.calculate_hashed_id8(security));
+
+    return encrypted;
+}
+
+} // namespace pki
+} // namespace vanetza