The first_validation is updated to rely on sei_in_sync (#496)

Special operations on the first validation is taken if the
SEI is not in sync. All validation has to be rewinded if so.
So far this decision has been made based on the validation
results. Now it is based on wether the SEI is in sync or
not.

Co-authored-by: bjornvolcker <[email protected]>

Author: bjornvolcker

lib/src/sv_auth.c

@@ -784,29 +784,14 @@ validate_authenticity(signed_video_t *self, bu_list_item_t *sei)
     }
   }
 
-  // If we lose an entire GOP (part from the associated SEI) it will be seen as valid. Here we fix
-  // it afterwards.
-  // TODO: Move this inside the verify_hashes_ functions. We should not need to perform any special
-  // actions on the output.
-  // TODO: Investigate if this part is actually needed.
-  // if (!validation_flags->is_first_validation) {
-  //   if ((valid == SV_AUTH_RESULT_OK) && (num_expected > 1) && (num_missed >= num_expected)) {
-  //     valid = SV_AUTH_RESULT_NOT_OK;
-  //   }
-  // }
   // The very first validation needs to be handled separately. If this is truly the start of a
   // stream we have all necessary information to successfully validate the authenticity. It can be
   // interpreted as being in sync with its signing counterpart. If this session validates the
   // authenticity of a segment of a stream, e.g., an exported file, we start out of sync. The first
   // SEI may be associated with a GOP prior to this segment.
-  if (validation_flags->is_first_validation) {
-    // Change status from SV_AUTH_RESULT_OK to SV_AUTH_RESULT_SIGNATURE_PRESENT if no valid BUs
-    // were found when collecting stats.
-    if ((valid == SV_AUTH_RESULT_OK) && !has_valid_bu && (sei && sei->bu->is_signed)) {
-      valid = SV_AUTH_RESULT_SIGNATURE_PRESENT;
-    }
+  if (validation_flags->is_first_validation && !validation_flags->sei_in_sync) {
     // If validation was successful, the |current_partial_gop| is in sync.
-    if (valid != SV_AUTH_RESULT_OK) {
+    if (valid != SV_AUTH_RESULT_OK && !has_valid_bu) {
       // We have validated the authenticity based on one single BU, but failed. A success can only
       // happen if we are at the beginning of the original stream. For all other cases, for example,
       // if we validate the authenticity of an exported file, the first SEI may be associated with a
@@ -821,7 +806,7 @@ validate_authenticity(signed_video_t *self, bu_list_item_t *sei)
       num_received = -1;
       // If no valid Bitstream Units were found, reset validation to be able to make more
       // attepts to synchronize the SEIs.
-      validation_flags->reset_first_validation = !has_valid_bu;
+      validation_flags->reset_first_validation = true;
     }
   }
   if (latest->public_key_has_changed) valid = SV_AUTH_RESULT_NOT_OK;
@@ -869,7 +854,7 @@ remove_sei_association(bu_list_t *bu_list, const bu_list_item_t *sei)
   bu_list_item_t *item = bu_list->first_item;
   while (item) {
     if (sei && item->associated_sei == sei) {
-      if (item->validation_status == 'M') {
+      if (item->tmp_validation_status == 'M') {
         const bu_list_item_t *item_to_remove = item;
         item = item->next;
         bu_list_remove_and_free_item(bu_list, item_to_remove);
@@ -1200,8 +1185,7 @@ maybe_validate_gop(signed_video_t *self, bu_info_t *bu)
     while (has_pending_partial_gop(self) && !stop_validating && max_loop > 0) {
       bu_list_item_t *sei = NULL;
       // Initialize latest validation if not validating intermediate GOPs.
-      if (!validation_flags->waiting_for_signature &&
-          (!validation_flags->has_auth_result || validation_flags->is_first_validation)) {
+      if (!validation_flags->waiting_for_signature && !validation_flags->has_auth_result) {
         latest->authenticity = SV_AUTH_RESULT_SIGNATURE_PRESENT;
         latest->number_of_expected_picture_nalus = 0;
         latest->number_of_received_picture_nalus = 0;
@@ -1223,7 +1207,7 @@ maybe_validate_gop(signed_video_t *self, bu_info_t *bu)
         validate_authenticity(self, sei);
       }
 
-      if (validation_flags->is_first_validation && (latest->authenticity != SV_AUTH_RESULT_OK)) {
+      if (validation_flags->is_first_validation && !validation_flags->sei_in_sync) {
         // Fetch the |tmp_validation_status| for later use.
         update_sei_in_validation(self, false, &sei_validation_status, NULL);
       }

tests/check/check_signed_video_auth.c

@@ -510,12 +510,8 @@ START_TEST(modify_one_p_frame)
   //             ISP                         P.P     (invalid, 3 pending)
   signed_video_accumulated_validation_t final_validation = {
       SV_AUTH_RESULT_NOT_OK, false, 15, 12, 3, SV_PUBKEY_VALIDATION_NOT_FEASIBLE, true, 0, 0};
-  struct validation_stats expected = {.valid_gops = 0,  // 2,
-      .valid_gops_with_missing_info = 1,  // 0,
-      .invalid_gops = 2,  // 1,
-      .pending_bu = 2,  // 3,
-      .missed_bu = 1,  // 0,
-      .final_validation = &final_validation};
+  struct validation_stats expected = {
+      .valid_gops = 2, .invalid_gops = 1, .pending_bu = 3, .final_validation = &final_validation};
   if (settings[_i].auth_level == SV_AUTHENTICITY_LEVEL_GOP) {
     // When in low bitrate mode the first validation fails and it is not possible to
     // know if it is due to a modified BU (SEI is in sync), or if the SEI is out of sync
@@ -2084,9 +2080,7 @@ START_TEST(no_public_key_in_sei_and_bad_public_key_on_validation_side)
   ck_assert_int_eq(sv_rc, SV_OK);
   ck_assert(auth_report);
 
-  // TODO: This test is correct but currently one SEI is not enough. The state "signature
-  // present" will be used until the bug is fixed.
-  ck_assert_int_eq(auth_report->latest_validation.authenticity, SV_AUTH_RESULT_SIGNATURE_PRESENT);
+  ck_assert_int_eq(auth_report->latest_validation.authenticity, SV_AUTH_RESULT_NOT_OK);
 
   signed_video_authenticity_report_free(auth_report);
   // Free bu_list_item and session.