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Validates using tmp_validation_status #269

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Dec 12, 2024
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Validates using tmp_validation_status #269

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75 changes: 42 additions & 33 deletions lib/src/signed_video_h26x_auth.c
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Original file line number Diff line number Diff line change
Expand Up @@ -207,7 +207,7 @@ prepare_for_link_and_gop_hash_verification(signed_video_t *self, h26x_nalu_list_
// Iterate through the NALU list until the end of the current GOP or SEI item is found.
while (item) {
// Skip non-pending items
if (item->validation_status != 'P') {
if (item->tmp_validation_status != 'P') {
item = item->next;
continue;
}
Expand Down Expand Up @@ -294,13 +294,13 @@ verify_hashes_with_hash_list(signed_video_t *self,
// is, the SEI NALU is invalid, all NALUs become invalid. Hence, verify_hashes_without_sei().
switch (self->gop_info->verified_signature_hash) {
case -1:
sei->validation_status = 'E';
sei->tmp_validation_status = 'E';
return verify_hashes_without_sei(self);
case 0:
sei->validation_status = 'N';
sei->tmp_validation_status = 'N';
return verify_hashes_without_sei(self);
case 1:
assert(sei->validation_status == 'P');
assert(sei->tmp_validation_status == 'P');
break;
default:
// We should not end up here.
Expand All @@ -325,7 +325,7 @@ verify_hashes_with_hash_list(signed_video_t *self,
// against the feasible hashes in the received |hash_list|.
while (item && !(found_next_gop || found_item_after_sei)) {
// If this item is not Pending or not part of the GOP hash, move to the next one.
if (item->validation_status != 'P' || !item->used_in_gop_hash) {
if (item->tmp_validation_status != 'P' || !item->used_in_gop_hash) {
DEBUG_LOG("Skipping non-pending NALU");
item = item->next;
continue;
Expand Down Expand Up @@ -354,8 +354,8 @@ verify_hashes_with_hash_list(signed_video_t *self,
uint8_t *expected_hash = &expected_hashes[compare_idx * hash_size];

if (memcmp(hash_to_verify, expected_hash, hash_size) == 0) {
// We have a match. Set validation_status and add missing nalus if we have detected any.
item->validation_status = order_ok ? '.' : 'N';
// We have a match. Set tmp_validation_status and add missing nalus if we have detected any.
item->tmp_validation_status = order_ok ? '.' : 'N';
// Add missing items to |nalu_list|.
int num_detected_missing_nalus =
(compare_idx - latest_match_idx) - 1 - num_invalid_nalus_since_latest_match;
Expand All @@ -381,7 +381,7 @@ verify_hashes_with_hash_list(signed_video_t *self,
// We have compared against all feasible hashes in |hash_list| without a match. Mark as NOT
// OK, or keep pending for second use.

item->validation_status = 'N';
item->tmp_validation_status = 'N';
// Update counters.
num_invalid_nalus_since_latest_match++;
}
Expand Down Expand Up @@ -419,15 +419,16 @@ verify_hashes_with_hash_list(signed_video_t *self,

// Done with the SEI. Mark as valid, because if we failed verifying the |document_hash| we would
// not be here.
sei->validation_status = '.';
sei->tmp_validation_status = '.';

if (num_expected_nalus) *num_expected_nalus = num_expected_hashes;
if (num_received_nalus) *num_received_nalus = num_verified_hashes;

return true;
}

/* Sets the |validation_status| of all items in |nalu_list| that are pending and |used_in_gop_hash|.
/* Sets the |tmp_validation_status| of all items in |nalu_list| that are pending and
* |used_in_gop_hash|.
*
* Returns the number of items marked and -1 upon failure. */
static int
Expand All @@ -440,23 +441,24 @@ set_validation_status_of_pending_items_used_in_gop_hash(signed_video_t *self,
h26x_nalu_list_t *nalu_list = self->nalu_list;
int num_marked_items = 0;

// Loop through the |nalu_list| and set the |validation_status| if the item is |used_in_gop_hash|
// Loop through the |nalu_list| and set the |tmp_validation_status| if the item is
// |used_in_gop_hash|
h26x_nalu_list_item_t *item = nalu_list->first_item;
while (item) {
if (item->used_in_gop_hash && item->validation_status == 'P') {
if (item->used_in_gop_hash && item->tmp_validation_status == 'P') {
if (!item->nalu->is_gop_sei) {
num_marked_items++;
}
item->validation_status = validation_status;
item->tmp_validation_status = validation_status;
}
item = item->next;
}
// Validates the SEI if the validation status has not been set previously. If the signature was
// corrupted, the validation status would already have been set. Otherwise, this indicates that
// the signature has been verified, confirming the SEI is valid.
if (sei->validation_status == 'P') {
if (sei->tmp_validation_status == 'P') {
assert(self->gop_info->verified_signature_hash == 1);
sei->validation_status = '.';
sei->tmp_validation_status = '.';
}
return num_marked_items;
}
Expand Down Expand Up @@ -508,11 +510,11 @@ verify_hashes_with_sei(signed_video_t *self, int *num_expected_nalus, int *num_r
}
} else if (self->gop_info->verified_signature_hash == 0) {
validation_status = 'N';
sei->validation_status = validation_status;
sei->tmp_validation_status = validation_status;
} else {
// An error occurred when verifying the GOP hash. Verify without a SEI.
validation_status = 'E';
sei->validation_status = validation_status;
sei->tmp_validation_status = validation_status;
// Remove |used_in_gop_hash| from marked NALUs.
remove_used_in_gop_hash(self->nalu_list);
return verify_hashes_without_sei(self);
Expand Down Expand Up @@ -541,8 +543,8 @@ verify_hashes_with_sei(signed_video_t *self, int *num_expected_nalus, int *num_r
}

/* Verifying hashes without the SEI means that we have nothing to verify against. Therefore, we mark
* all NALUs of the oldest pending GOP with |validation_status| = 'N'. This function is used both
* for unsigned videos as well as when the SEI has been modified or lost.
* all NALUs of the oldest pending GOP with |tmp_validation_status| = 'N'. This function is used
* both for unsigned videos as well as when the SEI has been modified or lost.
*
* Returns false if we failed verifying hashes, which happens if there is no list or if there are no
* pending NALUs. Otherwise, returns true. */
Expand All @@ -564,7 +566,7 @@ verify_hashes_without_sei(signed_video_t *self)
bool found_next_gop = false;
while (item && !found_next_gop) {
// Skip non-pending items.
if (item->validation_status != 'P') {
if (item->tmp_validation_status != 'P') {
item = item->next;
continue;
}
Expand All @@ -573,7 +575,7 @@ verify_hashes_without_sei(signed_video_t *self)
if (item->nalu->is_gop_sei) {
break;
}
item->validation_status = 'N';
item->tmp_validation_status = 'N';
num_marked_items++;

item = item->next;
Expand All @@ -591,7 +593,7 @@ verify_hashes_without_sei(signed_video_t *self)

/* Validates the authenticity using hashes in the |nalu_list|.
*
* In brief, the validation verifies hashes and sets the |validation_status| given the outcome.
* In brief, the validation verifies hashes and sets the |tmp_validation_status| given the outcome.
* Verifying a hash means comparing two and check if they are identical. There are three ways to
* verify hashes
* 1) verify_hashes_without_sei(): There is no SEI available, hence no expected hash to compare
Expand All @@ -606,8 +608,8 @@ verify_hashes_without_sei(signed_video_t *self)
* If we during verification detect missing NALUs, we add empty items (marked 'M') to the
* |nalu_list|.
*
* - After verification, hence the |validation_status| of each item in the list has been updated,
* statistics are collected from the list, using h26x_nalu_list_get_stats().
* - After verification, hence the |tmp_validation_status| of each item in the list has been
* updated, statistics are collected from the list, using h26x_nalu_list_get_stats().
* - Based on the statistics a validation decision can be made.
* - Update |latest_validation| with the validation result.
*/
Expand Down Expand Up @@ -855,7 +857,7 @@ is_recurrent_data_decoded(signed_video_t *self)
h26x_nalu_list_item_t *item = nalu_list->first_item;

while (item && !recurrent_data_decoded) {
if (item->nalu && item->nalu->is_gop_sei && item->validation_status == 'P') {
if (item->nalu && item->nalu->is_gop_sei && item->tmp_validation_status == 'P') {
const uint8_t *tlv_data = item->nalu->tlv_data;
size_t tlv_size = item->nalu->tlv_size;
recurrent_data_decoded = tlv_find_and_decode_optional_tags(self, tlv_data, tlv_size);
Expand Down Expand Up @@ -887,7 +889,7 @@ has_pending_gop(signed_video_t *self)
gop_state_update(gop_state, item->nalu);
// Collect statistics from pending and hashable NALUs only. The others are either out of date or
// not part of the validation.
if (item->validation_status == 'P' && item->nalu && item->nalu->is_hashable) {
if (item->tmp_validation_status == 'P' && item->nalu && item->nalu->is_hashable) {
num_pending_gop_ends += item->nalu->is_first_nalu_in_gop;
found_pending_gop_sei |= item->nalu->is_gop_sei;
found_pending_nalu_after_gop_sei |=
Expand Down Expand Up @@ -928,7 +930,7 @@ validation_is_feasible(const h26x_nalu_list_item_t *item)
// Validation for Golden SEIs are handled separately and therefore validation is not feasible.
if (item->nalu->is_golden_sei) return false;
if (!item->nalu->is_hashable) return false;
if (item->validation_status != 'P') return false;
if (item->tmp_validation_status != 'P') return false;
// Validation may be done upon a SEI.
if (item->nalu->is_gop_sei) return true;
// Validation may be done upon the end of a GOP.
Expand Down Expand Up @@ -961,25 +963,26 @@ maybe_validate_gop(signed_video_t *self, h26x_nalu_t *nalu)
if (!validation_feasible) {
// If this is the first arrived SEI, but could still not validate the authenticity, signal to
// the user that the Signed Video feature has been detected.
svrc_t status = SV_OK;
if (validation_flags->is_first_sei) {
// Check if the data is golden. If it is, update the validation status accordingly.
if (nalu->is_golden_sei) {
switch (self->gop_info->verified_signature_hash) {
case 1:
// Signature verified successfully.
nalu_list->last_item->validation_status = '.';
nalu_list->last_item->tmp_validation_status = '.';
latest->authenticity = SV_AUTH_RESULT_SIGNATURE_PRESENT;
break;
case 0:
// Signature verification failed.
nalu_list->last_item->validation_status = 'N';
nalu_list->last_item->tmp_validation_status = 'N';
latest->authenticity = SV_AUTH_RESULT_NOT_OK;
self->has_public_key = false;
break;
case -1:
default:
// Error occurred during verification; handle as an error.
nalu_list->last_item->validation_status = 'E';
nalu_list->last_item->tmp_validation_status = 'E';
latest->authenticity = SV_AUTH_RESULT_NOT_OK;
self->has_public_key = false;
}
Expand All @@ -990,9 +993,10 @@ maybe_validate_gop(signed_video_t *self, h26x_nalu_t *nalu)
latest->number_of_expected_picture_nalus = -1;
latest->number_of_received_picture_nalus = -1;
latest->number_of_pending_picture_nalus = h26x_nalu_list_num_pending_items(nalu_list);
status = h26x_nalu_list_update_status(nalu_list, true);
self->validation_flags.has_auth_result = true;
}
return SV_OK;
return status;
}

svrc_t status = SV_UNKNOWN_FAILURE;
Expand All @@ -1019,6 +1023,9 @@ maybe_validate_gop(signed_video_t *self, h26x_nalu_t *nalu)
validate_authenticity(self);
}

// Update |validation_status|.
SV_THROW(h26x_nalu_list_update_status(nalu_list, true));

// The flag |is_first_validation| is used to ignore the first validation if we start the
// validation in the middle of a stream. Now it is time to reset it.
validation_flags->is_first_validation = !validation_flags->signing_present;
Expand Down Expand Up @@ -1177,8 +1184,10 @@ signed_video_add_h26x_nalu(signed_video_t *self, const uint8_t *nalu_data, size_
h26x_nalu_list_copy_last_item(nalu_list, self->validation_flags.hash_algo_known);
// Make sure to return the first failure if both operations failed.
status = (status == SV_OK) ? copy_nalu_status : status;
if (status != SV_OK) nalu_list->last_item->validation_status = 'E';

if (status != SV_OK) {
nalu_list->last_item->validation_status = 'E';
nalu_list->last_item->tmp_validation_status = 'E';
}
free(nalu.nalu_data_wo_epb);

return status;
Expand Down
42 changes: 30 additions & 12 deletions lib/src/signed_video_h26x_nalu_list.c
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,7 @@ h26x_nalu_list_item_print(const h26x_nalu_list_item_t *item)
? "This NALU is missing"
: (item->nalu->is_gop_sei ? "SEI" : (item->nalu->is_first_nalu_in_gop ? "I" : "Other"));
char validation_status_str[2] = {'\0'};
memcpy(validation_status_str, &item->validation_status, 1);
memcpy(validation_status_str, &item->tmp_validation_status, 1);

printf("NALU type = %s\n", nalu_type_str);
printf("validation_status = %s%s%s%s\n", validation_status_str,
Expand Down Expand Up @@ -419,27 +419,27 @@ h26x_nalu_list_remove_missing_items(h26x_nalu_list_t *list)
while (item && !(found_first_pending_nalu && found_decoded_sei)) {
// Reset the invalid verification failure if we have not past the first pending item.
// Remove the missing NALU in the front.
if (item->validation_status == 'M' && (item == list->first_item)) {
if (item->tmp_validation_status == 'M' && (item == list->first_item)) {
const h26x_nalu_list_item_t *item_to_remove = item;
item = item->next;
h26x_nalu_list_remove_and_free_item(list, item_to_remove);
continue;
}
if (item->has_been_decoded && item->validation_status != 'U') {
if (item->has_been_decoded && item->tmp_validation_status != 'U') {
// Usually, these items were added because we verified hashes with a SEI not associated with
// this recording. This can happen if we export to file or fast forward in a recording. The
// SEI used to generate these missing items is set to 'U'.
item->validation_status = 'U';
item->tmp_validation_status = 'U';
found_decoded_sei = true;
}
// TODO: Resetting the item validation in the current GOP may affect the validation of the next
// GOP. This needs to be fixed.
if (item->validation_status == 'N') {
if (item->tmp_validation_status == 'N') {
// Reset validation status to 'P' for the next validation.
item->validation_status = 'P';
item->tmp_validation_status = 'P';
}
item = item->next;
if (item && item->validation_status == 'P') found_first_pending_nalu = true;
if (item && item->tmp_validation_status == 'P') found_first_pending_nalu = true;
}
}

Expand All @@ -451,7 +451,7 @@ h26x_nalu_list_get_next_sei_item(const h26x_nalu_list_t *list)

h26x_nalu_list_item_t *item = list->first_item;
while (item) {
if (item->nalu && item->nalu->is_gop_sei && item->validation_status == 'P') break;
if (item->nalu && item->nalu->is_gop_sei && item->tmp_validation_status == 'P') break;
item = item->next;
}
return item;
Expand Down Expand Up @@ -481,9 +481,10 @@ h26x_nalu_list_get_stats(const h26x_nalu_list_t *list,
item = item->next;
continue;
}
if (item->validation_status == 'M') local_num_missing_nalus++;
if (item->validation_status == 'N' || item->validation_status == 'E') local_num_invalid_nalus++;
if (item->validation_status == '.') {
if (item->tmp_validation_status == 'M') local_num_missing_nalus++;
if (item->tmp_validation_status == 'N' || item->tmp_validation_status == 'E')
local_num_invalid_nalus++;
if (item->tmp_validation_status == '.') {
// Do not count SEIs, since they are marked valid if the signature could be verified, which
// happens for out-of-sync SEIs for example.
has_valid_nalus |= !(item->nalu && item->nalu->is_gop_sei);
Expand All @@ -507,13 +508,30 @@ h26x_nalu_list_num_pending_items(const h26x_nalu_list_t *list)
int num_pending_nalus = 0;
h26x_nalu_list_item_t *item = list->first_item;
while (item) {
if (item->validation_status == 'P') num_pending_nalus++;
if (item->tmp_validation_status == 'P') num_pending_nalus++;
item = item->next;
}

return num_pending_nalus;
}

svrc_t
h26x_nalu_list_update_status(h26x_nalu_list_t *list, bool update)
{
if (!list) return SV_INVALID_PARAMETER;

h26x_nalu_list_item_t *item = list->first_item;
while (item) {
if (update) {
item->validation_status = item->tmp_validation_status;
} else {
item->tmp_validation_status = item->validation_status;
}
item = item->next;
}
return SV_OK;
}

/* Transforms all |validation_status| characters of the items in the |list| into a char string and
* returns that string if VALIDATION_STR is set. Transforms all |nalu_type| characters of the items
* in the |list| into a char string and returns that string if NALU_STR is set. */
Expand Down
16 changes: 14 additions & 2 deletions lib/src/signed_video_h26x_nalu_list.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,7 @@ h26x_nalu_list_copy_last_item(h26x_nalu_list_t* list, bool hash_algo_known);
* @brief Appends or prepends a certain item of a list with a new item marked as missing
*
* Searches through the |list| for the |item| and if found appends/prepends it with a new item that
* is marked as missing (|validation_status| = 'M'). The |nalu| of this missing item is a NULL
* is marked as missing (|tmp_validation_status| = 'M'). The |nalu| of this missing item is a NULL
* pointer.
*
* @param list The |list| including the |item|.
Expand Down Expand Up @@ -161,6 +161,18 @@ h26x_nalu_list_get_stats(const h26x_nalu_list_t* list,
int
h26x_nalu_list_num_pending_items(const h26x_nalu_list_t* list);

/**
* @brief Updates or resets validation status of all items in a list
*
* @param list The |list| to count pending items.
* @param update Updates |validation_status| with |tmp_validation_status| if 'true',
* otherwise resets |tmp_validation_status| with |validation_status|.
*
* @return An appropriate Signed Video Return Code.
*/
svrc_t
h26x_nalu_list_update_status(h26x_nalu_list_t* list, bool update);

/**
* @brief Returns a string with all authentication statuses of the items
*
Expand Down Expand Up @@ -195,7 +207,7 @@ h26x_nalu_list_clean_up(h26x_nalu_list_t* list);
/**
* @brief Prints all items in the list
*
* The |validation_status| as well as flags and hashes are printed for all items in the |list|.
* The |tmp_validation_status| as well as flags and hashes are printed for all items in the |list|.
*
* @param list The |list| to print items.
*/
Expand Down
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