assertion/assertion_referencer.cc

// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#include "assertion/assertion_referencer.h"

#include <memory>
#include <optional>

#include "absl/status/status.h"
#include "absl/status/status_macros.h"
#include "absl/status/statusor.h"
#include "absl/strings/cord.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"
#include "crypto/hash.h"
#include "jumbf/box_builder.h"
#include "jumbf/utils.h"
#include "proto/assertion.pb.h"
#include "proto/hashed_uri.pb.h"

namespace credentio {

absl::StatusOr<HashedUri> AssertionReferencer::Generate(
    const jumbf::BuiltSuperBox& assertion_box) const {
  if (!assertion_box.description_label().has_value()) {
    return absl::InvalidArgumentError(
        "the assertion box must have a description label");
  }
  HashedUri uri;
  uri.set_url(absl::StrCat("self#jumbf=c2pa.assertions/",
                           *assertion_box.description_label()));
  absl::Cord serialized_assertion = assertion_box.Peek();
  absl::string_view serialized_assertion_view = serialized_assertion.Flatten();
  ABSL_ASSIGN_OR_RETURN(auto hasher, hasher_factory_.Create());
  ABSL_ASSIGN_OR_RETURN(auto content,
                        jumbf::StripBoxHeaders(serialized_assertion_view));
  hasher->Update(content);
  uri.set_hash(hasher->Digest());
  return uri;
}

}  // namespace credentio