assertion/assertion_referencer.h

// 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.
//

#ifndef THIRD_PARTY_CREDENTIO_ASSERTION_ASSERTION_REFERENCER_H_
#define THIRD_PARTY_CREDENTIO_ASSERTION_ASSERTION_REFERENCER_H_

#include "absl/log/die_if_null.h"
#include "absl/status/statusor.h"
#include "crypto/hash.h"
#include "jumbf/box_builder.h"
#include "proto/assertion.pb.h"
#include "proto/hashed_uri.pb.h"

namespace credentio {
// A utility class to create a hashed, JUMBF-type URI to an assertion.
// For more details, see
// https://spec.c2pa.org/specifications/specifications/2.4/specs/C2PA_Specification.html#_uri_references
// and
// https://spec.c2pa.org/specifications/specifications/2.4/specs/C2PA_Specification.html#_hashed_uris.
class AssertionReferencer {
 public:
  explicit AssertionReferencer(const HasherFactory* hasher)
      : hasher_factory_(*ABSL_DIE_IF_NULL(hasher)) {}

  // Generates a hashed URI for the given assertion. The URI is relative to the
  // including manifest (e.g., "self#jumbf=c2pa.assertions/c2pa.hash.bmff.v3").
  // The `algorithm` field field is omitted under the assumption that the
  // HasherFactory's algorithm will be specified as the default hash algorithm
  // in the Claim.
  absl::StatusOr<HashedUri> Generate(
      const jumbf::BuiltSuperBox& assertion) const;

 private:
  const HasherFactory& hasher_factory_;
};
}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_ASSERTION_ASSERTION_REFERENCER_H_