components/webauthn/android/fido2api_native_android.cc

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <jni.h>

#include <cstdint>
#include <optional>
#include <utility>
#include <vector>

#include "base/android/jni_array.h"
#include "base/android/scoped_java_ref.h"
#include "device/fido/attestation_object.h"

// Must come after all headers that specialize FromJniType() / ToJniType().
#include "components/webauthn/android/jni_headers/Fido2Api_jni.h"

using base::android::JavaByteArrayToByteVector;
using base::android::JavaParamRef;
using base::android::ScopedJavaLocalRef;
using base::android::ToJavaByteArray;

namespace webauthn {

// Parses a CTAP2 attestation[1] and extracts the
// parts that the browser provides via Javascript API [2]. Called
// Fido2Api.java when constructing the makeCredential reply.
//
// [1] https://www.w3.org/TR/webauthn/#attestation-object
// [2] https://w3c.github.io/webauthn/#sctn-public-key-easy
static jboolean JNI_Fido2Api_ParseAttestationObject(
    JNIEnv* env,
    const base::android::JavaParamRef<jbyteArray>& jattestation_object_bytes,
    const base::android::JavaParamRef<jobject>& out_result) {
  std::vector<uint8_t> attestation_object_bytes;
  JavaByteArrayToByteVector(env, jattestation_object_bytes,
                            &attestation_object_bytes);
  std::optional<device::AttestationObject::ResponseFields> fields =
      device::AttestationObject::ParseForResponseFields(
          std::move(attestation_object_bytes), /*attestation_acceptable=*/true);
  if (!fields) {
    return false;
  }

  ScopedJavaLocalRef<jbyteArray> spki_java;
  if (fields->public_key_der) {
    spki_java.Reset(ToJavaByteArray(env, *fields->public_key_der));
  }

  Java_AttestationObjectParts_setAll(
      env, out_result, ToJavaByteArray(env, fields->authenticator_data),
      spki_java, fields->public_key_algo,
      ToJavaByteArray(env, fields->attestation_object_bytes));

  return true;
}

}  // namespace webauthn