cpp/src/parquet/encryption/key_encryption_key.h

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
//
//   http://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.

#pragma once

#include <cstdint>
#include <vector>

#include "arrow/util/base64.h"
#include "arrow/util/secure_string.h"

namespace parquet::encryption {

// In the double wrapping mode, each "data encryption key" (DEK) is encrypted with a “key
// encryption key” (KEK), that in turn is encrypted with a "master encryption key" (MEK).
// In a writer process, a random KEK is generated for each MEK ID, and cached in a <MEK-ID
// : KEK> map. This allows to perform an interaction with a KMS server only once for each
// MEK, in order to wrap its KEK. "Data encryption key" (DEK) wrapping is performed
// locally, and does not involve an interaction with a KMS server.
class KeyEncryptionKey {
 public:
  KeyEncryptionKey(::arrow::util::SecureString kek_bytes, std::string kek_id,
                   std::string encoded_wrapped_kek)
      : kek_bytes_(std::move(kek_bytes)),
        kek_id_(std::move(kek_id)),
        encoded_kek_id_(::arrow::util::base64_encode(kek_id_)),
        encoded_wrapped_kek_(std::move(encoded_wrapped_kek)) {}

  const ::arrow::util::SecureString& kek_bytes() const { return kek_bytes_; }

  const std::string& kek_id() const { return kek_id_; }

  const std::string& encoded_kek_id() const { return encoded_kek_id_; }

  const std::string& encoded_wrapped_kek() const { return encoded_wrapped_kek_; }

 private:
  ::arrow::util::SecureString kek_bytes_;
  std::string kek_id_;
  std::string encoded_kek_id_;
  std::string encoded_wrapped_kek_;
};

}  // namespace parquet::encryption