util/crypto/rsa_private_key.h

// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UTIL_CRYPTO_RSA_PRIVATE_KEY_H_
#define UTIL_CRYPTO_RSA_PRIVATE_KEY_H_

#include <openssl/base.h>
#include <openssl/evp.h>
#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <vector>

#include "platform/base/error.h"
#include "platform/base/macros.h"

namespace openscreen {

// Encapsulates an RSA private key. Can be used to generate new keys, export
// keys to other formats, or to extract a public key.
class RSAPrivateKey {
 public:
  RSAPrivateKey(RSAPrivateKey&& other) noexcept = default;
  RSAPrivateKey& operator=(RSAPrivateKey&& other) = default;
  ~RSAPrivateKey();

  // Create a new random instance. Can return nullptr if initialization fails.
  static ErrorOr<RSAPrivateKey> Create(uint16_t num_bits);

  // Create a new instance by importing an existing private key. The format is
  // an ASN.1-encoded PrivateKeyInfo block from PKCS #8.
  static ErrorOr<RSAPrivateKey> CreateFromPrivateKeyInfo(
      const std::vector<uint8_t>& input);

  // Create a new instance from an existing EVP_PKEY, taking a
  // reference to it. |key| must be an RSA key.
  static ErrorOr<RSAPrivateKey> CreateFromKey(EVP_PKEY* key);

  // Creates a copy of the object.
  ErrorOr<RSAPrivateKey> Copy() const;

  EVP_PKEY* key() { return key_.get(); }
  const EVP_PKEY* key() const { return key_.get(); }

  // Exports the private key to a PKCS #8 PrivateKeyInfo block.
  ErrorOr<std::vector<uint8_t>> ExportPrivateKey() const;

  // Exports the public key to an X509 SubjectPublicKeyInfo block.
  ErrorOr<std::vector<uint8_t>> ExportPublicKey() const;

 private:
  // Constructor is private. Use one of the Create*() methods above instead.
  RSAPrivateKey();

  bssl::UniquePtr<EVP_PKEY> key_;

  OSP_DISALLOW_COPY_AND_ASSIGN(RSAPrivateKey);
};

}  // namespace openscreen

#endif  // UTIL_CRYPTO_RSA_PRIVATE_KEY_H_