host/commands/secure_env/tpm_random_source.h

//
// Copyright (C) 2020 The Android Open Source Project
//
// 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
//
//      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 <keymaster/random_source.h>

struct ESYS_CONTEXT;

/**
 * Secure random number generator, pulling data from a TPM.
 *
 * RandomSource is used by the OpenSSL HMAC key and AES key implementations.
 */
class TpmRandomSource : public keymaster::RandomSource {
public:
  TpmRandomSource(ESYS_CONTEXT* esys);
  virtual ~TpmRandomSource() = default;

  keymaster_error_t GenerateRandom(
      uint8_t* buffer, size_t length) const override;

  keymaster_error_t AddRngEntropy(const uint8_t*, size_t) const;
private:
  ESYS_CONTEXT* esys_;
};