hkdf.h

/*
 * Copyright 2015 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.
 */

#ifndef SYSTEM_KEYMASTER_HKDF_H_
#define SYSTEM_KEYMASTER_HKDF_H_

#include "kdf.h"

#include <keymaster/serializable.h>

#include <keymaster/UniquePtr.h>

namespace keymaster {

/**
 * Rfc5869Sha256Kdf implements the key derivation function specified in RFC 5869 (using SHA256) and
 * outputs key material, as needed by ECIES. See https://tools.ietf.org/html/rfc5869 for details.
 */
class Rfc5869Sha256Kdf : public Kdf {
  public:
    ~Rfc5869Sha256Kdf() {}
    bool Init(Buffer& secret, Buffer& salt) {
        return Init(secret.peek_read(), secret.available_read(), salt.peek_read(),
                    salt.available_read());
    }

    bool Init(const uint8_t* secret, size_t secret_len, const uint8_t* salt, size_t salt_len) {
        return Kdf::Init(KM_DIGEST_SHA_2_256, secret, secret_len, salt, salt_len);
    }

    bool GenerateKey(const uint8_t* info, size_t info_len, uint8_t* output,
                     size_t output_len) override;
};

}  // namespace keymaster

#endif  // SYSTEM_KEYMASTER_HKDF_H_