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// Copyright 2017 Google Inc.
//
// 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 TINK_SUBTLE_HKDF_H_
#define TINK_SUBTLE_HKDF_H_
#include "absl/strings/string_view.h"
#include "tink/subtle/common_enums.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace subtle {
class Hkdf {
public:
// Computes hkdf according to RFC5869.
static crypto::tink::util::StatusOr<std::string> ComputeHkdf(
HashType hash,
absl::string_view ikm,
absl::string_view salt,
absl::string_view info,
size_t out_len);
// Computes symmetric key for ECIES with HKDF from the provided parameters.
// This function follows Shoup's recommendation of including ECIES
// ephemeral KEM bytes into the commputation of the symmetric key
// (cf. http://eprint.iacr.org/2001/112.pdf, Sections 15.6 and 15.6.1)
static crypto::tink::util::StatusOr<std::string> ComputeEciesHkdfSymmetricKey(
HashType hash,
absl::string_view kem_bytes,
absl::string_view shared_secret,
absl::string_view salt,
absl::string_view info,
size_t out_len);
};
} // namespace subtle
} // namespace tink
} // namespace crypto
#endif // TINK_SUBTLE_HKDF_H_