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/* Copyright 2015 OpenMarket Ltd
*
* 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.
*/
#include <cstddef>
#include <cstdint>
namespace axolotl {
/**
* The length of the buffer needed to hold a message.
*/
std::size_t encode_message_length(
std::uint32_t counter,
std::size_t ratchet_key_length,
std::size_t ciphertext_length,
std::size_t mac_length
);
struct MessageWriter {
std::uint8_t * ratchet_key;
std::uint8_t * ciphertext;
};
struct MessageReader {
std::uint8_t version;
std::uint32_t counter;
std::uint8_t const * input; std::size_t input_length;
std::uint8_t const * ratchet_key; std::size_t ratchet_key_length;
std::uint8_t const * ciphertext; std::size_t ciphertext_length;
};
/**
* Writes the message headers into the output buffer.
* Returns a writer struct populated with pointers into the output buffer.
*/
void encode_message(
MessageWriter & writer,
std::uint8_t version,
std::uint32_t counter,
std::size_t ratchet_key_length,
std::size_t ciphertext_length,
std::uint8_t * output
);
/**
* Reads the message headers from the input buffer.
* Populates the reader struct with pointers into the input buffer.
* On failure returns std::size_t(-1).
*/
std::size_t decode_message(
MessageReader & reader,
std::uint8_t const * input, std::size_t input_length,
std::size_t mac_length
);
} // namespace axolotl
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