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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 "axolotl/crypto.hh"
#include "axolotl/list.hh"
namespace axolotl {
typedef std::uint8_t SharedKey[32];
struct ChainKey {
std::uint32_t index;
SharedKey key;
};
struct MessageKey {
std::uint32_t index;
Aes256Key cipher_key;
SharedKey mac_key;
Aes256Iv iv;
};
struct SenderChain {
Curve25519KeyPair ratchet_key;
ChainKey chain_key;
};
struct ReceiverChain {
Curve25519PublicKey ratchet_key;
ChainKey chain_key;
};
struct SkippedMessageKey {
Curve25519PublicKey ratchet_key;
MessageKey message_key;
};
enum struct ErrorCode {
SUCCESS = 0, /*!< There wasn't an error */
NOT_ENOUGH_RANDOM = 1, /*!< Not enough entropy was supplied */
OUTPUT_BUFFER_TOO_SMALL = 2, /*!< Supplied output buffer is too small */
BAD_MESSAGE_VERSION = 3, /*!< The message version is unsupported */
BAD_MESSAGE_FORMAT = 4, /*!< The message couldn't be decoded */
BAD_MESSAGE_MAC = 5, /*!< The message couldn't be decrypted */
};
static std::size_t const MAX_RECEIVER_CHAINS = 5;
static std::size_t const MAX_SKIPPED_MESSAGE_KEYS = 40;
struct KdfInfo {
std::uint8_t const * root_info;
std::size_t root_info_length;
std::uint8_t const * ratchet_info;
std::size_t ratchet_info_length;
std::uint8_t const * message_info;
std::size_t message_info_length;
};
struct Session {
Session(
KdfInfo const & kdf_info
);
/** A pair of string to feed into the KDF identifing the application */
KdfInfo kdf_info;
/** The last error that happened encypting or decrypting a message */
ErrorCode last_error;
SharedKey root_key;
List<SenderChain, 1> sender_chain;
List<ReceiverChain, MAX_RECEIVER_CHAINS> receiver_chains;
List<SkippedMessageKey, MAX_SKIPPED_MESSAGE_KEYS> skipped_message_keys;
void initialise_as_bob(
std::uint8_t const * shared_secret, std::size_t shared_secret_length,
Curve25519PublicKey const & their_ratchet_key
);
void initialise_as_alice(
std::uint8_t const * shared_secret, std::size_t shared_secret_length,
Curve25519KeyPair const & our_ratchet_key
);
std::size_t encrypt_max_output_length(
std::size_t plaintext_length
);
std::size_t encrypt_random_length();
std::size_t encrypt(
std::uint8_t const * plaintext, std::size_t plaintext_length,
std::uint8_t const * random, std::size_t random_length,
std::uint8_t * output, std::size_t max_output_length
);
std::size_t decrypt_max_plaintext_length(
std::size_t input_length
);
std::size_t decrypt(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * plaintext, std::size_t max_plaintext_length
);
};
} // namespace axololt
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