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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.
*/
#ifndef OLM_SESSION_HH_
#define OLM_SESSION_HH_
#include "olm/ratchet.hh"
#define DESCRIBE_BUFFER_LEN 256
namespace olm {
struct Account;
enum struct MessageType {
PRE_KEY = 0,
MESSAGE = 1,
};
struct Session {
Session();
Ratchet ratchet;
OlmErrorCode last_error;
bool received_message;
char describe_buffer[DESCRIBE_BUFFER_LEN];
_olm_curve25519_public_key alice_identity_key;
_olm_curve25519_public_key alice_base_key;
_olm_curve25519_public_key bob_one_time_key;
/** The number of random bytes that are needed to create a new outbound
* session. This will be 64 bytes since two ephemeral keys are needed. */
std::size_t new_outbound_session_random_length();
/** Start a new outbound session. Returns std::size_t(-1) on failure. On
* failure last_error will be set with an error code. The last_error will be
* NOT_ENOUGH_RANDOM if the number of random bytes was too small. */
std::size_t new_outbound_session(
Account const & local_account,
_olm_curve25519_public_key const & identity_key,
_olm_curve25519_public_key const & one_time_key,
std::uint8_t const * random, std::size_t random_length
);
/** Start a new inbound session from a pre-key message.
* Returns std::size_t(-1) on failure. On failure last_error will be set
* with an error code. The last_error will be BAD_MESSAGE_FORMAT if
* the message headers could not be decoded. */
std::size_t new_inbound_session(
Account & local_account,
_olm_curve25519_public_key const * their_identity_key,
std::uint8_t const * pre_key_message, std::size_t message_length
);
/** The number of bytes written by session_id() */
std::size_t session_id_length();
/** An identifier for this session. Generated by hashing the public keys
* used to create the session. Returns the length of the session id on
* success or std::size_t(-1) on failure. On failure last_error will be set
* with an error code. The last_error will be OUTPUT_BUFFER_TOO_SMALL if
* the id buffer was too small. */
std::size_t session_id(
std::uint8_t * id, std::size_t id_length
);
/** True if this session can be used to decode an inbound pre-key message.
* This can be used to test whether a pre-key message should be decoded
* with an existing session or if a new session will need to be created.
* Returns true if the session is the same. Returns false if either the
* session does not match or the pre-key message could not be decoded.
*/
bool matches_inbound_session(
_olm_curve25519_public_key const * their_identity_key,
std::uint8_t const * pre_key_message, std::size_t message_length
);
/** Whether the next message will be a pre-key message or a normal message.
* An outbound session will send pre-key messages until it receives a
* message with a ratchet key. */
MessageType encrypt_message_type();
std::size_t encrypt_message_length(
std::size_t plaintext_length
);
/** The number of bytes of random data the encrypt method will need to
* encrypt a message. This will be 32 bytes if the session needs to
* generate a new ephemeral key, or will be 0 bytes otherwise. */
std::size_t encrypt_random_length();
/** Encrypt some plain-text. Returns the length of the encrypted message
* or std::size_t(-1) on failure. On failure last_error will be set with
* an error code. The last_error will be NOT_ENOUGH_RANDOM if the number
* of random bytes is too small. The last_error will be
* OUTPUT_BUFFER_TOO_SMALL if the output buffer is too small. */
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 * message, std::size_t message_length
);
/** An upper bound on the number of bytes of plain-text the decrypt method
* will write for a given input message length. */
std::size_t decrypt_max_plaintext_length(
MessageType message_type,
std::uint8_t const * message, std::size_t message_length
);
/** Decrypt a message. Returns the length of the decrypted plain-text or
* std::size_t(-1) on failure. On failure last_error will be set with an
* error code. The last_error will be OUTPUT_BUFFER_TOO_SMALL if the
* plain-text buffer is too small. The last_error will be
* BAD_MESSAGE_VERSION if the message was encrypted with an unsupported
* version of the protocol. The last_error will be BAD_MESSAGE_FORMAT if
* the message headers could not be decoded. The last_error will be
* BAD_MESSAGE_MAC if the message could not be verified */
std::size_t decrypt(
MessageType message_type,
std::uint8_t const * message, std::size_t message_length,
std::uint8_t * plaintext, std::size_t max_plaintext_length
);
/**
* Return a string describing this session and its state (not including the
* private key)
* The pointer returned refers to an internal buffer which will be valid
* up until the next time describe() is called.
*/
const char *describe();
};
std::size_t pickle_length(
Session const & value
);
std::uint8_t * pickle(
std::uint8_t * pos,
Session const & value
);
std::uint8_t const * unpickle(
std::uint8_t const * pos, std::uint8_t const * end,
Session & value
);
} // namespace olm
#endif /* OLM_SESSION_HH_ */
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