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/* Copyright 2016 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_INBOUND_GROUP_SESSION_H_
#define OLM_INBOUND_GROUP_SESSION_H_
#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef struct OlmInboundGroupSession OlmInboundGroupSession;
/** get the size of an inbound group session, in bytes. */
size_t olm_inbound_group_session_size();
/**
* Initialise an inbound group session object using the supplied memory
* The supplied memory should be at least olm_inbound_group_session_size()
* bytes.
*/
OlmInboundGroupSession * olm_inbound_group_session(
void *memory
);
/**
* A null terminated string describing the most recent error to happen to a
* group session */
const char *olm_inbound_group_session_last_error(
const OlmInboundGroupSession *session
);
/** Clears the memory used to back this group session */
size_t olm_clear_inbound_group_session(
OlmInboundGroupSession *session
);
/** Returns the number of bytes needed to store an inbound group session */
size_t olm_pickle_inbound_group_session_length(
const OlmInboundGroupSession *session
);
/**
* Stores a group session as a base64 string. Encrypts the session using the
* supplied key. Returns the length of the session on success.
*
* Returns olm_error() on failure. If the pickle output buffer
* is smaller than olm_pickle_inbound_group_session_length() then
* olm_inbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL"
*/
size_t olm_pickle_inbound_group_session(
OlmInboundGroupSession *session,
void const * key, size_t key_length,
void * pickled, size_t pickled_length
);
/**
* Loads a group session from a pickled base64 string. Decrypts the session
* using the supplied key.
*
* Returns olm_error() on failure. If the key doesn't match the one used to
* encrypt the account then olm_inbound_group_session_last_error() will be
* "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then
* olm_inbound_group_session_last_error() will be "INVALID_BASE64". The input
* pickled buffer is destroyed
*/
size_t olm_unpickle_inbound_group_session(
OlmInboundGroupSession *session,
void const * key, size_t key_length,
void * pickled, size_t pickled_length
);
/**
* Start a new inbound group session, based on the parameters supplied.
*
* Returns olm_error() on failure. On failure last_error will be set with an
* error code. The last_error will be:
*
* * OLM_INVALID_BASE64 if the session_key is not valid base64
* * OLM_BAD_RATCHET_KEY if the session_key is invalid
*/
size_t olm_init_inbound_group_session(
OlmInboundGroupSession *session,
uint32_t message_index,
/* base64-encoded key */
uint8_t const * session_key, size_t session_key_length
);
/**
* Get an upper bound on the number of bytes of plain-text the decrypt method
* will write for a given input message length. The actual size could be
* different due to padding.
*
* The input message buffer is destroyed.
*
* Returns olm_error() on failure.
*/
size_t olm_group_decrypt_max_plaintext_length(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length
);
/**
* Decrypt a message.
*
* The input message buffer is destroyed.
*
* Returns the length of the decrypted plain-text, or olm_error() on failure.
*
* On failure last_error will be set with an error code. The last_error will
* be:
* * OLM_OUTPUT_BUFFER_TOO_SMALL if the plain-text buffer is too small
* * OLM_INVALID_BASE64 if the message is not valid base-64
* * OLM_BAD_MESSAGE_VERSION if the message was encrypted with an unsupported
* version of the protocol
* * OLM_BAD_MESSAGE_FORMAT if the message headers could not be decoded
* * OLM_BAD_MESSAGE_MAC if the message could not be verified
* * OLM_BAD_CHAIN_INDEX if we do not have a ratchet key corresponding to the
* message's index (ie, it was sent before the ratchet key was shared with
* us)
*/
size_t olm_group_decrypt(
OlmInboundGroupSession *session,
/* input; note that it will be overwritten with the base64-decoded
message. */
uint8_t * message, size_t message_length,
/* output */
uint8_t * plaintext, size_t max_plaintext_length
);
#ifdef __cplusplus
} // extern "C"
#endif
#endif /* OLM_INBOUND_GROUP_SESSION_H_ */
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