292 lines
12 KiB
C++
292 lines
12 KiB
C++
/* Copyright 2015 OpenMarket Ltd
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef AXOLOTL_HH_
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#define AXOLOTL_HH_
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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static const size_t AXOLOTL_MESSAGE_TYPE_PRE_KEY = 0;
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static const size_t AXOLOTL_MESSAGE_TYPE_MESSAGE = 1;
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struct AxolotlAccount;
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struct AxolotlSession;
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/** The size of an account object in bytes */
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size_t axolotl_account_size();
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/** The size of a session object in bytes */
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size_t axolotl_session_size();
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/** Initialise an account object using the supplied memory
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* The supplied memory must be at least axolotl_account_size() bytes */
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AxolotlAccount * axolotl_account(
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void * memory
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);
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/** Initialise a session object using the supplied memory
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* The supplied memory must be at least axolotl_session_size() bytes */
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AxolotlSession * axolotl_session(
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void * memory
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);
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/** The value that axolotl will return from a function if there was an error */
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size_t axolotl_error();
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/** A null terminated string describing the most recent error to happen to an
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* account */
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const char * axolotl_account_last_error(
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AxolotlSession * account
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);
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/** A null terminated string describing the most recent error to happen to a
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* session */
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const char * axolotl_session_last_error(
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AxolotlSession * session
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);
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/** Returns the number of bytes needed to store an account */
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size_t axolotl_pickle_account_length(
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AxolotlAccount * account
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);
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/** Returns the number of bytes needed to store a session */
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size_t axolotl_pickle_session_length(
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AxolotlSession * session
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);
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/** Stores an account as a base64 string. Encrypts the account using the
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* supplied key. Returns the length of the pickled account on success.
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* Returns axolotl_error() on failure. If the pickle output buffer
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* is smaller than axolotl_pickle_account_length() then
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* axolotl_account_last_error() will be "OUTPUT_BUFFER_TOO_SMALL" */
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size_t axolotl_pickle_account(
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AxolotlAccount * account,
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void const * key, size_t key_length,
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void * pickled, size_t pickled_length
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);
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/** Stores a session as a base64 string. Encrypts the session using the
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* supplied key. Returns the length of the pickled session on success.
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* Returns axolotl_error() on failure. If the pickle output buffer
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* is smaller than axolotl_pickle_session_length() then
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* axolotl_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL" */
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size_t axolotl_pickle_session(
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AxolotlSession * session,
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void const * key, size_t key_length,
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void * pickled, size_t pickled_length
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);
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/** Loads an account from a pickled base64 string. Decrypts the account using
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* the supplied key. Returns axolotl_error() on failure. If the key doesn't
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* match the one used to encrypt the account then axolotl_account_last_error()
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* will be "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then
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* axolotl_account_last_error() will be "INVALID_BASE64". */
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size_t axolotl_unpickle_account(
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AxolotlAccount * account,
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void const * key, size_t key_length,
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void * pickled, size_t pickled_length
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);
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/** Loads a session from a pickled base64 string. Decrypts the session using
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* the supplied key. Returns axolotl_error() on failure. If the key doesn't
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* match the one used to encrypt the account then axolotl_session_last_error()
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* will be "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then
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* axolotl_session_last_error() will be "INVALID_BASE64". */
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size_t axolotl_unpickle_session(
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AxolotlSession * session,
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void const * key, size_t key_length,
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void * pickled, size_t pickled_length
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);
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/** The number of random bytes needed to create an account.*/
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size_t axolotl_create_account_random_length(
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AxolotlAccount * account
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);
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/** Creates a new account. Returns axolotl_error() on failure. If weren't
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* enough random bytes then axolotl_account_last_error() will be
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* "NOT_ENOUGH_RANDOM" */
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size_t axolotl_create_account(
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AxolotlAccount * account,
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void const * random, size_t random_length
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);
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/** The size of the output buffer needed to hold the identity keys */
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size_t axolotl_account_identity_keys_length(
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AxolotlAccount * account
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);
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/** Writes the public parts of the identity keys for the account into the
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* identity_keys output buffer. The output is formatted as though it was
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* created with sprintf(output, "[[%10d,\"%43s\"]\n]", key_id, key_base64).
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* The output can either be parsed as fixed width using the above format or by
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* a JSON parser. Returns axolotl_error() on failure. If the identity_keys
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* buffer was too small then axolotl_account_last_error() will be
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* "OUTPUT_BUFFER_TOO_SMALL". */
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size_t axolotl_account_identity_keys(
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AxolotlAccount * account,
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void * identity_keys, size_t identity_key_length
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);
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/** The size of the output buffer needed to hold the one time keys */
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size_t axolotl_account_one_time_keys_length(
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AxolotlAccount * account
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);
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/** Writes the public parts of the one time keys for the account into the
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* one_time_keys output buffer. The first key will be formatted as though it was
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* created with sprintf(output, "[[%10d,\"%43s\"]\n", key_id, key_base64).
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* subsequent keys are formatted with ",[%10d,\"%43s\"]\n". The final byte of
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* output will be "]". The output can either be parsed as fixed width using
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* the above format or by a JSON parser. Returns axolotl_error() on failure.
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* If the one_time_keys buffer was too small then axolotl_account_last_error()
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* will be "OUTPUT_BUFFER_TOO_SMALL". */
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size_t axolotl_account_one_time_keys(
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AxolotlAccount * account,
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void * one_time_keys, size_t one_time_keys_length
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);
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/* TODO: Add methods for marking keys as used, generating new keys, and
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* tracking which keys have been uploaded to the central servers */
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/** The number of random bytes needed to create an outbound session */
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size_t axolotl_create_outbound_session_random_length(
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AxolotlSession * session
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);
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/** Creates a new out-bound session for sending messages to a given identity_key
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* and one_time_key. Returns axolotl_error() on failure. If the keys couldn't be
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* decoded as base64 then axolotl_session_last_error() will be "INVALID_BASE64"
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* If there weren't enough random bytes then axolotl_session_last_error() will
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* be "NOT_ENOUGH_RANDOM". */
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size_t axolotl_create_outbound_session(
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AxolotlSession * session,
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AxolotlAccount * account,
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void const * their_identity_key, size_t their_identity_key_length,
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unsigned their_one_time_key_id,
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void const * their_one_time_key, size_t their_one_time_key_length,
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void const * random, size_t random_length
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);
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/** Create a new in-bound session for sending/receiving messages from an
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* incoming PRE_KEY message. Returns axolotl_error() on failure. If the base64
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* couldn't be decoded then axolotl_session_last_error will be "INVALID_BASE64".
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* If the message was for an unsupported protocol version then
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* axolotl_session_last_error() will be "BAD_MESSAGE_VERSION". If the message
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* couldn't be decoded then then axolotl_session_last_error() will be
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* "BAD_MESSAGE_FORMAT". If the message refers to an unknown one time
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* key then axolotl_session_last_error() will be "BAD_MESSAGE_KEY_ID". */
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size_t axolotl_create_inbound_session(
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AxolotlSession * session,
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AxolotlAccount * account,
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void * one_time_key_message, size_t message_length
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);
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/** Checks if the PRE_KEY message is for this in-bound session. This can happen
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* if multiple messages are sent to this account before this account sends a
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* message in reply. Returns axolotl_error() on failure. If the base64
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* couldn't be decoded then axolotl_session_last_error will be "INVALID_BASE64".
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* If the message was for an unsupported protocol version then
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* axolotl_session_last_error() will be "BAD_MESSAGE_VERSION". If the message
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* couldn't be decoded then then axolotl_session_last_error() will be
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* "BAD_MESSAGE_FORMAT". */
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size_t axolotl_matches_inbound_session(
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AxolotlSession * session,
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void * one_time_key_message, size_t message_length
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);
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/** Removes the one time keys that the session used from the account. Returns
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* axolotl_error() on failure. If the account doesn't have any matching one time
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* keys then axolotl_account_last_error() will be "BAD_MESSAGE_KEY_ID". */
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size_t axolotl_remove_one_time_keys(
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AxolotlAccount * account,
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AxolotlSession * session
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);
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/** The type of the next message that axolotl_encrypt() will return. Returns
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* AXOLOTL_MESSAGE_TYPE_PRE_KEY if the message will be a PRE_KEY message.
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* Returns AXOLOTL_MESSAGE_TYPE_MESSAGE if the message will be a normal message.
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* Returns axolotl_error on failure. */
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size_t axolotl_encrypt_message_type(
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AxolotlSession * session
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);
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/** The number of random bytes needed to encrypt the next message. */
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size_t axolotl_encrypt_random_length(
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AxolotlSession * session
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);
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/** The size of the next message in bytes for the given number of plain-text
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* bytes. */
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size_t axolotl_encrypt_message_length(
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AxolotlSession * session,
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size_t plaintext_length
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);
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/** Encrypts a message using the session. Returns the length of the message in
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* bytes on success. Writes the message as base64 into the message buffer.
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* Returns axolotl_error() on failure. If the message buffer is too small then
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* axolotl_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL". If there
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* weren't enough random bytes then axolotl_session_last_error() will be
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* "NOT_ENOUGH_RANDOM". */
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size_t axolotl_encrypt(
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AxolotlSession * session,
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void const * plaintext, size_t plaintext_length,
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void const * random, size_t random_length,
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void * message, size_t message_length
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);
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/** The maximum number of bytes of plain-text a given message could decode to.
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* The actual size could be different due to padding. Returns axolotl_error()
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* on failures. If the message base64 couldn't be decoded then
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* axolotl_session_last_error() will be "INVALID_BASE64". If the message
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* is for an unsupported version of the protocol then
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* axolotl_session_last_error() will be "BAD_MESSAGE_VERSION". If the message
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* couldn't be decoded then axolotl_session_last_error() will be
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* "BAD_MESSAGE_FORMAT". */
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size_t axolotl_decrypt_max_plaintext_length(
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AxolotlSession * session,
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size_t message_type,
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void * message, size_t message_length
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);
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/** Decrypts a message using the session. Returns the length of the plain-text
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* on success. Returns axolotl_error() on failure. If the plain-text buffer
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* is smaller than axolotl_decrypt_max_plaintext_length() then
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* axolotl_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL". If the
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* base64 couldn't be decoded then axolotl_session_last_error() will be
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* "INVALID_BASE64". If the message is for an unsupported version of the
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* protocol then axolotl_session_last_error() will be "BAD_MESSAGE_VERSION".
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* If the message couldn't be decoded then axolotl_session_last_error() will be
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* "BAD_MESSAGE_FORMAT". If the MAC on the message was invalid then
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* axolotl_session_last_error() will be "BAD_MESSAGE_MAC". */
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size_t axolotl_decrypt(
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AxolotlSession * session,
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size_t message_type,
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void * message, size_t message_length,
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void * plaintext, size_t max_plaintext_length
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);
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#ifdef __cplusplus
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}
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#endif
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#endif /* AXOLOTL_HH_ */
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