olm/include/axolotl/axolotl.hh
2015-06-22 17:50:56 +01:00

292 lines
12 KiB
C++

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