mirror of https://github.com/irungentoo/toxcore
318 lines
11 KiB
C
318 lines
11 KiB
C
/* toxencryptsave.h
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*
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* The Tox encrypted save functions.
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*
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* Copyright (C) 2013 Tox project All Rights Reserved.
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*
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* This file is part of Tox.
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*
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* Tox is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Tox is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Tox. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef TOXENCRYPTSAVE_H
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#define TOXENCRYPTSAVE_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdint.h>
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#include <stddef.h>
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#include <stdbool.h>
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#ifndef TOX_DEFINED
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#define TOX_DEFINED
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typedef struct Tox Tox;
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struct Tox_Options;
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#endif
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#define TOX_PASS_SALT_LENGTH 32
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#define TOX_PASS_KEY_LENGTH 32
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#define TOX_PASS_ENCRYPTION_EXTRA_LENGTH 80
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/**
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* ToxEncryptSave.
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*/
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#ifndef TOXES_DEFINED
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#define TOXES_DEFINED
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#endif /* TOXES_DEFINED */
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/*******************************************************************************
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*
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* :: API version
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*
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******************************************************************************/
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/**
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* The major version number. Incremented when the API or ABI changes in an
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* incompatible way.
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*/
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#define TOXES_VERSION_MAJOR 0u
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/**
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* The minor version number. Incremented when functionality is added without
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* breaking the API or ABI. Set to 0 when the major version number is
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* incremented.
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*/
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#define TOXES_VERSION_MINOR 0u
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/**
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* The patch or revision number. Incremented when bugfixes are applied without
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* changing any functionality or API or ABI.
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*/
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#define TOXES_VERSION_PATCH 0u
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/**
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* A macro to check at preprocessing time whether the client code is compatible
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* with the installed version of ToxAV.
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*/
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#define TOXES_VERSION_IS_API_COMPATIBLE(MAJOR, MINOR, PATCH) \
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(TOXES_VERSION_MAJOR == MAJOR && \
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(TOXES_VERSION_MINOR > MINOR || \
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(TOXES_VERSION_MINOR == MINOR && \
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TOXES_VERSION_PATCH >= PATCH)))
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/**
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* A macro to make compilation fail if the client code is not compatible with
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* the installed version of ToxAV.
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*/
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#define TOXES_VERSION_REQUIRE(MAJOR, MINOR, PATCH) \
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typedef char toxes_required_version[TOXES_IS_COMPATIBLE(MAJOR, MINOR, PATCH) ? 1 : -1]
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/**
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* A convenience macro to call toxES_version_is_compatible with the currently
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* compiling API version.
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*/
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#define TOXES_VERSION_IS_ABI_COMPATIBLE() \
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toxes_version_is_compatible(TOXES_VERSION_MAJOR, TOXES_VERSION_MINOR, TOXES_VERSION_PATCH)
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/**
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* Return the major version number of the library. Can be used to display the
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* ToxAV library version or to check whether the client is compatible with the
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* dynamically linked version of ToxAV.
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*/
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uint32_t toxes_version_major(void);
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/**
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* Return the minor version number of the library.
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*/
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uint32_t toxes_version_minor(void);
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/**
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* Return the patch number of the library.
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*/
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uint32_t toxes_version_patch(void);
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/**
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* Return whether the compiled library version is compatible with the passed
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* version numbers.
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*/
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bool toxes_version_is_compatible(uint32_t major, uint32_t minor, uint32_t patch);
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/* This module is conceptually organized into two parts. The first part are the functions
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* with "key" in the name. To use these functions, first derive an encryption key
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* from a password with tox_derive_key_from_pass, and use the returned key to
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* encrypt the data. The second part takes the password itself instead of the key,
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* and then delegates to the first part to derive the key before de/encryption,
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* which can simplify client code; however, key derivation is very expensive
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* compared to the actual encryption, so clients that do a lot of encryption should
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* favor using the first part intead of the second part.
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*
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* The encrypted data is prepended with a magic number, to aid validity checking
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* (no guarantees are made of course). Any data to be decrypted must start with
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* the magic number.
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*
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* Clients should consider alerting their users that, unlike plain data, if even one bit
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* becomes corrupted, the data will be entirely unrecoverable.
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* Ditto if they forget their password, there is no way to recover the data.
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*/
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/* Since apparently no one actually bothered to learn about the module previously,
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* the recently removed functions tox_encrypted_new and tox_get_encrypted_savedata
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* may be trivially replaced by calls to tox_pass_decrypt -> tox_new or
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* tox_get_savedata -> tox_pass_encrypt as appropriate. The removed functions
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* were never more than 5 line wrappers of the other public API functions anyways.
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* (As has always been, tox_pass_decrypt and tox_pass_encrypt are interchangeable
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* with tox_pass_key_decrypt and tox_pass_key_encrypt, as the client program requires.)
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*/
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typedef enum TOX_ERR_KEY_DERIVATION {
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TOX_ERR_KEY_DERIVATION_OK,
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/**
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* Some input data, or maybe the output pointer, was null.
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*/
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TOX_ERR_KEY_DERIVATION_NULL,
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/**
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* The crypto lib was unable to derive a key from the given passphrase,
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* which is usually a lack of memory issue. The functions accepting keys
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* do not produce this error.
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*/
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TOX_ERR_KEY_DERIVATION_FAILED
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} TOX_ERR_KEY_DERIVATION;
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typedef enum TOX_ERR_ENCRYPTION {
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TOX_ERR_ENCRYPTION_OK,
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/**
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* Some input data, or maybe the output pointer, was null.
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*/
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TOX_ERR_ENCRYPTION_NULL,
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/**
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* The crypto lib was unable to derive a key from the given passphrase,
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* which is usually a lack of memory issue. The functions accepting keys
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* do not produce this error.
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*/
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TOX_ERR_ENCRYPTION_KEY_DERIVATION_FAILED,
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/**
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* The encryption itself failed.
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*/
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TOX_ERR_ENCRYPTION_FAILED
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} TOX_ERR_ENCRYPTION;
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typedef enum TOX_ERR_DECRYPTION {
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TOX_ERR_DECRYPTION_OK,
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/**
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* Some input data, or maybe the output pointer, was null.
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*/
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TOX_ERR_DECRYPTION_NULL,
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/**
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* The input data was shorter than TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes
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*/
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TOX_ERR_DECRYPTION_INVALID_LENGTH,
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/**
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* The input data is missing the magic number (i.e. wasn't created by this
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* module, or is corrupted)
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*/
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TOX_ERR_DECRYPTION_BAD_FORMAT,
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/**
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* The crypto lib was unable to derive a key from the given passphrase,
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* which is usually a lack of memory issue. The functions accepting keys
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* do not produce this error.
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*/
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TOX_ERR_DECRYPTION_KEY_DERIVATION_FAILED,
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/**
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* The encrypted byte array could not be decrypted. Either the data was
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* corrupt or the password/key was incorrect.
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*/
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TOX_ERR_DECRYPTION_FAILED
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} TOX_ERR_DECRYPTION;
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/******************************* BEGIN PART 2 *******************************
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* For simplicty, the second part of the module is presented first. The API for
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* the first part is analgous, with some extra functions for key handling. If
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* your code spends too much time using these functions, consider using the part
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* 1 functions instead.
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*/
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/* Encrypts the given data with the given passphrase. The output array must be
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* at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
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* to tox_derive_key_from_pass and tox_pass_key_encrypt.
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*
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* returns true on success
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*/
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bool tox_pass_encrypt(const uint8_t *data, size_t data_len, const uint8_t *passphrase, size_t pplength, uint8_t *out,
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TOX_ERR_ENCRYPTION *error);
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/* Decrypts the given data with the given passphrase. The output array must be
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* at least data_len - TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long. This delegates
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* to tox_pass_key_decrypt.
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*
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* the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
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*
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* returns true on success
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*/
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bool tox_pass_decrypt(const uint8_t *data, size_t length, const uint8_t *passphrase, size_t pplength, uint8_t *out,
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TOX_ERR_DECRYPTION *error);
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/******************************* BEGIN PART 1 *******************************
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* And now part "1", which does the actual encryption, and is rather less cpu
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* intensive than part one. The first 3 functions are for key handling.
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*/
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/* This key structure's internals should not be used by any client program, even
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* if they are straightforward here.
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*/
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typedef struct {
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uint8_t salt[TOX_PASS_SALT_LENGTH];
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uint8_t key[TOX_PASS_KEY_LENGTH];
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} TOX_PASS_KEY;
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/* Generates a secret symmetric key from the given passphrase. out_key must be at least
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* TOX_PASS_KEY_LENGTH bytes long.
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* Be sure to not compromise the key! Only keep it in memory, do not write to disk.
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* The password is zeroed after key derivation.
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* The key should only be used with the other functions in this module, as it
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* includes a salt.
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* Note that this function is not deterministic; to derive the same key from a
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* password, you also must know the random salt that was used. See below.
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*
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* returns true on success
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*/
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bool tox_derive_key_from_pass(const uint8_t *passphrase, size_t pplength, TOX_PASS_KEY *out_key,
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TOX_ERR_KEY_DERIVATION *error);
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/* Same as above, except use the given salt for deterministic key derivation.
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* The salt must be TOX_PASS_SALT_LENGTH bytes in length.
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*/
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bool tox_derive_key_with_salt(const uint8_t *passphrase, size_t pplength, const uint8_t *salt, TOX_PASS_KEY *out_key,
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TOX_ERR_KEY_DERIVATION *error);
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/* This retrieves the salt used to encrypt the given data, which can then be passed to
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* derive_key_with_salt to produce the same key as was previously used. Any encrpyted
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* data with this module can be used as input.
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*
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* returns true if magic number matches
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* success does not say anything about the validity of the data, only that data of
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* the appropriate size was copied
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*/
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bool tox_get_salt(const uint8_t *data, uint8_t *salt);
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/* Now come the functions that are analogous to the part 2 functions. */
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/* Encrypt arbitrary with a key produced by tox_derive_key_*. The output
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* array must be at least data_len + TOX_PASS_ENCRYPTION_EXTRA_LENGTH bytes long.
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* key must be TOX_PASS_KEY_LENGTH bytes.
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* If you already have a symmetric key from somewhere besides this module, simply
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* call encrypt_data_symmetric in toxcore/crypto_core directly.
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*
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* returns true on success
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*/
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bool tox_pass_key_encrypt(const uint8_t *data, size_t data_len, const TOX_PASS_KEY *key, uint8_t *out,
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TOX_ERR_ENCRYPTION *error);
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/* This is the inverse of tox_pass_key_encrypt, also using only keys produced by
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* tox_derive_key_from_pass.
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*
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* the output data has size data_length - TOX_PASS_ENCRYPTION_EXTRA_LENGTH
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*
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* returns true on success
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*/
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bool tox_pass_key_decrypt(const uint8_t *data, size_t length, const TOX_PASS_KEY *key, uint8_t *out,
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TOX_ERR_DECRYPTION *error);
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/* Determines whether or not the given data is encrypted (by checking the magic number)
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*/
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bool tox_is_data_encrypted(const uint8_t *data);
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#ifdef __cplusplus
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}
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#endif
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#endif
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