lime_ffi.h File Reference

This header exports lime's functionality via a C89 interface. More...

Go to the source code of this file.

Classes
struct	lime_ffi_RecipientData_t
	The encrypt function input/output data structure. More...

Typedefs
typedef struct lime_manager_struct *	lime_manager_t
typedef struct lime_ffi_data_struct *	lime_ffi_data_t
typedef void(*	lime_ffi_Callback) (void *userData, const enum lime_ffi_CallbackReturn status, const char *message)
	Callback use to give a status on asynchronous operation. More...
typedef void(*	lime_ffi_X3DHServerPostData) (void *userData, lime_ffi_data_t limeData, const char *url, const char *from, const uint8_t *message, const size_t message_size)
	Post a message to the X3DH server. More...

Enumerations
enum	LIME_FFI_ERROR {   LIME_FFI_SUCCESS = 0, LIME_FFI_INVALID_CURVE_ARGUMENT = -1, LIME_FFI_INTERNAL_ERROR = -2, LIME_FFI_OUTPUT_BUFFER_TOO_SMALL = -3,   LIME_FFI_USER_NOT_FOUND = -4 }
enum	lime_ffi_CurveId { lime_ffi_CurveId_unset = 0, lime_ffi_CurveId_c25519 = 1, lime_ffi_CurveId_c448 = 2 }
enum	lime_ffi_EncryptionPolicy { lime_ffi_EncryptionPolicy_DRMessage, lime_ffi_EncryptionPolicy_cipherMessage, lime_ffi_EncryptionPolicy_optimizeUploadSize, lime_ffi_EncryptionPolicy_optimizeGlobalBandwidth }
enum	lime_ffi_PeerDeviceStatus {   lime_ffi_PeerDeviceStatus_untrusted =0, lime_ffi_PeerDeviceStatus_trusted =1, lime_ffi_PeerDeviceStatus_unsafe =2, lime_ffi_PeerDeviceStatus_fail,   lime_ffi_PeerDeviceStatus_unknown }
enum	lime_ffi_CallbackReturn { lime_ffi_CallbackReturn_success, lime_ffi_CallbackReturn_fail }

Functions
int	lime_ffi_processX3DHServerResponse (lime_ffi_data_t limeData, const int code, const uint8_t *response, const size_t response_size)
	Forward X3DH server response to the lime engine. More...
int	lime_ffi_manager_init (lime_manager_t *const manager, const char *db, const lime_ffi_X3DHServerPostData X3DH_post_data, void *userData)
	Initialise a Lime Manager, only one per end-point is required. More...
int	lime_ffi_manager_destroy (lime_manager_t manager)
	Destroy the internal structure used to interact with lime. More...
int	lime_ffi_create_user (lime_manager_t manager, const char *localDeviceId, const char *x3dhServerUrl, const enum lime_ffi_CurveId curve, const uint16_t OPkInitialBatchSize, const lime_ffi_Callback callback, void *callbackUserData)
	Insert a lime user in local base and publish him on the X3DH server. More...
int	lime_ffi_delete_user (lime_manager_t manager, const char *localDeviceId, const lime_ffi_Callback callback, void *callbackUserData)
	Delete a user from local database and from the X3DH server. More...
int	lime_ffi_is_user (lime_manager_t manager, const char *localDeviceId)
	Check if a user is present and active in local storage. More...
int	lime_ffi_encryptOutBuffersMaximumSize (const size_t plainMessageSize, const enum lime_ffi_CurveId curve, size_t *DRmessageSize, size_t *cipherMessageSize)
	Compute the maximum buffer sizes for the encryption outputs: DRmessage and cipherMessage. More...
int	lime_ffi_encrypt (lime_manager_t manager, const char *localDeviceId, const char *recipientUserId, lime_ffi_RecipientData_t *const recipients, const size_t recipientsSize, const uint8_t *const plainMessage, const size_t plainMessageSize, uint8_t *const cipherMessage, size_t *cipherMessageSize, const lime_ffi_Callback callback, void *callbackUserData, enum lime_ffi_EncryptionPolicy encryptionPolicy)
	Encrypt a buffer (text or file) for a given list of recipient devices. More...
enum lime_ffi_PeerDeviceStatus	lime_ffi_decrypt (lime_manager_t manager, const char *localDeviceId, const char *recipientUserId, const char *senderDeviceId, const uint8_t *const DRmessage, const size_t DRmessageSize, const uint8_t *const cipherMessage, const size_t cipherMessageSize, uint8_t *const plainMessage, size_t *plainMessageSize)
	Decrypt the given message. More...
int	lime_ffi_get_selfIdentityKey (lime_manager_t manager, const char *localDeviceId, uint8_t *const Ik, size_t *IkSize)
	retrieve self Identity Key, an EdDSA formatted public key More...
int	lime_ffi_set_peerDeviceStatus (lime_manager_t manager, const char *peerDeviceId, const uint8_t *const Ik, const size_t IkSize, enum lime_ffi_PeerDeviceStatus status)
	set the peer device status flag in local storage: unsafe, trusted or untrusted. More...
enum lime_ffi_PeerDeviceStatus	lime_ffi_get_peerDeviceStatus (lime_manager_t manager, const char *peerDeviceId)
	get the status of a peer device: unknown, untrusted, trusted, unsafe More...
int	lime_ffi_delete_peerDevice (lime_manager_t manager, const char *peerDeviceId)
	delete a peerDevice from local storage More...
int	lime_ffi_stale_sessions (lime_manager_t manager, const char *localDeviceId, const char *peerDeviceId)
	Stale all sessions between localDeviceId and peerDevice. If peerDevice keep using this session to encrypt and we decrypt with success, the session will be reactivated but to encrypt a message to this peerDevice, a new session will be created. If no session is active between the given device, this call has no effect. More...
int	lime_ffi_update (lime_manager_t manager, const lime_ffi_Callback callback, void *callbackUserData, uint16_t OPkServerLowLimit, uint16_t OPkBatchSize)
	Update: shall be called once a day at least, performs checks, updates and cleaning operations. More...
int	lime_ffi_set_x3dhServerUrl (lime_manager_t manager, const char *localDeviceId, const char *x3dhServerUrl)
	Set the X3DH key server URL for this identified user. More...
int	lime_ffi_get_x3dhServerUrl (lime_manager_t manager, const char *localDeviceId, char *x3dhServerUrl, size_t *x3dhServerUrlSize)
	Get the X3DH key server URL for this identified user. More...

Detailed Description

This header exports lime's functionality via a C89 interface.

General rules of this API to make life easier to anyone trying to use it from another langage:

• all interaction are done via pointer to opaque structure
• use only simple types:
  • size_t for all buffer or array size
  • const char * NULL terminated strings
  • uint8_t * for binary buffers
• no ownership of memory transfers across the API boundary.
  The API read data from const pointers and write output to buffers allocated by the caller.
• when exporting a binary blob, the function takes a pointer to the output buffer and a read/write pointer to the length.
  If the size of the provided buffer is insufficient, an error is returned.

Warning

Check carefully the lime_ffi_decrypt function's documentation as an output buffer too small on this one mean you would loose your decrypted message forever.

Author

Johan Pascal

Copyright

Copyright (C) 2018 Belledonne Communications SARL

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Typedef Documentation

lime_ffi_Callback

typedef void(* lime_ffi_Callback) (void *userData, const enum lime_ffi_CallbackReturn status, const char *message)

Callback use to give a status on asynchronous operation.

it returns a code and may return a string (could actually be empty) to detail what's happening callback is used on every operation possibly involving a connection to X3DH server: create_user, delete_user, encrypt and update

Parameters

[in]	userData	pointer to user defined data structure passed back to him
[in]	status	success or fail
[in]	message	in case of failure, an explanation, it may be empty

lime_ffi_data_t

typedef struct lime_ffi_data_struct* lime_ffi_data_t

lime_ffi_X3DHServerPostData

typedef void(* lime_ffi_X3DHServerPostData) (void *userData, lime_ffi_data_t limeData, const char *url, const char *from, const uint8_t *message, const size_t message_size)

Post a message to the X3DH server.

this function prototype is used to post data to the X3DH server The response must be sent back to the lime engine using the lime_ffi_processX3DHServerResponse function

Parameters

[in]	userData	pointer given when registering the callback
[in]	limeData	pointer to an opaque lime internal structure that must then be forwarded with the server response
[in]	url	X3DH server's URL
[in]	from	User identification on X3DH server (which shall challenge for password digest, this is not however part of lime)
[in]	message	The message to post to the X3DH server

lime_manager_t

typedef struct lime_manager_struct* lime_manager_t

Enumeration Type Documentation

lime_ffi_CallbackReturn

enum lime_ffi_CallbackReturn

what a Lime callback could possibly say

Enumerator
lime_ffi_CallbackReturn_success	operation completed successfully
lime_ffi_CallbackReturn_fail	operation failed, we shall have an explanation string too

lime_ffi_CurveId

enum lime_ffi_CurveId

Identifies the elliptic curve used in lime, the values assigned are used in localStorage and X3DH server so do not modify it or we'll loose sync with existing DB and X3DH server

Enumerator
lime_ffi_CurveId_unset	used as default to detected incorrect behavior
lime_ffi_CurveId_c25519	Curve 25519
lime_ffi_CurveId_c448	Curve 448-goldilocks

lime_ffi_EncryptionPolicy

enum lime_ffi_EncryptionPolicy

Manage the encryption policy : how is the user's plaintext encrypted

Enumerator
lime_ffi_EncryptionPolicy_DRMessage	the plaintext input is encrypted inside the Double Ratchet message (each recipient get a different encryption): not optimal for messages with numerous recipient
lime_ffi_EncryptionPolicy_cipherMessage	the plaintext input is encrypted with a random key and this random key is encrypted to each participant inside the Double Ratchet message(for a single recipient the overhead is 48 bytes)
lime_ffi_EncryptionPolicy_optimizeUploadSize	optimize upload size: encrypt in DR message if plaintext is short enougth to beat the overhead introduced by cipher message scheme, otherwise use cipher message. Selection is made on upload size only. This is the default policy used
lime_ffi_EncryptionPolicy_optimizeGlobalBandwidth	optimize bandwith usage: encrypt in DR message if plaintext is short enougth to beat the overhead introduced by cipher message scheme, otherwise use cipher message. Selection is made on uploadand download (from server to recipients) sizes added.

LIME_FFI_ERROR

enum LIME_FFI_ERROR

Enumerator
LIME_FFI_SUCCESS
LIME_FFI_INVALID_CURVE_ARGUMENT
LIME_FFI_INTERNAL_ERROR
LIME_FFI_OUTPUT_BUFFER_TOO_SMALL
LIME_FFI_USER_NOT_FOUND

lime_ffi_PeerDeviceStatus

enum lime_ffi_PeerDeviceStatus

A peer device status returned after encrypt, decrypt or when directly asking for the peer device status to spot new devices and give information on our trust on this device The values explicitely mapped to specific integers(untrusted, trusted, unsafe) are stored in local storage as integer Do not modify the mapping or we will loose backward compatibility with existing databases

Enumerator
lime_ffi_PeerDeviceStatus_untrusted	we know this device but do not trust it, that information shall be displayed to the end user, a colour code shall be enough
lime_ffi_PeerDeviceStatus_trusted	this peer device already got its public identity key validated, that information shall be displayed to the end user too
lime_ffi_PeerDeviceStatus_unsafe	this status is a helper for the library user. It is used only by the peerDeviceStatus accessor functions
lime_ffi_PeerDeviceStatus_fail	when returned by decrypt : we could not decrypt the incoming message when returned by encrypt in the peerStatus: we could not encrypt to this recipient(probably because it does not published keys on the X3DH server)
lime_ffi_PeerDeviceStatus_unknown	when returned after encryption or decryption, means it is the first time we communicate with this device (and thus create a DR session with it) when returned by a get_peerDeviceStatus: this device is not in localStorage

Function Documentation

lime_ffi_create_user()

int lime_ffi_create_user	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const char *	x3dhServerUrl,
		const enum lime_ffi_CurveId	curve,
		const uint16_t	OPkInitialBatchSize,
		const lime_ffi_Callback	callback,
		void *	callbackUserData
	)

Insert a lime user in local base and publish him on the X3DH server.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	Identify the local user acount to use, it must be unique and is also be used as Id on the X3DH key server, it shall be the GRUU
[in]	x3dhServerUrl	The complete url(including port) of the X3DH key server. It must connect using HTTPS. Example: https://sip5.linphone.org:25519
[in]	curve	Choice of elliptic curve to use as base for ECDH and EdDSA operation involved. Can be lime_ffi_CurveId_c25519 or lime_ffi_CurveId_c448.
[in]	OPkInitialBatchSize	Number of OPks in the first batch uploaded to X3DH server
[in]	callback	This operation contact the X3DH server and is thus asynchronous, when server responds, this callback will be called giving the exit status and an error message in case of failure
[in]	callbackUserData	this pointer will be forwarded to the callback as first parameter

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_decrypt()

enum lime_ffi_PeerDeviceStatus lime_ffi_decrypt	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const char *	recipientUserId,
		const char *	senderDeviceId,
		const uint8_t *const	DRmessage,
		const size_t	DRmessageSize,
		const uint8_t *const	cipherMessage,
		const size_t	cipherMessageSize,
		uint8_t *const	plainMessage,
		size_t *	plainMessageSize
	)

Decrypt the given message.

if specified localDeviceId is not found in local Storage, return an error

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	used to identify which local acount to use and also as the recipient device ID of the message, shall be the GRUU
[in]	recipientUserId	the Id of intended recipient, shall be a sip:uri of user or conference, is used as associated data to ensure no-one can mess with intended recipient it is not necessarily the sip:uri base of the GRUU as this could be a message from alice first device intended to bob being decrypted on alice second device
[in]	senderDeviceId	Identify sender Device. This field shall be extracted from signaling data in transport protocol, is used to rebuild the authenticated data associated to the encrypted message
[in]	DRmessage	Double Ratchet message targeted to current device
[in]	DRmessageSize	DRmessage buffer size
[in]	cipherMessage	when present (depends on encryption policy) holds a common part of the encrypted message. Set to NULL if not present in the incoming message.
[in]	cipherMessageSize	cipherMessage buffer size(set to 0 if no cipherMessage is present in the incoming message)
[out]	plainMessage	the output buffer: its size shall be MAX(cipherMessageSize, DRmessageSize)
[in,out]	plainMessageSize	plainMessage buffer size, updated with the actual size of the data written

Warning

The plainMessage buffer must be large enough to store the decrypted message or we face the possibility to not ever be able to decrypt the message.(internal successful decryption will remove the ability to decrypt the same message again). To avoid problem the size of the plain message shall be MAX(cipherMessageSize, DRmessageSize) as:

• The decrypted message is the same size of the encrypted one.
• The encrypted message(not alone but we can afford the temporary usage of few dozens bytes) is stored either in cipherMessage or DRmessage depends on encrypter's choice
• By allocating MAX(cipherMessageSize, DRmessageSize) bytes to the plainMessage buffer we ensure it can hold the decrypted message

Returns

fail if we cannot decrypt the message, unknown when it is the first message we ever receive from the sender device, untrusted for known but untrusted sender device, or trusted if it is

lime_ffi_delete_peerDevice()

int lime_ffi_delete_peerDevice	(	lime_manager_t	manager,
		const char *	peerDeviceId
	)

delete a peerDevice from local storage

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	peerDeviceId	The device Id to be removed from local storage, shall be its GRUU

Call is silently ignored if the device is not found in local storage

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_delete_user()

int lime_ffi_delete_user	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const lime_ffi_Callback	callback,
		void *	callbackUserData
	)

Delete a user from local database and from the X3DH server.

if specified localDeviceId is not found in local Storage, return an error

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	Identify the local user acount to use, it must be unique and is also be used as Id on the X3DH key server, it shall be the GRUU
[in]	callback	This operation contact the X3DH server and is thus asynchronous, when server responds, this callback will be called giving the exit status and an error message in case of failure
[in]	callbackUserData	this pointer will be forwarded to the callback as first parameter

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_encrypt()

int lime_ffi_encrypt	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const char *	recipientUserId,
		lime_ffi_RecipientData_t *const	recipients,
		const size_t	recipientsSize,
		const uint8_t *const	plainMessage,
		const size_t	plainMessageSize,
		uint8_t *const	cipherMessage,
		size_t *	cipherMessageSize,
		const lime_ffi_Callback	callback,
		void *	callbackUserData,
		enum lime_ffi_EncryptionPolicy	encryptionPolicy
	)

Encrypt a buffer (text or file) for a given list of recipient devices.

if specified localDeviceId is not found in local Storage, return an error

Clarification on recipients:

recipients information needed are a list of the device Id and one userId. The device Id shall be their GRUU while the userId is a sip:uri.

recipient User Id is used to identify the actual intended recipient. Example: alice have two devices and is signed up on a conference having
bob and claire as other members. The recipientUserId will be the conference sip:uri and device list will include:
     - alice other device
     - bob devices
     - claire devices
If Alice write to Bob only, the recipientUserId will be bob sip:uri and recipient devices list :
     - alice other device
     - bob devices

In all cases, the identified source of the message will be the localDeviceId

If the X3DH server can't provide keys for a peer device, its status is set to fail and its DRmessageSize is 0. Other devices get their encrypted message
If no peer device could get encrypted for all of them are missing keys on the X3DH server, the callback will be called with fail exit status

Note

all buffers are allocated by caller. If a buffer is too small to get the data, the function will return an error.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	used to identify which local acount to use and also as the identified source of the message, shall be the GRUU
[in]	recipientUserId	the Id of intended recipient, shall be a sip:uri of user or conference, is used as associated data to ensure no-one can mess with intended recipient
[in,out]	recipients	a list of RecipientData holding: the recipient device Id(GRUU) an allocated buffer large enough to store the DRmessage which must then be routed to that recipient the size of this buffer, updated with the actual size written in it when the operation is completed(after callbackStatus is executed) the peer Status. If peerStatus is set to fail, this entry is ignored otherwise the peerStatus is set by the encrypt, see lime_ffi_PeerDeviceStatus definition for details
[in]	recipientsSize	how many recipients are in the recipients array
[in]	plainMessage	a buffer holding the message to encrypt, can be text or data.
[in]	plainMessageSize	size of the plainMessage buffer
[out]	cipherMessage	points to the buffer to store the encrypted message which must be routed to all recipients(if one is produced, depends on encryption policy)
[in,out]	cipherMessageSize	size of the cipherMessage buffer, is updated with the size of the actual data written in it
[in]	callback	Performing encryption may involve the X3DH server and is thus asynchronous, when the operation is completed, this callback will be called giving the exit status and an error message in case of failure.
[in]	callbackUserData	this pointer will be forwarded to the callback as first parameter
[in]	encryptionPolicy	select how to manage the encryption: direct use of Double Ratchet message or encrypt in the cipher message and use the DR message to share the cipher message key default is optimized output size mode.

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_encryptOutBuffersMaximumSize()

int lime_ffi_encryptOutBuffersMaximumSize	(	const size_t	plainMessageSize,
		const enum lime_ffi_CurveId	curve,
		size_t *	DRmessageSize,
		size_t *	cipherMessageSize
	)

Compute the maximum buffer sizes for the encryption outputs: DRmessage and cipherMessage.

Parameters

[in]	plainMessageSize	size of the plain message to be encrypted
[in]	curve	Choice of elliptic curve to use as base for ECDH and EdDSA operation involved. Can be lime_ffi_CurveId_c25519 or lime_ffi_CurveId_c448.
[out]	DRmessageSize	maximum size of the DRmessage produced by the encrypt function
[out]	cipherMessageSize	maximum size of the cipherMessage produced by the encrypt function

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_get_peerDeviceStatus()

enum lime_ffi_PeerDeviceStatus lime_ffi_get_peerDeviceStatus	(	lime_manager_t	manager,
		const char *	peerDeviceId
	)

get the status of a peer device: unknown, untrusted, trusted, unsafe

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	peerDeviceId	The device Id of peer, shall be its GRUU

Returns

unknown if the device is not in localStorage, untrusted, trusted or unsafe according to the stored value of peer device status flag otherwise

lime_ffi_get_selfIdentityKey()

int lime_ffi_get_selfIdentityKey	(	lime_manager_t	manager,
		const char *	localDeviceId,
		uint8_t *const	Ik,
		size_t *	IkSize
	)

retrieve self Identity Key, an EdDSA formatted public key

if specified localDeviceId is not found in local Storage, return an error

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	used to identify which local account we're dealing with, shall be the GRUU
[out]	Ik	the EdDSA public identity key, formatted as in RFC8032
[in,out]	IkSize	size of the previous buffer, updated with the size of data actually written

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_get_x3dhServerUrl()

int lime_ffi_get_x3dhServerUrl	(	lime_manager_t	manager,
		const char *	localDeviceId,
		char *	x3dhServerUrl,
		size_t *	x3dhServerUrlSize
	)

Get the X3DH key server URL for this identified user.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	Identify the local user account, it must be unique and is also be used as Id on the X3DH key server, it shall be the GRUU, in a NULL terminated string
[in]	x3dhServerUrl	The complete url(including port) of the X3DH key server in a NULL terminated string
[in,out]	x3dhServerUrlSize	Size of the previous buffer, is updated with actual size of data written(without the '\0', would give the same result as strlen.)

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_is_user()

int lime_ffi_is_user	(	lime_manager_t	manager,
		const char *	localDeviceId
	)

Check if a user is present and active in local storage.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	used to identify which local account looking up, shall be the GRUU (Null terminated string)

Returns

LIME_FFI_SUCCESS if the user is active in the local storage, LIME_FFI_USER_NOT_FOUND otherwise

lime_ffi_manager_destroy()

int lime_ffi_manager_destroy

(

lime_manager_t

manager

)

Destroy the internal structure used to interact with lime.

Parameters

[in,out]

manager

pointer to the opaque structure used to interact with lime

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_manager_init()

int lime_ffi_manager_init	(	lime_manager_t *const	manager,
		const char *	db,
		const lime_ffi_X3DHServerPostData	X3DH_post_data,
		void *	userData
	)

Initialise a Lime Manager, only one per end-point is required.

Parameters

[out]	manager	pointer to the opaque structure used to interact with lime
[in]	db	string used to access DB (shall be filename for sqlite3), directly forwarded to SOCI session opening
[in]	X3DH_post_data	A function to send data to the X3DH server. The server response must be forwarded to lime using the lime_ffi_processX3DHServerResponse function
[in]	userData	pointer passed back to the X3DH_post_data callback

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_processX3DHServerResponse()

int lime_ffi_processX3DHServerResponse	(	lime_ffi_data_t	limeData,
		const int	code,
		const uint8_t *	response,
		const size_t	response_size
	)

Forward X3DH server response to the lime engine.

Parameters

[in]	limeData	A pointer to an opaque structure used internally (provided by the X3DHServerPostData function)
[in]	code	The response code given by X3DH server, connection is made through https, so we expect 200 for Ok
[in]	response	binary buffered server response
[in]	response_size	size of previous buffer

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_set_peerDeviceStatus()

int lime_ffi_set_peerDeviceStatus	(	lime_manager_t	manager,
		const char *	peerDeviceId,
		const uint8_t *const	Ik,
		const size_t	IkSize,
		enum lime_ffi_PeerDeviceStatus	status
	)

set the peer device status flag in local storage: unsafe, trusted or untrusted.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	peerDeviceId	The device Id of peer, shall be its GRUU
[in]	Ik	the EdDSA peer public identity key, formatted as in RFC8032 (optionnal, needed only if status is trusted)
[in]	IkSize	size of the previous buffer
[in]	status	value of flag to set: accepted values are trusted, untrusted, unsafe

return an error if given key doesn't match the one present in local storage(if we have a key) if the status flag value is unexpected (not one of trusted, untrusted, unsafe), ignore the call if the status flag is unsafe or untrusted, ignore the value of Ik and call the version of this function without it

if peer Device is not present in local storage and status is trusted or unsafe, it is added, if status is untrusted, it is just ignored

General algorithm followed by the set_peerDeviceStatus functions

• Status is valid? (not one of trusted, untrusted, unsafe)? No: return
• status is trusted
  • We have Ik? -> No: return
  • Device is already in storage but Ik differs from the given one : exception
  • Insert/update in local storage
• status is untrusted
  • Ik is ignored
  • Device already in storage? No: return
  • Device already in storage but current status is unsafe? Yes: return
  • update in local storage -status is unsafe
  • ignore Ik
  • insert/update the status. If inserted, insert an invalid Ik

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_set_x3dhServerUrl()

int lime_ffi_set_x3dhServerUrl	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const char *	x3dhServerUrl
	)

Set the X3DH key server URL for this identified user.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	Identify the local user account, it must be unique and is also be used as Id on the X3DH key server, it shall be the GRUU
[in]	x3dhServerUrl	The complete url(including port) of the X3DH key server. It must connect using HTTPS. Example: https://sip5.linphone.org:25519

Returns

LIME_FFI_SUCCESS or a negative error code

lime_ffi_stale_sessions()

int lime_ffi_stale_sessions	(	lime_manager_t	manager,
		const char *	localDeviceId,
		const char *	peerDeviceId
	)

Stale all sessions between localDeviceId and peerDevice. If peerDevice keep using this session to encrypt and we decrypt with success, the session will be reactivated but to encrypt a message to this peerDevice, a new session will be created. If no session is active between the given device, this call has no effect.

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	localDeviceId	Identify the local user account, it must be unique and is also be used as Id on the X3DH key server, it shall be the GRUU
[in]	peerDeviceId	The device Id of peer, shall be its GRUU

lime_ffi_update()

int lime_ffi_update	(	lime_manager_t	manager,
		const lime_ffi_Callback	callback,
		void *	callbackUserData,
		uint16_t	OPkServerLowLimit,
		uint16_t	OPkBatchSize
	)

Update: shall be called once a day at least, performs checks, updates and cleaning operations.

• check if we shall update a new SPk to X3DH server(SPk lifetime is set in settings)
• check if we need to upload OPks to X3DH server
• remove old SPks, clean double ratchet sessions (remove staled, clean their stored keys for skipped messages)

Is performed for all users founds in local storage

Parameters

[in]	manager	pointer to the opaque structure used to interact with lime
[in]	callback	Performing encryption may involve the X3DH server and is thus asynchronous, when the operation is completed, this callback will be called giving the exit status and an error message in case of failure.
[in]	callbackUserData	this pointer will be forwarded to the callback as first parameter
[in]	OPkServerLowLimit	If server holds less OPk than this limit, generate and upload a batch of OPks
[in]	OPkBatchSize	Number of OPks in a batch uploaded to server

Returns

LIME_FFI_SUCCESS or a negative error code