libsignal

README

libsignal [WIP]

This go library is an implementation of the signal asynchronous messaging protocol modified for use in OpenBazaar.

Modifications include:

• Removed all communication with the signal servers. This library only handles session state management, encryption, and decryption. It's up to you to implement a transport for the ciphertext.
• Removed prekey transport. Again, you need to implement a method of getting Alice's prekey bundle to Bob so that Bob can send the first message.
• Removed message metadata. Messages are not tagged with the recipient ID. This allows them to be stored on untrusted servers without leaking metadata. The cost, however, is that to decrypt a message one must iterative over all open sessions to decrypt the message. Assuming the number of sessions a user keeps open at any given time is relatively small, this shouldn't have scaling issues. It may be possible to improve the efficiency here by tagging each message with a shared secret that ratchets forward, but at the cost of more complexity.
• [TODO] Identity keys switched to RSA (which is what OpenBazaar/IPFS uses).

Documentation

Index

• Variables
• func ContactIdentityKey(id string) ([]byte, error)
• func MakePreKeyBundle(preKey ratchet.PreKeyRecord, signedPreKey ratchet.SignedPreKeyRecord, ...) (*ratchet.PreKeyBundle, error)
• func MyIdentityKey() []byte
• func NewStore(password, path string) (*store, error)
• type Client
  • func NewClient(datastorePath string, password string) (*Client, error)
  • func (c *Client) BuildMessage(plaintext string, recipient string, pkb *ratchet.PreKeyBundle) ([]byte, error)
  • func (c *Client) HandleReceivedMessage(msg []byte) (string, error)
• type OutgoingMessage
• type UnknownContactError
  • func (err UnknownContactError) Error() string

Variables

var EndSessionFlag uint32 = 1

var ErrBadPublicKey = errors.New("public key not formatted correctly")

var ErrCouldNotDecrypt = errors.New("could not decrypt message using any open sessions")

ErrInvalidMACForMessage signals an incoming message with invalid MAC.

var ErrInvalidMACForMessage = errors.New("invalid MAC for incoming message")

ErrInvalidMACForMessage signals an incoming message with invalid MAC.

var ErrStoreBadMAC = errors.New("wrong MAC calculated, possibly due to wrong passphrase")

ErrStoreBadMAC occurs when MAC verification fails on the records stored using password based encryption. The probable cause is using a wrong password.

var MessageTypeNotImplementedError = errors.New("envelope type not implemented")

MessageTypeNotImplementedError is raised in the unlikely event that an unhandled protocol message type is received.

Functions

func ContactIdentityKey

func ContactIdentityKey(id string) ([]byte, error)

ContactIdentityKey returns the serialized public key of the given contact

func MakePreKeyBundle

func MakePreKeyBundle(preKey ratchet.PreKeyRecord, signedPreKey ratchet.SignedPreKeyRecord, identityKey ratchet.IdentityKeyPair) (*ratchet.PreKeyBundle, error)

func MyIdentityKey

func MyIdentityKey() []byte

MyIdentityKey returns our serialized public identity key

func NewStore

func NewStore(password, path string) (*store, error)

Types

type Client

type Client struct {
	Store       *store
	IdentityKey *ratchet.IdentityKeyPair
	PreKeys     *preKeyState
	DeviceID    uint32
	PeerID      string
}

func NewClient

func NewClient(datastorePath string, password string) (*Client, error)

func (*Client) BuildMessage

func (c *Client) BuildMessage(plaintext string, recipient string, pkb *ratchet.PreKeyBundle) ([]byte, error)

func (*Client) HandleReceivedMessage

func (c *Client) HandleReceivedMessage(msg []byte) (string, error)

Authenticate and decrypt a received message

type OutgoingMessage

type OutgoingMessage struct {
	Recipient string
	Msg       string
	Flags     uint32
}

type UnknownContactError

type UnknownContactError struct {
	// contains filtered or unexported fields
}

UnknownContactError is returned when an unknown group id is encountered

func (UnknownContactError) Error

func (err UnknownContactError) Error() string