Add dependencies/vendor (whatsapp)

16 files changed, 1442 insertions, 0 deletions

diff --git a/vendor/go.mau.fi/libsignal/state/record/ChainState.go b/vendor/go.mau.fi/libsignal/state/record/ChainState.go
new file mode 100644
index 00000000..dd07bf89
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/ChainState.go
@@ -0,0 +1,157 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/kdf"
+	"go.mau.fi/libsignal/keys/chain"
+	"go.mau.fi/libsignal/keys/message"
+	"go.mau.fi/libsignal/util/bytehelper"
+)
+
+// NewReceiverChainPair will return a new ReceiverChainPair object.
+func NewReceiverChainPair(receiverChain *Chain, index int) *ReceiverChainPair {
+	return &ReceiverChainPair{
+		ReceiverChain: receiverChain,
+		Index:         index,
+	}
+}
+
+// ReceiverChainPair is a structure for a receiver chain key and index number.
+type ReceiverChainPair struct {
+	ReceiverChain *Chain
+	Index         int
+}
+
+// NewChain returns a new Chain structure for SessionState.
+func NewChain(senderRatchetKeyPair *ecc.ECKeyPair, chainKey *chain.Key,
+	messageKeys []*message.Keys) *Chain {
+
+	return &Chain{
+		senderRatchetKeyPair: senderRatchetKeyPair,
+		chainKey:             chainKey,
+		messageKeys:          messageKeys,
+	}
+}
+
+// NewChainFromStructure will return a new Chain with the given
+// chain structure.
+func NewChainFromStructure(structure *ChainStructure) (*Chain, error) {
+	// Alias to SliceToArray
+	getArray := bytehelper.SliceToArray
+
+	// Build the sender ratchet key from bytes.
+	senderRatchetKeyPublic, err := ecc.DecodePoint(structure.SenderRatchetKeyPublic, 0)
+	if err != nil {
+		return nil, err
+	}
+	var senderRatchetKeyPrivate ecc.ECPrivateKeyable
+	if len(structure.SenderRatchetKeyPrivate) == 32 {
+		senderRatchetKeyPrivate = ecc.NewDjbECPrivateKey(getArray(structure.SenderRatchetKeyPrivate))
+	}
+	senderRatchetKeyPair := ecc.NewECKeyPair(senderRatchetKeyPublic, senderRatchetKeyPrivate)
+
+	// Build our message keys from the message key structures.
+	messageKeys := make([]*message.Keys, len(structure.MessageKeys))
+	for i := range structure.MessageKeys {
+		messageKeys[i] = message.NewKeysFromStruct(structure.MessageKeys[i])
+	}
+
+	// Build our new chain state.
+	chainState := NewChain(
+		senderRatchetKeyPair,
+		chain.NewKeyFromStruct(structure.ChainKey, kdf.DeriveSecrets),
+		messageKeys,
+	)
+
+	return chainState, nil
+}
+
+// ChainStructure is a serializeable structure for chain states.
+type ChainStructure struct {
+	SenderRatchetKeyPublic  []byte
+	SenderRatchetKeyPrivate []byte
+	ChainKey                *chain.KeyStructure
+	MessageKeys             []*message.KeysStructure
+}
+
+// Chain is a structure used inside the SessionState that keeps
+// track of an ongoing ratcheting chain for a session.
+type Chain struct {
+	senderRatchetKeyPair *ecc.ECKeyPair
+	chainKey             *chain.Key
+	messageKeys          []*message.Keys
+}
+
+// SenderRatchetKey returns the sender's EC keypair.
+func (c *Chain) SenderRatchetKey() *ecc.ECKeyPair {
+	return c.senderRatchetKeyPair
+}
+
+// SetSenderRatchetKey will set the chain state with the given EC
+// key pair.
+func (c *Chain) SetSenderRatchetKey(key *ecc.ECKeyPair) {
+	c.senderRatchetKeyPair = key
+}
+
+// ChainKey will return the chain key in the chain state.
+func (c *Chain) ChainKey() *chain.Key {
+	return c.chainKey
+}
+
+// SetChainKey will set the chain state's chain key.
+func (c *Chain) SetChainKey(key *chain.Key) {
+	c.chainKey = key
+}
+
+// MessageKeys will return the message keys associated with the
+// chain state.
+func (c *Chain) MessageKeys() []*message.Keys {
+	return c.messageKeys
+}
+
+// SetMessageKeys will set the chain state with the given message
+// keys.
+func (c *Chain) SetMessageKeys(keys []*message.Keys) {
+	c.messageKeys = keys
+}
+
+// AddMessageKeys will append the chain state with the given
+// message keys.
+func (c *Chain) AddMessageKeys(keys *message.Keys) {
+	c.messageKeys = append(c.messageKeys, keys)
+}
+
+// PopFirstMessageKeys will remove the first message key from
+// the chain's list of message keys.
+func (c *Chain) PopFirstMessageKeys() *message.Keys {
+	removed := c.messageKeys[0]
+	c.messageKeys = c.messageKeys[1:]
+
+	return removed
+}
+
+// structure returns a serializeable structure of the chain state.
+func (c *Chain) structure() *ChainStructure {
+	// Alias to ArrayToSlice
+	getSlice := bytehelper.ArrayToSlice
+
+	// Convert our message keys into a serializeable structure.
+	messageKeys := make([]*message.KeysStructure, len(c.messageKeys))
+	for i := range c.messageKeys {
+		messageKeys[i] = message.NewStructFromKeys(c.messageKeys[i])
+	}
+
+	// Convert our sender ratchet key private
+	var senderRatchetKeyPrivate []byte
+	if c.senderRatchetKeyPair.PrivateKey() != nil {
+		senderRatchetKeyPrivate = getSlice(c.senderRatchetKeyPair.PrivateKey().Serialize())
+	}
+
+	// Build the chain structure.
+	return &ChainStructure{
+		SenderRatchetKeyPublic:  c.senderRatchetKeyPair.PublicKey().Serialize(),
+		SenderRatchetKeyPrivate: senderRatchetKeyPrivate,
+		ChainKey:                chain.NewStructFromKey(c.chainKey),
+		MessageKeys:             messageKeys,
+	}
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/Doc.go b/vendor/go.mau.fi/libsignal/state/record/Doc.go
new file mode 100644
index 00000000..036419da
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/Doc.go
@@ -0,0 +1,3 @@
+// Package record provides the state and record of an ongoing double
+// ratchet session.
+package record
diff --git a/vendor/go.mau.fi/libsignal/state/record/PendingKeyExchangeState.go b/vendor/go.mau.fi/libsignal/state/record/PendingKeyExchangeState.go
new file mode 100644
index 00000000..ac647215
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/PendingKeyExchangeState.go
@@ -0,0 +1,91 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/keys/identity"
+	"go.mau.fi/libsignal/util/bytehelper"
+)
+
+// NewPendingKeyExchange will return a new PendingKeyExchange object.
+func NewPendingKeyExchange(sequence uint32, localBaseKeyPair, localRatchetKeyPair *ecc.ECKeyPair,
+	localIdentityKeyPair *identity.KeyPair) *PendingKeyExchange {
+
+	return &PendingKeyExchange{
+		sequence:             sequence,
+		localBaseKeyPair:     localBaseKeyPair,
+		localRatchetKeyPair:  localRatchetKeyPair,
+		localIdentityKeyPair: localIdentityKeyPair,
+	}
+}
+
+// NewPendingKeyExchangeFromStruct will return a PendingKeyExchange object from
+// the given structure. This is used to get a deserialized pending prekey exchange
+// fetched from persistent storage.
+func NewPendingKeyExchangeFromStruct(structure *PendingKeyExchangeStructure) *PendingKeyExchange {
+	// Return nil if no structure was provided.
+	if structure == nil {
+		return nil
+	}
+
+	// Alias the SliceToArray method.
+	getArray := bytehelper.SliceToArray
+
+	// Convert the bytes in the given structure to ECC objects.
+	localBaseKeyPair := ecc.NewECKeyPair(
+		ecc.NewDjbECPublicKey(getArray(structure.LocalBaseKeyPublic)),
+		ecc.NewDjbECPrivateKey(getArray(structure.LocalBaseKeyPrivate)),
+	)
+	localRatchetKeyPair := ecc.NewECKeyPair(
+		ecc.NewDjbECPublicKey(getArray(structure.LocalRatchetKeyPublic)),
+		ecc.NewDjbECPrivateKey(getArray(structure.LocalRatchetKeyPrivate)),
+	)
+	localIdentityKeyPair := identity.NewKeyPair(
+		identity.NewKey(ecc.NewDjbECPublicKey(getArray(structure.LocalIdentityKeyPublic))),
+		ecc.NewDjbECPrivateKey(getArray(structure.LocalIdentityKeyPrivate)),
+	)
+
+	// Return the PendingKeyExchange with the deserialized keys.
+	return &PendingKeyExchange{
+		sequence:             structure.Sequence,
+		localBaseKeyPair:     localBaseKeyPair,
+		localRatchetKeyPair:  localRatchetKeyPair,
+		localIdentityKeyPair: localIdentityKeyPair,
+	}
+}
+
+// PendingKeyExchangeStructure is a serializable structure for pending
+// key exchanges. This structure is used for persistent storage of the
+// key exchange state.
+type PendingKeyExchangeStructure struct {
+	Sequence                uint32
+	LocalBaseKeyPublic      []byte
+	LocalBaseKeyPrivate     []byte
+	LocalRatchetKeyPublic   []byte
+	LocalRatchetKeyPrivate  []byte
+	LocalIdentityKeyPublic  []byte
+	LocalIdentityKeyPrivate []byte
+}
+
+// PendingKeyExchange is a structure for storing a pending
+// key exchange for a session state.
+type PendingKeyExchange struct {
+	sequence             uint32
+	localBaseKeyPair     *ecc.ECKeyPair
+	localRatchetKeyPair  *ecc.ECKeyPair
+	localIdentityKeyPair *identity.KeyPair
+}
+
+// structre will return a serializable structure of a pending key exchange
+// so it can be persistently stored.
+func (p *PendingKeyExchange) structure() *PendingKeyExchangeStructure {
+	getSlice := bytehelper.ArrayToSlice
+	return &PendingKeyExchangeStructure{
+		Sequence:                p.sequence,
+		LocalBaseKeyPublic:      getSlice(p.localBaseKeyPair.PublicKey().PublicKey()),
+		LocalBaseKeyPrivate:     getSlice(p.localBaseKeyPair.PrivateKey().Serialize()),
+		LocalRatchetKeyPublic:   getSlice(p.localRatchetKeyPair.PublicKey().PublicKey()),
+		LocalRatchetKeyPrivate:  getSlice(p.localRatchetKeyPair.PrivateKey().Serialize()),
+		LocalIdentityKeyPublic:  getSlice(p.localIdentityKeyPair.PublicKey().PublicKey().PublicKey()),
+		LocalIdentityKeyPrivate: getSlice(p.localIdentityKeyPair.PrivateKey().Serialize()),
+	}
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/PendingPreKeyState.go b/vendor/go.mau.fi/libsignal/state/record/PendingPreKeyState.go
new file mode 100644
index 00000000..27a8878b
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/PendingPreKeyState.go
@@ -0,0 +1,62 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/util/optional"
+)
+
+// NewPendingPreKey will return a new pending pre key object.
+func NewPendingPreKey(preKeyID *optional.Uint32, signedPreKeyID uint32,
+	baseKey ecc.ECPublicKeyable) *PendingPreKey {
+
+	return &PendingPreKey{
+		preKeyID:       preKeyID,
+		signedPreKeyID: signedPreKeyID,
+		baseKey:        baseKey,
+	}
+}
+
+// NewPendingPreKeyFromStruct will return a new pending prekey object from the
+// given structure.
+func NewPendingPreKeyFromStruct(preKey *PendingPreKeyStructure) (*PendingPreKey, error) {
+	baseKey, err := ecc.DecodePoint(preKey.BaseKey, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	pendingPreKey := NewPendingPreKey(
+		preKey.PreKeyID,
+		preKey.SignedPreKeyID,
+		baseKey,
+	)
+
+	return pendingPreKey, nil
+}
+
+// PendingPreKeyStructure is a serializeable structure for pending
+// prekeys.
+type PendingPreKeyStructure struct {
+	PreKeyID       *optional.Uint32
+	SignedPreKeyID uint32
+	BaseKey        []byte
+}
+
+// PendingPreKey is a structure for pending pre keys
+// for a session state.
+type PendingPreKey struct {
+	preKeyID       *optional.Uint32
+	signedPreKeyID uint32
+	baseKey        ecc.ECPublicKeyable
+}
+
+// structure will return a serializeable structure of the pending prekey.
+func (p *PendingPreKey) structure() *PendingPreKeyStructure {
+	if p != nil {
+		return &PendingPreKeyStructure{
+			PreKeyID:       p.preKeyID,
+			SignedPreKeyID: p.signedPreKeyID,
+			BaseKey:        p.baseKey.Serialize(),
+		}
+	}
+	return nil
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/PreKeyRecord.go b/vendor/go.mau.fi/libsignal/state/record/PreKeyRecord.go
new file mode 100644
index 00000000..dcd630d2
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/PreKeyRecord.go
@@ -0,0 +1,90 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/util/bytehelper"
+	"go.mau.fi/libsignal/util/optional"
+)
+
+// PreKeySerializer is an interface for serializing and deserializing
+// PreKey objects into bytes. An implementation of this interface should be
+// used to encode/decode the object into JSON, Protobuffers, etc.
+type PreKeySerializer interface {
+	Serialize(preKey *PreKeyStructure) []byte
+	Deserialize(serialized []byte) (*PreKeyStructure, error)
+}
+
+// NewPreKeyFromBytes will return a prekey record from the given bytes using the given serializer.
+func NewPreKeyFromBytes(serialized []byte, serializer PreKeySerializer) (*PreKey, error) {
+	// Use the given serializer to decode the signal message.
+	preKeyStructure, err := serializer.Deserialize(serialized)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewPreKeyFromStruct(preKeyStructure, serializer)
+}
+
+// NewPreKeyFromStruct returns a PreKey record using the given serializable structure.
+func NewPreKeyFromStruct(structure *PreKeyStructure, serializer PreKeySerializer) (*PreKey, error) {
+	// Create the prekey record from the structure.
+	preKey := &PreKey{
+		structure:  *structure,
+		serializer: serializer,
+	}
+
+	// Generate the ECC key from bytes.
+	publicKey := ecc.NewDjbECPublicKey(bytehelper.SliceToArray(structure.PublicKey))
+	privateKey := ecc.NewDjbECPrivateKey(bytehelper.SliceToArray(structure.PrivateKey))
+	keyPair := ecc.NewECKeyPair(publicKey, privateKey)
+	preKey.keyPair = keyPair
+
+	return preKey, nil
+}
+
+// NewPreKey record returns a new pre key record that can
+// be stored in a PreKeyStore.
+func NewPreKey(id uint32, keyPair *ecc.ECKeyPair, serializer PreKeySerializer) *PreKey {
+	return &PreKey{
+		structure: PreKeyStructure{
+			ID:         id,
+			PublicKey:  keyPair.PublicKey().Serialize(),
+			PrivateKey: bytehelper.ArrayToSlice(keyPair.PrivateKey().Serialize()),
+		},
+		keyPair:    keyPair,
+		serializer: serializer,
+	}
+}
+
+// PreKeyStructure is a structure for serializing PreKey records.
+type PreKeyStructure struct {
+	ID         uint32
+	PublicKey  []byte
+	PrivateKey []byte
+}
+
+// PreKey record is a structure for storing pre keys inside
+// a PreKeyStore.
+type PreKey struct {
+	structure  PreKeyStructure
+	keyPair    *ecc.ECKeyPair
+	serializer PreKeySerializer
+}
+
+// ID returns the pre key record's id.
+func (p *PreKey) ID() *optional.Uint32 {
+	// TODO: manually set this to empty if empty
+	return optional.NewOptionalUint32(p.structure.ID)
+}
+
+// KeyPair returns the pre key record's key pair.
+func (p *PreKey) KeyPair() *ecc.ECKeyPair {
+	return p.keyPair
+}
+
+// Serialize uses the PreKey serializer to return the PreKey
+// as serialized bytes.
+func (p *PreKey) Serialize() []byte {
+	structure := p.structure
+	return p.serializer.Serialize(&structure)
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/SessionRecord.go b/vendor/go.mau.fi/libsignal/state/record/SessionRecord.go
new file mode 100644
index 00000000..01e817e4
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/SessionRecord.go
@@ -0,0 +1,197 @@
+package record
+
+import (
+	"bytes"
+)
+
+// archivedStatesMaxLength describes how many previous session
+// states we should keep track of.
+const archivedStatesMaxLength int = 40
+
+// SessionSerializer is an interface for serializing and deserializing
+// a Signal Session into bytes. An implementation of this interface should be
+// used to encode/decode the object into JSON, Protobuffers, etc.
+type SessionSerializer interface {
+	Serialize(state *SessionStructure) []byte
+	Deserialize(serialized []byte) (*SessionStructure, error)
+}
+
+// NewSessionFromBytes will return a Signal Session from the given
+// bytes using the given serializer.
+func NewSessionFromBytes(serialized []byte, serializer SessionSerializer, stateSerializer StateSerializer) (*Session, error) {
+	// Use the given serializer to decode the session.
+	sessionStructure, err := serializer.Deserialize(serialized)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewSessionFromStructure(sessionStructure, serializer, stateSerializer)
+}
+
+// NewSession creates a new session record and uses the given session and state
+// serializers to convert the object into storeable bytes.
+func NewSession(serializer SessionSerializer, stateSerializer StateSerializer) *Session {
+	record := Session{
+		sessionState:   NewState(stateSerializer),
+		previousStates: []*State{},
+		fresh:          true,
+		serializer:     serializer,
+	}
+
+	return &record
+}
+
+// NewSessionFromStructure will return a new Signal Session from the given
+// session structure and serializer.
+func NewSessionFromStructure(structure *SessionStructure, serializer SessionSerializer,
+	stateSerializer StateSerializer) (*Session, error) {
+
+	// Build our previous states from structure.
+	previousStates := make([]*State, len(structure.PreviousStates))
+	for i := range structure.PreviousStates {
+		var err error
+		previousStates[i], err = NewStateFromStructure(structure.PreviousStates[i], stateSerializer)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Build our current state from structure.
+	sessionState, err := NewStateFromStructure(structure.SessionState, stateSerializer)
+	if err != nil {
+		return nil, err
+	}
+
+	// Build and return our session.
+	session := &Session{
+		previousStates: previousStates,
+		sessionState:   sessionState,
+		serializer:     serializer,
+		fresh:          false,
+	}
+
+	return session, nil
+}
+
+// NewSessionFromState creates a new session record from the given
+// session state.
+func NewSessionFromState(sessionState *State, serializer SessionSerializer) *Session {
+	record := Session{
+		sessionState:   sessionState,
+		previousStates: []*State{},
+		fresh:          false,
+		serializer:     serializer,
+	}
+
+	return &record
+}
+
+// SessionStructure is a public, serializeable structure for Signal
+// Sessions. The states defined in the session are immuteable, as
+// they should not be changed by anyone but the serializer.
+type SessionStructure struct {
+	SessionState   *StateStructure
+	PreviousStates []*StateStructure
+}
+
+// Session encapsulates the state of an ongoing session.
+type Session struct {
+	serializer     SessionSerializer
+	sessionState   *State
+	previousStates []*State
+	fresh          bool
+}
+
+// SetState sets the session record's current state to the given
+// one.
+func (r *Session) SetState(sessionState *State) {
+	r.sessionState = sessionState
+}
+
+// IsFresh is used to determine if this is a brand new session
+// or if a session record has already existed.
+func (r *Session) IsFresh() bool {
+	return r.fresh
+}
+
+// SessionState returns the session state object of the current
+// session record.
+func (r *Session) SessionState() *State {
+	return r.sessionState
+}
+
+// PreviousSessionStates returns a list of all currently maintained
+// "previous" session states.
+func (r *Session) PreviousSessionStates() []*State {
+	return r.previousStates
+}
+
+// HasSessionState will check this record to see if the sender's
+// base key exists in the current and previous states.
+func (r *Session) HasSessionState(version int, senderBaseKey []byte) bool {
+	// Ensure the session state version is identical to this one.
+	if r.sessionState.Version() == version && (bytes.Compare(senderBaseKey, r.sessionState.SenderBaseKey()) == 0) {
+		return true
+	}
+
+	// Loop through all of our previous states and see if this
+	// exists in our state.
+	for i := range r.previousStates {
+		if r.previousStates[i].Version() == version && bytes.Compare(senderBaseKey, r.previousStates[i].SenderBaseKey()) == 0 {
+			return true
+		}
+	}
+
+	return false
+}
+
+// ArchiveCurrentState moves the current session state into the list
+// of "previous" session states, and replaces the current session state
+// with a fresh reset instance.
+func (r *Session) ArchiveCurrentState() {
+	r.PromoteState(NewState(r.sessionState.serializer))
+}
+
+// PromoteState takes the given session state and replaces it with the
+// current state, pushing the previous current state to "previousStates".
+func (r *Session) PromoteState(promotedState *State) {
+	r.previousStates = r.prependStates(r.previousStates, r.sessionState)
+	r.sessionState = promotedState
+
+	// Remove the last state if it has reached our maximum length
+	if len(r.previousStates) > archivedStatesMaxLength {
+		r.previousStates = r.removeLastState(r.previousStates)
+	}
+}
+
+// Serialize will return the session as serialized bytes so it can be
+// persistently stored.
+func (r *Session) Serialize() []byte {
+	return r.serializer.Serialize(r.Structure())
+}
+
+// prependStates takes an array/slice of states and prepends it with
+// the given session state.
+func (r *Session) prependStates(states []*State, sessionState *State) []*State {
+	return append([]*State{sessionState}, states...)
+}
+
+// removeLastState takes an array/slice of states and removes the
+// last element from it.
+func (r *Session) removeLastState(states []*State) []*State {
+	return states[:len(states)-1]
+}
+
+// Structure will return a simple serializable session structure
+// from the given structure. This is used for serialization to persistently
+// store a session record.
+func (r *Session) Structure() *SessionStructure {
+	previousStates := make([]*StateStructure, len(r.previousStates))
+	for i := range r.previousStates {
+		previousStates[i] = r.previousStates[i].structure()
+	}
+	return &SessionStructure{
+		SessionState:   r.sessionState.structure(),
+		PreviousStates: previousStates,
+	}
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/SessionState.go b/vendor/go.mau.fi/libsignal/state/record/SessionState.go
new file mode 100644
index 00000000..d0f61d5c
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/SessionState.go
@@ -0,0 +1,531 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/kdf"
+	"go.mau.fi/libsignal/keys/chain"
+	"go.mau.fi/libsignal/keys/identity"
+	"go.mau.fi/libsignal/keys/message"
+	"go.mau.fi/libsignal/keys/root"
+	"go.mau.fi/libsignal/keys/session"
+	"go.mau.fi/libsignal/logger"
+	"go.mau.fi/libsignal/util/errorhelper"
+	"go.mau.fi/libsignal/util/optional"
+)
+
+const maxMessageKeys int = 2000
+const maxReceiverChains int = 5
+
+// StateSerializer is an interface for serializing and deserializing
+// a Signal State into bytes. An implementation of this interface should be
+// used to encode/decode the object into JSON, Protobuffers, etc.
+type StateSerializer interface {
+	Serialize(state *StateStructure) []byte
+	Deserialize(serialized []byte) (*StateStructure, error)
+}
+
+// NewStateFromBytes will return a Signal State from the given
+// bytes using the given serializer.
+func NewStateFromBytes(serialized []byte, serializer StateSerializer) (*State, error) {
+	// Use the given serializer to decode the signal message.
+	stateStructure, err := serializer.Deserialize(serialized)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewStateFromStructure(stateStructure, serializer)
+}
+
+// NewState returns a new session state.
+func NewState(serializer StateSerializer) *State {
+	return &State{serializer: serializer}
+}
+
+// NewStateFromStructure will return a new session state with the
+// given state structure.
+func NewStateFromStructure(structure *StateStructure, serializer StateSerializer) (*State, error) {
+	// Keep a list of errors, so they can be handled once.
+	errors := errorhelper.NewMultiError()
+
+	// Convert our ecc keys from bytes into object form.
+	localIdentityPublic, err := ecc.DecodePoint(structure.LocalIdentityPublic, 0)
+	errors.Add(err)
+	remoteIdentityPublic, err := ecc.DecodePoint(structure.RemoteIdentityPublic, 0)
+	errors.Add(err)
+	senderBaseKey, err := ecc.DecodePoint(structure.SenderBaseKey, 0)
+	errors.Add(err)
+	var pendingPreKey *PendingPreKey
+	if structure.PendingPreKey != nil {
+		pendingPreKey, err = NewPendingPreKeyFromStruct(structure.PendingPreKey)
+		errors.Add(err)
+	}
+	senderChain, err := NewChainFromStructure(structure.SenderChain)
+	errors.Add(err)
+
+	// Build our receiver chains from structure.
+	receiverChains := make([]*Chain, len(structure.ReceiverChains))
+	for i := range structure.ReceiverChains {
+		receiverChains[i], err = NewChainFromStructure(structure.ReceiverChains[i])
+		errors.Add(err)
+	}
+
+	// Handle any errors. The first error will always be returned if there are multiple.
+	if errors.HasErrors() {
+		return nil, errors
+	}
+
+	// Build our state object.
+	state := &State{
+		localIdentityPublic:  identity.NewKey(localIdentityPublic),
+		localRegistrationID:  structure.LocalRegistrationID,
+		needsRefresh:         structure.NeedsRefresh,
+		pendingKeyExchange:   NewPendingKeyExchangeFromStruct(structure.PendingKeyExchange),
+		pendingPreKey:        pendingPreKey,
+		previousCounter:      structure.PreviousCounter,
+		receiverChains:       receiverChains,
+		remoteIdentityPublic: identity.NewKey(remoteIdentityPublic),
+		remoteRegistrationID: structure.RemoteRegistrationID,
+		rootKey:              root.NewKey(kdf.DeriveSecrets, structure.RootKey),
+		senderBaseKey:        senderBaseKey,
+		senderChain:          senderChain,
+		serializer:           serializer,
+		sessionVersion:       structure.SessionVersion,
+	}
+
+	return state, nil
+}
+
+// StateStructure is the structure of a session state. Fields are public
+// to be used for serialization and deserialization.
+type StateStructure struct {
+	LocalIdentityPublic  []byte
+	LocalRegistrationID  uint32
+	NeedsRefresh         bool
+	PendingKeyExchange   *PendingKeyExchangeStructure
+	PendingPreKey        *PendingPreKeyStructure
+	PreviousCounter      uint32
+	ReceiverChains       []*ChainStructure
+	RemoteIdentityPublic []byte
+	RemoteRegistrationID uint32
+	RootKey              []byte
+	SenderBaseKey        []byte
+	SenderChain          *ChainStructure
+	SessionVersion       int
+}
+
+// State is a session state that contains the structure for
+// all sessions. Session states are contained inside session records.
+// The session state is implemented as a struct rather than protobuffers
+// to allow other serialization methods.
+type State struct {
+	localIdentityPublic  *identity.Key
+	localRegistrationID  uint32
+	needsRefresh         bool
+	pendingKeyExchange   *PendingKeyExchange
+	pendingPreKey        *PendingPreKey
+	previousCounter      uint32
+	receiverChains       []*Chain
+	remoteIdentityPublic *identity.Key
+	remoteRegistrationID uint32
+	rootKey              *root.Key
+	senderBaseKey        ecc.ECPublicKeyable
+	senderChain          *Chain
+	serializer           StateSerializer
+	sessionVersion       int
+}
+
+// SenderBaseKey returns the sender's base key in bytes.
+func (s *State) SenderBaseKey() []byte {
+	if s.senderBaseKey == nil {
+		return nil
+	}
+	return s.senderBaseKey.Serialize()
+}
+
+// SetSenderBaseKey sets the sender's base key with the given bytes.
+func (s *State) SetSenderBaseKey(senderBaseKey []byte) {
+	s.senderBaseKey, _ = ecc.DecodePoint(senderBaseKey, 0)
+}
+
+// Version returns the session's version.
+func (s *State) Version() int {
+	return s.sessionVersion
+}
+
+// SetVersion sets the session state's version number.
+func (s *State) SetVersion(version int) {
+	s.sessionVersion = version
+}
+
+// RemoteIdentityKey returns the identity key of the remote user.
+func (s *State) RemoteIdentityKey() *identity.Key {
+	return s.remoteIdentityPublic
+}
+
+// SetRemoteIdentityKey sets this session's identity key for the remote
+// user.
+func (s *State) SetRemoteIdentityKey(identityKey *identity.Key) {
+	s.remoteIdentityPublic = identityKey
+}
+
+// LocalIdentityKey returns the session's identity key for the local
+// user.
+func (s *State) LocalIdentityKey() *identity.Key {
+	return s.localIdentityPublic
+}
+
+// SetLocalIdentityKey sets the session's identity key for the local
+// user.
+func (s *State) SetLocalIdentityKey(identityKey *identity.Key) {
+	s.localIdentityPublic = identityKey
+}
+
+// PreviousCounter returns the counter of the previous message.
+func (s *State) PreviousCounter() uint32 {
+	return s.previousCounter
+}
+
+// SetPreviousCounter sets the counter for the previous message.
+func (s *State) SetPreviousCounter(previousCounter uint32) {
+	s.previousCounter = previousCounter
+}
+
+// RootKey returns the root key for the session.
+func (s *State) RootKey() session.RootKeyable {
+	return s.rootKey
+}
+
+// SetRootKey sets the root key for the session.
+func (s *State) SetRootKey(rootKey session.RootKeyable) {
+	s.rootKey = rootKey.(*root.Key)
+}
+
+// SenderRatchetKey returns the public ratchet key of the sender.
+func (s *State) SenderRatchetKey() ecc.ECPublicKeyable {
+	return s.senderChain.senderRatchetKeyPair.PublicKey()
+}
+
+// SenderRatchetKeyPair returns the public/private ratchet key pair
+// of the sender.
+func (s *State) SenderRatchetKeyPair() *ecc.ECKeyPair {
+	return s.senderChain.senderRatchetKeyPair
+}
+
+// HasReceiverChain will check to see if the session state has
+// the given ephemeral key.
+func (s *State) HasReceiverChain(senderEphemeral ecc.ECPublicKeyable) bool {
+	return s.receiverChain(senderEphemeral) != nil
+}
+
+// HasSenderChain will check to see if the session state has a
+// sender chain.
+func (s *State) HasSenderChain() bool {
+	return s.senderChain != nil
+}
+
+// receiverChain will loop through the session state's receiver chains
+// and compare the given ephemeral key. If it is found, then the chain
+// and index will be returned as a pair.
+func (s *State) receiverChain(senderEphemeral ecc.ECPublicKeyable) *ReceiverChainPair {
+	receiverChains := s.receiverChains
+
+	for i, receiverChain := range receiverChains {
+		chainSenderRatchetKey, err := ecc.DecodePoint(receiverChain.senderRatchetKeyPair.PublicKey().Serialize(), 0)
+		if err != nil {
+			logger.Error("Error getting receiverchain: ", err)
+		}
+
+		// If the chainSenderRatchetKey equals our senderEphemeral key, return it.
+		if chainSenderRatchetKey.PublicKey() == senderEphemeral.PublicKey() {
+			return NewReceiverChainPair(receiverChain, i)
+		}
+	}
+
+	return nil
+}
+
+// ReceiverChainKey will use the given ephemeral key to generate a new
+// chain key.
+func (s *State) ReceiverChainKey(senderEphemeral ecc.ECPublicKeyable) *chain.Key {
+	receiverChainAndIndex := s.receiverChain(senderEphemeral)
+	receiverChain := receiverChainAndIndex.ReceiverChain
+
+	if receiverChainAndIndex == nil || receiverChain == nil {
+		return nil
+	}
+
+	return chain.NewKey(
+		kdf.DeriveSecrets,
+		receiverChain.chainKey.Key(),
+		receiverChain.chainKey.Index(),
+	)
+}
+
+// AddReceiverChain will add the given ratchet key and chain key to the session
+// state.
+func (s *State) AddReceiverChain(senderRatchetKey ecc.ECPublicKeyable, chainKey session.ChainKeyable) {
+	// Create a keypair structure with our sender ratchet key.
+	senderKey := ecc.NewECKeyPair(senderRatchetKey, nil)
+
+	// Create a Chain state object that will hold our sender key, chain key, and
+	// message keys.
+	chain := NewChain(senderKey, chainKey.(*chain.Key), []*message.Keys{})
+
+	// Add the Chain state to our list of receiver chain states.
+	s.receiverChains = append(s.receiverChains, chain)
+
+	// If our list of receiver chains is too big, delete the oldest entry.
+	if len(s.receiverChains) > maxReceiverChains {
+		i := 0
+		s.receiverChains = append(s.receiverChains[:i], s.receiverChains[i+1:]...)
+	}
+}
+
+// SetSenderChain will set the given ratchet key pair and chain key for this session
+// state.
+func (s *State) SetSenderChain(senderRatchetKeyPair *ecc.ECKeyPair, chainKey session.ChainKeyable) {
+	// Create a Chain state object that will hold our sender key, chain key, and
+	// message keys.
+	chain := NewChain(senderRatchetKeyPair, chainKey.(*chain.Key), []*message.Keys{})
+
+	// Set the sender chain.
+	s.senderChain = chain
+}
+
+// SenderChainKey will return the chain key of the session state.
+func (s *State) SenderChainKey() session.ChainKeyable {
+	chainKey := s.senderChain.chainKey
+	return chain.NewKey(kdf.DeriveSecrets, chainKey.Key(), chainKey.Index())
+}
+
+// SetSenderChainKey will set the chain key in the chain state for this session to
+// the given chain key.
+func (s *State) SetSenderChainKey(nextChainKey session.ChainKeyable) {
+	senderChain := s.senderChain
+	senderChain.SetChainKey(nextChainKey.(*chain.Key))
+}
+
+// HasMessageKeys returns true if we have message keys associated with the given
+// sender key and counter.
+func (s *State) HasMessageKeys(senderEphemeral ecc.ECPublicKeyable, counter uint32) bool {
+	// Get our chain state that has our chain key.
+	chainAndIndex := s.receiverChain(senderEphemeral)
+	receiverChain := chainAndIndex.ReceiverChain
+
+	// If the chain is empty, we don't have any message keys.
+	if receiverChain == nil {
+		return false
+	}
+
+	// Get our message keys from our receiver chain.
+	messageKeyList := receiverChain.MessageKeys()
+
+	// Loop through our message keys and compare its index with the
+	// given counter.
+	for _, messageKey := range messageKeyList {
+		if messageKey.Index() == counter {
+			return true
+		}
+	}
+
+	return false
+}
+
+// RemoveMessageKeys removes the message key with the given sender key and
+// counter. It will return the removed message key.
+func (s *State) RemoveMessageKeys(senderEphemeral ecc.ECPublicKeyable, counter uint32) *message.Keys {
+	// Get our chain state that has our chain key.
+	chainAndIndex := s.receiverChain(senderEphemeral)
+	chainKey := chainAndIndex.ReceiverChain
+
+	// If the chain is empty, we don't have any message keys.
+	if chainKey == nil {
+		return nil
+	}
+
+	// Get our message keys from our receiver chain.
+	messageKeyList := chainKey.MessageKeys()
+
+	// Loop through our message keys and compare its index with the
+	// given counter. When we find a match, remove it from our list.
+	var rmIndex int
+	for i, messageKey := range messageKeyList {
+		if messageKey.Index() == counter {
+			rmIndex = i
+			break
+		}
+	}
+
+	// Retrive the message key
+	messageKey := chainKey.messageKeys[rmIndex]
+
+	// Delete the message key from the given position.
+	chainKey.messageKeys = append(chainKey.messageKeys[:rmIndex], chainKey.messageKeys[rmIndex+1:]...)
+
+	return message.NewKeys(
+		messageKey.CipherKey(),
+		messageKey.MacKey(),
+		messageKey.Iv(),
+		messageKey.Index(),
+	)
+}
+
+// SetMessageKeys will update the chain associated with the given sender key with
+// the given message keys.
+func (s *State) SetMessageKeys(senderEphemeral ecc.ECPublicKeyable, messageKeys *message.Keys) {
+	chainAndIndex := s.receiverChain(senderEphemeral)
+	chainState := chainAndIndex.ReceiverChain
+
+	// Add the message keys to our chain state.
+	chainState.AddMessageKeys(
+		message.NewKeys(
+			messageKeys.CipherKey(),
+			messageKeys.MacKey(),
+			messageKeys.Iv(),
+			messageKeys.Index(),
+		),
+	)
+
+	if len(chainState.MessageKeys()) > maxMessageKeys {
+		chainState.PopFirstMessageKeys()
+	}
+}
+
+// SetReceiverChainKey sets the session's receiver chain key with the given chain key
+// associated with the given senderEphemeral key.
+func (s *State) SetReceiverChainKey(senderEphemeral ecc.ECPublicKeyable, chainKey session.ChainKeyable) {
+	chainAndIndex := s.receiverChain(senderEphemeral)
+	chainState := chainAndIndex.ReceiverChain
+	chainState.SetChainKey(chainKey.(*chain.Key))
+}
+
+// SetPendingKeyExchange will set the session's pending key exchange state to the given
+// sequence and key pairs.
+func (s *State) SetPendingKeyExchange(sequence uint32, ourBaseKey, ourRatchetKey *ecc.ECKeyPair,
+	ourIdentityKey *identity.KeyPair) {
+
+	s.pendingKeyExchange = NewPendingKeyExchange(
+		sequence,
+		ourBaseKey,
+		ourRatchetKey,
+		ourIdentityKey,
+	)
+}
+
+// PendingKeyExchangeSequence will return the session's pending key exchange sequence
+// number.
+func (s *State) PendingKeyExchangeSequence() uint32 {
+	return s.pendingKeyExchange.sequence
+}
+
+// PendingKeyExchangeBaseKeyPair will return the session's pending key exchange base keypair.
+func (s *State) PendingKeyExchangeBaseKeyPair() *ecc.ECKeyPair {
+	return s.pendingKeyExchange.localBaseKeyPair
+}
+
+// PendingKeyExchangeRatchetKeyPair will return the session's pending key exchange ratchet
+// keypair.
+func (s *State) PendingKeyExchangeRatchetKeyPair() *ecc.ECKeyPair {
+	return s.pendingKeyExchange.localRatchetKeyPair
+}
+
+// PendingKeyExchangeIdentityKeyPair will return the session's pending key exchange identity
+// keypair.
+func (s *State) PendingKeyExchangeIdentityKeyPair() *identity.KeyPair {
+	return s.pendingKeyExchange.localIdentityKeyPair
+}
+
+// HasPendingKeyExchange will return true if there is a valid pending key exchange waiting.
+func (s *State) HasPendingKeyExchange() bool {
+	return s.pendingKeyExchange != nil
+}
+
+// SetUnacknowledgedPreKeyMessage will return unacknowledged pre key message with the
+// given key ids and base key.
+func (s *State) SetUnacknowledgedPreKeyMessage(preKeyID *optional.Uint32, signedPreKeyID uint32, baseKey ecc.ECPublicKeyable) {
+	s.pendingPreKey = NewPendingPreKey(
+		preKeyID,
+		signedPreKeyID,
+		baseKey,
+	)
+}
+
+// HasUnacknowledgedPreKeyMessage will return true if this session has an unacknowledged
+// pre key message.
+func (s *State) HasUnacknowledgedPreKeyMessage() bool {
+	return s.pendingPreKey != nil
+}
+
+// UnackPreKeyMessageItems will return the session's unacknowledged pre key messages.
+func (s *State) UnackPreKeyMessageItems() (*UnackPreKeyMessageItems, error) {
+	preKeyID := s.pendingPreKey.preKeyID
+	signedPreKeyID := s.pendingPreKey.signedPreKeyID
+	baseKey, err := ecc.DecodePoint(s.pendingPreKey.baseKey.Serialize(), 0)
+	if err != nil {
+		return nil, err
+	}
+	return NewUnackPreKeyMessageItems(preKeyID, signedPreKeyID, baseKey), nil
+}
+
+// ClearUnackPreKeyMessage will clear the session's pending pre key.
+func (s *State) ClearUnackPreKeyMessage() {
+	s.pendingPreKey = nil
+}
+
+// SetRemoteRegistrationID sets the remote user's registration id.
+func (s *State) SetRemoteRegistrationID(registrationID uint32) {
+	s.remoteRegistrationID = registrationID
+}
+
+// RemoteRegistrationID returns the remote user's registration id.
+func (s *State) RemoteRegistrationID() uint32 {
+	return s.remoteRegistrationID
+}
+
+// SetLocalRegistrationID sets the local user's registration id.
+func (s *State) SetLocalRegistrationID(registrationID uint32) {
+	s.localRegistrationID = registrationID
+}
+
+// LocalRegistrationID returns the local user's registration id.
+func (s *State) LocalRegistrationID() uint32 {
+	return s.localRegistrationID
+}
+
+// Serialize will return the state as bytes using the given serializer.
+func (s *State) Serialize() []byte {
+	return s.serializer.Serialize(s.structure())
+}
+
+// structure will return a serializable structure of the
+// the given state so it can be persistently stored.
+func (s *State) structure() *StateStructure {
+	// Convert our receiver chains into a serializeable structure
+	receiverChains := make([]*ChainStructure, len(s.receiverChains))
+	for i := range s.receiverChains {
+		receiverChains[i] = s.receiverChains[i].structure()
+	}
+
+	// Convert our pending key exchange into a serializeable structure
+	var pendingKeyExchange *PendingKeyExchangeStructure
+	if s.pendingKeyExchange != nil {
+		pendingKeyExchange = s.pendingKeyExchange.structure()
+	}
+
+	// Build and return our state structure.
+	return &StateStructure{
+		LocalIdentityPublic:  s.localIdentityPublic.Serialize(),
+		LocalRegistrationID:  s.localRegistrationID,
+		NeedsRefresh:         s.needsRefresh,
+		PendingKeyExchange:   pendingKeyExchange,
+		PendingPreKey:        s.pendingPreKey.structure(),
+		PreviousCounter:      s.previousCounter,
+		ReceiverChains:       receiverChains,
+		RemoteIdentityPublic: s.remoteIdentityPublic.Serialize(),
+		RemoteRegistrationID: s.remoteRegistrationID,
+		RootKey:              s.rootKey.Bytes(),
+		SenderBaseKey:        s.senderBaseKey.Serialize(),
+		SenderChain:          s.senderChain.structure(),
+		SessionVersion:       s.sessionVersion,
+	}
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/SignedPreKeyRecord.go b/vendor/go.mau.fi/libsignal/state/record/SignedPreKeyRecord.go
new file mode 100644
index 00000000..f11ab088
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/SignedPreKeyRecord.go
@@ -0,0 +1,112 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/util/bytehelper"
+)
+
+// SignedPreKeySerializer is an interface for serializing and deserializing
+// SignedPreKey objects into bytes. An implementation of this interface should be
+// used to encode/decode the object into JSON, Protobuffers, etc.
+type SignedPreKeySerializer interface {
+	Serialize(signedPreKey *SignedPreKeyStructure) []byte
+	Deserialize(serialized []byte) (*SignedPreKeyStructure, error)
+}
+
+// NewSignedPreKeyFromBytes will return a signed prekey record from the given
+// bytes using the given serializer.
+func NewSignedPreKeyFromBytes(serialized []byte, serializer SignedPreKeySerializer) (*SignedPreKey, error) {
+	// Use the given serializer to decode the signal message.
+	signedPreKeyStructure, err := serializer.Deserialize(serialized)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewSignedPreKeyFromStruct(signedPreKeyStructure, serializer)
+}
+
+// NewSignedPreKeyFromStruct returns a SignedPreKey record using the given
+// serializable structure.
+func NewSignedPreKeyFromStruct(structure *SignedPreKeyStructure,
+	serializer SignedPreKeySerializer) (*SignedPreKey, error) {
+
+	// Create the signed prekey record from the structure.
+	signedPreKey := &SignedPreKey{
+		structure:  *structure,
+		serializer: serializer,
+		signature:  bytehelper.SliceToArray64(structure.Signature),
+	}
+
+	// Generate the ECC key from bytes.
+	publicKey := ecc.NewDjbECPublicKey(bytehelper.SliceToArray(structure.PublicKey))
+	privateKey := ecc.NewDjbECPrivateKey(bytehelper.SliceToArray(structure.PrivateKey))
+	keyPair := ecc.NewECKeyPair(publicKey, privateKey)
+	signedPreKey.keyPair = keyPair
+
+	return signedPreKey, nil
+}
+
+// NewSignedPreKey record creates a new signed pre key record
+// with the given properties.
+func NewSignedPreKey(id uint32, timestamp int64, keyPair *ecc.ECKeyPair,
+	sig [64]byte, serializer SignedPreKeySerializer) *SignedPreKey {
+
+	return &SignedPreKey{
+		structure: SignedPreKeyStructure{
+			ID:         id,
+			Timestamp:  timestamp,
+			PublicKey:  keyPair.PublicKey().Serialize(),
+			PrivateKey: bytehelper.ArrayToSlice(keyPair.PrivateKey().Serialize()),
+			Signature:  bytehelper.ArrayToSlice64(sig),
+		},
+		keyPair:    keyPair,
+		signature:  sig,
+		serializer: serializer,
+	}
+}
+
+// SignedPreKeyStructure is a flat structure of a signed pre key, used
+// for serialization and deserialization.
+type SignedPreKeyStructure struct {
+	ID         uint32
+	PublicKey  []byte
+	PrivateKey []byte
+	Signature  []byte
+	Timestamp  int64
+}
+
+// SignedPreKey record is a structure for storing a signed
+// pre key in a SignedPreKey store.
+type SignedPreKey struct {
+	structure  SignedPreKeyStructure
+	keyPair    *ecc.ECKeyPair
+	signature  [64]byte
+	serializer SignedPreKeySerializer
+}
+
+// ID returns the record's id.
+func (s *SignedPreKey) ID() uint32 {
+	return s.structure.ID
+}
+
+// Timestamp returns the record's timestamp
+func (s *SignedPreKey) Timestamp() int64 {
+	return s.structure.Timestamp
+}
+
+// KeyPair returns the signed pre key record's key pair.
+func (s *SignedPreKey) KeyPair() *ecc.ECKeyPair {
+	return s.keyPair
+}
+
+// Signature returns the record's signed prekey signature.
+func (s *SignedPreKey) Signature() [64]byte {
+	return s.signature
+}
+
+// Serialize uses the SignedPreKey serializer to return the SignedPreKey
+// as serialized bytes.
+func (s *SignedPreKey) Serialize() []byte {
+	structure := s.structure
+	return s.serializer.Serialize(&structure)
+}
diff --git a/vendor/go.mau.fi/libsignal/state/record/UnacknowledgedPreKey.go b/vendor/go.mau.fi/libsignal/state/record/UnacknowledgedPreKey.go
new file mode 100644
index 00000000..61fe0644
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/record/UnacknowledgedPreKey.go
@@ -0,0 +1,69 @@
+package record
+
+import (
+	"go.mau.fi/libsignal/ecc"
+	"go.mau.fi/libsignal/util/optional"
+)
+
+// NewUnackPreKeyMessageItems returns message items that are unacknowledged.
+func NewUnackPreKeyMessageItems(preKeyID *optional.Uint32, signedPreKeyID uint32,
+	baseKey ecc.ECPublicKeyable) *UnackPreKeyMessageItems {
+
+	return &UnackPreKeyMessageItems{
+		preKeyID:       preKeyID,
+		signedPreKeyID: signedPreKeyID,
+		baseKey:        baseKey,
+	}
+}
+
+// NewUnackPreKeyMessageItemsFromStruct will return a new unacknowledged prekey
+// message items object from the given structure.
+func NewUnackPreKeyMessageItemsFromStruct(structure *UnackPreKeyMessageItemsStructure) *UnackPreKeyMessageItems {
+	baseKey, _ := ecc.DecodePoint(structure.BaseKey, 0)
+	return NewUnackPreKeyMessageItems(
+		structure.PreKeyID,
+		structure.SignedPreKeyID,
+		baseKey,
+	)
+}
+
+// UnackPreKeyMessageItemsStructure is a serializable structure for unackowledged
+// prekey message items.
+type UnackPreKeyMessageItemsStructure struct {
+	PreKeyID       *optional.Uint32
+	SignedPreKeyID uint32
+	BaseKey        []byte
+}
+
+// UnackPreKeyMessageItems is a structure for messages that have not been
+// acknowledged.
+type UnackPreKeyMessageItems struct {
+	preKeyID       *optional.Uint32
+	signedPreKeyID uint32
+	baseKey        ecc.ECPublicKeyable
+}
+
+// PreKeyID returns the prekey id of the unacknowledged message.
+func (u *UnackPreKeyMessageItems) PreKeyID() *optional.Uint32 {
+	return u.preKeyID
+}
+
+// SignedPreKeyID returns the signed prekey id of the unacknowledged message.
+func (u *UnackPreKeyMessageItems) SignedPreKeyID() uint32 {
+	return u.signedPreKeyID
+}
+
+// BaseKey returns the ECC public key of the unacknowledged message.
+func (u *UnackPreKeyMessageItems) BaseKey() ecc.ECPublicKeyable {
+	return u.baseKey
+}
+
+// structure will return a serializable base structure
+// for unacknowledged prekey message items.
+func (u *UnackPreKeyMessageItems) structure() *UnackPreKeyMessageItemsStructure {
+	return &UnackPreKeyMessageItemsStructure{
+		PreKeyID:       u.preKeyID,
+		SignedPreKeyID: u.signedPreKeyID,
+		BaseKey:        u.baseKey.Serialize(),
+	}
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/Doc.go b/vendor/go.mau.fi/libsignal/state/store/Doc.go
new file mode 100644
index 00000000..9a018d3d
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/Doc.go
@@ -0,0 +1,3 @@
+// Package store provides the storage interfaces for storing the state of
+// ongoing double ratchet sessions and keys.
+package store
diff --git a/vendor/go.mau.fi/libsignal/state/store/IdentityKeyStore.go b/vendor/go.mau.fi/libsignal/state/store/IdentityKeyStore.go
new file mode 100644
index 00000000..05ad8d1e
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/IdentityKeyStore.go
@@ -0,0 +1,29 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/keys/identity"
+	"go.mau.fi/libsignal/protocol"
+)
+
+// IdentityKey provides an interface to identity information.
+type IdentityKey interface {
+	// Get the local client's identity key pair.
+	GetIdentityKeyPair() *identity.KeyPair
+
+	// Return the local client's registration ID.
+	//
+	// Clients should maintain a registration ID, a random number between 1 and 16380
+	// that's generated once at install time.
+	GetLocalRegistrationId() uint32
+
+	// Save a remote client's identity key in our identity store.
+	SaveIdentity(address *protocol.SignalAddress, identityKey *identity.Key)
+
+	// Verify a remote client's identity key.
+	//
+	// Determine whether a remote client's identity is trusted. Trust is based on
+	// 'trust on first use'. This means that an identity key is considered 'trusted'
+	// if there is no entry for the recipient in the local store, or if it matches the
+	// saved key for a recipient in the local store.
+	IsTrustedIdentity(address *protocol.SignalAddress, identityKey *identity.Key) bool
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/MessageKeyStore.go b/vendor/go.mau.fi/libsignal/state/store/MessageKeyStore.go
new file mode 100644
index 00000000..fea2eed0
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/MessageKeyStore.go
@@ -0,0 +1,21 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/keys/message"
+)
+
+// MessageKey store is an interface describing the optional local storage
+// of message keys.
+type MessageKey interface {
+	// Load a local message key by id
+	LoadMessageKey(keyID uint32) *message.Keys
+
+	// Store a local message key
+	StoreMessageKey(keyID uint32, key *message.Keys)
+
+	// Check to see if the store contains a message key with id.
+	ContainsMessageKey(keyID uint32) bool
+
+	// Delete a message key from local storage.
+	RemoveMessageKey(keyID uint32)
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/PreKeyStore.go b/vendor/go.mau.fi/libsignal/state/store/PreKeyStore.go
new file mode 100644
index 00000000..a132be65
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/PreKeyStore.go
@@ -0,0 +1,21 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/state/record"
+)
+
+// PreKey store is an interface describing the local storage
+// of PreKeyRecords
+type PreKey interface {
+	// Load a local PreKeyRecord
+	LoadPreKey(preKeyID uint32) *record.PreKey
+
+	// Store a local PreKeyRecord
+	StorePreKey(preKeyID uint32, preKeyRecord *record.PreKey)
+
+	// Check to see if the store contains a PreKeyRecord
+	ContainsPreKey(preKeyID uint32) bool
+
+	// Delete a PreKeyRecord from local storage.
+	RemovePreKey(preKeyID uint32)
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/SessionStore.go b/vendor/go.mau.fi/libsignal/state/store/SessionStore.go
new file mode 100644
index 00000000..e18fc024
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/SessionStore.go
@@ -0,0 +1,17 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/protocol"
+	"go.mau.fi/libsignal/state/record"
+)
+
+// Session store is an interface for the persistent storage of session
+// state information for remote clients.
+type Session interface {
+	LoadSession(address *protocol.SignalAddress) *record.Session
+	GetSubDeviceSessions(name string) []uint32
+	StoreSession(remoteAddress *protocol.SignalAddress, record *record.Session)
+	ContainsSession(remoteAddress *protocol.SignalAddress) bool
+	DeleteSession(remoteAddress *protocol.SignalAddress)
+	DeleteAllSessions()
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/SignalProtocolStore.go b/vendor/go.mau.fi/libsignal/state/store/SignalProtocolStore.go
new file mode 100644
index 00000000..081e0380
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/SignalProtocolStore.go
@@ -0,0 +1,15 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/groups/state/store"
+)
+
+// SignalProtocol store is an interface that implements the
+// methods for all stores needed in the Signal Protocol.
+type SignalProtocol interface {
+	IdentityKey
+	PreKey
+	Session
+	SignedPreKey
+	store.SenderKey
+}
diff --git a/vendor/go.mau.fi/libsignal/state/store/SignedPreKeyStore.go b/vendor/go.mau.fi/libsignal/state/store/SignedPreKeyStore.go
new file mode 100644
index 00000000..058cd670
--- /dev/null
+++ b/vendor/go.mau.fi/libsignal/state/store/SignedPreKeyStore.go
@@ -0,0 +1,24 @@
+package store
+
+import (
+	"go.mau.fi/libsignal/state/record"
+)
+
+// SignedPreKey store is an interface that describes how to persistently
+// store signed PreKeys.
+type SignedPreKey interface {
+	// LoadSignedPreKey loads a local SignedPreKeyRecord
+	LoadSignedPreKey(signedPreKeyID uint32) *record.SignedPreKey
+
+	// LoadSignedPreKeys loads all local SignedPreKeyRecords
+	LoadSignedPreKeys() []*record.SignedPreKey
+
+	// Store a local SignedPreKeyRecord
+	StoreSignedPreKey(signedPreKeyID uint32, record *record.SignedPreKey)
+
+	// Check to see if store contains the given record
+	ContainsSignedPreKey(signedPreKeyID uint32) bool
+
+	// Delete a SignedPreKeyRecord from local storage
+	RemoveSignedPreKey(signedPreKeyID uint32)
+}