Official cwtch.im peer and server implementations. https://cwtch.im
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package model
import (
"crypto/rand"
"cwtch.im/cwtch/protocol"
"errors"
"fmt"
"git.openprivacy.ca/openprivacy/libricochet-go/utils"
"github.com/golang/protobuf/proto"
"golang.org/x/crypto/nacl/secretbox"
"io"
"log"
"sync"
"time"
)
// Group defines and encapsulates Cwtch's conception of group chat. Which are sessions
// tied to a server under a given group key. Each group has a set of messages.
type Group struct {
GroupID string
SignedGroupID []byte
GroupKey [32]byte
GroupServer string
Timeline Timeline
Accepted bool
Owner string
IsCompromised bool
InitialMessage []byte
Attributes map[string]string
lock sync.Mutex
NewMessage chan Message `json:"-"`
}
// NewGroup initializes a new group associated with a given CwtchServer
func NewGroup(server string) (*Group, error) {
group := new(Group)
group.GroupServer = server
var groupID [16]byte
if _, err := io.ReadFull(rand.Reader, groupID[:]); err != nil {
log.Printf("Error: Cannot read from random: %v\n", err)
return nil, err
}
group.GroupID = fmt.Sprintf("%x", groupID)
var groupKey [32]byte
if _, err := io.ReadFull(rand.Reader, groupKey[:]); err != nil {
log.Printf("Error: Cannot read from random: %v\n", err)
return nil, err
}
copy(group.GroupKey[:], groupKey[:])
group.Owner = "self"
group.Attributes = make(map[string]string)
return group, nil
}
// SignGroup adds a signature to the group.
func (g *Group) SignGroup(signature []byte) {
g.SignedGroupID = signature
copy(g.Timeline.SignedGroupID[:], g.SignedGroupID)
}
// Compromised should be called if we detect a a groupkey leak.
func (g *Group) Compromised() {
g.IsCompromised = true
}
// GetInitialMessage returns the first message of the group, if one was sent with the invite.
func (g *Group) GetInitialMessage() []byte {
g.lock.Lock()
defer g.lock.Unlock()
return g.InitialMessage
}
// Invite generates a invitation that can be sent to a cwtch peer
func (g *Group) Invite(initialMessage []byte) ([]byte, error) {
if g.SignedGroupID == nil {
return nil, errors.New("group isn't signed")
}
g.InitialMessage = initialMessage[:]
gci := &protocol.GroupChatInvite{
GroupName: g.GroupID,
GroupSharedKey: g.GroupKey[:],
ServerHost: g.GroupServer,
SignedGroupId: g.SignedGroupID[:],
InitialMessage: initialMessage[:],
}
cp := &protocol.CwtchPeerPacket{
GroupChatInvite: gci,
}
invite, err := proto.Marshal(cp)
return invite, err
}
// AddMessage takes a DecryptedGroupMessage and adds it to the Groups Timeline
func (g *Group) AddMessage(message *protocol.DecryptedGroupMessage, sig []byte) *Message {
g.lock.Lock()
timelineMessage := &Message{
Message: message.GetText(),
Timestamp: time.Unix(int64(message.GetTimestamp()), 0),
Received: time.Now(),
Signature: sig,
PeerID: message.GetOnion(),
PreviousMessageSig: message.GetPreviousMessageSig(),
}
seen := g.Timeline.Insert(timelineMessage)
g.lock.Unlock()
// Send a new Message notification if we have an app that is listening.
if g.NewMessage != nil && !seen {
g.NewMessage <- *timelineMessage
}
return timelineMessage
}
// GetTimeline provides a safe copy of the timeline-=
func (g *Group) GetTimeline() (t []Message) {
g.lock.Lock()
t = g.Timeline.GetMessages()
g.lock.Unlock()
return
}
//EncryptMessage takes a message and encrypts the message under the group key.
func (g *Group) EncryptMessage(message *protocol.DecryptedGroupMessage) ([]byte, error) {
var nonce [24]byte
if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
log.Printf("Error: Cannot read from random: %v\n", err)
return nil, err
}
wire, err := proto.Marshal(message)
utils.CheckError(err)
encrypted := secretbox.Seal(nonce[:], []byte(wire), &nonce, &g.GroupKey)
return encrypted, nil
}
// DecryptMessage takes a ciphertext and returns true and the decrypted message if the
// cipher text can be successfully decrypted,else false.
func (g *Group) DecryptMessage(ciphertext []byte) (bool, *protocol.DecryptedGroupMessage) {
var decryptNonce [24]byte
copy(decryptNonce[:], ciphertext[:24])
decrypted, ok := secretbox.Open(nil, ciphertext[24:], &decryptNonce, &g.GroupKey)
if ok {
dm := &protocol.DecryptedGroupMessage{}
err := proto.Unmarshal(decrypted, dm)
if err == nil {
return true, dm
}
}
return false, nil
}
// SetAttribute allows applications to store arbitrary configuration info at the group level.
func (g *Group) SetAttribute(name string, value string) {
g.lock.Lock()
defer g.lock.Unlock()
g.Attributes[name] = value
}
// GetAttribute returns the value of a value set with SetAttribute. If no such value has been set exists is set to false.
func (g *Group) GetAttribute(name string) (value string, exists bool) {
g.lock.Lock()
defer g.lock.Unlock()
value, exists = g.Attributes[name]
return
}