func (jv *JVSS) initSecret(sid SID) error {
// Initialise shared secret of given type if necessary
if _, ok := jv.secrets[sid]; !ok {
log.Lvl2(fmt.Sprintf("Node %d: Initialising %s shared secret", jv.Index(), sid))
sec := &Secret{
receiver: poly.NewReceiver(jv.keyPair.Suite, jv.info, jv.keyPair),
deals: make(map[int]*poly.Deal),
sigs: make(map[int]*poly.SchnorrPartialSig),
numConfs: 0,
}
jv.secrets[sid] = sec
}
secret := jv.secrets[sid]
// Initialise and broadcast our deal if necessary
if len(secret.deals) == 0 {
kp := config.NewKeyPair(jv.keyPair.Suite)
deal := new(poly.Deal).ConstructDeal(kp, jv.keyPair, jv.info.T, jv.info.R, jv.pubKeys)
log.Lvl2(fmt.Sprintf("Node %d: Initialising %v deal", jv.Index(), sid))
secret.deals[jv.Index()] = deal
db, _ := deal.MarshalBinary()
msg := &SecInitMsg{
Src: jv.Index(),
SID: sid,
Deal: db,
}
if err := jv.Broadcast(msg); err != nil {
return err
}
}
return nil
}
// ComputeSharedSecret will make the exchange of dealers between
// the peers and will compute the sharedsecret at the end
func (p *Peer) ComputeSharedSecret() *poly.SharedSecret {
// Construct the dealer
dealerKey := cliutils.KeyPair(p.suite)
dealer := new(poly.Deal).ConstructDeal(&dealerKey, &p.key, p.info.T, p.info.R, p.pubKeys)
// Construct the receiver
receiver := poly.NewReceiver(p.suite, p.info, &p.key)
// add already its own dealer
_, err := receiver.AddDeal(p.Id, dealer)
if err != nil {
dbg.Fatal(p.String(), "could not add its own dealer >< ABORT")
}
// Send the dealer struct TO every one
err = p.SendToAll(dealer)
dbg.Lvl3(p.Name, "sent its dealer to every peers. (err =", err, ")")
// Receive the dealer struct FROM every one
// wait with a chan to get ALL dealers
dealChan := make(chan *poly.Deal)
for _, rp := range p.remote {
go func(rp RemotePeer) {
d := new(poly.Deal).UnmarshalInit(p.info.T, p.info.R, p.info.N, p.suite)
err := p.suite.Read(rp.Conn, d)
if err != nil {
dbg.Fatal(p.Name, "received a strange dealer from", rp.String(), ":", err)
}
dealChan <- d
}(rp)
}
// wait to get all dealers
dbg.Lvl3(p.Name, "wait to receive every other peer's dealer...")
n := 0
for {
// get the dealer and add it
d := <-dealChan
dbg.Lvl3(p.Name, "collected one more dealer (count =", n, ")")
// TODO: get the response back to the dealer
_, err := receiver.AddDeal(p.Id, d)
if err != nil {
dbg.Fatal(p.Name, "has error when adding the dealer:", err)
}
n += 1
// we get enough dealers to compute the shared secret
if n == p.info.T-1 {
dbg.Lvl3(p.Name, "received every Dealers")
break
}
}
sh, err := receiver.ProduceSharedSecret()
if err != nil {
dbg.Fatal(p.Name, "could not produce shared secret. Abort. (err", err, ")")
}
dbg.Lvl3(p.Name, "produced shared secret !")
return sh
}
func (jv *JVSS) initSecret(sid SID) error {
if sid.IsLTSS() && jv.ltssInit {
return errors.New("Only one longterm secret allowed per JVSS instance")
}
// Initialise shared secret of given type if necessary
if sec, err := jv.secrets.secret(sid); sec == nil && err != nil {
log.Lvlf4("Node %d: Initialising %s shared secret", jv.Index(),
sid)
sec := &secret{
receiver: poly.NewReceiver(jv.keyPair.Suite, jv.info, jv.keyPair),
deals: make(map[int]*poly.Deal),
sigs: make(map[int]*poly.SchnorrPartialSig),
numLongtermConfs: 0,
}
jv.secrets.addSecret(sid, sec)
}
secret, err := jv.secrets.secret(sid)
if err != nil { // this should never happen here
log.Error(err)
return err
}
// Initialise and broadcast our deal if necessary
if len(secret.deals) == 0 {
kp := config.NewKeyPair(jv.keyPair.Suite)
deal := new(poly.Deal).ConstructDeal(kp, jv.keyPair, jv.info.T, jv.info.R, jv.pubKeys)
log.Lvlf4("Node %d: Initialising %v deal", jv.Index(), sid)
secret.deals[jv.Index()] = deal
db, _ := deal.MarshalBinary()
msg := &SecInitMsg{
Src: jv.Index(),
SID: sid,
Deal: db,
}
if err := jv.Broadcast(msg); err != nil {
log.Print(jv.Name(), "Error broadcast secInit:", err)
return err
}
}
return nil
}
// First, let's generate the set of dealers and the set of receivers.
// A dealer create a secret and can distribute shares of its secret
// A receiver is one that receives such a share.
// A dealer create its shares and then encrypt each share for the respective
// receivers. In order to do that, a dealers need to know each public key of the
// receivers, so it can encrypt each share with the respective public key. That
// way, only the respective receiver can decrypt its own share.
// The joint.go library is designed such that the set of dealers and receivers
// can be completely disjoint. However, since the goal is to be able to
// reconstruct a secret from some shares, there is a mimimal threshold of share
// to have in order to reconstruct that secret. Therefore, the number of dealers
// must AT LEAST be equal to that threshold (info.T in our example)
func generateDealerReceiver(info poly.Threshold, ndeals, nreceivers int) ([]*poly.Deal, []*poly.Receiver) {
// Generate the keys of the receivers
receiverKeys := generateKeyPairList(nreceivers)
// From it construct the list of the public keys that must be given to a
// dealer. This is list is KNOWN.
receiverPublics := generatePublicListFromPrivate(receiverKeys)
receivers := make([]*poly.Receiver, nreceivers)
for i := 0; i < nreceivers; i++ {
// Create a receiver by giving it the suite, the info about the
// polynomials used and its private / public key
receivers[i] = poly.NewReceiver(suite, info, receiverKeys[i])
}
dealers := make([]*poly.Deal, ndeals)
for i := 0; i < ndeals; i++ {
// Create a deal (holded by a dealer) with a fresh longterm, ephemereal
// public /private key, the info, and the public keys of the receivers
dealers[i] = new(poly.Deal).ConstructDeal(generateKeyPair(), generateKeyPair(), info.T, info.R, receiverPublics)
}
return dealers, receivers
}
