double ratchet first implementation

client/identity.go

@@ -15,6 +15,7 @@ import (
 	"forge.redroom.link/yves/meowlib"
 	"github.com/ProtonMail/gopenpgp/v2/helper"
 	"github.com/google/uuid"
+	doubleratchet "github.com/status-im/doubleratchet"
 )
 
 const maxHiddenCount = 30
@@ -122,6 +123,21 @@ func (id *Identity) InvitePeer(MyName string, ContactName string, MessageServerU
 	peer.MyPullServers = MessageServerUids
 	peer.MyName = MyName
 	peer.InvitationMessage = InvitationMessage
+
+	// Generate DR keypair and root key for the initiator side
+	drKp, err := doubleratchet.DefaultCrypto{}.GenerateDH()
+	if err != nil {
+		return nil, err
+	}
+	peer.DrKpPrivate = base64.StdEncoding.EncodeToString(drKp.PrivateKey())
+	peer.DrKpPublic = base64.StdEncoding.EncodeToString(drKp.PublicKey())
+	drRootKey := make([]byte, 32)
+	if _, err = rand.Read(drRootKey); err != nil {
+		return nil, err
+	}
+	peer.DrRootKey = base64.StdEncoding.EncodeToString(drRootKey)
+	peer.DrInitiator = true
+
 	id.Peers.StorePeer(&peer)
 
 	return &peer, nil
@@ -187,6 +203,10 @@ func (id *Identity) AnswerInvitation(MyName string, ContactName string, MessageS
 	peer.MyPullServers = MessageServerIdxs
 	peer.MyName = MyName
 	peer.InvitationId = ReceivedContact.InvitationId
+	// Adopt DR material from the initiator's ContactCard
+	peer.DrRootKey = ReceivedContact.DrRootKey
+	peer.ContactDrPublicKey = ReceivedContact.DrPublicKey
+	peer.DrInitiator = false
 	id.Peers.StorePeer(&peer)
 
 	return &peer, nil