diff --git a/dfssc/sign/protocol.go b/dfssc/sign/protocol.go
index 617a2593d0edfec9a9808a8aad4e3dccd82a8f98..21a870c01e6d43c8fc59096e05ec5d9104b39f6b 100644
--- a/dfssc/sign/protocol.go
+++ b/dfssc/sign/protocol.go
@@ -18,6 +18,12 @@ import (
 // * Promises rounds
 // * Signature round
 func (m *SignatureManager) Sign() error {
+
+	defer func() {
+		m.finished = true
+		m.closeConnections()
+	}()
+
 	myID, nextIndex, err := m.Initialize()
 	if err != nil {
 		return err
@@ -72,9 +78,7 @@ func (m *SignatureManager) Sign() error {
 	dAPI.DLog("exiting signature round")
 	m.OnProgressUpdate(seqLen+1, seqLen+1)
 
-	// Network's job is done, cleaning time
-	// Shutdown and platform client and TODO peer server & connections
-	return m.platformConn.Close()
+	return nil
 }
 
 // GetClient retrieves the Client to the specified sequence id provided it exists
@@ -135,11 +139,13 @@ func (m *SignatureManager) promiseRound(pendingSet, sendSet []uint32, myID uint3
 	}
 }
 
-// closeAllPeerClient tries to close all established connection with other peers
-func (m *SignatureManager) closeAllPeerClient() {
-	for k, client := range m.peersConn {
-		_ = client.Close()
-		// Remove associated grpc client
+// closeConnections tries to close all established connection with other peers and platform.
+// It also stops the local server.
+func (m *SignatureManager) closeConnections() {
+	_ = m.platformConn.Close()
+	for k, peer := range m.peersConn {
+		_ = peer.Close()
 		delete(m.peers, k)
 	}
+	m.cServer.Stop()
 }
diff --git a/dfssc/sign/starter.go b/dfssc/sign/starter.go
index d69eb0f716630af5efdf2361f50acdc1d9c91c25..dded16ca2394df08b77fbef829b2ac21525e901a 100644
--- a/dfssc/sign/starter.go
+++ b/dfssc/sign/starter.go
@@ -3,7 +3,6 @@ package sign
 import (
 	"errors"
 	"fmt"
-	"log"
 	"strconv"
 	"sync"
 	"time"
@@ -43,10 +42,13 @@ type SignatureManager struct {
 	mail         string
 	archives     *Archives
 	seal         []byte
+	cancelled    bool
+	finished     bool
 
 	// Callbacks
 	OnSignerStatusUpdate func(mail string, status SignerStatus, data string)
 	OnProgressUpdate     func(current int, end int)
+	Cancel               chan interface{}
 }
 
 // Archives stores the received and sent messages, as evidence if needed
@@ -69,6 +71,7 @@ func NewSignatureManager(passphrase string, c *contract.JSON) (*SignatureManager
 			sentSignatures:     make([]*cAPI.Signature, 0),
 			receivedSignatures: make([]*cAPI.Signature, 0),
 		},
+		Cancel: make(chan interface{}),
 	}
 	var err error
 	_, _, _, err = m.auth.LoadFiles()
@@ -80,7 +83,7 @@ func NewSignatureManager(passphrase string, c *contract.JSON) (*SignatureManager
 	dAPI.SetIdentifier(m.mail)
 
 	m.cServer = m.GetServer()
-	go func() { log.Fatalln(net.Listen("0.0.0.0:"+strconv.Itoa(viper.GetInt("local_port")), m.cServer)) }()
+	go func() { _ = net.Listen("0.0.0.0:"+strconv.Itoa(viper.GetInt("local_port")), m.cServer) }()
 
 	conn, err := net.Connect(viper.GetString("platform_addrport"), m.auth.Cert, m.auth.Key, m.auth.CA, nil)
 	if err != nil {
@@ -114,28 +117,49 @@ func (m *SignatureManager) ConnectToPeers() error {
 		Ip:           localIps,
 	})
 	if err != nil {
+		m.finished = true
+		m.closeConnections()
 		return err
 	}
 
-	for {
+	c := make(chan error)
+	go connectToPeersLoop(m, stream, c)
+
+	select {
+	case err = <-c:
+		if err != nil {
+			m.finished = true
+			m.closeConnections()
+		}
+		return err
+	case <-m.Cancel:
+		m.cancelled = true
+		m.closeConnections()
+		return errors.New("Signature cancelled")
+	}
+}
+
+func connectToPeersLoop(m *SignatureManager, stream pAPI.Platform_JoinSignatureClient, c chan error) {
+	for !m.cancelled {
 		userConnected, err := stream.Recv()
 		if err != nil {
-			return err
+			c <- err
+			return
 		}
 		errorCode := userConnected.GetErrorCode()
 		if errorCode.Code != pAPI.ErrorCode_SUCCESS {
-			return errors.New(errorCode.Message)
+			c <- errors.New(errorCode.Message)
+			return
 		}
 		ready, err := m.addPeer(userConnected.User)
 		if err != nil {
 			continue // Unable to connect to this user, ignore it for the moment
 		}
 		if ready {
-			break
+			c <- nil
+			return
 		}
 	}
-
-	return nil
 }
 
 // addPeer stores a peer from the platform and tries to establish a connection to this peer.
@@ -158,6 +182,11 @@ func (m *SignatureManager) addPeer(user *pAPI.User) (ready bool, err error) {
 		if err == nil {
 			break
 		}
+
+		if m.cancelled {
+			err = errors.New("Signature cancelled")
+			break
+		}
 	}
 
 	if err != nil {
@@ -200,28 +229,46 @@ func (m *SignatureManager) addPeer(user *pAPI.User) (ready bool, err error) {
 func (m *SignatureManager) SendReadySign() (signatureUUID string, err error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Minute)
 	defer cancel()
-	launch, err := m.platform.ReadySign(ctx, &pAPI.ReadySignRequest{
-		ContractUuid: m.contract.UUID,
-	})
-	if err != nil {
+
+	c := make(chan *pAPI.LaunchSignature)
+	go func() {
+		launch, _ := m.platform.ReadySign(ctx, &pAPI.ReadySignRequest{
+			ContractUuid: m.contract.UUID,
+		})
+		c <- launch
+	}()
+
+	var launch *pAPI.LaunchSignature
+	select {
+	case launch = <-c: // OK
+	case <-m.Cancel:
+		m.cancelled = true
+		m.closeConnections()
+		err = errors.New("Signature cancelled")
 		return
 	}
 
 	errorCode := launch.GetErrorCode()
 	if errorCode.Code != pAPI.ErrorCode_SUCCESS {
 		err = errors.New(errorCode.Code.String() + " " + errorCode.Message)
+		m.finished = true
+		m.closeConnections()
 		return
 	}
 
 	// Check signers from platform data
 	if len(m.contract.Signers) != len(launch.KeyHash) {
 		err = errors.New("Corrupted DFSS file: bad number of signers, unable to sign safely")
+		m.finished = true
+		m.closeConnections()
 		return
 	}
 
 	for i, s := range m.contract.Signers {
 		if s.Hash != fmt.Sprintf("%x", launch.KeyHash[i]) {
 			err = errors.New("Corrupted DFSS file: signer " + s.Email + " has an invalid hash, unable to sign safely")
+			m.finished = true
+			m.closeConnections()
 			return
 		}
 	}
@@ -264,3 +311,8 @@ func (m *SignatureManager) FindID() (uint32, error) {
 	}
 	return 0, errors.New("Mail couldn't be found amongst signers")
 }
+
+// IsTerminated returns true if the signature is cancelled or finished
+func (m *SignatureManager) IsTerminated() bool {
+	return m.cancelled || m.finished
+}
diff --git a/gui/signform/signform.go b/gui/signform/signform.go
index 74b855db678f2d0465922be717d41cd1c5a2def1..5f8ead1c50f7d7357f7244397f4c648e901fee21 100644
--- a/gui/signform/signform.go
+++ b/gui/signform/signform.go
@@ -22,9 +22,11 @@ type Widget struct {
 	table                    *ui.QTableWidget
 	progressBar              *ui.QProgressBar
 	feedbackLabel            *ui.QLabel
+	cancelButton             *ui.QPushButton
 	lines                    []line
 	statusMax, statusCurrent int32
 	feedback                 string
+	running                  bool
 }
 
 func NewWidget(contract *contract.JSON, pwd string) *Widget {
@@ -40,6 +42,7 @@ func NewWidget(contract *contract.JSON, pwd string) *Widget {
 	w.feedbackLabel = ui.NewLabelFromDriver(w.FindChild("mainLabel"))
 	w.table = ui.NewTableWidgetFromDriver(w.FindChild("signersTable"))
 	w.progressBar = ui.NewProgressBarFromDriver(w.FindChild("progressBar"))
+	w.cancelButton = ui.NewPushButtonFromDriver(w.FindChild("cancelButton"))
 
 	m, err := sign.NewSignatureManager(
 		pwd,
@@ -56,6 +59,18 @@ func NewWidget(contract *contract.JSON, pwd string) *Widget {
 		w.statusMax = int32(max)
 	}
 
+	w.cancelButton.OnClicked(func() {
+		// Render an immediate feedback to user
+		f := "Cancelling signature process..."
+		w.feedback = f
+		w.feedbackLabel.SetText(f)
+		w.cancelButton.SetDisabled(true)
+		w.statusMax = 1
+		w.statusCurrent = 0
+		// Ask for cancellation in a separate goroutine to avoid blocking Qt
+		go func() { w.manager.Cancel <- true }()
+	})
+
 	w.initLines()
 	w.signerUpdated(viper.GetString("email"), sign.StatusConnected, "It's you!")
 	go func() {
@@ -70,6 +85,8 @@ func NewWidget(contract *contract.JSON, pwd string) *Widget {
 	return w
 }
 
+// execute() is called in a goroutine OUTSIDE of Qt loop.
+// WE SHOULD NOT CALL ANY QT FUNCTION FROM IT.
 func (w *Widget) execute() error {
 	w.feedback = "Connecting to peers..."
 	err := w.manager.ConnectToPeers()
@@ -84,6 +101,7 @@ func (w *Widget) execute() error {
 	}
 
 	w.feedback = "Signature in progress..."
+	w.running = true
 	err = w.manager.Sign()
 	if err != nil {
 		return err
@@ -109,6 +127,7 @@ func (w *Widget) Tick() {
 	w.feedbackLabel.SetText(w.feedback)
 	w.progressBar.SetMaximum(w.statusMax)
 	w.progressBar.SetValue(w.statusCurrent)
+	w.cancelButton.SetDisabled(w.running || w.manager.IsTerminated())
 	for _, l := range w.lines {
 		l.cellA.SetIcon(icons[l.status])
 		l.cellA.SetText(icons_labels[l.status])