diff --git a/go.mod b/go.mod
index 6613c8e..afc3196 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module example
 go 1.14
 
 require (
-	github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210117185306-6b939806742d
+	github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210209195150-ac5d00b89229
 	github.com/gin-gonic/gin v1.6.3 // indirect
 	github.com/stretchr/testify v1.6.1
 )
diff --git a/go.sum b/go.sum
index db054ef..e83a3d5 100644
--- a/go.sum
+++ b/go.sum
@@ -22,6 +22,8 @@ github.com/allegro/bigcache v1.2.1-0.20190218064605-e24eb225f156/go.mod h1:Cb/ax
 github.com/aristanetworks/goarista v0.0.0-20170210015632-ea17b1a17847/go.mod h1:D/tb0zPVXnP7fmsLZjtdUhSsumbK/ij54UXjjVgMGxQ=
 github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210117185306-6b939806742d h1:F42/D0P7nMaLqHc/7f4P3PxyMNAiqZWxWrF3C/et6FM=
 github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210117185306-6b939806742d/go.mod h1:10oM1DQMpukFfSzNsjSQG2rE6UjoGsXT4iIxWIiVbu0=
+github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210209195150-ac5d00b89229 h1:sGoixDV1snh3rbWslF6wjGsBvGoM3Ca/I5H+NR3YvG0=
+github.com/arnaucube/go-blindsecp256k1 v0.0.0-20210209195150-ac5d00b89229/go.mod h1:10oM1DQMpukFfSzNsjSQG2rE6UjoGsXT4iIxWIiVbu0=
 github.com/aws/aws-sdk-go v1.25.48/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
 github.com/btcsuite/btcd v0.0.0-20171128150713-2e60448ffcc6 h1:Eey/GGQ/E5Xp1P2Lyx1qj007hLZfbi0+CoVeJruGCtI=
diff --git a/main.go b/main.go
index d93e7b9..ff3c248 100644
--- a/main.go
+++ b/main.go
@@ -39,7 +39,12 @@ func postBlindSign(c *gin.Context) {
 		return
 	}
 	k := secretRs[key]
-	sBlind := sk.BlindSign(m, k)
+	sBlind, err := sk.BlindSign(m, k)
+	if err != nil {
+		c.String(http.StatusBadRequest, "err on BlindSign: "+err.Error())
+		return
+	}
+	delete(secretRs, key)
 	c.JSON(http.StatusOK, gin.H{"sBlind": sBlind.String()})
 }
 
@@ -53,5 +58,5 @@ func main() {
 	r.POST("/blindsign", postBlindSign)
 	r.Static("/web", "./client")
 
-	r.Run(":3000")
+	r.Run("127.0.0.1:3000")
 }