Add check in mta_proof (bnb-chain#205)

* Add check in mta_proof

* go fmt on range_proof.go

This reverts commit 4871684.

(cherry picked from commit bde1ac3)

Author: yycen

crypto/mta/proofs.go

@@ -194,6 +194,20 @@ func (pf *ProofBobWC) Verify(ec elliptic.Curve, pk *paillier.PublicKey, NTilde,
 	q3 := new(big.Int).Mul(q, q)
 	q3 = new(big.Int).Mul(q, q3)
 
+	gcd := big.NewInt(0)
+	if pf.S.Cmp(zero) == 0 {
+		return false
+	}
+	if gcd.GCD(nil, nil, pf.S, pk.N).Cmp(one) != 0 {
+		return false
+	}
+	if pf.V.Cmp(zero) == 0 {
+		return false
+	}
+	if gcd.GCD(nil, nil, pf.V, pk.N).Cmp(one) != 0 {
+		return false
+	}
+
 	// 3.
 	if pf.S1.Cmp(q3) > 0 {
 		return false

crypto/mta/range_proof.go

@@ -22,6 +22,7 @@ const (
 
 var (
 	zero = big.NewInt(0)
+	one  = big.NewInt(1)
 )
 
 type (