2 files changed, 40 insertions, 4 deletions
diff --git a/nizk/stage2/stage2.go b/nizk/stage2/stage2.go
index a17000f..88bfa59 100644
--- a/nizk/stage2/stage2.go
+++ b/nizk/stage2/stage2.go
@@ -47,7 +47,16 @@ type Commitment struct {
 	Z_ *Point
 }
 
-func NewStatement(typ Type, a, b, r, x, y, r_, x_, y_ *Scalar) *Statement {
+func NewStatement(typ Type) *Statement {
+	var s [8]*Scalar
+	for i := range s {
+		s[i] = Curve.RandomScalar()
+	}
+
+	return NewStatementFromScalars(typ, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7])
+}
+
+func NewStatementFromScalars(typ Type, a, b, r, x, y, r_, x_, y_ *Scalar) *Statement {
 	if typ > Set || typ < None {
 		panic("unknown type")
 	}
diff --git a/nizk/stage2/stage2_test.go b/nizk/stage2/stage2_test.go
index e4e6e5c..a33a468 100644
--- a/nizk/stage2/stage2_test.go
+++ b/nizk/stage2/stage2_test.go
@@ -7,16 +7,43 @@ import (
 )
 
 func TestVerification(t *testing.T) {
+	var st [3]*Statement
+	for i, typ := range []Type{None, Unset, Set} {
+		st[i] = NewStatement(typ)
+		c, p := st[i].Commit(), st[i].Proof()
+		if !c.Verify(p) {
+			t.Fatalf("Couldn't verify proof for %v, case %d\n", typ, i)
+		}
+	}
+
+	for _, ind := range [][2]int{{0, 1}, {1, 2}, {2, 0}} {
+		c, p := st[ind[0]].Commit(), st[ind[1]].Proof()
+		if c.Verify(p) {
+			t.Fatalf("Shouldn't be able to verify %d with proof %d", ind[0], ind[1])
+		}
+	}
+}
+
+func TestVerificationFromScalar(t *testing.T) {
 	var s [8]*Scalar
+	var st [3]*Statement
+
 	for i := range s {
 		s[i] = Curve.RandomScalar()
 	}
 
 	for i, typ := range []Type{None, Unset, Set} {
-		st := NewStatement(typ, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7])
-		c, p := st.Commit(), st.Proof()
+		st[i] = NewStatementFromScalars(typ, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7])
+		c, p := st[i].Commit(), st[i].Proof()
 		if !c.Verify(p) {
 			t.Fatalf("Couldn't verify proof for %v, case %d\n", typ, i)
 		}
 	}
-}
-\ No newline at end of file
+
+	for _, ind := range [][2]int{{0, 1}, {1, 2}, {2, 1}, {2, 0}} {
+		c, p := st[ind[0]].Commit(), st[ind[1]].Proof()
+		if c.Verify(p) {
+			t.Fatalf("Shouldn't be able to verify %d with proof %d", ind[0], ind[1])
+		}
+	}
+}