1 files changed, 16 insertions, 43 deletions

diff --git a/nizk/commit/commit.go b/nizk/commit/commit.go
index d9d06b5..5238c15 100644
--- a/nizk/commit/commit.go
+++ b/nizk/commit/commit.go
@@ -1,9 +1,7 @@
 package commit
 
 import (
-	"crypto/sha512"
-
-	"kesim.org/seal/curve"
+	. "kesim.org/seal/nizk"
 )
 
 // This is a construction of a proof of a statement of the form
@@ -11,13 +9,6 @@ import (
 //		|| [(Φ = g^(αβ+1)) && (A = g^α) && (Β = g^β)]
 // for given Φ, A and B
 
-type Scalar = curve.Curve25519Scalar
-type Point = curve.Curve25519Point
-
-var Curve = curve.Curve25519
-var g = Curve.Generator()
-var one = Curve.ScalarOne()
-
 type Statement struct {
 	α    *Scalar
 	β    *Scalar
@@ -45,14 +36,14 @@ func commitment(α, β *Scalar, plus bool) *Commitment {
 	φ := α.Mul(β)
 
 	if plus {
-		Φ = g.Exp(φ.Add(one))
+		Φ = G.Exp(φ.Add(One))
 	} else {
-		Φ = g.Exp(φ)
+		Φ = G.Exp(φ)
 	}
 	return &Commitment{
 		Φ: Φ,
-		A: g.Exp(α),
-		B: g.Exp(β),
+		A: G.Exp(α),
+		B: G.Exp(β),
 	}
 }
 
@@ -72,25 +63,19 @@ func (s *Statement) Proof() *Proof {
 	r2 = Curve.RandomScalar()
 	ω = Curve.RandomScalar()
 
-	if s == nil {
-		panic("s is nil")
-	} else if ω == nil {
-		panic("ω is nil")
-	}
-
 	if s.plus {
-		ε[0][0] = g.Exp(r1)
-		ε[0][1] = s.B.Exp(r1).Mul(g.Exp(ω))
-		ε[1][0] = g.Exp(r2)
+		ε[0][0] = G.Exp(r1)
+		ε[0][1] = s.B.Exp(r1).Mul(G.Exp(ω))
+		ε[1][0] = G.Exp(r2)
 		ε[1][1] = s.B.Exp(r2)
 	} else {
-		ε[0][0] = g.Exp(r1)
+		ε[0][0] = G.Exp(r1)
 		ε[0][1] = s.B.Exp(r1)
-		ε[1][0] = g.Exp(r2).Mul(s.A.Exp(ω))
-		ε[1][1] = s.B.Exp(r2).Mul(s.Φ.Div(g).Exp(ω))
+		ε[1][0] = G.Exp(r2).Mul(s.A.Exp(ω))
+		ε[1][1] = s.B.Exp(r2).Mul(s.Φ.Div(G).Exp(ω))
 	}
 
-	ch := challenge(g, s.Φ, s.A, s.B, ε[0][0], ε[0][1], ε[1][0], ε[1][1])
+	ch := Challenge(G, s.Φ, s.A, s.B, ε[0][0], ε[0][1], ε[1][0], ε[1][1])
 	pr := &Proof{}
 
 	if s.plus {
@@ -108,24 +93,12 @@ func (s *Statement) Proof() *Proof {
 	return pr
 }
 
-func challenge(points ...*Point) *Scalar {
-	h512 := sha512.New()
-	for _, p := range points {
-		h512.Write(p.Bytes())
-	}
-	ch, e := Curve.ScalarFromBytes(h512.Sum(nil))
-	if e != nil {
-		panic(e)
-	}
-	return ch
-}
-
 func (c *Commitment) Verify(p *Proof) bool {
 	var ε [2][2]*Point
-	ε[0][0] = g.Exp(p.Rho[0]).Mul(c.A.Exp(p.Ch[0]))
+	ε[0][0] = G.Exp(p.Rho[0]).Mul(c.A.Exp(p.Ch[0]))
 	ε[0][1] = c.B.Exp(p.Rho[0]).Mul(c.Φ.Exp(p.Ch[0]))
-	ε[1][0] = g.Exp(p.Rho[1]).Mul(c.A.Exp(p.Ch[1]))
-	ε[1][1] = c.B.Exp(p.Rho[1]).Mul(c.Φ.Div(g).Exp(p.Ch[1]))
-	ch := challenge(g, c.Φ, c.A, c.B, ε[0][0], ε[0][1], ε[1][0], ε[1][1])
+	ε[1][0] = G.Exp(p.Rho[1]).Mul(c.A.Exp(p.Ch[1]))
+	ε[1][1] = c.B.Exp(p.Rho[1]).Mul(c.Φ.Div(G).Exp(p.Ch[1]))
+	ch := Challenge(G, c.Φ, c.A, c.B, ε[0][0], ε[0][1], ε[1][0], ε[1][1])
 	return p.Ch[0].Add(p.Ch[1]).Equal(ch)
 }