From 1dd0089e5f689eef3464452fbc70f0adf11d8ebc Mon Sep 17 00:00:00 2001
From: Özgür Kesim <oec@codeblau.de>
Date: Wed, 13 Nov 2024 18:06:47 +0100
Subject: WiP: stage2 refactor started, no functioning test

---
 nizk/stage2.go      | 21 ++++++++++++---------
 nizk/stage2_test.go | 14 +++++++++++++-
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/nizk/stage2.go b/nizk/stage2.go
index efdda9c..8747ebf 100644
--- a/nizk/stage2.go
+++ b/nizk/stage2.go
@@ -4,16 +4,15 @@ import (
 	. "kesim.org/seal/common"
 )
 
-func (b *Bit) CommitStage2(lost bool, prev *Stage) (s *Stage, c *StageCommitment, p *Stage2Proof) {
+func (b *Bit) CommitStage2(lost bool, prev *Stage) (s *Stage, c *StageCommitment) {
 	x := Curve.RandomScalar()
 	r := Curve.RandomScalar()
 	return b.CommitStage2FromScalars(lost, prev, x, r)
 }
 
-func (b *Bit) CommitStage2FromScalars(lost bool, prev *Stage, x, r *Scalar) (s *Stage, c *StageCommitment, p *Stage2Proof) {
+func (b *Bit) CommitStage2FromScalars(lost bool, prev *Stage, x, r *Scalar) (s *Stage, c *StageCommitment) {
 	s = b.stage(x, r)
 	c = s.commit(lost)
-	p = s.proof2(lost, prev)
 	return
 }
 
@@ -32,7 +31,7 @@ type Stage2Proof struct {
 	R3 [2]*Scalar
 }
 
-func (s *Stage) proof2(lost bool, prev *Stage) *Stage2Proof {
+func (s *Stage) proof2(lost bool, prev *Stage) (rev *StageReveal, pr *Stage2Proof, e error) {
 	var (
 		e1, e1_ [3]Bytes
 		e2, e2_ [3]Bytes
@@ -53,9 +52,13 @@ func (s *Stage) proof2(lost bool, prev *Stage) *Stage2Proof {
 	bc := prev.bit.com
 	pc := prev.com
 	rvp := prev.rev
-	rev := &StageReveal{
-		Y: G.Exp(Curve.RandomScalar()), // TODO! BUG! THIS HAS TO BE Pj<i(X_j)/Pj>i(X_j)
-	}
+
+	// TODO: Calculate Y based on the Xs and our own X_i
+	// as Π_(i<k) X_k / Π_(i>k) X_k
+	// For now:
+	Y := G.Exp(Curve.RandomScalar())
+
+	rev = &StageReveal{Y: Y}
 	if s.bit.IsSet() {
 		rev.Z = c.R.Exp(s.x)
 	} else {
@@ -141,7 +144,7 @@ func (s *Stage) proof2(lost bool, prev *Stage) *Stage2Proof {
 	points = append(points, e3_[:]...)
 
 	ch := Challenge(points...)
-	pr := &Stage2Proof{}
+	pr = &Stage2Proof{}
 
 	if lost {
 		pr.Ch[0] = w[0]
@@ -193,7 +196,7 @@ func (s *Stage) proof2(lost bool, prev *Stage) *Stage2Proof {
 	}
 
 	s.prf2 = pr
-	return pr
+	return rev, pr, e
 }
 
 func (c *Commitment) VerifyStage2(pcom, ccom *StageCommitment, prev, crev *StageReveal, p *Stage2Proof) bool {
diff --git a/nizk/stage2_test.go b/nizk/stage2_test.go
index 75c99ef..4d507d7 100644
--- a/nizk/stage2_test.go
+++ b/nizk/stage2_test.go
@@ -3,11 +3,23 @@ package nizk
 import (
 	"testing"
 
-//	. "kesim.org/seal/common"
+	// . "kesim.org/seal/common"
 )
 
 func TestStage2Simple(t *testing.T) {
+/*
+	id := Curve.RandomScalar()
+	b1 := NewBit(id, true)
+	b2 := NewBit(id, true)
 
+	_, _ = b1.Commit()
+	s1, c1 := b1.CommitStage1()
+	curr, _ := b2.Commit()
+	_, c2, p2 := b2.CommitStage2(true, s1)
+
+	if !curr.VerifyStage2(c1, c2, r1, r2, p2) {
+	}
+	*/
 }
 
 func TestStage2FromScalar(t *testing.T) {
-- 
cgit v1.2.3