nizk, bidder: introduced schnorr-signatures as proof for commitments of A=G^a and B=G^b

1 files changed, 12 insertions, 16 deletions

diff --git a/bidder/bid.go b/bidder/bid.go
index 55feaf8..5a87aa1 100644
--- a/bidder/bid.go
+++ b/bidder/bid.go
@@ -1,7 +1,6 @@
 package bidder
 
 import (
-	"crypto/ed25519"
 	"fmt"
 
 	. "kesim.org/seal/nizk"
@@ -10,8 +9,9 @@ import (
 )
 
 type bid struct {
-	id ed25519.PrivateKey
-	ID ed25519.PublicKey
+	// TODO: These should probably become ed25519.(Private|Public)Key's
+	id *Scalar
+	Id *Point
 
 	price uint64 // bigendian encoding of the bid
 	n     uint8  // number of bits encoded in zbid.
@@ -29,18 +29,14 @@ func NewBid(price uint64, bitlength uint8) (*bid, error) {
 		return nil, fmt.Errorf("price %d too large for given bitlength %d", price, bitlength)
 	}
 
-	var (
-		e   error
-		bid = &bid{
-			price: price,
-		}
-	)
-
-	bid.ID, bid.id, e = ed25519.GenerateKey(nil)
-	if e != nil {
-		return nil, e
+	bid := &bid{
+		price: price,
+		n:     bitlength,
 	}
 
+	bid.id = Curve.RandomScalar()
+	bid.Id = G.Exp(bid.id)
+
 	bid.bits = make([]*commit.Statement, bitlength)
 	for i := bitlength; i > 0; i-- {
 		set := (price>>(i-1)&1 != 0)
@@ -53,12 +49,12 @@ func NewBid(price uint64, bitlength uint8) (*bid, error) {
 
 // Commit returns the public commitment to the bits and a signature
 // TODO: return signature over bid
-func (bid *bid) Commit() (c []*commit.Commitment, pub ed25519.PublicKey, sig []byte) {
+func (bid *bid) Commit() (c []*commit.Commitment) {
 	c = make([]*commit.Commitment, len(bid.bits))
 	for i := range bid.bits {
-		c[i] = bid.bits[i].Commit()
+		c[i] = bid.bits[i].Commit(bid.Id)
 	}
-	return c, bid.ID, nil
+	return c
 }
 
 func (bid *bid) Result() {