ecdsa dkls

tss/ecdsa/dkls/ecdsaDKLS.go

@@ -0,0 +1,73 @@
+// Reference: https://eprint.iacr.org/2018/499.pdf
+// 2 out of 2 party threhsold signature scheme
+// Figure 1 and Protocol 1 and 2
+
+package dkls
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"errors"
+	"math/big"
+
+	"github.com/cloudflare/circl/group"
+)
+
+// Input: myGroup, the group we operate in
+// Input: sk, the real secret key
+// Output: share1, share2 the multiplicative secret key shares for 2 parties.
+func KeyShareGen(myGroup group.Group, sk group.Scalar) (group.Scalar, group.Scalar) {
+	share1 := myGroup.RandomNonZeroScalar(rand.Reader)
+	share1Inv := myGroup.NewScalar()
+	share1Inv.Inv(share1)
+
+	share2 := myGroup.NewScalar()
+	share2.Mul(share1Inv, sk)
+
+	return share1, share2
+}
+
+func hashToInt(hash []byte, c elliptic.Curve) *big.Int {
+	orderBits := c.Params().N.BitLen()
+	orderBytes := (orderBits + 7) / 8
+
+	if len(hash) > orderBytes {
+		hash = hash[:orderBytes]
+	}
+
+	ret := new(big.Int).SetBytes(hash)
+	excess := len(hash)*8 - orderBits
+	if excess > 0 {
+		ret.Rsh(ret, uint(excess))
+	}
+	return ret
+}
+
+// ECDSA threshold signature verification
+// Input: (r,s), the signature
+// Input: hashMSG, the message
+// Input: publicKey, the ECDSA public key
+// Output: verification passed or not
+func Verify(r, s group.Scalar, hashMSG []byte, publicKey *ecdsa.PublicKey) error {
+	rBig := new(big.Int)
+	sBig := new(big.Int)
+
+	rByte, errByte := r.MarshalBinary()
+	if errByte != nil {
+		panic(errByte)
+	}
+	rBig.SetBytes(rByte)
+
+	sByte, errByte := s.MarshalBinary()
+	if errByte != nil {
+		panic(errByte)
+	}
+	sBig.SetBytes(sByte)
+
+	verify := ecdsa.Verify(publicKey, hashMSG, rBig, sBig)
+	if !verify {
+		return errors.New("ECDSA threshold verification failed")
+	}
+	return nil
+}

tss/ecdsa/ot/ecdsaTSSOTParty.go → tss/ecdsa/dkls/ecdsaDKLSParty.go

@@ -1,8 +1,8 @@
-package ECDSAOT
+package dkls
 
 import (
 	"github.com/cloudflare/circl/group"
-	"github.com/cloudflare/circl/tss/ecdsa/ot/Fmul"
+	"github.com/cloudflare/circl/tss/ecdsa/dkls/fmul"
 )
 
 // The sender of Fmul
@@ -18,10 +18,10 @@ type AlicePre struct {
 
 	a         group.Scalar      // A random blinding for beaver's triple
 	ta        group.Scalar      // Additive share of a*b
-	receivera Fmul.ReceiverFmul // Receiver of Fmul for a*b
+	receivera fmul.ReceiverFmul // Receiver of Fmul for a*b
 
 	tkA           group.Scalar      // Additive share of 1/kA*1/kB
-	receiverkAInv Fmul.ReceiverFmul // Receiver of Fmul for 1/kA*1/kB
+	receiverkAInv fmul.ReceiverFmul // Receiver of Fmul for 1/kA*1/kB
 	myGroup       group.Group       // The elliptic curve we operate in
 }
 
@@ -37,10 +37,10 @@ type BobPre struct {
 
 	b       group.Scalar    // A random blinding for beaver's triple
 	tb      group.Scalar    // Additive share of a*b
-	senderb Fmul.SenderFmul // Sender of Fmul for a*b
+	senderb fmul.SenderFmul // Sender of Fmul for a*b
 
 	tkB         group.Scalar    // Additive share of 1/kA*1/kB
-	senderkBInv Fmul.SenderFmul // Sender of Fmul for 1/kA*1/kB
+	senderkBInv fmul.SenderFmul // Sender of Fmul for 1/kA*1/kB
 	myGroup     group.Group     // The elliptic curve we operate in
 }
 
@@ -53,7 +53,7 @@ type Alice struct {
 	ta       group.Scalar // Additive share of a*b
 	tkA      group.Scalar // Additive share of 1/kA*1/kB
 	Rx       group.Scalar // x coordinate of point [kA][kB]G
-	beaver   group.Scalar //skA/(kA*a)
+	beaver   group.Scalar // skA/(kA*a)
 }
 
 type Bob struct {
@@ -64,6 +64,5 @@ type Bob struct {
 	tb       group.Scalar // Additive share of a*b
 	tkB      group.Scalar // Additive share of 1/kA*1/kB
 	Rx       group.Scalar // x coordinate of point [kA][kB]G
-	beaver   group.Scalar //skB/(kB*b)
-
+	beaver   group.Scalar // skB/(kB*b)
 }