commetns

pkg/zkproofs/ciphertext_ciphertext_equality.go

@@ -68,15 +68,15 @@ func NewCiphertextCiphertextEqualityProof(
 
 	// Generate random scalars
 	curve := curves.ED25519()
-	ys, err := GenerateRandomScalar(curve)
+	ys, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}
-	yx, err := GenerateRandomScalar(curve)
+	yx, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}
-	yr, err := GenerateRandomScalar(curve)
+	yr, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}
@@ -149,7 +149,7 @@ func VerifyCiphertextCiphertextEquality(
 		return false
 	}
 
-	// validate proof for nil values
+	// validate proof for nil and zero values
 	if !proof.validateContents() {
 		return false
 	}

pkg/zkproofs/ciphertext_commitment_equality.go

@@ -61,17 +61,17 @@ func NewCiphertextCommitmentEqualityProof(
 
 	// Generate random masking factors
 	curve := curves.ED25519()
-	ys, err := GenerateRandomScalar(curve)
+	ys, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}
 
-	yx, err := GenerateRandomScalar(curve)
+	yx, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}
 
-	yr, err := GenerateRandomScalar(curve)
+	yr, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}

pkg/zkproofs/ciphertext_validity.go

@@ -48,12 +48,12 @@ func NewCiphertextValidityProof(pedersenOpening *curves.Scalar, pubKey curves.Po
 
 	// Step 1: Generate random blinding factors for the proof
 	curve := curves.ED25519()
-	rBlind, err := GenerateRandomScalar(curve) // Blinding factor for random value r
+	rBlind, err := GenerateRandomNonZeroScalar(curve) // Blinding factor for random value r
 	if err != nil {
 		return nil, err
 	}
 
-	xBlind, err := GenerateRandomScalar(curve) // Blinding factor for random value x
+	xBlind, err := GenerateRandomNonZeroScalar(curve) // Blinding factor for random value x
 	if err != nil {
 		return nil, err
 	}

pkg/zkproofs/pubkey_validity.go

@@ -36,10 +36,10 @@ func NewPubKeyValidityProof(pubKey curves.Point, privKey curves.Scalar) (*PubKey
 
 	eg := elgamal.NewTwistedElgamal()
 	H := eg.GetH()
-	
+
 	// Prover generates a random scalar y
 	curve := curves.ED25519()
-	y, err := GenerateRandomScalar(curve)
+	y, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}

pkg/zkproofs/utils.go

@@ -7,19 +7,21 @@ import (
 	"github.com/coinbase/kryptology/pkg/core/curves"
 )
 
-// Generates a non-zero random scalar. The chances of generating a zero scalar are very low.
-func GenerateRandomScalar(curve *curves.Curve) (curves.Scalar, error) {
-	attempts := 0
-	scalar := curve.Scalar.Random(rand.Reader)
-	// Try 5 times to generate a non zero scalar. The chance that this fails with a normal random number generator is impossibly low.
-	for scalar.IsZero() && attempts < 5 {
-		curve.Scalar.Random(rand.Reader)
-		attempts += 1
-	}
+// GenerateRandomNonZeroScalar Generates a non-zero random scalar.
+// Parameters:
+// - curve: The elliptic curve to use for scalar generation.
+// Returns:
+// - A non-zero random scalar.
+// - An error if the scalar generation fails.
+func GenerateRandomNonZeroScalar(curve *curves.Curve) (curves.Scalar, error) {
+	var scalar curves.Scalar
 
-	if scalar.IsZero() {
-		return nil, errors.New("failed to generate a non-zero scalar")
+	for attempts := 0; attempts < 5; attempts++ {
+		scalar = curve.Scalar.Random(rand.Reader)
+		if !scalar.IsZero() {
+			return scalar, nil
+		}
 	}
 
-	return scalar, nil
+	return nil, errors.New("failed to generate a non-zero scalar")
 }

pkg/zkproofs/zero_balance.go

@@ -38,7 +38,7 @@ func NewZeroBalanceProof(
 
 	// Generate random masking factor y
 	curve := curves.ED25519()
-	y, err := GenerateRandomScalar(curve)
+	y, err := GenerateRandomNonZeroScalar(curve)
 	if err != nil {
 		return nil, err
 	}