Merge pull request #4 from sei-protocol/mj/audit

Add validations for zero values

pkg/zkproofs/ciphertext_ciphertext_equality.go

@@ -1,9 +1,9 @@
 package zkproofs
 
 import (
-	"crypto/rand"
 	"encoding/json"
 	"errors"
+
 	"github.com/coinbase/kryptology/pkg/core/curves"
 	"github.com/sei-protocol/sei-cryptography/pkg/encryption/elgamal"
 )
@@ -67,10 +67,19 @@ func NewCiphertextCiphertextEqualityProof(
 	r := *destinationOpening
 
 	// Generate random scalars
-	ed25519 := curves.ED25519()
-	ys := ed25519.Scalar.Random(rand.Reader)
-	yx := ed25519.Scalar.Random(rand.Reader)
-	yr := ed25519.Scalar.Random(rand.Reader)
+	curve := curves.ED25519()
+	ys, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
+	yx, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
+	yr, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
 
 	eg := elgamal.NewTwistedElgamal()
 	G := eg.GetG()
@@ -133,16 +142,15 @@ func VerifyCiphertextCiphertextEquality(
 	sourceCiphertext *elgamal.Ciphertext,
 	destinationCiphertext *elgamal.Ciphertext,
 ) bool {
-	// validate proof for nil values
-	if proof == nil || proof.Y0 == nil || proof.Y1 == nil || proof.Y2 == nil || proof.Y3 == nil || proof.Zs == nil ||
-		proof.Zx == nil || proof.Zr == nil {
+	// validate inputs
+	if proof == nil || sourcePubKey == nil || destinationPubKey == nil ||
+		sourceCiphertext == nil || sourceCiphertext.C == nil || sourceCiphertext.D == nil ||
+		destinationCiphertext == nil || destinationCiphertext.C == nil || destinationCiphertext.D == nil {
 		return false
 	}
 
-	// validate other input
-	if sourcePubKey == nil || destinationPubKey == nil ||
-		sourceCiphertext == nil || sourceCiphertext.C == nil || sourceCiphertext.D == nil ||
-		destinationCiphertext == nil || destinationCiphertext.C == nil || destinationCiphertext.D == nil {
+	// validate proof for nil and zero values
+	if !proof.validateContents() {
 		return false
 	}
 
@@ -213,6 +221,21 @@ func VerifyCiphertextCiphertextEquality(
 	return lhsY3.Equal(rhsY3)
 }
 
+func (c *CiphertextCiphertextEqualityProof) validateContents() bool {
+	// Validate that fields are not nil
+	if c == nil || c.Y0 == nil || c.Y1 == nil || c.Y2 == nil || c.Y3 == nil || c.Zs == nil ||
+		c.Zx == nil || c.Zr == nil {
+		return false
+	}
+
+	// Validate that fields are non zero. Though it is technically possible if the randomly generated scalars are zero, it is highly unlikely (1 in 2^255 chance)
+	if c.Y0.IsIdentity() || c.Y1.IsIdentity() || c.Y2.IsIdentity() || c.Y3.IsIdentity() || c.Zr.IsZero() || c.Zs.IsZero() || c.Zx.IsZero() {
+		return false
+	}
+
+	return true
+}
+
 // MarshalJSON for CiphertextCiphertextEqualityProof
 func (p *CiphertextCiphertextEqualityProof) MarshalJSON() ([]byte, error) {
 	// Serialize the points and scalars to a format you prefer

pkg/zkproofs/ciphertext_ciphertext_equality_test.go

@@ -415,4 +415,40 @@ func TestVerifyCiphertextCiphertextEquality_InvalidInputs(t *testing.T) {
 		)
 		require.False(t, valid, "Proof verification should fail for nil destination ciphertext")
 	})
+
+	t.Run("Invalid Proof Params", func(t *testing.T) {
+		// Y2 is zero point
+		clone := *proof
+		clone.Y2 = curves.ED25519().NewIdentityPoint()
+		valid := VerifyCiphertextCiphertextEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			&destinationKeypair.PublicKey,
+			sourceCiphertext,
+			sourceCiphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Zx = curves.ED25519().Scalar.Zero()
+		valid = VerifyCiphertextCiphertextEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			&destinationKeypair.PublicKey,
+			sourceCiphertext,
+			sourceCiphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Y1 = nil
+		valid = VerifyCiphertextCiphertextEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			&destinationKeypair.PublicKey,
+			sourceCiphertext,
+			sourceCiphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+	})
 }

pkg/zkproofs/ciphertext_commitment_equality.go

@@ -1,9 +1,9 @@
 package zkproofs
 
 import (
-	"crypto/rand"
 	"encoding/json"
 	"errors"
+
 	"github.com/coinbase/kryptology/pkg/core/curves"
 	"github.com/sei-protocol/sei-cryptography/pkg/encryption/elgamal"
 )
@@ -59,11 +59,22 @@ func NewCiphertextCommitmentEqualityProof(
 	G := eg.GetG() // Fixed base point G
 	H := eg.GetH() // Fixed base point H
 
-	ed25519 := curves.ED25519()
 	// Generate random masking factors
-	ys := ed25519.Scalar.Random(rand.Reader)
-	yx := ed25519.Scalar.Random(rand.Reader)
-	yr := ed25519.Scalar.Random(rand.Reader)
+	curve := curves.ED25519()
+	ys, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
+
+	yx, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
+
+	yr, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
 
 	// Compute Y0 = ys * P
 	Y0 := P.Mul(ys)
@@ -118,14 +129,13 @@ func VerifyCiphertextCommitmentEquality(
 	sourceCiphertext *elgamal.Ciphertext,
 	pedersenCommitment *curves.Point,
 ) bool {
-	// Validate proof
-	if proof == nil || proof.Y0 == nil || proof.Y1 == nil || proof.Y2 == nil || proof.Zs == nil || proof.Zx == nil ||
-		proof.Zr == nil {
+	// Validate input
+	if proof == nil || sourcePubKey == nil || sourceCiphertext == nil || pedersenCommitment == nil {
 		return false
 	}
 
-	// Validate input
-	if sourcePubKey == nil || sourceCiphertext == nil || pedersenCommitment == nil {
+	// Validate proof
+	if !proof.validateContents() {
 		return false
 	}
 
@@ -176,6 +186,18 @@ func VerifyCiphertextCommitmentEquality(
 	return lhsY2.Equal(rhsY2)
 }
 
+func (c *CiphertextCommitmentEqualityProof) validateContents() bool {
+	if c.Y0 == nil || c.Y1 == nil || c.Y2 == nil || c.Zs == nil || c.Zx == nil || c.Zr == nil {
+		return false
+	}
+
+	if c.Y0.IsIdentity() || c.Y1.IsIdentity() || c.Y2.IsIdentity() || c.Zs.IsZero() || c.Zx.IsZero() || c.Zr.IsZero() {
+		return false
+	}
+
+	return true
+}
+
 // MarshalJSON for CiphertextCommitmentEqualityProof
 func (p *CiphertextCommitmentEqualityProof) MarshalJSON() ([]byte, error) {
 	// Serialize the points and scalars to a format you prefer

pkg/zkproofs/ciphertext_commitment_equality_test.go

@@ -261,6 +261,39 @@ func TestVerifyCiphertextCommitmentEquality_InvalidInput(t *testing.T) {
 		require.False(t, valid, "Proof verification should fail for proof with nil fields")
 	})
 
+	t.Run("Invalid Proof Params", func(t *testing.T) {
+		// Y2 is zero point
+		clone := *proof
+		clone.Y2 = curves.ED25519().NewIdentityPoint()
+		valid := VerifyCiphertextCommitmentEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			sourceCiphertext,
+			&sourceCiphertext.C,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Zx = curves.ED25519().Scalar.Zero()
+		valid = VerifyCiphertextCommitmentEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			sourceCiphertext,
+			&sourceCiphertext.C,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Y1 = nil
+		valid = VerifyCiphertextCommitmentEquality(
+			&clone,
+			&sourceKeypair.PublicKey,
+			sourceCiphertext,
+			&sourceCiphertext.C,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+	})
+
 	t.Run("Invalid Source Public Key", func(t *testing.T) {
 		// Source public key is nil
 		valid := VerifyCiphertextCommitmentEquality(

pkg/zkproofs/ciphertext_validity.go

@@ -1,7 +1,6 @@
 package zkproofs
 
 import (
-	crand "crypto/rand"
 	"encoding/json"
 	"errors"
 	"math/big"
@@ -48,8 +47,16 @@ func NewCiphertextValidityProof(pedersenOpening *curves.Scalar, pubKey curves.Po
 	x, _ := ed25519.Scalar.SetBigInt(message)
 
 	// Step 1: Generate random blinding factors for the proof
-	rBlind := ed25519.Scalar.Random(crand.Reader) // Blinding factor for random value r
-	xBlind := ed25519.Scalar.Random(crand.Reader) // Blinding factor for random value x
+	curve := curves.ED25519()
+	rBlind, err := GenerateRandomNonZeroScalar(curve) // Blinding factor for random value r
+	if err != nil {
+		return nil, err
+	}
+
+	xBlind, err := GenerateRandomNonZeroScalar(curve) // Blinding factor for random value x
+	if err != nil {
+		return nil, err
+	}
 
 	// Step 2: Create commitments
 	rBlindH := H.Mul(rBlind)            // rBlind * H
@@ -88,8 +95,11 @@ func NewCiphertextValidityProof(pedersenOpening *curves.Scalar, pubKey curves.Po
 // - ciphertext: The ciphertext to prove the validity of.
 func VerifyCiphertextValidity(proof *CiphertextValidityProof, pubKey curves.Point, ciphertext *elgamal.Ciphertext) bool {
 	// Validate input
-	if proof == nil || proof.Commitment1 == nil || proof.Commitment2 == nil || proof.Response1 == nil ||
-		proof.Response2 == nil || pubKey == nil || ciphertext == nil || ciphertext.C == nil || ciphertext.D == nil {
+	if proof == nil || pubKey == nil || ciphertext == nil || ciphertext.C == nil || ciphertext.D == nil {
+		return false
+	}
+
+	if !proof.validateContents() {
 		return false
 	}
 
@@ -119,6 +129,18 @@ func VerifyCiphertextValidity(proof *CiphertextValidityProof, pubKey curves.Poin
 	return recomputedCommitment1.Equal(proof.Commitment1) && recomputedCommitment2.Equal(proof.Commitment2)
 }
 
+func (p *CiphertextValidityProof) validateContents() bool {
+	if p.Commitment1 == nil || p.Commitment2 == nil || p.Response1 == nil || p.Response2 == nil {
+		return false
+	}
+
+	if p.Commitment1.IsIdentity() || p.Commitment2.IsIdentity() || p.Response1.IsZero() || p.Response2.IsZero() {
+		return false
+	}
+
+	return true
+}
+
 // MarshalJSON for CiphertextValidityProof
 func (p *CiphertextValidityProof) MarshalJSON() ([]byte, error) {
 	// Serialize the points and scalars to a format you prefer

pkg/zkproofs/ciphertext_validity_test.go

@@ -5,6 +5,7 @@ import (
 	"math/big"
 	"testing"
 
+	"github.com/coinbase/kryptology/pkg/core/curves"
 	"github.com/sei-protocol/sei-cryptography/pkg/encryption/elgamal"
 	testutils "github.com/sei-protocol/sei-cryptography/pkg/testing"
 	"github.com/stretchr/testify/require"
@@ -155,6 +156,30 @@ func TestVerifyCiphertextValidityProof_Invalid_Input(t *testing.T) {
 		require.False(t, validated, "Validation should fail for proof with nil fields")
 	})
 
+	t.Run("Invalid Proof Params", func(t *testing.T) {
+		// Y2 is zero point
+		clone := *proof
+		clone.Commitment1 = curves.ED25519().NewIdentityPoint()
+		valid := VerifyCiphertextValidity(
+			&clone, keys.PublicKey, ciphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Response1 = curves.ED25519().Scalar.Zero()
+		valid = VerifyCiphertextValidity(
+			&clone, keys.PublicKey, ciphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+
+		clone = *proof
+		clone.Commitment2 = nil
+		valid = VerifyCiphertextValidity(
+			&clone, keys.PublicKey, ciphertext,
+		)
+		require.False(t, valid, "Proof verification should fail for proof params with zero value")
+	})
+
 	t.Run("Invalid Public Key", func(t *testing.T) {
 		// Proof challenge is nil
 		validated := VerifyCiphertextValidity(proof, nil, ciphertext)

pkg/zkproofs/pubkey_validity.go

@@ -1,9 +1,9 @@
 package zkproofs
 
 import (
-	"crypto/rand"
 	"encoding/json"
 	"errors"
+
 	"github.com/coinbase/kryptology/pkg/core/curves"
 	"github.com/sei-protocol/sei-cryptography/pkg/encryption/elgamal"
 )
@@ -36,8 +36,13 @@ func NewPubKeyValidityProof(pubKey curves.Point, privKey curves.Scalar) (*PubKey
 
 	eg := elgamal.NewTwistedElgamal()
 	H := eg.GetH()
+
 	// Prover generates a random scalar y
-	y := curves.ED25519().Scalar.Random(rand.Reader)
+	curve := curves.ED25519()
+	y, err := GenerateRandomNonZeroScalar(curve)
+	if err != nil {
+		return nil, err
+	}
 
 	// Commitment Y = y * H
 	Y := H.Mul(y)
@@ -65,9 +70,12 @@ func NewPubKeyValidityProof(pubKey curves.Point, privKey curves.Scalar) (*PubKey
 // Parameters:
 // - pubKey: The PublicKey to validate.
 // - proof: The proof that the prover knows the corresponding PrivateKey.
-func VerifyPubKeyValidity(pubKey curves.Point, proof PubKeyValidityProof) bool {
+func VerifyPubKeyValidity(pubKey curves.Point, proof *PubKeyValidityProof) bool {
 	// Validate input
-	if pubKey == nil || proof.Y == nil || proof.Z == nil {
+	if proof == nil || pubKey == nil {
+		return false
+	}
+	if !proof.validateContents() {
 		return false
 	}
 
@@ -92,6 +100,18 @@ func VerifyPubKeyValidity(pubKey curves.Point, proof PubKeyValidityProof) bool {
 	return lhs.Equal(rhs)
 }
 
+func (p *PubKeyValidityProof) validateContents() bool {
+	if p.Y == nil || p.Z == nil {
+		return false
+	}
+
+	if p.Y.IsIdentity() || p.Z.IsZero() {
+		return false
+	}
+
+	return true
+}
+
 // MarshalJSON for PubKeyValidityProof
 func (p *PubKeyValidityProof) MarshalJSON() ([]byte, error) {
 	// Serialize the points and scalars to a format you prefer