feat: Improve error handling in ECIES encryption and decryption funct…

…ions

eciesbls12381_test.go

@@ -2,7 +2,11 @@ package eciesbls12381
 
 import (
 	"bytes"
+	"errors"
 	"testing"
+
+	"github.com/drand/kyber"
+	bls "github.com/drand/kyber-bls12381"
 )
 
 // TestGenerateECPrivateKey tests the GenerateECPrivateKey function.
@@ -24,10 +28,15 @@ func TestGenerateECKeypair(t *testing.T) {
 // TestGetECPublicKeyFromPrivateKey tests the GetECPublicKeyFromPrivateKey function.
 func TestGetECPublicKeyFromPrivateKey(t *testing.T) {
 	_, privateKey := GenerateECKeypair()
-	publicKey := GetECPublicKeyFromPrivateKey(privateKey)
-	if publicKey == nil {
+	publicKey, err := GetECPublicKeyFromPrivateKey(privateKey)
+	if err != nil || publicKey == nil {
 		t.Error("Failed to derive public key from private key")
 	}
+
+	_, err = GetECPublicKeyFromPrivateKey(nil)
+	if err == nil {
+		t.Error("Expected an error when private key is nil")
+	}
 }
 
 // TestEncryptWithECAndDecryptWithEC tests the EncryptWithEC and DecryptWithEC functions.
@@ -70,3 +79,72 @@ func TestInvalidDecryptWithEC(t *testing.T) {
 		t.Errorf("Decryption should have returned nil, got %s", string(plaintext))
 	}
 }
+
+// TestEncryptWithECError tests EncryptWithEC to cover error handling.
+func TestEncryptWithECError(t *testing.T) {
+	// Test with nil public key
+	message := []byte("Hello, BLS12381!")
+	_, err := EncryptWithEC(nil, message)
+	if err == nil {
+		t.Error("Expected an error when public key is nil")
+	}
+
+	// Test with nil message
+	publicKey, _ := GenerateECKeypair()
+	_, err = EncryptWithEC(publicKey, nil)
+	if err == nil {
+		t.Error("Expected an error when message is nil")
+	}
+}
+
+// TestDecryptWithECError tests DecryptWithEC to cover error handling.
+func TestDecryptWithECError(t *testing.T) {
+	// Test with nil private key
+	ciphertext := []byte("encrypted message")
+	_, err := DecryptWithEC(nil, ciphertext)
+	if err == nil {
+		t.Error("Expected an error when private key is nil")
+	}
+
+	// Test with nil ciphertext
+	_, privateKey := GenerateECKeypair()
+	_, err = DecryptWithEC(privateKey, nil)
+	if err == nil {
+		t.Error("Expected an error when ciphertext is nil")
+	}
+}
+
+// Mocking a faulty encrypt function to force an error
+type faultyEncryptSuite struct {
+	kyber.Group
+}
+
+func (f *faultyEncryptSuite) Point() kyber.Point {
+	return &faultyPoint{}
+}
+
+type faultyPoint struct {
+	kyber.Point
+}
+
+func (p *faultyPoint) Mul(s kyber.Scalar, q kyber.Point) kyber.Point {
+	return p
+}
+
+func (p *faultyPoint) MarshalBinary() ([]byte, error) {
+	return nil, errors.New("forced error")
+}
+
+func TestEncryptWithECForcedError(t *testing.T) {
+	oldSuite := suite
+	defer func() { suite = oldSuite }()
+	suite = &faultyEncryptSuite{Group: bls.NewBLS12381Suite().G2()}
+
+	publicKey, _ := GenerateECKeypair()
+	message := []byte("Hello, BLS12381!")
+
+	_, err := EncryptWithEC(publicKey, message)
+	if err == nil {
+		t.Error("Encryption should have failed with a forced error")
+	}
+}