diff --git a/kona-crypto/src/jmh/java/com/tencent/kona/crypto/perf/SM2SignatureConstantTimeTest.java b/kona-crypto/src/jmh/java/com/tencent/kona/crypto/perf/SM2SignatureConstantTimeTest.java
index adf2a4a6..e653dd56 100644
--- a/kona-crypto/src/jmh/java/com/tencent/kona/crypto/perf/SM2SignatureConstantTimeTest.java
+++ b/kona-crypto/src/jmh/java/com/tencent/kona/crypto/perf/SM2SignatureConstantTimeTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022, 2024, THL A29 Limited, a Tencent company. All rights reserved.
+ * Copyright (C) 2022, 2025, THL A29 Limited, a Tencent company. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,8 +26,6 @@
 import com.tencent.kona.crypto.spec.SM2SignatureParameterSpec;
 import com.tencent.kona.crypto.util.Constants;
 import com.tencent.kona.sun.security.ec.ECOperator;
-import org.bouncycastle.asn1.gm.GMObjectIdentifiers;
-import org.bouncycastle.jce.provider.BouncyCastleProvider;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Fork;
@@ -44,7 +42,6 @@
 
 import java.math.BigInteger;
 import java.security.KeyPair;
-import java.security.Security;
 import java.security.Signature;
 import java.security.interfaces.ECPublicKey;
 import java.util.concurrent.TimeUnit;
@@ -76,7 +73,6 @@ public class SM2SignatureConstantTimeTest {
 
     static {
         TestUtils.addProviders();
-        Security.addProvider(new BouncyCastleProvider());
     }
 
     private static KeyPair keyPair(BigInteger priKeyValue) {
@@ -89,7 +85,7 @@ private static KeyPair keyPair(BigInteger priKeyValue) {
     @State(Scope.Thread)
     public static class SignerHolder {
 
-        @Param({"KonaCrypto", "KonaCrypto-Native", "BC"})
+        @Param({"KonaCrypto", "KonaCrypto-Native"})
         String provider;
 
         @Param({"Small", "Mid", "Big"})
@@ -111,22 +107,21 @@ public void setup() throws Exception {
                 case "Big": keyPair = KEY_PAIR_BIG;
             }
 
-            if ("KonaCrypto".equals(provider)) {
-                signer = Signature.getInstance("SM2", provider);
-                signer.setParameter(new SM2SignatureParameterSpec(
-                        ID, (ECPublicKey) keyPair.getPublic()));
-                signer.initSign(keyPair.getPrivate());
-            } else if ("BC".equals(provider)) {
-                signer = Signature.getInstance(
-                        GMObjectIdentifiers.sm2sign_with_sm3.toString(), provider);
-                signer.setParameter(new org.bouncycastle.jcajce.spec.SM2ParameterSpec(ID));
-                signer.initSign(keyPair.getPrivate());
-            }
+            signer = Signature.getInstance("SM2", provider);
+            signer.setParameter(new SM2SignatureParameterSpec(
+                    ID, (ECPublicKey) keyPair.getPublic()));
+            signer.initSign(keyPair.getPrivate());
+
+            data = data(dataType);
+        }
 
+        private static byte[] data(String dataType) {
             switch (dataType) {
-                case "Small": data = MESG_SMALL; break;
-                case "Mid": data = MESG_MID; break;
-                case "Big": data = MESG_BIG;
+                case "Small": return MESG_SMALL;
+                case "Mid": return MESG_MID;
+                case "Big": return MESG_BIG;
+                default: throw new IllegalArgumentException(
+                        "Unsupported data type: " + dataType);
             }
         }
     }
diff --git a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Signature.java b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Signature.java
index 9f5b02a5..c6ff2a6e 100644
--- a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Signature.java
+++ b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/SM2Signature.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022, 2023, THL A29 Limited, a Tencent company. All rights reserved.
+ * Copyright (C) 2022, 2025, THL A29 Limited, a Tencent company. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify
@@ -130,6 +130,10 @@ protected void engineInitVerify(PublicKey publicKey)
     @Override
     protected void engineSetParameter(AlgorithmParameterSpec params)
             throws InvalidAlgorithmParameterException {
+        privateKey = null;
+        publicKey = null;
+        id = null;
+
         if (!(params instanceof SM2SignatureParameterSpec)) {
             throw new InvalidAlgorithmParameterException(
                     "Only accept SM2SignatureParameterSpec");
diff --git a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/nativeImpl/SM2Signature.java b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/nativeImpl/SM2Signature.java
index f84ecab2..577d5336 100644
--- a/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/nativeImpl/SM2Signature.java
+++ b/kona-crypto/src/main/java/com/tencent/kona/crypto/provider/nativeImpl/SM2Signature.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022, 2024, THL A29 Limited, a Tencent company. All rights reserved.
+ * Copyright (C) 2022, 2025, THL A29 Limited, a Tencent company. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify
@@ -63,6 +63,10 @@ public final class SM2Signature extends SignatureSpi {
     @Override
     protected void engineInitSign(PrivateKey privateKey, SecureRandom random)
             throws InvalidKeyException {
+        sm2 = null;
+        this.privateKey = null;
+        buffer.reset();
+
         if (!(privateKey instanceof ECPrivateKey)) {
             throw new InvalidKeyException("Only ECPrivateKey accepted!");
         }
@@ -87,6 +91,10 @@ protected void engineInitSign(PrivateKey privateKey)
     @Override
     protected void engineInitVerify(PublicKey publicKey)
             throws InvalidKeyException {
+        this.privateKey = null;
+        this.publicKey = null;
+        buffer.reset();
+
         if (!(publicKey instanceof ECPublicKey)) {
             throw new InvalidKeyException("Only ECPublicKey accepted!");
         }
@@ -97,6 +105,10 @@ protected void engineInitVerify(PublicKey publicKey)
     @Override
     protected void engineSetParameter(AlgorithmParameterSpec params)
             throws InvalidAlgorithmParameterException {
+        privateKey = null;
+        publicKey = null;
+        id = null;
+
         if (!(params instanceof SM2SignatureParameterSpec)) {
             throw new InvalidAlgorithmParameterException(
                     "Only accept SM2SignatureParameterSpec");