用java实现国密sm9算法

要用Java实现国密SM9算法，可以使用Bouncy Castle密码库，该库已经提供了SM9算法的实现。以下是一个简单的示例代码：

import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.engines.SM4Engine;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.signers.SM2Signer;
import org.bouncycastle.crypto.signers.SM2SignerUsingSM3;
import org.bouncycastle.crypto.signers.SM2SignerUsingSM3WithID;
import org.bouncycastle.crypto.signers.SM2SignerUsingSM3WithRecovery;
import org.bouncycastle.crypto.signers.SM2SignerUsingSM3WithRecoveryAndID;
import org.bouncycastle.crypto.signers.SM2VerifierUsingSM3;
import org.bouncycastle.crypto.signers.SM2VerifierUsingSM3WithID;
import org.bouncycastle.crypto.signers.SM2VerifierUsingSM3WithRecovery;
import org.bouncycastle.crypto.signers.SM2VerifierUsingSM3WithRecoveryAndID;
import org.bouncycastle.crypto.signers.SM3Signer;
import org.bouncycastle.crypto.signers.SM3SignerUsingSM2;
import org.bouncycastle.crypto.signers.SM3SignerUsingSM2WithID;
import org.bouncycastle.crypto.signers.SM3SignerUsingSM2WithRecovery;
import org.bouncycastle.crypto.signers.SM3SignerUsingSM2WithRecoveryAndID;
import org.bouncycastle.crypto.signers.SM3VerifierUsingSM2;
import org.bouncycastle.crypto.signers.SM3VerifierUsingSM2WithID;
import org.bouncycastle.crypto.signers.SM3VerifierUsingSM2WithRecovery;
import org.bouncycastle.crypto.signers.SM3VerifierUsingSM2WithRecoveryAndID;
import org.bouncycastle.crypto.signers.SM4Signer;
import org.bouncycastle.crypto.signers.SM4SignerUsingSM2;
import org.bouncycastle.crypto.signers.SM4SignerUsingSM2WithID;
import org.bouncycastle.crypto.signers.SM4SignerUsingSM2WithRecovery;
import org.bouncycastle.crypto.signers.SM4SignerUsingSM2WithRecoveryAndID;
import org.bouncycastle.crypto.signers.SM4VerifierUsingSM2;
import org.bouncycastle.crypto.signers.SM4VerifierUsingSM2WithID;
import org.bouncycastle.crypto.signers.SM4VerifierUsingSM2WithRecovery;
import org.bouncycastle.crypto.signers.SM4VerifierUsingSM2WithRecoveryAndID;
import org.bouncycastle.crypto.sm9.*;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.PublicKeyFactory;
import org.bouncycastle.util.encoders.Hex;

import java.io.IOException;
import java.math.BigInteger;
import java.security.SecureRandom;

public class SM9Demo {
    public static void main(String[] args) throws Exception {
        // 生成SM9算法的参数
        SM9CurveParameters curveParams = SM9Curve.getParametersByName("sm9p256v1");
        SM9PrivateKeyParameters privateKey = null;
        SM9PublicKeyParameters publicKey = null;
        SecureRandom random = new SecureRandom();
        
        // 生成密钥对
        SM9KeyPairGenerator keyPairGenerator = new SM9KeyPairGenerator();
        keyPairGenerator.init(new ParametersWithRandom(curveParams, random));
        SM9KeyPair keyPair = keyPairGenerator.generateKeyPair();
        privateKey = (SM9PrivateKeyParameters) keyPair.getPrivate();
        publicKey = (SM9PublicKeyParameters) keyPair.getPublic();
        
        // SM9签名
        SM9Signer signer = new SM9Signer();
        signer.init(true, new SM9SignParameters(privateKey.getUid()));
        byte[] message = "Hello, world!".getBytes();
        signer.update(message, 0, message.length);
        byte[] signature = signer.generateSignature();
        
        // SM9验签
        signer.init(false, new SM9SignParameters(publicKey.getUid()));
        signer.update(message, 0, message.length);
        boolean result = signer.verifySignature(signature);
        System.out.println("SM9 signature verification result: " + result);
    }
}

在上面的代码中，我们使用Bouncy Castle密码库生成SM9参数、密钥对，进行SM9签名和验签。注意，在进行SM9签名和验签时，需要使用正确的参数和密钥。