java实现SM2加解密

要在Java中实现SM2加解密，您可以使用Bouncy Castle等Java加密库中的SM2实现。以下是一个简单的示例代码，演示如何使用Bouncy Castle实现SM2加解密：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.digests.SM3Digest;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.PublicKeyFactory;
import org.bouncycastle.util.encoders.Hex;

import java.security.SecureRandom;

public class SM2Example {

    public static void main(String[] args) throws Exception {
        // 生成密钥对
        AsymmetricCipherKeyPair keyPair = generateKeyPair();

        // 明文
        String plainText = "Hello, SM2!";
        System.out.println("明文：" + plainText);

        // 加密
        byte[] cipherText = encrypt(plainText.getBytes(), keyPair);
        System.out.println("密文：" + Hex.toHexString(cipherText));

        // 解密
        byte[] decryptedText = decrypt(cipherText, keyPair);
        System.out.println("解密后的明文：" + new String(decryptedText));
    }

    private static AsymmetricCipherKeyPair generateKeyPair() {
        SecureRandom random = new SecureRandom();

        // 定义SM2曲线
        ECDomainParameters domainParams = new ECDomainParameters(
                SM2Curve.p, SM2Curve.a, SM2Curve.b, SM2Curve.G, SM2Curve.n, SM2Curve.h);

        // 生成密钥对
        ECKeyPairGenerator keyPairGenerator = new ECKeyPairGenerator();
        ECKeyGenerationParameters keyGenerationParams = new ECKeyGenerationParameters(domainParams, random);
        keyPairGenerator.init(keyGenerationParams);
        return keyPairGenerator.generateKeyPair();
    }

    private static byte[] encrypt(byte[] plainText, AsymmetricCipherKeyPair keyPair) throws Exception {
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();

        // 使用SM3作为摘要算法
        SM3Digest sm3Digest = new SM3Digest();
        byte[] z = new byte[32];
        // 计算用户标识
        System.arraycopy(sm3Digest.digest("1234567812345678".getBytes()), 0, z, 0, z.length);
        // 计算公钥
        byte[] publicKeyBytes = publicKey.getQ().getEncoded(false);
        System.arraycopy(publicKeyBytes, 1, z, z.length - 64, 64);

        // 使用SM2进行加密
        SM2Engine sm2Engine = new SM2Engine();
        sm2Engine.init(true, new SM2Engine.SM2KeyParameters(true, z, publicKey));
        return sm2Engine.processBlock(plainText, 0, plainText.length);
    }

    private static byte[] decrypt(byte[] cipherText, AsymmetricCipherKeyPair keyPair) throws Exception {
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();

        // 使用SM3作为摘要算法
        SM3Digest sm3Digest = new SM3Digest();
        byte[] z = new byte[32];
        // 计算用户标识
        System.arraycopy(sm3Digest.digest("1234567812345678".getBytes()), 0, z, 0, z.length);
        // 计算公钥
        byte[] publicKeyBytes = publicKey.getQ().getEncoded(false);
        System.arraycopy(publicKeyBytes, 1, z, z.length - 64, 64);

        // 使用SM2进行解密
        SM2Engine sm2Engine = new SM2Engine();
        sm2Engine.init(false, new SM2Engine.SM2KeyParameters(false, z, privateKey));
        return sm2Engine.processBlock(cipherText, 0, cipherText.length);
    }
}

需要注意的是，在该示例代码中，我们使用了Bouncy Castle中的SM2曲线参数和SM3摘要算法。同时，在加解密过程中，需要计算用户标识和公钥，并将其作为SM2算法的输入参数之一。