SM2算法加密java代码

以下是Java代码实现SM2算法加密：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.CipherParameters;
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.params.ParametersWithRandom;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.PublicKeyFactory;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.util.encoders.Hex;

import java.security.SecureRandom;

public class SM2Util {

    // 国密推荐的椭圆曲线参数
    private static final String SM2_ECC_PARAM = "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF";
    private static final String SM2_ECC_A = "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC";
    private static final String SM2_ECC_B = "28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93";
    private static final String SM2_ECC_GX = "32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE171F6241CACD9A2ED";
    private static final String SM2_ECC_GY = "BC3736A2F4F6779C59BDCEE36B692153D0A9877CC62A474002DF32E52139F0A0";
    private static final String SM2_ECC_N = "FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123";

    /**
     * 生成SM2公私钥对
     *
     * @return 公私钥对
     */
    public static SM2KeyPair generateKeyPair() {
        ECDomainParameters domainParameters = new ECDomainParameters(
                SM2Util.getCurve(),
                SM2Util.getGPoint(),
                SM2Util.getN());
        ECKeyPairGenerator keyPairGenerator = new ECKeyPairGenerator();
        ECKeyGenerationParameters keyGenerationParameters = new ECKeyGenerationParameters(domainParameters, new SecureRandom());
        keyPairGenerator.init(keyGenerationParameters);
        AsymmetricCipherKeyPair keyPair = keyPairGenerator.generateKeyPair();
        ECPrivateKeyParameters privateKeyParameters = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKeyParameters = (ECPublicKeyParameters) keyPair.getPublic();
        return new SM2KeyPair(Hex.toHexString(privateKeyParameters.getD().toByteArray()),
                Hex.toHexString(publicKeyParameters.getQ().getEncoded(true)));
    }

    /**
     * 加密数据
     *
     * @param publicKey 公钥
     * @param data      待加密数据
     * @return 加密结果
     */
    public static String encrypt(String publicKey, String data) {
        ECPublicKeyParameters publicKeyParameters = (ECPublicKeyParameters) PublicKeyFactory.createKey(Hex.decode(publicKey));
        SM2Engine engine = new SM2Engine();
        engine.init(true, new ParametersWithRandom(publicKeyParameters, new SecureRandom()));
        byte[] input = data.getBytes();
        byte[] output = engine.processBlock(input, 0, input.length);
        return Hex.toHexString(output);
    }

    /**
     * 解密数据
     *
     * @param privateKey 私钥
     * @param data       待解密数据
     * @return 解密结果
     */
    public static String decrypt(String privateKey, String data) {
        ECPrivateKeyParameters privateKeyParameters = (ECPrivateKeyParameters) PrivateKeyFactory.createKey(Hex.decode(privateKey));
        SM2Engine engine = new SM2Engine();
        engine.init(false, privateKeyParameters);
        byte[] input = Hex.decode(data);
        byte[] output = engine.processBlock(input, 0, input.length);
        return new String(output);
    }

    /**
     * 获取SM2曲线参数
     */
    public static ECDomainParameters getCurve() {
        return new ECDomainParameters(
                SM2Util.getCurve(),
                SM2Util.getGPoint(),
                SM2Util.getN());
    }

    /**
     * 获取SM2曲线
     */
    private static org.bouncycastle.math.ec.ECCurve getCurve() {
        return new org.bouncycastle.math.ec.ECCurve.Fp(
                Hex.decode(SM2_ECC_PARAM),
                Hex.decode(SM2_ECC_A),
                Hex.decode(SM2_ECC_B));
    }

    /**
     * 获取SM2曲线生成点G
     */
    private static ECPoint getGPoint() {
        org.bouncycastle.math.ec.ECCurve curve = SM2Util.getCurve();
        return curve.createPoint(
                new java.math.BigInteger(Hex.toHexString(SM2Util.getGx()), 16),
                new java.math.BigInteger(Hex.toHexString(SM2Util.getGy()), 16));
    }

    /**
     * 获取SM2曲线参数N
     */
    private static java.math.BigInteger getN() {
        return new java.math.BigInteger(Hex.toHexString(SM2_ECC_N), 16);
    }

    /**
     * 获取SM2曲线生成点Gx
     */
    private static byte[] getGx() {
        return Hex.decode(SM2_ECC_GX);
    }

    /**
     * 获取SM2曲线生成点Gy
     */
    private static byte[] getGy() {
        return Hex.decode(SM2_ECC_GY);
    }
}

其中，`SM2KeyPair`为公私钥对的封装类，`generateKeyPair()`方法用于生成SM2公私钥对；`encrypt(String publicKey, String data)`方法用于加密数据，其中`publicKey`为公钥，`data`为待加密数据；`decrypt(String privateKey, String data)`方法用于解密数据，其中`privateKey`为私钥，`data`为待解密数据。