国密SM2: 加解密实现 java代码完整示例

国家密码管理局于2010年12月17日发布了SM2算法，并要求现有的基于RSA算法的电子认证系统、密钥管理系统、应用系统进升级改造，使用支持国密SM2算法的证书。

基于ECC椭圆曲线算法的SM2算法，则普遍采用256位密钥长度，它的单位安全强度相对较高，在工程应用中比较难以实现，破译或求解难度基本上是指数级的。因此，SM2算法可以用较少的计算能力提供比RSA算法更高的安全强度，而所需的密钥长度却远比RSA算法低。 

pom依赖引入 ：

      org.bouncycastle
      bcprov-jdk15to18
      1.68

 具体Java代码SM2算法加解密实现Demo：

package com.xinan.security.sm2;
import org.bouncycastle.asn1.gm.GMNamedCurves;
import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPublicKey;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECParameterSpec;
import org.bouncycastle.jce.spec.ECPrivateKeySpec;
import org.bouncycastle.jce.spec.ECPublicKeySpec;
import org.bouncycastle.util.encoders.Hex;

import java.math.BigInteger;
import java.security.*;
import java.security.spec.ECGenParameterSpec;
/**
 *SM2算法工具类
 * @version 1.0
 */
public class SM2Utils {
    public static KeyPair createECKeyPair() {
        final ECGenParameterSpec sm2Spec = new ECGenParameterSpec("sm2p256v1");

        // 获取一个椭圆曲线类型的密钥对生成器
        final KeyPairGenerator kpg;
        try {
            kpg = KeyPairGenerator.getInstance("EC", new BouncyCastleProvider());
            kpg.initialize(sm2Spec, new SecureRandom());

            return kpg.generateKeyPair();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    public static String encrypt(String publicKeyHex, String data) {
        return encrypt(getECPublicKeyByPublicKeyHex(publicKeyHex), data, 1);
    }

    public static String encrypt(BCECPublicKey publicKey, String data, int modeType) {
        //加密模式
        SM2Engine.Mode mode = SM2Engine.Mode.C1C3C2;
        if (modeType != 1) {
            mode = SM2Engine.Mode.C1C2C3;
        }
        ECParameterSpec ecParameterSpec = publicKey.getParameters();
        ECDomainParameters ecDomainParameters = new ECDomainParameters(ecParameterSpec.getCurve(),
                ecParameterSpec.getG(), ecParameterSpec.getN());
        ECPublicKeyParameters ecPublicKeyParameters = new ECPublicKeyParameters(publicKey.getQ(), ecDomainParameters);

        SM2Engine sm2Engine = new SM2Engine(mode);

        sm2Engine.init(true, new ParametersWithRandom(ecPublicKeyParameters, new SecureRandom()));
        byte[] arrayOfBytes = null;
        try {
            byte[] in = data.getBytes("utf-8");

            arrayOfBytes = sm2Engine.processBlock(in, 0, in.length);
        } catch (Exception e) {
            System.out.println("SM2加密时出现异常:" + e.getMessage());
            e.printStackTrace();
        }
        return Hex.toHexString(arrayOfBytes);
    }

    public static String decrypt(String privateKeyHex, String cipherData) {
        return decrypt(getBCECPrivateKeyByPrivateKeyHex(privateKeyHex), cipherData, 1);
    }

    public static String decrypt(BCECPrivateKey privateKey, String cipherData, int modeType) {
        //解密模式
        SM2Engine.Mode mode = SM2Engine.Mode.C1C3C2;
        if (modeType != 1) {
            mode = SM2Engine.Mode.C1C2C3;
        }

        byte[] cipherDataByte = Hex.decode(cipherData);
        ECParameterSpec ecParameterSpec = privateKey.getParameters();
        ECDomainParameters ecDomainParameters = new ECDomainParameters(ecParameterSpec.getCurve(),
                ecParameterSpec.getG(), ecParameterSpec.getN());
        ECPrivateKeyParameters ecPrivateKeyParameters = new ECPrivateKeyParameters(privateKey.getD(),
                ecDomainParameters);

        SM2Engine sm2Engine = new SM2Engine(mode);
        sm2Engine.init(false, ecPrivateKeyParameters);
        String result = null;
        try {
            byte[] arrayOfBytes = sm2Engine.processBlock(cipherDataByte, 0, cipherDataByte.length);
            result = new String(arrayOfBytes, "utf-8");
        } catch (Exception e) {
            System.out.println("SM2解密时出现异常" + e.getMessage());
        }
        return result;
    }

    private static X9ECParameters x9ECParameters = GMNamedCurves.getByName("sm2p256v1");

    private static ECParameterSpec ecDomainParameters = new ECParameterSpec(x9ECParameters.getCurve(), x9ECParameters.getG(), x9ECParameters.getN());

    public static BCECPublicKey getECPublicKeyByPublicKeyHex(String pubKeyHex) {

        if (pubKeyHex.length() > 128) {
            pubKeyHex = pubKeyHex.substring(pubKeyHex.length() - 128);
        }
        String stringX = pubKeyHex.substring(0, 64);
        String stringY = pubKeyHex.substring(stringX.length());
        BigInteger x = new BigInteger(stringX, 16);
        BigInteger y = new BigInteger(stringY, 16);

        ECPublicKeySpec ecPublicKeySpec = new ECPublicKeySpec(x9ECParameters.getCurve().createPoint(x, y), ecDomainParameters);

        return new BCECPublicKey("EC", ecPublicKeySpec, BouncyCastleProvider.CONFIGURATION);
    }

    public static BCECPrivateKey getBCECPrivateKeyByPrivateKeyHex(String privateKeyHex) {
        BigInteger d = new BigInteger(privateKeyHex, 16);
        ECPrivateKeySpec ecPrivateKeySpec = new ECPrivateKeySpec(d, ecDomainParameters);
        return new BCECPrivateKey("EC", ecPrivateKeySpec, BouncyCastleProvider.CONFIGURATION);
    }

    public static void main(String[] args) {
        String publicKeyHex = null;
        String privateKeyHex = null;
        KeyPair keyPair = createECKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        if (publicKey instanceof BCECPublicKey) {
            //获取65字节非压缩缩的十六进制公钥串(0x04)
            publicKeyHex = Hex.toHexString(((BCECPublicKey) publicKey).getQ().getEncoded(false));
            System.out.println("SM2公钥：" + publicKeyHex);
        }
        PrivateKey privateKey = keyPair.getPrivate();
        if (privateKey instanceof BCECPrivateKey) {
            //获取32字节十六进制私钥串
            privateKeyHex = ((BCECPrivateKey) privateKey).getD().toString(16);
            System.out.println("SM2私钥：" + privateKeyHex);
        }

        /**
         * 公钥加密
         */
        String data = "=========需要加密的数据=========";

        //将十六进制公钥串转换为 BCECPublicKey 公钥对象
        String encryptData = encrypt(publicKeyHex, data);
        System.out.println("加密结果：" + encryptData);

        /**
         * 私钥解密
         */
        //将十六进制私钥串转换为 BCECPrivateKey 私钥对象
        data = decrypt(privateKeyHex, encryptData);
        System.out.println("解密结果：" + data);
    }

}