用sm2公钥加密数据的Java代码

下面是用 Java 实现使用 SM2 公钥加密数据的代码示例：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

import java.security.Security;

public class SM2EncryptionDemo {

    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        // 生成 SM2 密钥对
        ECKeyPairGenerator gen = new ECKeyPairGenerator();
        gen.initialize(CryptoUtils.getSM2Params());
        AsymmetricCipherKeyPair keyPair = gen.generateKeyPair();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();

        // 待加密的数据
        String plainText = "Hello, world!";
        byte[] plainBytes = plainText.getBytes("UTF-8");

        // 使用公钥加密数据
        byte[] cipherBytes = CryptoUtils.SM2Encrypt(publicKey, plainBytes);

        // 打印加密结果
        System.out.println("Plain text: " + plainText);
        System.out.println("Cipher text: " + Hex.toHexString(cipherBytes));
    }
}

其中，`CryptoUtils` 中的 `SM2Encrypt` 方法用于使用 SM2 公钥加密数据，代码如下：

import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;

import java.security.SecureRandom;

public class CryptoUtils {

    // 获取 SM2 参数
    public static SM2Parameters getSM2Params() {
        return SM2Util.getDefaultParameters();
    }

    // 使用 SM2 公钥加密数据
    public static byte[] SM2Encrypt(ECPublicKeyParameters publicKey, byte[] plainText) throws InvalidCipherTextException {
        SM2Engine engine = new SM2Engine();
        ParametersWithRandom params = new ParametersWithRandom(publicKey, new SecureRandom());
        engine.init(true, params);
        return engine.processBlock(plainText, 0, plainText.length);
    }
}

需要注意的是，上述代码中使用的 `SM2Util` 是我自己封装的一个工具类，用于获取 SM2 的默认参数，代码如下：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import java.math.BigInteger;
import java.security.Security;

public class SM2Util {

    // 获取 SM2 默认参数
    public static SM2Parameters getDefaultParameters() {
        Security.addProvider(new BouncyCastleProvider());
        ECDomainParameters ecParams = new ECDomainParameters(
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16), // p
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", 16), // a
                new BigInteger("28E9FA9E9D9F5E34411C1D2F8F98F06F1ECF40D9BFD648968B3E23FB4C776293", 16), // b
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16), // n
                new BigInteger("1", 16) // h
        );
        ECKeyPairGenerator gen = new ECKeyPairGenerator();
        gen.initialize(ecParams);
        AsymmetricCipherKeyPair keyPair = gen.generateKeyPair();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        return new SM2Parameters(ecParams, publicKey, privateKey);
    }

}