java sm2加密

Java中实现SM2加密需要使用Bouncy Castle库。以下是一个示例代码：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
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.signers.SM2Signer;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;

import java.security.KeyPair;
import java.security.Security;

public class SM2EncryptionExample {

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

        // 生成SM2密钥对
        KeyPair keyPair = generateKeyPair();

        byte[] plaintext = "Hello, SM2".getBytes();
        byte[] ciphertext = encrypt(plaintext, keyPair.getPublic());

        System.out.println("密文: " + new String(ciphertext));

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

    // 生成SM2密钥对
    public static KeyPair generateKeyPair() {
        try {
            ECNamedCurveParameterSpec spec = ECNamedCurveParameterSpec.getByName("sm2p256v1");
            ECDomainParameters ecParams = new ECDomainParameters(spec.getCurve(), spec.getG(), spec.getN());

            ECKeyGenerationParameters keyGenParams = new ECKeyGenerationParameters(ecParams, null);
            ECKeyPairGenerator generator = new ECKeyPairGenerator();
            generator.init(keyGenParams);
            AsymmetricCipherKeyPair keyPair = generator.generateKeyPair();

            ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
            ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();

            return new KeyPair(new BCECPrivateKey(privateKey), new BCECPublicKey(publicKey));
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    // 使用公钥进行加密
    public static byte[] encrypt(byte[] plaintext, java.security.PublicKey publicKey) {
        try {
            SM2Engine engine = new SM2Engine();
            engine.init(true, new ParametersWithRandom(publicKey, new SecureRandom()));
            return engine.processBlock(plaintext, 0, plaintext.length);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    // 使用私钥进行解密
    public static byte[] decrypt(byte[] ciphertext, java.security.PrivateKey privateKey) {
        try {
            SM2Engine engine = new SM2Engine();
            engine.init(false, privateKey);
            return engine.processBlock(ciphertext, 0, ciphertext.length);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }
}

请注意，这里使用了Bouncy Castle库提供的SM2引擎进行加密和解密操作。你需要将Bouncy Castle库添加到你的项目中，以便能够使用相关的类和方法。