java sm2加密解密

Java 中可以使用 Bouncy Castle 库来实现 SM2 的加密和解密。以下是一个简单的示例代码：

import org.bouncycastle.asn1.x9.X9ECParameters;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.engines.SM2Engine;
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.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

import java.security.Security;

public class SM2Demo {

    public static void main(String[] args) throws Exception {
        // 添加 Bouncy Castle 作为安全提供程序
        Security.addProvider(new BouncyCastleProvider());

        // 生成随机密钥对
        X9ECParameters ecParams = X9ECParameters.getInstance("sm2p256v1");
        ECKeyPairGenerator keyPairGenerator = new ECKeyPairGenerator();
        keyPairGenerator.init(new ECKeyGenerationParameters(ecParams, new SecureRandom()));
        AsymmetricCipherKeyPair keyPair = keyPairGenerator.generateKeyPair();

        // 转换为 Bouncy Castle 的密钥格式
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) PrivateKeyFactory.createKey(keyPair.getPrivate().getEncoded());
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) PublicKeyFactory.createKey(keyPair.getPublic().getEncoded());

        // 明文数据
        byte[] plaintext = "Hello, world!".getBytes(StandardCharsets.UTF_8);

        // 加密
        CipherParameters encryptParams = new ParametersWithRandom(publicKey, new SecureRandom());
        SM2Engine encryptEngine = new SM2Engine();
        encryptEngine.init(true, encryptParams);
        byte[] ciphertext = encryptEngine.processBlock(plaintext, 0, plaintext.length);

        // 输出密文
        System.out.println("Ciphertext: " + Hex.toHexString(ciphertext));

        // 解密
        CipherParameters decryptParams = privateKey;
        SM2Engine decryptEngine = new SM2Engine();
        decryptEngine.init(false, decryptParams);
        byte[] plaintext2 = decryptEngine.processBlock(ciphertext, 0, ciphertext.length);

        // 输出明文
        System.out.println("Plaintext: " + new String(plaintext2, StandardCharsets.UTF_8));
    }
}

需要注意的是，Bouncy Castle 库可能需要单独引入，具体可以参考相关文档。此外，SM2 的密钥长度和加密算法都与传统的 RSA、AES 等算法有所不同，需要根据具体需求进行调整。