java sm2 证书

Java原生的加密库中并没有直接支持SM2证书的API。但是可以通过引入Bouncy Castle加密库来实现SM2证书的生成和使用。

以下是生成SM2证书的示例代码：

import java.io.FileOutputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.cert.X509Certificate;
import java.util.Date;
import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.cert.X509v3CertificateBuilder;
import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.operator.jcajce.JcaContentVerifierProviderBuilder;

public class SM2CertificateGenerator {

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

        // 生成SM2密钥对
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("EC", "BC");
        kpg.initialize(256);
        KeyPair keyPair = kpg.generateKeyPair();

        // 构建证书
        X500Name issuer = new X500Name("CN=Test CA, O=Test Org");
        X500Name subject = new X500Name("CN=Test User, O=Test Org");
        X509v3CertificateBuilder certBuilder = new X509v3CertificateBuilder(
                issuer,
                BigInteger.valueOf(System.currentTimeMillis()),
                new Date(System.currentTimeMillis() - 86400000L),
                new Date(System.currentTimeMillis() + 86400000L),
                subject,
                keyPair.getPublic()
        );

        // 签名证书
        ContentSigner signer = new JcaContentSignerBuilder("SM3withSM2")
                .setProvider("BC")
                .build(keyPair.getPrivate());
        X509Certificate cert = new JcaX509CertificateConverter()
                .setProvider("BC")
                .getCertificate(certBuilder.build(signer));

        // 保存证书
        FileOutputStream out = new FileOutputStream("sm2_cert.cer");
        out.write(cert.getEncoded());
        out.close();

        // 验证证书
        cert.verify(new JcaContentVerifierProviderBuilder().setProvider("BC").build(keyPair.getPublic()));
    }

}

以上代码使用Bouncy Castle加密库生成了一个SM2证书，并将其保存到文件中。其中使用了SM3withSM2算法进行证书签名。在验证证书的过程中，需要使用证书的公钥进行验证。