sm2算法Java实现

以下是Java中使用Bouncy Castle库实现SM2算法的示例代码：

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.x9.X9ObjectIdentifiers;
import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
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.ECParameterSpec;
import org.bouncycastle.util.encoders.Hex;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.Signature;
import java.security.spec.ECGenParameterSpec;

public class SM2Example {

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

        // 生成SM2密钥对
        KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("EC", "BC");
        kpGenerator.initialize(new ECGenParameterSpec("sm2p256v1"));
        KeyPair keyPair = kpGenerator.generateKeyPair();

        // 获取SM2公私钥参数
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();

        // 加载SM2公私钥参数
        ECParameterSpec ecSpec = ECParameterSpec.fromNamedCurve("sm2p256v1");
        ECDomainParameters domainParams = new ECDomainParameters(ecSpec.getCurve(), ecSpec.getG(), ecSpec.getN());
        ECPublicKeyParameters sm2PublicKey = new ECPublicKeyParameters(publicKey.getQ(), domainParams);
        ECPrivateKeyParameters sm2PrivateKey = new ECPrivateKeyParameters(privateKey.getD(), domainParams);

        // SM2签名示例
        byte[] message = "Hello, World!".getBytes("UTF-8");
        SM2Signer signer = new SM2Signer();
        signer.init(true, sm2PrivateKey);
        signer.update(message, 0, message.length);
        byte[] signature = signer.generateSignature();

        // SM2验签示例
        Signature verifier = Signature.getInstance("SM3withSM2", "BC");
        verifier.initVerify(sm2PublicKey);
        verifier.update(message, 0, message.length);
        boolean result = verifier.verify(signature);

        System.out.println("message: " + Hex.toHexString(message));
        System.out.println("signature: " + Hex.toHexString(signature));
        System.out.println("verify result: " + result);
    }

}

需要注意的是，Bouncy Castle库中的SM2实现使用的是国密SM3算法作为摘要函数，因此验签时需要指定签名算法为"SM3withSM2"。此外，SM2算法中的密钥长度为256位，因此需要使用"sm2p256v1"作为曲线参数。