java sm2withsm3

Java中的SM2withSM3是一种椭圆曲线数字签名算法，其中SM2是用于密钥交换和数字签名的椭圆曲线公钥密码系统，SM3是一种密码哈希算法。

下面是一个使用Java实现SM2withSM3数字签名的示例代码：

import org.bouncycastle.crypto.params.ECDomainParameters;
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.math.ec.ECPoint;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.util.Base64;

public class SM2withSM3Example {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC", "BC");
        keyPairGenerator.initialize(new ECDomainParameters(SM2Util.SM2_ECC_CURVE, SM2Util.SM2_ECC_POINT_G, SM2Util.SM2_ECC_N), new SecureRandom());
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();

        String message = "Hello, world!";
        byte[] messageBytes = message.getBytes();
        SM2Signer signer = new SM2Signer();
        signer.init(true, privateKey);
        signer.update(messageBytes, 0, messageBytes.length);
        byte[] signature = signer.generateSignature();

        ECPoint publicKeyPoint = publicKey.getQ();
        byte[] x = publicKeyPoint.getAffineXCoord().getEncoded();
        byte[] y = publicKeyPoint.getAffineYCoord().getEncoded();
        byte[] publicKeyBytes = new byte[64];
        System.arraycopy(x, 0, publicKeyBytes, 32 - x.length, x.length);
        System.arraycopy(y, 0, publicKeyBytes, 64 - y.length, y.length);

        String signatureBase64 = Base64.getEncoder().encodeToString(signature);
        String publicKeyBase64 = Base64.getEncoder().encodeToString(publicKeyBytes);

        System.out.println("Message: " + message);
        System.out.println("Signature: " + signatureBase64);
        System.out.println("Public key: " + publicKeyBase64);
    }
}

此代码使用Bouncy Castle作为加密提供程序，生成一个SM2密钥对，并使用私钥对消息进行数字签名。签名后，将公钥和签名转换为Base64字符串进行输出。