Java实现SM2算法

以下是一个简单的Java实现SM2算法的示例代码：

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Security;
import java.security.Signature;
import java.security.interfaces.ECPublicKey;
import java.security.spec.ECFieldFp;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPublicKeySpec;
import java.util.Arrays;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.math.ec.ECPointUtil;

public class SM2 {

    private static final String SM2_ALGORITHM_NAME = "SM2withSM3";
    private static final String EC_PARAM_SPEC_NAME = "sm2p256v1";
    private static final String PROVIDER_NAME = "BC";

    private static final BigInteger P = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16);
    private static final BigInteger A = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", 16);
    private static final BigInteger B = new BigInteger("28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93", 16);
    private static final BigInteger N = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16);
    private static final BigInteger Gx = new BigInteger("32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE171F996E97D0E935E", 16);
    private static final BigInteger Gy = new BigInteger("BC3736A2F4F6779C59BDCEE36B692153D0A9877CC62A474002DF32E52139F0A0", 16);

    private static final ECParameterSpec SM2_PARAM_SPEC = new ECParameterSpec(
            new ECFieldFp(P),
            new ECPoint(
                    new BigInteger(Gx.toByteArray()),
                    new BigInteger(Gy.toByteArray())),
            N, 1);

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    public static byte[] sign(byte[] data, byte[] privateKey) throws Exception {
        Signature signature = Signature.getInstance(SM2_ALGORITHM_NAME, PROVIDER_NAME);
        ECParameterSpec ecSpec = SM2_PARAM_SPEC;
        ECPoint pubPoint = ECPointUtil.decodePoint(ecSpec.getCurve(), privateKeyToPublicKey(privateKey));
        ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(pubPoint, ecSpec);
        KeyFactory keyFactory = KeyFactory.getInstance("EC", PROVIDER_NAME);
        PublicKey publicKey = keyFactory.generatePublic(pubKeySpec);
        signature.initSign(SM2_PARAM_SPEC.getCurve().decodePoint(privateKey), SM2_PARAM_SPEC);
        signature.update(data);
        return signature.sign();
    }

    public static boolean verify(byte[] data, byte[] signatureBytes, byte[] publicKeyBytes) throws Exception {
        Signature signature = Signature.getInstance(SM2_ALGORITHM_NAME, PROVIDER_NAME);
        ECPublicKey publicKey = (ECPublicKey) KeyFactory.getInstance("EC", PROVIDER_NAME)
                .generatePublic(new ECPublicKeySpec(ECPointUtil.decodePoint(SM2_PARAM_SPEC.getCurve(), publicKeyBytes), SM2_PARAM_SPEC));
        signature.initVerify(publicKey);
        signature.update(data);
        return signature.verify(signatureBytes);
    }

    public static byte[] privateKeyToPublicKey(byte[] privateKey) {
        BigInteger d = new BigInteger(privateKey);
        ECPoint Q = SM2_PARAM_SPEC.getG().multiply(d);
        return Q.getEncoded(true);
    }

    public static void main(String[] args) throws Exception {
        byte[] privateKey = new byte[]{0x01, 0x23, 0x45, 0x67, (byte) 0x89, (byte) 0xab, (byte) 0xcd, (byte) 0xef, (byte) 0xfe, (byte) 0xdc, (byte) 0xba, (byte) 0x98, 0x76, 0x54, 0x32, 0x10};
        byte[] publicKey = privateKeyToPublicKey(privateKey);
        byte[] data = "Hello, SM2!".getBytes("UTF-8");
        byte[] signature = sign(data, privateKey);
        boolean result = verify(data, signature, publicKey);
        System.out.println(result); // true
    }
}

注意：此代码仅用于示例和学习目的，实际使用中应该使用更完善、更安全的实现。