package com.malk.lianan;

import cn.hutool.core.codec.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;

public class RsaUtil {

    private final static String KEY_RSA = "RSA";
    private final static String KEY_RSA_SIGNATURE = "SHA256WithRSA";
    private static BouncyCastleProvider bouncyCastleProvider = new BouncyCastleProvider();

    public static String sign(byte[] data, String privateKey) {
        String str = "";
        try {
// 解密由 base64 编码的私钥
            byte[] bytes = decryptBase64(privateKey);
// 构造 PKCS8EncodedKeySpec 对象
            PKCS8EncodedKeySpec pkcs = new PKCS8EncodedKeySpec(bytes);
// 指定的加密算法
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA,bouncyCastleProvider);
// 取私钥对象
            PrivateKey key = factory.generatePrivate(pkcs);
// 用私钥对信息生成数字签名
            Signature signature =Signature.getInstance(KEY_RSA_SIGNATURE,bouncyCastleProvider);
            signature.initSign(key);
            signature.update(data);
            str = encryptBase64(signature.sign());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return str;
    }
    public static byte[] decryptBase64(String key) throws Exception {
        return Base64.decode(key);
    }
    public static String encryptBase64(byte[] key) throws Exception {
        return new String(Base64.encode(key));
    }

}