AdvisorServer/src/main/java/com/syzb/common/util/RsaUtil.java

package com.syzb.common.util;

import cn.hutool.core.codec.Base64;
import com.syzb.common.util.logger.LoggerUtil;
import org.apache.commons.lang3.exception.ExceptionUtils;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;

public class RsaUtil {

    /**
     * RSA最大加密大小
     */
    private final static int MAX_ENCRYPT_BLOCK = 117;

    /**
     * **
     * RSA最大解密大小
     */
    private final static int MAX_DECRYPT_BLOCK = 128;

    /**
     * 公钥加密
     *
     * @param pubKey 公钥字符串
     * @param str    需要加密操作的字符串
     * @return 结果再Base64加密后的字符串
     * @throws Exception
     */
    public static String pubKeyEncryption(String pubKey, String str) {
        try {
            // String 转 公钥
            PublicKey rsaPublicKey = getPublicKey(pubKey);
            //公钥加密
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] inputArray = str.getBytes();
            int inputLength = inputArray.length;
            // 分段加密
            int offSet = 0;
            byte[] resultBytes = {};
            byte[] cache;
            while (inputLength - offSet > 0) {
                if (inputLength - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(inputArray, offSet, MAX_ENCRYPT_BLOCK);
                    offSet += MAX_ENCRYPT_BLOCK;
                } else {
                    cache = cipher.doFinal(inputArray, offSet, inputLength - offSet);
                    offSet = inputLength;
                }
                resultBytes = Arrays.copyOf(resultBytes, resultBytes.length + cache.length);
                System.arraycopy(cache, 0, resultBytes, resultBytes.length - cache.length, cache.length);
            }
            return Base64.encode(resultBytes);
        } catch (Exception exception) {
            LoggerUtil.info("RsaUtil.pubKeyEncryption异常：" + ExceptionUtils.getStackTrace(exception));
            return null;
        }
    }

    /**
     * 用私钥 解密
     *
     * @param priKey              私钥字符串
     * @param encryptionBase64Str RSA加密后又base64编码后的字符串
     * @return 解密结果
     * @throws Exception
     */
    public static String priKeyDecryption(String priKey, String encryptionBase64Str) {
        try {
            // base64 解码
            byte[] base64 = Base64.decode(encryptionBase64Str);
            // String 转 私钥
            PrivateKey rsaPrivateKey = getPrivateKey(priKey);
            //私钥解密
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            // 返回UTF-8编码的解密信息
            int inputLen = base64.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(base64, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(base64, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            out.close();
            return out.toString(StandardCharsets.UTF_8);
        } catch (Exception exception) {
            LoggerUtil.info("RsaUtil.priKeyDecryption异常：" + ExceptionUtils.getStackTrace(exception));
            return null;
        }
    }

    /**
     * String转公钥PublicKey
     *
     * @param key
     * @return
     * @throws Exception
     */
    private static PublicKey getPublicKey(String key) throws Exception {
        byte[] keyBytes = Base64.decode(key);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePublic(keySpec);
    }

    /**
     * String转私钥PrivateKey
     *
     * @param key
     * @return
     * @throws Exception
     */
    private static PrivateKey getPrivateKey(String key) throws Exception {
        byte[] keyBytes = Base64.decode(key);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePrivate(keySpec);
    }

}