java封装RSA非对称加密工具类

import cn.hutool.core.text.StrBuilder;
import com.example.common.core.exception.CustomException;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.io.*;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * 非对称加密工具类
 *
 */
@Slf4j
public class RSASecurityUtils {
    /**
     * 指定加密算法为RSA
     */

    private static final String ALGORITHM = "RSA";
    /**
     * 密钥长度，注：只加密关键信息即可（过长字符串RSA加解密性能较差）
     */
    private static final int KEYSIZE = 1024;//1024、2048、3072、4096...长度无限制，越长性能越差安全性越高

    /**
     * 生成密钥对
     *
     * @throws Exception
     */
    public String[] generateKeyPair() throws Exception {
        String[] pair = new String[2];
        // /**可信任的随机数源 */
        // SecureRandom secureRandom = new SecureRandom();
        /** 为RSA算法创建一个KeyPairGenerator对象 */
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);
        /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
        // keyPairGenerator.initialize(KEYSIZE, secureRandom);
        keyPairGenerator.initialize(KEYSIZE);//默认随机数源
        /** 生成密匙对 */
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        /** 得到公钥 */
        Key publicKey = keyPair.getPublic();
        /** 得到私钥 */
        Key privateKey = keyPair.getPrivate();
        try {
            /** 密钥转字符串 */
            byte[] privateData = privateKey.getEncoded();
            String privateStr = Base64.encodeBase64String(privateData);
            byte[] publicData = publicKey.getEncoded();
            String publicStr = Base64.encodeBase64String(publicData);
            pair[0] = publicStr;
            pair[1] = privateStr;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return pair;
    }

    /**
     * 公钥加密方法
     *
     * @param source 源数据
     * @return
     * @throws Exception
     */
    public static String encrypt(String publicKey, String source) throws Exception {
        Key key = stringToPublicKey(publicKey);
        /** 得到Cipher对象来实现对源数据的RSA加密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] b = source.getBytes();
        /** 执行加密操作 */
        byte[] b1 = cipher.doFinal(b);
        return Base64.encodeBase64String(b1);
    }

    /**
     * 私钥加密方法
     *
     * @param source 源数据
     * @return
     * @throws Exception
     */
    public static String encryptPriKey(String privateKey, String source) throws Exception {
        Key key = stringToPrivateKey(privateKey);
        /** 得到Cipher对象来实现对源数据的RSA加密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] b = source.getBytes();
        /** 执行加密操作 */
        byte[] b1 = cipher.doFinal(b);
        return Base64.encodeBase64String(b1);
    }

    /**
     * 私钥解密算法
     *
     * @param cryptograph 密文
     * @return
     * @throws Exception
     */
    public static String decrypt(String privateKey, String cryptograph) throws Exception {
        Key key = stringToPrivateKey(privateKey);
        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] b1 = Base64.decodeBase64(cryptograph);
        /** 执行解密操作 */
        byte[] b = cipher.doFinal(b1);
        return new String(b);
    }

    /**
     * 公钥解密算法
     *
     * @param cryptograph 密文
     * @return
     * @throws Exception
     */
    public static String decryptPubKey(String publicKey, String cryptograph) throws Exception {
        Key key = stringToPublicKey(publicKey);
        /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] b1 = Base64.decodeBase64(cryptograph);
        /** 执行解密操作 */
        byte[] b = cipher.doFinal(b1);
        return new String(b);
    }

    /**
     * 密钥串转privateKey
     *
     * @param keyStr
     * @return
     * @throws Exception
     */
    public static Key stringToPrivateKey(String keyStr) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(keyStr);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }

    /**
     * 密钥串转publicKey
     *
     * @param keyStr
     * @return
     * @throws Exception
     */
    public static PublicKey stringToPublicKey(String keyStr) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(keyStr);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    /**
     * 从文件读取key
     *
     * @param filePath
     * @return
     */
    public static String getKey(String filePath) {
        StrBuilder strBuilder = new StrBuilder("");
        File file = new File(filePath);
        if (!file.exists()) {
            throw new CustomException("密钥文件地址错误！");
        }
        try (FileInputStream fileInputStream = new FileInputStream(file);
             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(fileInputStream))) {
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                strBuilder.append(line);
            }
        } catch (FileNotFoundException e) {
            throw new CustomException("密钥文件地址错误！");
        } catch (IOException e) {
            throw new CustomException("密钥文件读取错误！");
        }
        return strBuilder.toString().trim();
    }

}